| overlapping cytotoxic t-lymphocyte and b-cell antigenic sites on the influenza virus h5 hemagglutinin. | to define the recognition site of cytotoxic t lymphocytes (ctls) on influenza virus h5 hemagglutinin (ha), an h5 ha-specific ctl clone was examined for the ability to recognize monoclonal antibody-selected ha variants of influenza virus a/turkey/ontario/7732/66 (h5n9). on the basis of 51cr release assays with the variants, a ctl epitope was located near residue 168 of h5 ha. to define the epitope more precisely, a series of overlapping peptides corresponding to this region was synthesized and te ... | 1990 | 1700833 |
| a quantitative measurement of the effect of avian influenza virus on the ability of turkeys to eliminate pasteurella multocida from the respiratory tract. | the effect of avian influenza virus (aiv) infection on the ability of turkeys to eliminate pasteurella multocida from the respiratory tract was evaluated. four-week-old turkeys were experimentally infected with an apathogenic aiv subtype (h5n2) by the oculonasal route and subsequently superinfected with p multocida (urbach strain) by the intranasal route three days after infection with aiv. quantitative clearance of p multocida from the trachea and lung was determined using a pour plate techniqu ... | 1991 | 1780577 |
| biologic potential of amantadine-resistant influenza a virus in an avian model. | amantadine has been accepted for both the treatment and prophylaxis of influenza a virus infections. although amantadine-resistant mutants have been shown to be readily generated both in the laboratory and in children treated with rimantadine, little is known about their biologic properties, such as genetic stability, transmissibility, or pathogenicity, compared with the parental virus. this study examined these properties using an avian influenza virus, a/chicken/pennsylvania/1370/83 (h5n2). va ... | 1989 | 2723453 |
| mutations at the cleavage site of the hemagglutinin after the pathogenicity of influenza virus a/chick/penn/83 (h5n2). | six variants that form plaques in chick embryo cells in the absence of trypsin have been isolated from the apathogenic avian influenza virus a/chick/pennsylvania/1/83 (h5n2). unlike the wild-type, the plaque variants contain a hemagglutinin that is cleaved in chick embryo cells and mdck cells. the variants differ also from the wild-type in their pathogenicity for chickens. nucleotide sequence and oligosaccharide analysis of the hemagglutinin have revealed that, unlike natural isolates with incre ... | 1989 | 2916326 |
| defective interfering virus associated with a/chicken/pennsylvania/83 influenza virus. | the a/chicken/pennsylvania/1/83 influenza virus, isolated from a respiratory infection of chickens, is an avirulent h5n2 virus containing subgenomic rnas (w.j. bean, y. kawaoka, j.m. wood, j.e. pearson, and r.g. webster, j. virol. 54:151-160, 1985). we show here that defective interfering particles are present in this virus population. the virus had a low ratio of plaque-forming to hemagglutinating units and produced interference with standard virus multiplication in infectious center reduction ... | 1987 | 3573146 |
| influenza viruses and paramyxoviruses in ducks in the atlantic flyway, 1977-1983, including an h5n2 isolate related to the virulent chicken virus. | from 1977 to 1983, waterfowl migrating along the atlantic flyway were annually monitored for orthomyxoviruses and paramyxoviruses in an area in central new york state. a total of 168 influenza isolates were obtained from 1,430 waterfowl. twenty-four combinations of hemagglutinin and neuraminidase subtypes were detected, with as many as 12 found in a single year. one combination, an h5n2 isolate in 1982, was closely related to the virulent chicken virus that appeared in pennsylvania in 1983. the ... | 1985 | 3833237 |
| glycosylation affects cleavage of an h5n2 influenza virus hemagglutinin and regulates virulence. | based on nucleotide sequence analysis of the hemagglutinin (ha) gene from the virulent and avirulent a/chicken/pennsylvania/83 influenza viruses, it was previously postulated that acquisition of virulence was associated with a point mutation that resulted in loss of a glycosylation site. since there are two potential glycosylation sites in this region of the ha molecule and since all asn-xaa-thr/ser sequences in the has of different strains are not necessarily glycosylated, the question remained ... | 1987 | 3467357 |
| what is the potential of avirulent influenza viruses to complement a cleavable hemagglutinin and generate virulent strains? | a large pool of avirulent influenza viruses are maintained in the wild ducks and shorebirds of the world, but we know little about their potential to become virulent. it is well established that the hemagglutinin (ha) is pivitol in determining virulence and that a constellation of other genes is also necessary (r. rott, m. orlich, and c. scholtissek, 1976, j. virol. 19, 54-60). the question we are asking here is the ability of avirulent influenza viruses to provide the gene constellation that wi ... | 1989 | 2763464 |
| virulent avian influenza a viruses: their effect on avian lymphocytes and macrophages in vivo and in vitro. | to investigate the pathogenesis of virulent avian influenza a viruses, the effect of a/turkey/ont/7732/66 (h5n9) (ty/ont), a/tern/south africa/1961 (h5n3) (tern/s.a.) and a/chicken/pennsylvania/1370/83 (h5n2) (ck/penn) on avian lymphoid cell populations was examined in vivo. previous studies have shown that infection of chickens with ty/ont resulted in the extensive destruction of lymphoid tissues. in this study, other virulent avian h5 influenza viruses, tern/s.a. or ck/penn, had little or no e ... | 1989 | 2685173 |
| [circulation of the influenza a virus of h13 serosubtype among seagulls in the northern caspian (1979-1985)]. | the results of seven-year ecologo-virological studies (1979-1985) of laridae colonies on the island zhemchuzhnyi, northern kaspian sea, showed annual isolation of influenza a viruses. altogether, 95 hemagglutinating agent have been isolated. strains with 4 different combinations of surface antigens were identified: h5n2, h13n2, h13n3, h13n6. the possibility of transovarial transmission is confirmed by the fact of isolation of an influenza virus strain a/black-headed herring gull/astrakhan/458/85 ... | 1989 | 2531497 |
| induction and activity of class ii-restricted, lyt-2+ cytolytic t lymphocytes specific for the influenza h5 hemagglutinin. | in influenza a virus infections, ctl are a significant component of the host immune response which limits viral replication and promotes recovery. to examine the ctl response to the influenza virus a/ty/ont/7732/66[h5n9], particularly the h5 hemagglutinin, a long term ctl line was generated from spleen cells of a/ty/ont-immune balb/c [h-2d] mice secondarily stimulated in vitro with a/ty/cal/hurst-2/71[h5n2]. this ctl line was highly specific for influenza viruses of the h5 subtype. from this lin ... | 1989 | 2466897 |
| protection against lethal influenza with neuraminidase. | the role of the neuraminidase in eliciting protection against a lethal influenza a virus [a/ck/penn/1370/83 (h5n2)] infection was investigated in chickens. isolated n2 neuraminidase administered in adjuvant did not prevent infection but did prevent systemic spread of virus and death of chickens. n2 expressed in a recombinant vaccinia virus protected chickens when administered in adjuvant but was less effective when allowed to replicate and produce pox on the chicken's comb. chickens vaccinated w ... | 1988 | 2452514 |
| the neuraminidases of the virulent and avirulent a/chicken/pennsylvania/83 (h5n2) influenza a viruses: sequence and antigenic analyses. | to define the sequence changes that occurred in an avian influenza virus neuraminidase (na) during the evolution of virulence, we have studied the na of the virulent and avirulent a/chick/penn/83 (h5n2) influenza viruses. a comparison of the deduced amino acid sequence from these viruses shows that the virulent strain, which evolved from the avirulent by the accumulation of point mutations (bean et al., 1985), acquired four amino acid changes in the na: one in the transmembrane segment, one in t ... | 1985 | 2414922 |
| effects of chicken embryo age on time to death following infection by avian influenza viruses: implications for distinguishing highly pathogenic isolates. | when white leghorn (wl) chick embryos ranging in age from 8 to 13 days were inoculated with a variety of avian influenza virus (aiv) isolates, strain-specific differences in embryo mean death times (mdt) were observed. non-highly pathogenic (nhp) strains killed 8 or 9 day-old embryos much more rapidly than 12 or 13 day-old embryos. highly pathogenic (hp) strains, however, were less sensitive to embryo age resulting in similar mdts in both older and younger embryos. these observations were consis ... | 1990 | 2166979 |
| origin and molecular changes associated with emergence of a highly pathogenic h5n2 influenza virus in mexico. | in october of 1993, there was decreased egg production and increased mortality among mexican chickens, in association with serologic evidence of an h5n2 influenza virus. first isolated from chickens in may of 1994, after spreading widely in the country, the virus caused only a mild respiratory syndrome in specific pathogen-free chickens. because eradication of the virus by destruction of infected birds posed major obstacles to the poultry industry in mexico, we were able to conduct a "field expe ... | 1995 | 7483266 |
| protection of chickens from lethal influenza virus infection by influenza a/chicken/pennsylvania/1/83 virus: characterization of the protective effect. | the influenza a/chicken/pennsylvania/1/83 (h5n2) virus is the first known example of an influenza virus isolated from a natural infection which contained primarily defective interfering particles (t. m. chambers and r. g. webster, j. virol. 61, 1517-1523, 1987). in chickens, coinoculation of this virus together with the closely related but highly virulent influenza a/chicken/pennsylvania/1370/83 virus results in reduced mortality compared to virulent virus infection alone (bean et al., j. virol. ... | 1991 | 2053293 |
| reassortants with equine 1 (h7n7) influenza virus hemagglutinin in an avian influenza virus genetic background are pathogenic in chickens. | reassortants possessing the hemagglutinin (ha) gene from a/equine/london/1416/73 (h7n7) [eq/lond] and five or more genes from a/chicken/pennsylvania/1370/83 (h5n2) [ck/penn] were lethal in chickens. this result demonstrates that horses can maintain influenza viruses whose has are capable of promoting virulence. thus, reassortment of equine and avian influenza virus genes could generate viruses that might be lethal in domestic poultry. | 1991 | 1871981 |
| a type-specific avian influenza virus subunit vaccine for turkeys: induction of protective immunity to challenge infection. | the fraction np/ha (nucleoprotein/haemagglutinin) obtained from n-octyl-beta-d-glucopyranoside-treated influenza a h5n2 virus was highly enriched for np with residual haemagglutinin. this preparation was incorporated in iscoms. this potent 'immunostimulating complex' induced the production of high antibody titres in turkeys. the np/ha iscoms preparation was found to protect turkeys from both homologous and heterologous challenge infection as shown by reduced viral titres in the lung and trachea ... | 1994 | 7887025 |
| emergence of a potentially pathogenic h5n2 influenza virus in chickens. | highly pathogenic influenza a viruses periodically infect both humans and nonhuman animals, including chickens. to gain insight into the origin of influenza outbreaks in poultry, we investigated two h5n2 viruses, a/chicken/pennsylvania/13609/93 (ck/pa/93) and a/chicken/florida/25717/93 (ck/fla/93), that had been isolated in live-bird markets in pennsylvania and florida during surveillance studies in 1993. phylogenetic analysis of the ha genes of these isolates, as well as h5n2 viruses isolated f ... | 1994 | 8184538 |
| emergence of highly pathogenic virus during selective chicken passage of the prototype mildly pathogenic chicken/pennsylvania/83 (h5n2) influenza virus. | the prototype mildly pathogenic a/chicken/pennsylvania/21525/83 (h5n2) avian influenza virus, which was isolated more than 5 months before the emergence of highly pathogenic virus in the major 1983 pennsylvania outbreak, was examined for the presence of minority subpopulations of highly pathogenic virus. selective serial passage of the parental mildly pathogenic virus in leghorn hens did not lead to recovery of highly pathogenic virus. however, several highly pathogenic reisolates were recovered ... | 1991 | 1838476 |
| protection of chickens against highly pathogenic avian influenza virus (h5n2) by recombinant fowlpox viruses. | two recombinant fowlpox viruses containing the avian influenza h5 hemaglutinin (ha) gene were evaluated for their ability to protect chickens against challenge with a highly pathogenic isolate of avian influenza virus (h5n2). susceptible chickens were vaccinated with the parent fowlpox vaccine virus or recombinant viruses either by wing-web puncture or comb scarification. following challenge 4 weeks later with highly pathogenic avian influenza virus, all birds vaccinated by the wing-web method w ... | 1991 | 1649592 |
| enhancement of antibody response of turkeys to trivalent avian influenza vaccine by positively charged liposomal avridine adjuvant. | trivalent avian influenza (aiv) antigens (h4n8, h5n2 and h7n3), mixed with positively charged, negatively charged and neutral avridine-containing liposomes, and oil-emulsion were subcutaneously administered to 6-week-old turkeys. charged liposomal avridine adjuvant, either positive or negative, produced a better antibody response than uncharged liposomal avridine or oil-emulsion adjuvants when used in a trivalent avian influenza vaccine. the antibody response to the different antigens was genera ... | 1992 | 1502840 |
| a pathogenesis study of highly pathogenic avian influenza virus h5n2 in chickens, using immunohistochemistry. | eighteen specific pathogen-free chickens (nine hens older than 1 year and nine 15-week-old males) were inoculated with highly pathogenic avian influenza virus a/chicken/pennsylvania/1370/1983 (h5n2). birds were serially killed and tissues collected for histological and immunohistochemical evaluation. in the group of older hens, disease was acute or peracute. by immunohistochemistry, antigen was abundant in capillary endothelium in multiple organs, and staining for antigen in parenchymal cells wa ... | 1992 | 1469128 |
| effect of route of administration on the efficacy of a recombinant fowlpox virus against h5n2 avian influenza. | a recombinant fowlpox vaccine virus containing the h5 hemagglutinin gene of avian influenza virus was administered to susceptible chickens via wing-web puncture, eye drop, instillation into the nares, and drinking water. even though there was a negligible hemagglutination-inhibition (hi) serologic response, all 10 chickens vaccinated by wing-web puncture remained without obvious signs of disease and survived challenge with a highly pathogenic strain of h5n2 avian influenza virus. all unvaccinate ... | 1992 | 1336657 |
| molecular changes in a/chicken/pennsylvania/83 (h5n2) influenza virus associated with acquisition of virulence. | one of the unresolved questions concerning the acquisition of virulence by the a/chicken/pennsylvania/83 (h5n2) influenza virus is which gene segments other than the hemagglutinin (ha) showed changes that were relevant. to answer this question, reassortants were made possessing the hemagglutinin gene of the virulent virus and the seven other genes from the avirulent parent. since both the virulent and avirulent h5n2 strains are antigenically almost indistinguishable, it was necessary to transfer ... | 1986 | 3946082 |
| pathogenicity of three avian influenza viruses for leghorn hens of different ages. | pronounced host effects on clinical responses to influenza virus infection were not observed in any of seven trials in which young (26-43 weeks) and olf (65-94 weeks) leghorn hens were inoculated with low pathogenic subtype h5n2, h4n8, or h3n2 virus. in two of seven trials, where hens were infected with h4n8 or h3n2 virus, morbidity rates were slightly higher for old hens than for young hens. these observations indicate that host age effects of the severity of uncomplicated influenza virus infec ... | 1996 | 8883807 |
| circulation of influenza viruses and paramyxoviruses in waterfowl originating from two different areas of north america. | migratory waterfowl and shore birds harbour a wide range of influenza viruses, some of which have been implicated in influenza outbreaks in mammals and domestic birds. in the present study, a comparison was made of two marshalling areas for different migratory flyways of waterfowl in north america over a 6-8-year period. virtually all known influenza subtypes were isolated and the predominant subtype changed from year to year. a marked difference between the two locations was that the predominan ... | 1985 | 3878741 |
| isolation of avian influenza virus (subtype h5n2) from chicken eggs during a natural outbreak. | avian influenza virus (a/chicken/pennsylvania/83; h5n2) was recovered from the yolk, albumen, and shell surface of eggs obtained from naturally infected chicken flocks in pennsylvania and virginia. these findings represent the first reported isolation of avian influenza virus from the internal contents of eggs from naturally infected flocks. the need for adequate safeguards to prevent spread of the virus during commercial movement of table and hatching eggs, cracked and "checked" eggs, and egg f ... | 1985 | 3833221 |
| vaccination as a strategy to reduce the emergence of amantadine- and rimantadine-resistant strains of a/chick/pennsylvania/83 (h5n2) influenza virus. | the influenza a virus (a/chick/pennsylvania/83 (h5n2) that caused up to 80% mortality in chickens provided a model system for testing the efficacy of chemotherapeutic agents against highly virulent influenza virus. amantadine and rimantadine administered to chickens in drinking water were efficacious both prophylactically and therapeutically. however, under conditions simulating natural transmission of virus amantadine and rimantadine-resistant viruses arose and were transmitted to contact birds ... | 1986 | 3793657 |
| emergence of amantadine-resistant h5n2 avian influenza virus during a simulated layer flock treatment program. | an experiment was designed to simulate field conditions in which preventive treatment is not initiated until after some chickens in a flock are infected with avian influenza (ai). twelve hens began to receive amantadine hydrochloride on the day they were inoculated (day 0) with highly pathogenic ai virus, a/chicken/pa/1370/83. these hens remained clinically normal through 8 days postinoculation (pi), but five died after day 9; mean death time (mdt) was 18 days. three of 12 hens given amantadine ... | 1987 | 3675425 |
| characterization of virulent and avirulent a/chicken/pennsylvania/83 influenza a viruses: potential role of defective interfering rnas in nature. | in april 1983, an influenza virus of low virulence appeared in chickens in pennsylvania. subsequently, in october 1983, the virus became virulent and caused high mortality in poultry. the causative agent has been identified as an influenza virus of the h5n2 serotype. the hemagglutinin is antigenically closely related to tern/south africa/61 (h5n3) and the neuraminidase is similar to that from human h2n2 strains (e.g., a/japan/305/57) and from some avian influenza virus strains (e.g., a/turkey/ma ... | 1985 | 3973976 |
| highly pathogenic virus recovered from chickens infected with mildly pathogenic 1986 isolates of h5n2 avian influenza virus. | a combination of in vitro and in vivo selection procedures was used to examine the possibility that certain mildly pathogenic field isolates of avian influenza (ai) virus may contain minority subpopulations of highly pathogenic virus. two mildly pathogenic h5n2 isolates, a/chicken/new jersey/12508/86 (nj12508) and a/chicken/florida/27716/86 (fl27716), recovered from chickens epidemiologically associated with urban live-bird markets, were cloned in trypsin-free chicken embryo fibroblast cultures. ... | 1988 | 3202767 |
| protection against virulent h5 avian influenza virus infection in chickens by an inactivated vaccine produced with recombinant vaccinia virus. | a cloned cdna copy of the haemagglutinin (ha) gene of a/chicken/scotland/59 (h5n1) influenza virus has been expressed in vaccinia virus. this pox virus is poorly infectious or non-infectious for chickens. however, immunization of chickens with lysates of cell cultures infected with the recombinant vaccinia virus, that had been emulsified with adjuvant and which contained an estimated 0.5 microgram influenza ha, elicited a substantial neutralizing antibody response to influenza virus. challenges ... | 1988 | 3048009 |
| influence of dietary calcium stress on lethality of avian influenza viruses for laying chickens. | the effect of calcium stress was studied in an attempt to reproduce lethal infections in laying chickens with a/chicken/alabama/75 (h4n8) influenza virus and with two nonpathogenic h5n2 influenza viruses from the 1983-84 outbreak in the eastern united states. hens were fed calcium-deficient or standard diets for 7 to 14 days; then the calcium-deficient feed was replaced with standard feed supplemented with ad libitum oyster shell, and both groups of hens were inoculated with virus. when hens wer ... | 1986 | 3028353 |
| influenza virus surveillance in waterfowl in pennsylvania after the h5n2 avian outbreak. | during the latter stages of the lethal h5n2 influenza eradication program in domestic poultry in pennsylvania in 1983-84, surveillance of waterfowl was done to determine if these birds harbored influenza viruses that might subsequently appear in poultry. from late june to november 1984, 182 hemagglutinating viruses were isolated from 2043 wild birds, primarily ducks, in the same geographical area as the earlier lethal h5n2 avian influenza outbreak. the virus isolates from waterfowl included para ... | 1986 | 3015104 |
| efficacy of avian influenza oil-emulsion vaccines in chickens of various ages. | an experimental avian influenza (ai) oil-emulsion vaccine was formulated with 1 part inactivated a/turkey/wisconsin/68 (h5n9) ai virus emulsified in 4 parts oil. broilers were vaccinated subcutaneously (sc) either at 1 or 3 days old or at 4 or 5 wks old. commercial white leghorn (wl) layers were vaccinated sc at 12 and 20 wks old or at only 20 wks old. maximum geometric mean hemagglutination-inhibition titers postvaccination (pv) were 1:86-1:320 for broilers, 1:597 for twice-vaccinated layers, a ... | 1987 | 2960309 |
| host range of a/chicken/pennsylvania/83 (h5n2) influenza virus. | the highly pathogenic a/chicken/penn./1370/83 (h5n2) avian influenza virus, which caused 80% mortality in chickens in pennsylvania, produced only mild transient illness in experimentally infected pheasants, little or no clinical signs in ring-billed gulls and pigs, and no clinical signs in pekin ducks. virus could be recovered from only the upper respiratory tract of gulls and pigs for 1-2 days. infection in ducks resulted in intestinal replication of virus in only 1 out of 12 ducks. by contrast ... | 1985 | 3985875 |
| characterization of adaptation of an avian influenza a (h5n2) virus to a mammalian host. | we have used the mouse model to monitor the acquisition of virulence of a non-pathogenic influenza a virus upon adaptation to a new mammalian host. an avian strain, a/mallard duck/pennsylvania/10218/84 (h5n2) (mld/pa/84) was adapted to mice by 23 serial lung-to-lung passages until a highly virulent mouse-adapted (ma) variant (mld/pa/84-ma) emerged. this ma variant was characterized and compared to the parental strain as well as some of its intermediate passage variants. ma variant caused broncho ... | 2000 | 10989685 |
| chemotherapy and vaccination: a possible strategy for the control of highly virulent influenza virus. | the influenza a virus [a/chicken/pennsylvania/1370/83 (h5n2)] that caused up to 80% mortality among chickens provided a model system for testing the efficacy of chemotherapeutic agents against highly virulent influenza virus. amantadine and rimantadine administered in drinking water were efficacious both prophylactically and therapeutically. however, under conditions simulating natural transmission of virus, amantadine- and rimantadine-resistant viruses arose and were transmitted to other birds ... | 1985 | 4009792 |
| characterization of h5n2 influenza viruses from italian poultry. | from october 1997 to january 1998, highly pathogenic h5n2 avian influenza viruses caused eight outbreaks of avian influenza in northern italy. a nonpathogenic h5n9 influenza virus was also isolated during the outbreaks as a result of virological and epidemiological surveillance to control the spread of avian influenza to neighbouring regions. antigenic analysis showed that the italian h5n2 isolates were antigenically similar to, although distinguishable from, a/hk/156/97, a human influenza h5n1 ... | 2001 | 11172104 |
| evolution of the a/chicken/pennsylvania/83 (h5n2) influenza virus. | the epidemiological features of the h5n2 outbreak of influenza in poultry were studied by sequencing the ha genes of several viruses isolated during the epidemic. comparison of the nucleotide sequences of the ha genes indicated there was a single introduction of virulent virus. the variation rate (silent mutations) in the ha gene of the virulent ck/penn virus was 9.0 or 14.4% per 10 years depending on the viruses compared and was similar to that in h3 ha gene of human influenza a virus. the viru ... | 1985 | 4036005 |
| wildlife surveillance associated with an outbreak of lethal h5n2 avian influenza in domestic poultry. | wildlife surveillance was conducted for influenza viruses in conjunction with the 1983-84 lethal h5n2 avian influenza epizootic in domestic poultry in pennsylvania, new jersey, maryland, and virginia. virus-isolation attempts made on cloacal and tracheal swabs from 4,466 birds and small rodents within the quarantined areas and 1,511 waterfowl in nearby maryland yielded only a single h5n2 isolate from a pen-raised chukar in pennsylvania. antibodies against hemagglutinin type 5 and/or neuraminidas ... | 1985 | 4074241 |
| standardization of inactivated h5n2 influenza vaccine and efficacy against lethal a/chicken/pennsylvania/1370/83 infection. | the hemagglutinin concentration of beta-propiolactone-inactivated influenza vaccine containing a/duck/n.y./189/82 (h5n2) virus was measured by single-radial-immunodiffusion (srd) test. after administration of vaccine to chickens in freund's complete adjuvant, vaccine efficacy was assessed by challenge with lethal a/chicken/penn./1370/83 (h5n2) virus. srd potency values correlated with post-vaccination antibody levels and protection against infection. | 1985 | 4074253 |
| is virulence of h5n2 influenza viruses in chickens associated with loss of carbohydrate from the hemagglutinin? | the a/chick/penn/83 (h5n2) influenza virus that appeared in chickens in pennsylvania in april 1983 and subsequently became virulent in october 1983, was examined for plaque-forming ability and cleavability of the hemagglutinin (ha) molecule. the avirulent virus produced plaques and cleaved the ha only in the presence of trypsin. in contrast, the virulent virus produced plaques and cleaved the ha precursor into ha1 and ha2 in the presence or absence of trypsin. the apparent molecular weight of th ... | 1984 | 6516214 |
| presence of avian influenza virus (aiv) subtypes h5n2 and h7n1 in emus (dromaius novaehollandiae) and rheas (rhea americana): virus isolation and serologic findings. | avian influenza virus (aiv) subtypes h5n2 and h7n1 were isolated from emus (dromaius novaehollandiae) and rheas (rhea americana) in texas and north carolina. all the rheas and emus had a history of respiratory disease except one emu, which was clinically normal. the isolates were not pathogenic for chickens and turkeys under the conditions of the experiment. humoral antibodies to all known hemagglutinin (h) subtypes except h10, h13, and h14 and to all nine neuraminidase (n) subtypes were found i ... | 1995 | 7794192 |
| molecular changes in virulent mutants arising from avirulent avian influenza viruses during replication in 14-day-old embryonated eggs. | the emergence of virulent avian influenza viruses in poultry is unpredictable. to gain insight into the mechanism for this event, we sought to identify the molecular changes in virulent mutants that occur during replication in 14-day-old embryonated chicken eggs. after three passages in 14-day-old eggs, avirulent h5 viruses with the k/r-k-k/t-r sequence at the hemagglutinin (ha) cleavage site became virulent in chickens, concomitantly acquiring high ha cleavability, whereas those with the r-e-t- ... | 1995 | 7831837 |
| tissue tropism and replicative properties of waterfowl-origin influenza viruses in chickens. | waterfowl-origin influenza (wfoi) viruses were evaluated for their tissue tropism and replicative properties in chickens. the 14 wfoi isolates used in this study represented 13 different hemagglutinin-neuraminidase combinations recovered during 1987 and 1988 and included isolates possessing the h5 and h7 hemagglutinin subtypes and one isolate possessing the h5n2 combination. following intravenous challenge, the frequencies of virus recovery within individual experiments were generally higher for ... | 1995 | 8561736 |
| heterogeneity in the haemagglutinin gene and emergence of the highly pathogenic phenotype among recent h5n2 avian influenza viruses from mexico. | molecular changes in the haemagglutinin (ha)-coding regions and proteolytic cleavage sites from multiple h5n2 subtype viruses isolated during a recent outbreak of avian influenza (ai) in central mexico have been characterized. eighteen isolates, collected during a 15 month period (october 1993 to january 1995) from six central states, were sequenced. none of the 18 predicted ha1 amino acid sequences were identical and changes were not restricted to a specific region of the sequence. phylogenetic ... | 1996 | 8757992 |
| assessment of the ability of ratite-origin influenza viruses to infect and produce disease in rheas and chickens. | pathobiologic characteristics were determined for three mildly pathogenic (mp) ratite-origin avian influenza viruses (aivs). ratite-origin aivs produced respiratory disease in rheas, and virus was reisolated from oropharyngeal and cloacal swabs on days 2-6 postinoculation. inoculation of two ratite-origin aivs in the upper respiratory tract of chickens resulted in viral infections, but the mean chicken infectious dose (cid50) for a/emu/texas/39924/93 (h5n2) (emu/texas) virus was 500-fold lower t ... | 1996 | 8790896 |
| comparative pathology of chickens experimentally inoculated with avian influenza viruses of low and high pathogenicity. | pathologic changes and distribution of viral antigen as determined by immunohistochemistry were compared among 4-wk-old specific-pathogen-free chickens inoculated intratracheally with avian influenza virus (aiv) isolates of either low or high pathogenicity. viruses of low pathogenicity, previously characterized as mildly pathogenic (mp), included a/chicken/pennsylvania/21525/83 (h5n2) (mp-penn) and a/chicken/alabama/7395/75 (h4n8) (mp-alab). viruses of high pathogenicity included a/chicken/penns ... | 1997 | 9087329 |
| cross-protection among lethal h5n2 influenza viruses induced by dna vaccine to the hemagglutinin. | inoculation of mice with hemagglutinin (ha)-expressing dna affords reliable protection against lethal influenza virus infection, while in chickens the same strategy has yielded variable results. here we show that gene gun delivery of dna encoding an h5 ha protein confers complete immune protection to chickens challenged with lethal h5 viruses. in tests of the influence of promoter selection on vaccine efficacy, close correlations were obtained between immune responses and the dose of dna adminis ... | 1997 | 9094608 |
| pathogenicity and diagnosis of h5n2 mexican avian influenza viruses in chickens. | chickens were inoculated with one of five h5n2 mexican-origin avian influenza virus (aiv) isolates to determine their pathogenicity for chickens and to determine the ability of routine virologic and serologic tests to detect infections. in laboratory infections, three aivs, h5/94, m5/94, and j12/94, produced sporadic illness and death and were categorized as mildly pathogenic. q1/95 produced illness and death in all inoculated chickens and was categorized as highly lethal and highly pathogenic ( ... | 1997 | 9201397 |
| virulence-associated sequence duplication at the hemagglutinin cleavage site of avian influenza viruses. | recent highly pathogenic (hp) field isolates of avian influenza (ai) virus from mexico all possess an insertion of at least two basic amino acids (arg-lys) at the cleavage site of the hemagglutinin (ha) glycoprotein. one hp isolate has additional information which yields a 4 amino acid insert (arg-lys-arg-lys). we present here the nucleotide sequence of the ha gene of this unique isolate and compare it to recent h5n2 and other avian influenza isolates. the complete ha nucleotide sequence of the ... | 1997 | 9213392 |
| pathobiology of h5n2 mexican avian influenza virus infections of chickens. | to determine the association between specific structural changes in the hemagglutinin gene and pathogenicity of avian influenza viruses (aivs), groups of 4-week-old white plymouth rock chickens were inoculated intravenously or intranasally with aivs of varying pathogenicities isolated from chickens in central mexico during 1994-1995. mildly pathogenic (mp) viruses had a common hemagglutinin-connecting peptide sequence of pro-gln-arg-glu-thr-arg decreases gly and had restricted capability for rep ... | 1997 | 9396136 |
| efficacy of recombinant fowl poxvirus vaccine in protecting chickens against a highly pathogenic mexican-origin h5n2 avian influenza virus. | internationally and nationally, governments and the poultry industries have used various strategies to control avian influenza (ai), ranging from a minimum of living with mildly pathogenic ai virus (aiv) infections to the other extreme of implementing a total quarantine-slaughter approach for eradication of highly pathogenic (hp) forms of the disease. however, recent economic considerations in various countries have prompted a broader reevaluation of vaccination as one of several tools to be use ... | 1997 | 9454926 |
| efficacy of inactivated h5n2 influenza vaccines against lethal a/chicken/queretaro/19/95 infection. | the control and eventual eradication of h5n2 influenza virus from domestic poultry in mexico is dependent on the use of avian influenza (ai) vaccine strategies. this study was performed to determine the amount of hemagglutinin (ha) antigen required to control the signs of disease from a highly pathogenic h5n2 influenza virus (a/chicken/ queretaro/19/95) and the amount of antigen required to prevent shedding of virus from vaccinated birds. six commercial inactivated water in oil h5n2 vaccines ava ... | 1998 | 9645315 |
| characterization of avian h5n1 influenza viruses from poultry in hong kong. | the transmission of avian h5n1 influenza viruses to 18 humans in hong kong in 1997 with six deaths established that avian influenza viruses can transmit to and cause lethal infection in humans. this report characterizes the antigenic and biological properties of the h5n1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in hong kong during 1997 and compares them with those of virus isolated from the index human case. each of the h5n1 viruses from hong kong ... | 1998 | 9878612 |
| distinct pathogenesis of hong kong-origin h5n1 viruses in mice compared to that of other highly pathogenic h5 avian influenza viruses. | in 1997, an outbreak of virulent h5n1 avian influenza virus occurred in poultry in hong kong (hk) and was linked to a direct transmission to humans. the factors associated with transmission of avian influenza virus to mammals are not fully understood, and the potential risk of other highly virulent avian influenza a viruses infecting and causing disease in mammals is not known. in this study, two avian and one human hk-origin h5n1 virus along with four additional highly pathogenic h5 avian influ ... | 2000 | 10627555 |
| isolation and characterization of avian influenza viruses, including highly pathogenic h5n1, from poultry in live bird markets in hanoi, vietnam, in 2001. | since 1997, outbreaks of highly pathogenic (hp) h5n1 and circulation of h9n2 viruses among domestic poultry in asia have posed a threat to public health. to better understand the extent of transmission of avian influenza viruses (aiv) to humans in asia, we conducted a cross-sectional virologic study in live bird markets (lbm) in hanoi, vietnam, in october 2001. specimens from 189 birds and 18 environmental samples were collected at 10 lbm. four influenza a viruses of the h4n6 (n = 1), h5n2 (n = ... | 2005 | 15767421 |
| failure of a recombinant fowl poxvirus vaccine containing an avian influenza hemagglutinin gene to provide consistent protection against influenza in chickens preimmunized with a fowl pox vaccine. | vaccines against mildly pathogenic avian influenza (ai) have been used in turkeys within the united states as part of a comprehensive control strategy. recently, ai vaccines have been used in control programs against highly pathogenic (hp) ai of chickens in pakistan and mexico. a recombinant fowl pox-ai hemagglutinin subtype (h) 5 gene insert vaccine has been shown to protect specific-pathogen-free chickens from hp h5 ai virus (aiv) challenge and has been licensed by the usda for emergency use. ... | 2000 | 10737653 |
| sequence analysis of related low-pathogenic and highly pathogenic h5n2 avian influenza isolates from united states live bird markets and poultry farms from 1983 to 1989. | the last highly pathogenic outbreak of avian influenza in the united states was caused by an h5n2 influenza virus in pennsylvania and new jersey in 1983-84. through a combined federal and state eradication effort, the outbreak was controlled. however, in 1986-89, multiple h5n2 viruses were isolated from poultry farms and the live bird markets (lbms) in the united states. to determine the epidemiologic relationships of these viruses, the complete coding sequence of the nonstructural gene and the ... | 2000 | 10879916 |
| prevention and treatment of bronchopneumonia in mice caused by mouse-adapted variant of avian h5n2 influenza a virus using monoclonal antibody against conserved epitope in the ha stem region. | the effects of monoclonal antibody (mab) c179 recognizing a conformational epitope in the middle of the hemagglutinine (ha) stem region were examined in a mouse model in the experiments of prevention and treatment of lethal bronchopneumonia caused by influenza a virus of h5 subtype. to model the lethal infection, avian nonpathogenic strain a/mallard duck/pennsylvania/10218/84 (h5n2) was adapted to mice. this resulted in highly pathogenic pneumovirulent mouse-adapted (ma) variant, which was chara ... | 2000 | 11003481 |
| field study on the use of inactivated h5n2 vaccine in avian species. | | 2005 | 16157578 |
| avian influenza virus subtypes inside and outside the live bird markets, 1993-2000: a spatial and temporal relationship. | between 1993 and 2000, gallinaceous birds, waterfowl, and environmental specimens from the live bird markets (lbms) of the northeastern united states and non-lbm premises were tested for the presence of avian influenza virus (aiv), pathogenic properties of aiv subtypes, especially of hemagglutinin (h) subtypes h5 and h7, and a possible association between lbm and non-lbm infections. ten h subtypes of aiv were isolated from the lbm specimens: h1, h2, h3, h4, h5, h6, h7, h9, h10, and h11. during t ... | 2002 | 12061638 |
| avian paramyxoviruses and influenza viruses isolated from mallard ducks (anas platyrhynchos) in new zealand. | a comprehensive study using virological and serological approaches was carried out to determine the status of live healthy mallard ducks (anas platyrhynchos) in new zealand for infections with avian paramyxoviruses (apmv) and influenza viruses (aiv). thirty-three viruses isolated from 321 tracheal and cloacal swabs were characterized as: 6 aiv (two h5n2 and four h4n6), 10 apmv-1 and 17 apmv-4. of 335 sera samples tested for aiv antibodies, 109 (32.5%) sera were positive by nucleoprotein-blocking ... | 2002 | 12111409 |
| avian influenza a virus subtype h5n2 in a red-lored amazon parrot. | a 3-month-old red-lored amazon parrot (amazona autumnalis autumnalis) was evaluated for severe lethargy. | 2006 | 16426196 |
| structure of antigenic sites on the haemagglutinin molecule of h5 avian influenza virus and phenotypic variation of escape mutants. | to elucidate the structure of the antigenic sites of avian h5 influenza virus haemagglutinin (ha) we analysed escape mutants of a mouse-adapted variant of the h5n2 strain a/mallard/pennsylvania/10218/84. a panel of five anti-h5 monoclonal antibodies (mabs) was used to select 16 escape mutants. the mutants were tested by elisa and haemagglutination inhibition with this panel of anti-h5 mabs and the ha genes of the mutants were sequenced. the sequencing demonstrated that the amino acid changes wer ... | 2002 | 12237433 |
| preparation of a standardized, efficacious agricultural h5n3 vaccine by reverse genetics. | options for the control of emerging and reemerging h5n1 influenza viruses include improvements in biosecurity and the use of inactivated vaccines. commercially available h5n2 influenza vaccine prevents disease signs and reduces virus load but does not completely prevent virus shedding after challenge with h5n1 virus. by using reverse genetics, we prepared an h5n3 vaccine whose hemagglutinin is 99.6% homologous to that of a/ck/hk/86.3/02 (h5n1). we used the internal genes of a/pr/8/34 and the h5 ... | 2003 | 14554086 |
| report on avian influenza in the eastern hemisphere during 1997-2002. | since the fourth international symposium on avian influenza (ai) there has been considerable ai activity in the eastern hemisphere. the higher profile of ai resulting from the human infections with h5n1 and h9n2 viruses in hong kong, in 1997 and 1999, respectively, resulted in increased reporting and active surveillance. there have been three reported incidents of high-pathogenicity (hp) ai: h5n2 in northeastern italy in 1997 (eight outbreaks); h5n1 in hong kong in 1997 recurring in 2001 and 200 ... | 2003 | 14575066 |
| control and eradication strategies of avian influenza in mexico. | in december 1994, a highly pathogenic (hp) avian influenza (ai) outbreak occurred in mexico, caused by the subtype h5n2, affecting two main regions of egg and poultry-meat production. at that time, governmental actions included immediate stamping out of the affected flocks, disinfection of affected premises, quarantine measures in the region, strict movement controls on poultry and their products and vaccination. with these policies, the disease was eradicated in a relatively short time. the las ... | 2006 | 16450453 |
| avian influenza in the western hemisphere including the pacific islands and australia. | between 1997 and 2001, there was one report of highly pathogenic avian influenza (hpai) in the western hemisphere and pacific basin. in 1997, in new south wales, australia, an outbreak caused by avian influenza (ai) virus subtype h7n4 involved both chickens and emus. all other reports of infections in poultry and isolations from wild bird species in the region pertained to low pathogenicity (lp) ai virus. animal health officials in canada reported isolations of subtypes h1, h6, h7, and h10 from ... | 2003 | 14575067 |
| avian influenza in italy 1997-2001. | from 1997 to 2001, italy has been affected by two epidemics of high-pathogenicity avian influenza. the first epidemic was caused by a virus of the h5n2 subtype and was limited to eight premises in backyard and semi-intensive flocks. the prompt identification of the disease was followed by the implementation of european union (eu) directive 92/40/eec and resulted in the eradication of infection without serious consequences to the poultry industry. the 1999-00 epidemic was caused by a virus of the ... | 2003 | 14575074 |
| immunity to mexican h5n2 avian influenza viruses induced by a fowl pox-h5 recombinant. | the presence of highly pathogenic h5n2 avian influenza in domestic poultry in mexico that is not being eradicated by conventional depopulation methods constitutes an imminent problem for poultry producers and agricultural authorities in the united states. the present report considers the candidate vaccines available to h5n2 influenza virus and establishes that a fowl pox-h5 recombinant can provide protection from lethal mexican h5n2, and prevent shedding in the feces and transmission to contact ... | 1996 | 8790900 |
| an arg-lys insertion at the hemagglutinin cleavage site of an h5n2 avian influenza isolate. | recent isolations of h5n2 subtype avian influenza (ai) viruses in north america have raised questions concerning their origin, transmission to commercial poultry, and potential for virulence. one ratite-origin isolate of low pathogenicity, a/emu/tx/39924/93 (h5n2), was subjected to a procedure that rapidly selects and/or amplifies highly pathogenic (hp) strains. the resulting highly virulent derivative had an altered hemagglutinin (ha) gene containing an additional six nucleotides at position 97 ... | 1996 | 8879123 |
| susceptibility of pigeons to avian influenza. | susceptibility to infection with avian influenza virus (aiv) was studied in pigeons inoculated via oculonasal (experiment 1) or intravenous (experiment 2) route. chickens were included as susceptible hosts in both experiments. two subtypes each of the highly pathogenic aiv (hpaiv; hp ck/pa h5n2 and hp ck/australia h7n7) and non-pathogenic aiv (npaiv; np ck/pa h5n2 and np emu/tx h7n1) at a dose of 10(5) embryo infective dose per bird were used as inoculum. the pigeons inoculated with hp ck/pa h5n ... | 1996 | 8883790 |
| influenza h5 virus escape mutants: immune protection and antibody production in mice. | avian h5n1 influenza a viruses are considered to be of high pandemic potential as they are able to cross the avian-human species barrier and cause disease in humans. in the present study we assessed the impact of amino acid substitutions in the hemagglutinin (ha) of antigenic escape mutants of influenza a/mallard/pennsylvania/10218/84 (h5n2) (mld/pa/84-ma) virus on the level of neutralizing antibodies and the ability to protect mice against challenge with the wild type h5 influenza virus. beta-p ... | 2004 | 14749187 |
| receptor specificity of h5 influenza virus escape mutants. | the binding of viruses to synthetic polyacrylamide (paa)-based sialylglycoconjugates was used to characterize the receptor specificities of antibody escape mutants of the influenza virus a/mallard/pennsylvania/10218/84 (h5n2). the sialylglycoconjugates that were used carried identical terminal neu5acalpha2-3gal moieties but differed in the structure of the next saccharide residue(s). our data show that mutations in the vicinity of the haemagglutinin (ha) receptor-binding site (rbs) effect the re ... | 2004 | 15019242 |
| cross-protective immunity in mice induced by live-attenuated or inactivated vaccines against highly pathogenic influenza a (h5n1) viruses. | because of the time required to identify and produce an antigenically well-matched pandemic vaccine, vaccines that offer broader cross-reactive immunity and protection are desirable. we have compared a live attenuated influenza vaccine (laiv) and inactivated influenza vaccine (iiv) based on a related h5 hemagglutinin (ha) from a nonpathogenic avian influenza virus, a/duck/pottsdam/1042-6/86 (h5n2), for the ability to induce cross-reactive immunity and/or cross-protective efficacy against a conte ... | 2006 | 17030078 |
| influenza surveillance in birds in italian wetlands (1992-1998): is there a host restricted circulation of influenza viruses in sympatric ducks and coots? | we report the results of a 6-year serological and virological monitoring performed in ducks and coots in italy, in order to assess the degree of influenza a virus circulation in these birds during wintering. a total of 1039 sera collected from 1992 to 1998 was screened by a double antibody sandwich blocking elisa (np-elisa): seroprevalence of antibodies to influenza a viruses was significantly higher in ducks compared to coots (52.2% vs. 7.1%, respectively). the hemagglutination-inhibition (hi) ... | 2004 | 15036528 |
| characterization of recent h5 subtype avian influenza viruses from us poultry. | in the us, the isolation of h5 subtype avian influenza (ai) viruses has been uncommon in commercial chickens and turkeys, although sporadic isolations have been made from the live bird markets or its supply chain since 1986. in 2002, two different outbreaks of h5 ai occurred in commercial chicken or turkey operations. the first occurred in texas and was identified as a h5n3 subtype ai virus. the second outbreak was caused by a h5n2 virus isolated from a turkey farm in california. in this study w ... | 2004 | 15223555 |
| effect of vaccine use in the evolution of mexican lineage h5n2 avian influenza virus. | an outbreak of avian influenza (ai) caused by a low-pathogenic h5n2 type a influenza virus began in mexico in 1993 and several highly pathogenic strains of the virus emerged in 1994-1995. the highly pathogenic virus has not been reported since 1996, but the low-pathogenic virus remains endemic in mexico and has spread to two adjacent countries, guatemala and el salvador. measures implemented to control the outbreak and eradicate the virus in mexico have included a widespread vaccination program ... | 2004 | 15254209 |
| generation of reassortant influenza vaccines by reverse genetics that allows utilization of a diva (differentiating infected from vaccinated animals) strategy for the control of avian influenza. | vaccination of poultry with inactivated influenza vaccine can be an effective tool in the control of avian influenza (ai). one major concern of using inactivated vaccine is vaccine-induced antibody interference with serologic surveillance and epidemiology. in the united states, low pathogenicity h5 and h7 subtype ai viruses have caused serious economic losses in the poultry industry. most of these viruses also have the accompanying n2 subtype and no h5n1 or h7n8 subtype ai viruses have been iden ... | 2004 | 15297071 |
| vaccination of chickens against h5n1 avian influenza in the face of an outbreak interrupts virus transmission. | vaccination of chickens with a commercially available killed h5n2 vaccine was being evaluated as an additional tool to enhanced biosecurity measures and intensive surveillance for control of highly pathogenic avian influenza subtype h5n1 disease in hong kong in 2002. in december 2002 to january 2003, there were outbreaks of h5n1 disease in waterfowl in two recreational parks, wild water birds, several poultry markets and five chicken farms. in addition to quarantine, depopulation of the affected ... | 2004 | 15370037 |
| [h5n1: vaccine solutions for humans and other animals]. | the hypervirulence of h5n1 influenza virus makes it impossible to produce a vaccine traditionally (with egg embryos), but there are alternative solutions. a live recombinant fowl-pox h5 virus is used for avian pathology. an inactivated h5n2 adjuvant vaccine is rendered immunogenic by using hemagglutinin h5 (diva technique). disease prevention strategies differ between european and asian countries. who has opted for a recombinant vaccine based on a non pathogenic virus (pr8) to which modified h5 ... | 2006 | 17195620 |
| new avian influenza a virus subtype combination h5n7 identified in danish mallard ducks. | during the past years increasing incidences of influenza a zoonosis have made it of uppermost importance to possess methods for rapid and precise identification and characterisation of influenza a viruses. we present here a convenient one-step rt-pcr method that will amplify full-length haemagglutinin (ha) and neuraminidase (na) directly from clinical samples and from all known subtypes of influenza a. we applied the method on samples collected in september 2003 from a danish flock of mallards w ... | 2005 | 15763149 |
| experimental study to determine if low-pathogenicity and high-pathogenicity avian influenza viruses can be present in chicken breast and thigh meat following intranasal virus inoculation. | two low-pathogenicity (lp) and two high-pathogenicity (hp) avian influenza (ai) viruses were inoculated into chickens by the intranasal route to determine the presence of the ai virus in breast and thigh meat as well as any potential role that meat could fill as a transmission vehicle. the lpai viruses caused localized virus infections in respiratory and gastrointestinal (gi) tracts. virus was not detected in blood, bone marrow, or breast and thigh meat, and feeding breast and thigh meat from vi ... | 2005 | 15839417 |
| [generation of attenuated h5n1 and h5n2 subtypes of influenza virus recombinants by reverse genetics system]. | the ha connecting peptide at cleavage site, pqrerrkkr / gl, of an h5n1 subtype avian influenza virus (aiv) was replaced with pqresr / gl, and then the modified ha gene was cloned into the transcription/expression vector, phw2000, constructing a plasmid named phw524-ha. the na (n1) gene from the h5n1 virus and the na (n2) gene from an h9n2 aiv were also cloned into phw2000 separately, resulting in plasmids phw506-na and phw206-na. with the organization of phw524-ha, phw506-na or phw206-na, and si ... | 2005 | 15847163 |
| h5n2 avian influenza outbreak in texas in 2004: the first highly pathogenic strain in the united states in 20 years? | in early 2004, an h5n2 avian influenza virus (aiv) that met the molecular criteria for classification as a highly pathogenic aiv was isolated from chickens in the state of texas in the united states. however, clinical manifestations in the affected flock were consistent with avian influenza caused by a low-pathogenicity aiv and the representative virus (a/chicken/texas/298313/04 [tx/04]) was not virulent for experimentally inoculated chickens. the hemagglutinin (ha) gene of the tx/04 isolate was ... | 2005 | 16103192 |
| immunization with influenza a np-expressing vaccinia virus recombinant protects mice against experimental infection with human and avian influenza viruses. | two-fold immunization of balb/c mice with a vaccinia virus recombinant expressing the np protein of influenza a/pr8/34 (h1n1) virus under the control of a strong synthetic promoter induced specific antibodies and protected animals against low-dose challenge by mouse-adapted heterosubtypic variants of human a/aichi2/68 (h3n2) and avian a/mallard/pennsylvania/10218/84 (h5n2) influenza virus strains. the surviving immunized animals had lower anti-hemagglutinin antibody titers compared to non-immuni ... | 2006 | 16292596 |
| haematological and histological findings in birds experimentally infected with highly pathogenic h5n2 avian influenza virus. | experimental infection of specific-pathogen-free (spf) leghorn chickens with a highly pathogenic h5n2 avian influenza virus produced cellular hyperplasia in the bone marrow at 36 hours post infection (hpi) and haematological evidence of monocytosis, thrombocytopenia and heterophilia was also detected. an early, significant and progressive haematological change was thrombocytopenia starting at 24 hpi without an increase of prothrombin time. the findings suggest that highly pathogenic avian influe ... | 2005 | 16363150 |
| ecology and epidemiology of avian influenza in north and south america. | wild waterfowl and shorebirds are known to be the natural reservoir for influenza a viruses. surveillance studies in waterfowl and shorebirds in north america show that influenza a viruses are repeatedly recovered from these birds. however, the virus recovery is influenced by geography, season, age and species of birds. in addition to the natural reservoir, the live-bird marketing system (lbms) in certain regions of the united states has been recognized as a man-made reservoir of influenza virus ... | 2006 | 16447492 |
| use of avian influenza vaccination in hong kong. | outbreaks of h5n1 highly pathogenic avian influenza (hpai) that occurred in hong kong up until february/march 2002 were controlled by stamping out. with endemic presence of the virus in the region and large daily importation of poultry to hong kong, the administration considered that further risk management measures, in addition to improved biosecurity and enhanced surveillance, were necessary to prevent outbreaks. vaccination using a killed h5n2 vaccine was evaluated over a 12-month period in t ... | 2006 | 16447504 |
| phylogenetic analyses of genes from south african lpai viruses isolated in 2004 from wild aquatic birds suggests introduction by eurasian migrants. | in 2004, south africa experienced its first recorded outbreak of a highly pathogenic notifiable avian influenza (hpnai) viral strain of the h5n2 subtype in ostriches in the eastern cape province. the traditional ostrich-farming areas in the western cape province report almost yearly outbreaks of low pathogenicity avian influenza (lpai) in ostriches, which is attributed to introduction by wild birds and certain climatic patterns. during the winter of 2004, lpai h3n8, h4n8, h5n2 and h5n1 avian inf ... | 2006 | 16447511 |
| microassay for measuring thermal inactivation of h5n1 high pathogenicity avian influenza virus in naturally infected chicken meat. | a precise, reproducible microassay was developed to measure thermal inactivation of high pathogenicity avian influenza (hpai) virus in chicken meat. small pieces of breast or thigh meat (0.05 g) from chickens infected with a/chicken/pennsylvania/1370/1983 (h5n2) (pa/83) or a/chicken/korea/es/2003 (h5n1) (korea/03) hpai viruses were tested for inactivation in the heating block of a thermocycler. korea/03 infected thigh and breast meat had higher virus concentrations (10(6.8) and 10(5.6) mean embr ... | 2006 | 16481058 |
| dual expression of the ha protein of h5n2 avian influenza virus in a baculovirus system. | baculovirus/insect cell system is used widely for recombinant protein production. the hemagglutinin (ha) gene of h5n2 avian influenza virus (aiv) 1209 strain and the enhanced green fluorescent protein (egfp) gene were cloned into pfastbac dual vector that has two promoters and cloning sites, allowing simultaneous expression of these two genes. the ha protein of aiv was fused with a hexahistidine (his6) tag for purification. the coexpression of egfp allowed identification of the recombinant bacul ... | 2006 | 16530857 |
| influenza virus circulation in wild aquatic birds in italy during h5n2 and h7n1 poultry epidemic periods (1998 to 2000). | two epidemics of avian influenza due to h5 and h7 highly pathogenic viruses occurred in poultry in italy in 1997/98 and 1999/2000, respectively. the circulation of these serotypes in wild aquatic birds was investigated examining 638 cloacal swabs and 621 sera collected from 150 gulls, 162 coots, and 326 ducks trapped in italian wetlands from 1998 to 2000. seroprevalences against influenza a viruses, detected by a double-antibody sandwich-blocking enzyme-linked immunosorbent assay (elisa), were 1 ... | 2005 | 16537162 |
| update on molecular epidemiology of h1, h5, and h7 influenza virus infections in poultry in north america. | avian influenza is endemic in wild birds in north america, and the virus routinely has been transmitted from this reservoir to poultry. influenza, once introduced into poultry, can become endemic within the poultry population. it may be successfully eradicated by human intervention, or the virus may fail to successfully spread on its own. in the last 5 yr, influenza virus has been isolated from poultry in the united states on numerous occasions, and, with the use of molecular epidemiology, the r ... | 2003 | 14575082 |
| pathogenicity of a ratite-origin influenza a h5 virus in ostriches (struthio camelus). | ostriches were inoculated with a highly pathogenic avian influenza (hpai) virus of ratite origin, a/emu/texas/39924/93 (h5n2) done clb. the aim of this study was to evaluate the pathogenicity of this isolate for ostriches and to assess the ability of routine virologic and serologic tests to detect infection. avian influenza virus (aiv) was isolated from tracheal swabs from 2 to 12 days postinfection and from cloacal swabs from 3 to 10 days postinfection. aiv was also isolated from a wide range o ... | 2003 | 14575143 |
| comparison of the transmission characteristics of low and high pathogenicity avian influenza a virus (h5n2). | low pathogenicity avian influenza a strains (lpai) of the h5 and h7 type are noted for their ability to transform into highly pathogenic counterparts (hpai). here we compare the transmission characteristics in poultry of lpai h5n2 (a/chicken/pennsylvania/83) and corresponding hpai virus by means of transmission experiments. in the experiments, five inoculated animals are placed in a cage with five contact animals, and the infection chain is monitored by taking blood samples, and samples from the ... | 2003 | 14596543 |
| resistance of immune-suppressed pigeons to subtypes h5n2 and h6n1 low pathogenic avian influenza virus. | resistance to infection with avian influenza virus (aiv) was studied in healthy and immune-suppressed pigeons, which were treated with the immunosuppressant cyclophosphamide (cy) before infection. two subtypes of low pathogenic aiv (lpaiv; ck/tw/h5 and ck/tw/h6) were inoculated via the oculonasal route. nested reverse transcriptase-polymerase chain reaction (nested rt-pcr) and virus isolation were used as detection methods. the cy-treated and -untreated pigeons in both experiments did not shed v ... | 2006 | 16863079 |