Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
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| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |