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antibodies to new variants of subtype a(h3 n2) influenza virus in pigs.following an explosive epidemic of a(h3n2) influenza among the human population of czechoslovakia in 1983, haemagglutination-inhibiting antibodies (titre range 10-640) against strains a/texas/77, a/bangkok/79 and a/philipines 2/83 were detected in 93% of sera collected from 135 pigs on three farms. only 6.6% of sera were negative. anti-neuraminidase antibodies were detected at rates of 81% and 23% in two and one of the herds, respectively. antibodies against a/rnp were demonstrated by the immuno ...19852860799
swine influenza a at fort dix, new jersey (january-february 1976). iv. summary and speculation.influenza a/new jersey/76 virus was detected at fort dix from january 19 through february 9, 1976 and infected at least 230 military personnel. thirteen hospital admissions for acute respiratory disease were associated with influenza a/new jersey infection, and additional members of index training companies may have been hospitalized with influenza a/new jersey. this virus was likely introduced into the reception center by an incoming trainee. although our studies could not eliminate the possibi ...1977342615
avian-to-human transmission of the pb1 gene of influenza a viruses in the 1957 and 1968 pandemics.we determined the origin and evolutionary pathways of the pb1 genes of influenza a viruses responsible for the 1957 and 1968 human pandemics and obtained information on the variable or conserved region of the pb1 protein. the evolutionary tree constructed from nucleotide sequences suggested the following: (i) the pb1 gene of the 1957 human pandemic strain, a/singapore/1/57 (h2n2), was probably introduced from avian species and was maintained in humans until 1968; (ii) in the 1968 pandemic strain ...19892795713
identification of h3n2 influenza virus isolated from pigs with respiratory problems in spain. 19882839928
evolutionary pathways of the pa genes of influenza a viruses.nucleotide sequences of the pa genes of influenza a viruses, isolated from a variety of host species, were analyzed to determine the evolutionary pathways of these genes and the host specificity of the genes. results of maximum parsimony analysis of the nucleotide sequences indicate at least five lineages for the pa genes. those from human strains represent a single lineage, whereas the avian genes appear to have evolved as two lineages--one comprising genes from many kinds of birds (e.g., chick ...19892800339
porcine influenza outbreak in east anglia due to influenza a virus (h3n2) 19872832998
epizootics of respiratory tract disease in swine in belgium due to h3n2 influenza virus and experimental reproduction of disease.in belgium, influenza virus was isolated from swine in 22 epizootics of respiratory tract disease in swine during 1984. in 8 of the epizootics, h3n2 influenza virus, related to the a/port chalmers/1/73 strain, was isolated. intratracheal inoculation of the isolates induced clinical signs. it was concluded that the a/port chalmers/1/73 strain was established in the belgian swine population and was responsible for the epizootics of respiratory tract disease in swine.19852413789
antibody responses of swine to type a influenza viruses in the most recent several years.a serological survey was conducted on 4,080 swine sera collected for the years 1985-90. the swine sera positive to a/new jersey/8/76 (swine type h1n1) strain were observed in annual (10-20%) and monthly (20-40%) incidences during the observation period except for occasional months. antibodies to recent human h1n1 viruses in swine were recognized in relation to the human h1n1 influenza epidemics. antibody responses of swine to human h3n2 strains appeared irrespective of human epidemics with the v ...19921318751
swine influenza virus and the recycling of influenza-a viruses in man.sera collected in 1967 and 1972 from people in the 0-100 age-group showed haemagglutination-inhibition (h.i.) antibody to swine virus a/iowa/15/30 (hsw1n1) in greatest number and with highest titre in people born before 1918. a slight decrease was observed from 1967 to 1972 in the number of sera with antibody to swine virus and in the height of the titres. the recently isolated a/new jersey/10/76 (hsw1n1) virus showed a result comparable to that of the swine/1930 virus in sera of 1972. on the an ...197659252
evolutionary pathways of n2 neuraminidases of swine and human influenza a viruses: origin of the neuraminidase genes of two reassortants (h1n2) isolated from pigs.the complete nucleotide sequences of the neuraminidase (na) genes of two reassortant (h1n2) and two h3n2 influenza a viruses isolated from pigs were determined and phylogenetic relationships between these and previously reported n2 na genes were investigated. on the basis of pairwise nucleotide sequence identity, the na genes of two reassortants, a/sw/kanagawa/2/78 and a/sw/ehime/1/80, were most closely related to those of human influenza a virus strains isolated in 1972 and the earliest availab ...19912005434
pandemic influenza: a zoonosis?in the last two decades, influenza a viruses have been found to occur throughout the animal kingdom, mainly in birds, notably aquatic ones, in which infection is largely intestinal, waterborne, and asymptomatic. the domestic duck of southern china, raised in countless numbers all year round mainly as an adjunct to rice farming, is the principal host of influenza a viruses. studies based on hong kong h3n2 viruses from southern china suggest that pandemic strains originate from the domestic duck t ...19921609163
amino acid sequence identity between the ha1 of influenza a (h3n2) viruses grown in mammalian and primary chick kidney cells.primary isolation of type a influenza (h3n2) virus in mammalian madin darby canine kidney (mdck) cells results in a virus with haemagglutinin (ha) identical to that of the virus replicating in the infected individual, whereas similar isolation of virus in the embryonated egg results in the selection of variants with amino acid substitutions in the globular head region of the ha molecule. to determine whether other mammalian and avian host cells routinely used in laboratory isolation of influenza ...19921588320
characterization of an influenza a (h3n2) virus isolated from pigs in england in 1987. 19882838122
isolation of human (h3n2) influenza virus and prevalence of the virus-antibody in swine. 19872828738
seroprevalence of porcine and human influenza a virus antibodies in pigs between 1986 and 1988 in hassia.1,268 sera collected from slaughtered pigs in hassia (frg) from 1986 to 1988 were tested for antibodies against porcine and human influenza a virus strains using the single radial haemolysis test (srht). antibodies against the porcine strains (subtype h1n1) a/swine/arnsberg/1/81, a/swine/iowa/15/30 and a/new jersey/7/76 were detected in 411 (32.4%), 318 (25.1%) and 304 (24.0%) of sera, respectively. up to 1988 a slight increase (10%) in the seroprevalence to a/swine/arnsberg/1/81 was noticed, wh ...19892559562
[pathologic consequences of a severe influenza outbreak (swine virus a/h1n1) under natural conditions in the non-immune sow at the beginning of pregnancy].pathological consequences of a severe outbreak of swine influenza (h1n1 virus) in the non immune sow at the beginning of pregnancy, under natural conditions. a sudden acute outbreak of fever, depression, anorexia and coughing in a group of nulliparous sows from a herd that was currently under epidemiological investigation lead to build a particular disposal of observation. the clinical signs were daily recorded including rectal temperature. blood was taken from the sows at the beginning of the t ...19892550169
[the prevalence of antibodies to influenza virus and respiratory coronavirus in fattening pigs in spain].the presence of antibodies to two influenza viruses of the type a (h1n1 and h3n2) and to a porcine respiratory coronavirus was investigated in a study lasting a year. 735 blood serum samples were collected from 79 closed pig fattening farms in the province segovia (spain). hemagglutination inhibition was used with influenza viruses. the percentage of positive results was 78.5% and 62.5% respectively for the serotypes h1n1 and h3n2. a clear reduction in the spread of antibodies was observed in th ...19892554624
[vaccinations in pigs].efficacious and safe gi-negative vaccines are available for vaccination against aujeszky's disease. an intensive vaccination programme carried out consistently will result in the reduction of virus circulating among pig populations. combined vaccination and culling of gi-seropositive pigs may lead to eradication of aujeszky's disease virus in a stock. vaccination of susceptible gilts, sows and boars against parvovirus infections is advisable. the actual period for which a sow is protected agains ...19902161569
outbreaks of classical swine influenza in pigs in england in 1986.serum samples from pig herds in great britain have been examined for antibodies to influenza virus since 1968. antibodies to h3n2 virus strains have been found since 1968 and the serological data presented here suggests that h3n2 virus strains continue to persist in the pig population. an outbreak of acute respiratory disease occurred in a 400-sow unit. the outbreak was characterised by coughing, anorexia, fever, inappetence and loss of condition. the gilts and weaners were affected and the morb ...19872820111
influenza a viruses: epidemiologic study in fatteners in spain (1987-89).2,979 sera were collected from slaughtered swine in two geographic areas of spain from 1987 to 1989. they were tested for antibodies against an h1n1- and h3n2-influenza virus by haemagglutination-inhibition tests (hi). the percentage of positive sera was higher in area i (78%-69.2%) than in area ii (63.1%-60.4%) for both viruses respectively. the coexistence of high titres to both h1n1- and h3n2-influenza virus became apparent in cold months simultaneously in each area, although influenza viruse ...19921320310
sero-epidemiological screening of pig sera collected at the slaughterhouse to detect herds infected with aujeszky's disease virus, porcine influenza virus and actinobacillus (haemophilus) pleuropneumoniae in the framework of an integrated quality control (iqc) system.over a period of six months, approximately 4700 blood samples were collected from 97 pig-finishing farms in the provinces of noord-brabant and gelderland and screened for antibodies with respect to aujeszky's disease virus (adv), porcine influenza virus (pi) and actinobacillus (haemophilus) pleuropneumoniae (app). there were significant differences in the percentages of seropositive pigs between the two provinces, which may be related to the difference in the density of the pig population in the ...19902176752
pathogenicity of concurrent infection of pigs with porcine respiratory coronavirus and swine influenza virus.combinations of porcine respiratory coronavirus (prcv) and either of two swine influenza viruses (h1n1 or h3n2) were administered intranasally and by aerosol to six- to eight-week-old specific pathogen-free pigs. the clinical responses, gross respiratory lesions and growth performances of these pigs were studied and compared with those of single (prcv, h1n1 or h3n2) and mock-infected animals. prcv infection caused fever, growth retardation and lung lesions, but no respiratory symptoms. infection ...19921334565
a new concept of the epidemic process of influenza a virus.influenza a virus was discovered in 1933, and since then four major variants have caused all the epidemics of human influenza a. each had an era of solo world prevalence until 1977 as follows: h0n1 (old style) strains until 1946, h1n1 (old style) strains until 1957, h2n2 strains until 1968, then h3n2 strains, which were joined in 1977 by a renewed prevalence of h1n1 (old style) strains. serological studies show that h2n2 strains probably had had a previous era of world prevalence during the last ...19873301379
antigenic variant of swine influenza virus causing proliferative and necrotizing pneumonia in pigs.a new antigenic variant of swine influenza virus was isolated from the lungs of pigs experiencing respiratory problems in 7 different swine herds in quebec. pigs of different ages were affected, and the main clinical signs were fever, dyspnea, and abdominal respiration. coughing was not a constant finding of the syndrome. at necropsy, macroscopic lesions included the overall appearance of pale animals, general lymphadenopathy, hepatic congestion, and consolidation of the lungs. histopathologic f ...19921333815
origin of the hemagglutinin gene of h3n2 influenza viruses from pigs in china.influenza viruses of the h3n2 subtype similar to aichi/2/68 and victoria/3/75 persist in pigs many years after their antigenic counterparts have disappeared from humans (shortridge et al. (1977). science 19, 1454-1455). to provide information on the mechanism of conservation of these influenza viruses in pigs, the hemagglutinin (ha) of four isolates from swine derived from taiwan and southern china were analyzed antigenically and genetically. the reactivity pattern of these viruses with a panel ...19883336940
antigenic and biochemical analysis of influenza "a" h3n2 viruses isolated from pigs.four influenza a-h3n2 viruses isolated in pigs from different herds in central italy in the period 1981/82 have been antigenically and biochemically analysed. three of them a/sw/italy/2/81, a/sw/italy/7/81, a/sw/italy/8/82 were found to be serologically related to a/bangkok/1/79 (h3n2). these three viruses were shown to have an identical electrophoretic pattern, as regards virus induced polypeptides and were clearly distinguishable from the virus a/sw/italy/6/81 which was antigenically related t ...19853155941
the nucleoprotein as a possible major factor in determining host specificity of influenza h3n2 viruses.in an attempt to assess the importance of the nucleoprotein (np) in the determination of host specificity, a series of experiments was performed on influenza a viruses of the h3n2 subtype. we have examined rescue of mutants of a/fpv/rostock/34 with temperature-sensitive (ts) lesions in the nucleoprotein (np) gene by double infection of chick embryo cells with h3n2 strains isolated from different species. the ts mutants could be rescued by all avian h3n2 strains but not by any of the human h3n2 i ...19852416114
[immunovirologic markers of the risk of influenza a h3n2 among swine].a seroepidemiological survey using the radial haemolysis test has been performed on a representative sampling of the pig herds in brittany. since 1978, influenza a h3n2 strains spread in that reservoir giving subclinical infections. we detected antibodies directed against the influenza prototypes isolated during the human outbreaks from 1973 to 1977. only one h3n2 virus was isolated in 1980: its antigenic structure was in agreement with the previous serological data. in 1984 outbreaks of swine i ...19854095329
haemagglutination-inhibiting (hi) antibodies against strains of influenza a virus in horse and pig sera in nigeria.sera from horses and pigs obtained from lagos and ibadan respectively were examined for haemagglutination-inhibiting (hi) antibodies to two strains each of h3n2 and h1n1 subtypes of influenza a virus. more horse sera had hi antibodies to the h3n2 than the h1n1 strains while pig sera reacted almost equally with strains of both subtypes. all the horse sera had hi antibodies to the two strains of h3n2 subtype (a/mississippi/1/85 and a/leningrad/360/86), while 87% and 14% of the horses examined were ...19902100750
variation in seropositivity for some respiratory disease agents in finishing pigs: epidemiological studies on some health parameters and farm and management conditions in the herds.the relationship between the extent of seropositivity for aujeszky's disease virus (adv), actinobacillus pleuropneumoniae (app.) serotype 2 and porcine influenza (pi) viruses serotype h1n1 and h3n2 in pigs on the one hand and the health status of the pigs and some farm and management conditions in the herds on the other hand was studied in 45 pig finishing herds, all members of one integration group. the health status was assessed by the extent of clinical signs, the use of veterinary drugs and ...19921315466
prevalence of hong kong (h3n2) influenza virus-antibody in swine. 19852995716
[adsorbed subunit influenza vaccine: its isolation and characteristics].experimental batches of adsorbed subunit influenza vaccine were prepared from the envelope of glycoprotein antigens separated from the influenza virion by treatment with a cationic detergent (cetyltrimethylammonium bromide). purified and concentrated influenza virus strains a(h1n1) and a(h3n2) were obtained by gradient centrifugation; additional purification, with a view to removing ovalbumin and structural components of the chorioallantoic membrane, was achieved by gelfiltration. the compositio ...19863727396
[influenza epizootic in swine due to strain a (victoria/3/75 h3n2)].studies were carried out on the first grippe epizootic in pigs in bulgaria. the affected animals showed a rise in temperature (40.5 to 41.8 degrees c), loss of appetite, abdominal type of respiration, and noisy and painful cough. the infection ran its course with a picture typical of a virus disease which did not respond to broad-spectrum antibiotic treatment. on an average the duration of the clinical course lasted 4 to 5 days, affecting almost all swine on a pig breeding farm, with single deat ...19816274080
characteristics of a swine recombinant influenza virus isolated in 1980: recombination between swine and the earliest hong kong (h3n2) viruses.a recombinant (h1n2, formerly hsw1n2), a/swine/ehime/1/80 was found to possess antigenic biological and genomic characteristics different from those of a previous a/swine/kanagawa/2/78 (h1n2) strain. five monoclonal antibodies to a/nj/8/76 differentiated the haemagglutinin molecules of the former virus from the latter, showing that these viruses differed at two-antigenic determinants at least. immuno-double diffusion tests with antisera to the isolated neuraminidase and neuraminidase-inhibition ...19854060856
influenza virus infection of tracheal gland cells in culture.influenza virus-induced tracheobronchitis causes limited epithelial deciliation but markedly decreased mucociliary transport. this suggests that virus-induced alterations in airway mucus play a role in decreased mucociliary transport. airway submucosal glands are a primary source of mucus. therefore, we examined virus-gland cell interactions by exposing primary cultures of isolated feline tracheal gland cells to influenza a/scotland/840/74 h3n2 virus for 1 h at a multiplicity of infection of 0.1 ...19883357204
molecular evidence for a role of domestic ducks in the introduction of avian h3 influenza viruses to pigs in southern china, where the a/hong kong/68 (h3n2) strain emerged.the haemagglutinins (has) of five h3 influenza a viruses isolated from domestic ducks and one from a goose in southern china were analysed antigenically and genetically. the patterns of reactivity of two of the duck viruses and the goose virus with a panel of monoclonal antibodies to 10 different epitopes on the h3 ha were similar to those of influenza viruses isolated from wild ducks and pigs, as well as those of the earliest human h3 viruses. the other three isolates from domestic ducks were d ...19911875195
characterization of a 1980-swine recombinant influenza virus possessing h1 hemagglutinin and n2 neuraminidase similar to that of the earliest hong kong (h3n2) virus.a recombinant (h1n2, formerly hsw 1n2), a/swine/ehime/1/80 was found to possess antigenic, biological and genomic characteristics different from those of a previous a/swine/kanagawa/2/78 (h1n2) strain. five monoclonal antibodies to a/nj/8/76 definitely differentiated the hemagglutinin molecules of the former virus from the latter, showing that these viruses differed, at least, at two antigenic determinants. neuraminidase-inhibition tests with monoclonal antibodies to different h2n2 and h3n2 viru ...19854062559
the follow-up study of swine and hong kong influenza virus infection among japanese hogs.pigs in miyagi prefecture, japan were examined for swine (hssw1n1) and hong kong (h3n2) influenza virus infection by serological tests. the results obtained revealed that a swine influenza was prevalent with relatively high positive ratios throughout that time, and that the hong kong influenza virus closely related to a recent human epidemic strain, a/yamanashi/2/77, also persisted, corresponding to a human endemic. these epidemiological findings strongly suggested the possibility of direct tran ...19826285546
the demonstration of the influenza virus by the method of the immune electron microscopy.the direct and indirect method of the immune electron microscopy (iem) was used for the identification of two influenza viruses of the type a--[strain a/chabarovsk/77 (h1n1) and a/texas/77 (h3n2)]--by means of reference specific rat- and human- convalescent sera. in the cross-testing different dilutions of the virus in the allantoic fluid and of the sera were examined for the determination of the appropriate rates for the formation of the immunocomplexes. in the demonstration of the immunocomple ...19853926876
antibody responses of swine to type a influenza viruses during the past ten years in japan.a total of 6346 swine sera collected at an abattoir in the city of obihiro, hokkaido during the years 1978-87 were tested for the presence of antibodies to swine and human influenza viruses. a high incidence of antibody to a/new jersey/8/76 (swine type h1n1) virus was observed throughout the 10 years except for the occasional month and a single long period of 15 months. antibodies to human h3n2 virus in swine appeared to be related to the epidemics of human influenza which occurred in the study ...19883378588
the possible origin h1n1 (hsw1n1) virus in the swine population of japan and antigenic analysis of the isolates.virus isolation and serological studies on swine sera collected during 1973 to 1978 showed that h1n1 (hsw1n1) influenza viruses first appeared in the swine population of japan about may 1977. with the exception of one strain, both haemagglutinin and neuraminidase subunits of all the h1n1 viruses isolated from swine in japan and from pigs imported from north america were antigenically indistinguishable from those of a/nj/8/76 virus, suggesting the introduction of swine influenza virus into japan ...19826182266
[grouping of influenza a virus np proteins].a comparative study of influenza a virus np proteins was carried out using peptide mapping. thirty-five strains of all main serotypes of human and animal viruses were tested. the greatest diversity was found in np proteins of human influenza viruses belonging to different serotypes, while within serotypes the variability is less pronounced. four main groups of np proteins were distinguished and designated np0, np1, np2, and np3. the np0 group includes proteins of viruses of hon1 serotype, np pro ...19817257320
[antiviral action of swine leukocyte interferon in mouse experiments].swine leukocytes had previously been found to produce interferon which has an antiviral effect not only in swine cells but also in human cells. preliminary experiments in tissue cultures showed the culture of primarily trypsinized mouse embryo fibroblasts to be as sensitive to swine interferon as human diploid cells. the experiment studying the antiviral effect of swine leukocyte interferon in the animals demonstrated it to protect mice against the pathogenic a/aishi/68 (h3n2) strain; with a red ...19816171098
intraepidemic heterogeneity of influenza a (h3n2) viruses in 1985: antigenic analysis and sensitivity to non-specific inhibitors.during the influenza outbreak of 1984-85 22 strains of h3n2 viruses were isolated in finland. an intra-epidemic heterogeneity was demonstrated in an antigenic analysis by haemagglutination inhibition test with antisera produced in rats. the strains could be classified into three groups which corresponded to the following reference strains: group i: a/hong kong/1/84, a/hong kong/3/84; group ii: a/philippines/2/82; group iii: a/caen/1/84. seven of the isolates were entirely insensitive to gamma-in ...19863807442
influenza in swine in belgium (1969-1986): epizootiologic aspects.from 1984 until 1986, influenza isolates were obtained from 59 outbreaks of respiratory tract disease in belgium. in 21 of the outbreaks, h3n2-influenza virus isolates, related to the human a/port chalmers/1/73 strain were obtained. all other isolates were h1n1-influenza virus strains. the prevalence of variants of the human h3n2-influenza virus in the belgium swine population was determined by examining sow sera which had been collected between 1969 and 1984. the results of this serological stu ...19882851410
isolation and serological characterization of influenza a virus from a pig in thailand.a hemagglutinating agent was isolated from a pig in thailand in 1978 during the early febrile stage of an influenza-like illness and identified as influenza a virus. the isolate contained hemagglutinin and neuraminidase antigens that were antigenically indistinguishable from those of a/tokyo/6/73 (h3n2), a port chalmers-like strain isolated in japan. serological tests also indicated that prevalence of h3n2 virus in the swine population in thailand.19817311111
antigenic and genetic analysis of a/hong kong (h3n2) influenza viruses isolated from swine and man.two h3n2 strains of influenza a virus isolated from pigs in japan and thailand were characterized antigenically and genetically. a/swine/wadayama/5/69 (isolated in japan in 1969) was antigenically similar to a human strain, a/aichi/2/68, while a/swine/bangkok/9/78 (a swine isolate in thailand) was closely related to a/bangkok/36/78, a contemporary human isolate. gel electrophoresis and oligonucleotide mapping of the virus rna revealed genetic similarity between a/swine/wadayama/5/69 and a/aichi/ ...19816171614
human influenza a viruses in pigs: isolation of a h3n2 strain antigenically related to a/england/42/72 and evidence for continuous circulation of human viruses in the pig population.an influenza virus strain isolated in northern italy in 1977 was identified as belonging to the h3n2 subtype (a/swine/italy/1850/77). a close antigenic relationship to the human strain a/england/42/72 was demonstrated. serologic surveys of 548 pig sera from 53 farms in two provinces in northern italy demonstrated the existence of antibodies to the swine/italy/1850/77 strain and to a/hong kong/1/68, a/victoria/3/75 and h 1 n 1 (hsw 1 n 1) strains in the pig population.19826184032
serological evidence of natural recombinant influenza virus (hsw1n2) infection among pigs in japan.a new recombinant influenza a virus (hsw1n2) infection among hogs in miyagi prefecture, japan, was confirmed by serological examinations. nineteen out of twenty sera collected in one farm in january 1979 showed high haemagglutination inhibition antibody titres to hsw1 antigen (a/new jersey/8/76) and also significant neuraminidase inhibition antibody titres to n2 antigen of the hong kong 1973 variant (a/port chalmers/1/73) but not to n1 antigen. the results indicate the occurrence of genetic reas ...19816116417
nucleoproteins of animal influenza viruses, in contrast to those of human strains, are not cleaved in infected cells.we previously reported that nucleoproteins (nps) of human influenza viruses are cleaved in infected cells and, as a result, two forms of np, uncleaved (mol. wt. 56000) and cleaved (mol. wt. 53000) were accumulated late in infection. here, we report that nps of animal influenza viruses of non-human origin (isolated from pigs, equids , seals, whales, birds) exhibited proteolytic resistance in infected cells and did not undergo a change in mol. wt. in the course of infection. the resistance of the ...19846374032
surveillance of influenza in houston, texas, usa: gradual transition from a/victoria/75 (h3n2) to a/texas/77 (h3n2) predominance and antigenic characterization of "intermediate" strains.influenza epidemics in houston, texas, usa, during the winters of 1975-76, 1976-77, and 1977-78 were attributed to a/victoria/3/75 (h3n2), b/hong kong/5/72, and a/texas/1/77 (h3n2)-like viruses, respectively. both a/victoria and a/texas viruses were detected towards the end of the 1976-77 epidemic and throughout the 1977-78 epidemic. to determine if there had been a gradual transition in the predominant strain, 267 viral isolates from the 1975-76 epidemic were tested for a/texas virus. eight spe ...19836190585
antigenic characteristics and genome composition of a naturally occurring recombinant influenza virus isolated from a pig in japan.we performed antigenic analysis of the haemagglutinin and neuraminidase subunits of a recombinant virus (a/swine/kanagawa/2/78) isolated from a pig in japan in 1978, using a series of monoclonal antibodies to h1 (hsw1) haemagglutinin and n2 neuraminidases of h2n2 and h3n2 viruses. results obtained in haemagglutination inhibition tests with five monoclonal antibodies to the haemagglutinin of a/nj/8/76 (h1n1) revealed that the haemagglutinin of three h1n1 and the recombinant viruses were indisting ...19836198440
zoonotic studies on influenza in pigs and birds, india, 1980-81.five hundred and twenty pig sera collected from pune, maharashtra state, india during 1980 were examined in haemagglutination inhibition (hi) tests to determine the antibody prevalence to nine human influenza virus strains covering the subtypes a(hon1), a(h1n1), a(h2n2), a(h3n2), type b and one swine influenza virus strain a(hsw1n1). this study indicated considerable prevalence of antibodies to the four h3n2 strains isolated from 1973 onwards, particularly to the two recent h3n2 strains, limited ...19836315619
isolation of a recombinant influenza virus (hsw 1 n2) from swine in japan.outbreaks of swine influenza were first observed in japan in 1978. a number of influenza viruses were isolated from diseased swine. almost all viruses isolated were swine influenza virus (hsw 1 n1) but two viruses isolated from the nasal swabs of swine showing clinical signs of influenza in the kanagawa prefecture were characterized antigenically as hsw 1 n2. analysis of swine sera showed that influenza virus hsw 1 n2 was epidemic in the farm from which the virus had been isolated. the new virus ...19806255900
lung alterations in guinea-pigs infected with influenza virus.guinea-pigs were infected intranasally with influenza a hong kong 68 (h3n2) virus. infective particles were re-isolated from lung homogenates up to 3 days after inoculation and indicated local replication. the subsequent lung inflammatory stages were studied by light microscopy, scanning and transmission electron microscopy (tem). lung alterations appeared after 24 h and intensified up to 7 days after virus inoculation, progressively decreasing until 3 weeks thereafter. the damage was reversible ...19846330181
prevalence of influenza viruses a-h1n1 and a-h3n2 in swine in the netherlands.in the period december 1979-may 1980 a respiratory disease spread rapidly through pig herds in the netherlands. surveillance of 12 pig farms resulted in isolation of 22 influenza a-swine-h1n1 (hsw1n1) strains from 9 pig herds. the morbidity rate was high but the mortality rate was nil. retardation in growth was observed. sera collected from affected pig herds showed a fourfold increase in haemagglutination inhibition (hi) titre against a-swine-h1n1 virus. sera collected on five farms showed a ge ...19836851479
reactogenicity, immunogenicity, and antibody persistence in adults given inactivated influenza virus vaccines - 1978.monovalent a/ussr/77 (h1n1) and trivalent a/ussr/77, a/texas/77 (h3n2), and b/hong kong/72 influenza virus vaccines from four manufacturers were tested in 292 adult volunteers. systemic reactions were mild and resembled those with 1976 (swine) vaccines containing similar doses (in micrograms) of viral hemagglutinin. trivalent vaccines caused more local inflammation than did monovalent, especially in older women. two doses containing 7 micrograms of hemagglutinin each were required to induce a ti ...19836622888
the ecology of influenza viruses: a who memorandum.influenza a viruses continue to be isolated from man, pigs, horses, and a wide range of avian species, especially ducks. the recent isolation of an influenza a virus from seals has added an additional mammal to the list of natural hosts for these viruses. in contrast, influenza b viruses have been isolated only from man.the haemagglutinin of a virus isolated from gulls in the united states of america could not be identified with reference antisera and may constitute a new haemagglutinin subtype. ...19816978194
[comparison of the 35s-methionine oligopeptide maps of influenza a virus np proteins].tryptic mapping of radioactive methionine-labeled np proteins of 15 species of human influenzae a viruses and 11 animal viruses was performed. on the basis of similarities and differences of peptide maps, np proteins were divided into 4 groups designated a, b, c, and d. group a included viruses a/ws/33 and a/pr/8/34; group b viruses h1n1 (apart from those isolated after 1977 and wsn virus), h2n2, h3n2, and 8 species of animal influenza viruses, group c 4 species of h1n1 viruses isolated in 1977- ...19836659469
evidence for interspecies transmission and reassortment of influenza a viruses in pigs in southern china.the asian/57, hong kong/68, and russian/77 pandemics of this century appeared or reappeared in china. interspecies transmission and genetic reassortment of influenza viruses have been implicated in the origin of these human pandemic influenza viruses. pigs have been suspected to be the "mixing vessel" where reassortment occurs. to investigate this possibility, 104 porcine influenza viruses collected at random from southern china from 1976 to 1982, including 32 h3n2 isolates and 72 h1n1 isolates, ...19948030245
serological studies on swine influenza in egypt.480 pig serum samples collected from november 1979-october 1980 and 200 human sera collected in the same period, nearly have been used in serological investigations. 52.5% sera were positive against swine influenza (hsw1n1) 10% only of human sera were positive against (hsw1n1) virus. by using (h3n2) human virus, 10.4% of pig sera were positive, while 41% of human sera were positive against this virus.19816282772
prevalence of hemagglutination inhibition antibody to current strains of the h3n2 and h1n1 subtypes of influenza a virus in sera collected from the elderly in 1976.sera were collected in 1976 from 182 individuals born between 1876-1935, who included patients in a large local nursing home in orange county, california, and patients and staff at the university of california, irvine medical center. sera were treated with receptor-destroying enzyme and assayed for hemagglutination inhibition (hi) antibody to recent strains of influenza a virus. the antigens tested were: a/victoria/3/76 and a/texas/1/77 for subtype h3n2; a/new jersey/8/76, a/x53 and a/swine/1976 ...19827072705
analysis of the influenza virus gene pool of avian species from southern china.although southern china has been considered the epicenter of human influenza pandemics, little is known about the genetic composition of influenza viruses in lower mammals or birds in that region. to provide information on the molecular epidemiology of these viruses, we used dot blot hybridization and phylogenetic methods to study the internal genes (pb1, pb2, pa, np, m, and ns) of 106 avian influenza a viruses isolated from a total of 11,798 domestic ducks, chickens, and geese raised in souther ...19948291238
the binding of staphylococcal protein a by the sera of different animal species.the capacity of purified immunoglobulin or serum to bind (125i)-labeled staphylococcal protein a (spa) was measured by means of an immunofiltration assay that facilitated the examination of large numbers of sera and required only a minute quantity of each. sera from 80 species, including humans, laboratory animals, domestic animals, and a variety of african mammals were examined. a wide interspecies variation in the spa-binding capacity of serum immunoglobulins was confirmed. only small variatio ...19827061862
[epizootic swine influenza on animal farms in brittany].since 1976, seroepidemiological surveys using radial haemolysis and isolation trials from samples collected from pigs at the abattoir showed that brittany was an important reservoir of swine subclinical infections due to the human influenza a viruses h3n2. influenza a h1sw n1sw subclinical infections sporadically occurred from 1979 to 1981. in january 1982 an epizootic started in finistère which spread from west to east. the h1sw and n1sw antigens of 28 stains isolated from 1979 to 1982 were stu ...19836658105
prevalence of infections with enzootic respiratory and enteric viruses in feeder pigs entering fattening herds.the prevalence of infections with h1n1- and h3n2-influenza viruses, porcine respiratory coronavirus (prcv), transmissible gastroenteritis virus (tgev) and porcine epidemic diarrhoea virus (pedv) in feeder pigs shortly after their entry into fattening units was examined. ten groups of pigs with acute respiratory disease during the months september to october 1991 and seven groups of pigs with acute diarrhoea during the months february to march 1992 were investigated. on arrival in the fattening h ...19947900243
recent h3n2 swine influenza virus with haemagglutinin and nucleoprotein genes similar to 1975 human strains.of the four pandemic strains of human influenza a virus observed this century, the 1977 virus strain was very similar in all genes to a 1950 isolate. since mammalian influenza a viruses change annually by genetic drift, this reappearance could only be attributed at that time to conservation of the virus in a frozen state. we report here the isolation of swine influenza a viruses with haemagglutinin and nucleoprotein genes which are virtually identical to those of the human virus that circulated ...19957897358
determination of hemagglutination-inhibition titers to influenza a virus in porcine sera by use of an enzyme-linked immunosorbent assay.an elisa-based method to estimate hemagglutination-inhibition (hi) titer was developed. subtype specificity was obtained by using purified h1 and h3 hemagglutinin antigens. using the linear relation that exists between elisa and hi methods, regression lines for h1n1- and h3n2-monospecific porcine antisera were constructed. approximation of actual hi titer could be obtained from insertion of elisa values into the appropriate regression line. the hi estimations were within 50% of the actual measur ...19938214894
serological studies on the potential synergism of porcine reproductive and respiratory syndrome virus and influenza-, corona- and paramyxoviruses in the induction of respiratory symptoms in swine.sera from 265 finishing pigs belonging to 70 herds, in which severe respiratory disorders were observed, were examined for antibody prevalence to porcine reproductive and respiratory syndrome virus (prrsv), influenza virus subtypes h3n2 and h1n1, porcine respiratory corona virus (prcv) and a recently described porcine paramyxovirus (ppmv). by immunoperoxidase-monolayer assay 69.1% of these sera were positive for prrsv. hemagglutination inhibiting activity was found in 55.1% of the sera for influ ...19938128802
[factors associated with the occurrence of influenza a virus infections in fattening swine].in august of 1989 sera from 2115 finishing pigs out of 214 herds in the north of schleswig- holstein (germany) were tested for antibodies against three strains of influenza a viruses by using the haemagglutination inhibition test. seroprevalences of a/swine/nederland/25/80 (h1n1), a/philippines/2/82 (h3n2), and a/port chalmers/1/73 (h3n2) on herd level were 23.4%, 20.6% and 5.1% respectively. the mean within herd prevalences were 9.6%, 14.7% and 0.6%, respectively. antibodies against h1n1 and h3 ...19947945181
antigenic characterization of an h3n2 swine influenza virus isolated from pigs with proliferative and necrotizing pneumonia in quebec.a new strain of swine influenza a virus, designated a/swine/saint-hyacinthe/150/90 has been isolated from pigs with severe proliferative and necrotizing pneumonia in quebec. the antigenic characterization of the hemagglutinin was performed by hemagglutination inhibition test, immunoblot and indirect immunoprecipitation using polyclonal antisera. only the last test was able to detect an antigenic relationship between the hemagglutinin of this isolate and an h3 subtype influenza virus. the immunop ...19947889461
genetic analysis of porcine h3n2 viruses originating in southern china.from immunological and phylogenetic analyses of h3 influenza viruses isolated from pigs and ducks in the people's republic of china (china), hong kong, taiwan and japan, between 1968 and 1982, we arrived at the following conclusions. the h3 haemagglutinin and n2 neuraminidase genes from swine isolates can be segregated into four mammalian lineages, including: (i) the earliest human strains; (ii) early swine strains including hong kong isolates from 1976-1977; (iii) an intermediate strain between ...19957897351
[pneumonia diagnosis in living swine using lung lavage].in pigs coming from fattening units with tenacious pneumonitis problems the attempt was made to find an etiological diagnosis in living pigs by bronchoalveolar lavage (bal) and serological examinations on antibodies against mycoplasma hyopneumonia, actinobacillus pleuropneumoniae and influenza-a-virus (serotypes h1n1 and h3n2). in some cases the results of the bacteriological examinations of the bal were compared with the post mortem findings. both methods yield similar results. mycoplasma hyopn ...19938250824
dual infections of prrsv/influenza or prrsv/actinobacillus pleuropneumoniae in the respiratory tract.to study the effect of a previous porcine respiratory and reproductive syndrome-infection (prrs) of the respiratory tract on influenza virus and actinobacillus pleuropneumoniae (app) infections, 3-week-old specific-pathogen-free (spf) piglets were intranasally infected with prrs virus. one week later, when the lung alveolar macrophages of prrsv infected pigs were lowest in number, a second infection was applied by intranasal aerosol of influenza virus h3n2 or by endobronchial instillation of a m ...19979220621
serological studies of influenza viruses in pigs in great britain 1991-2.samples from a sow serum bank representative of the pig population of great britain collected during 1991-2, were examined for antibodies to influenza a, b and c viruses, using viruses which had been isolated from a variety of hosts. for influenza a viruses there was evidence of the continued circulation of classical swine h1n1 virus (26%) seroprevalence), and human h3n2 viruses (39%) which are antigenically most closely-related to a/port chalmers/1/73 virus. in addition antibodies were detected ...19957781739
large outbreak of swine influenza in southern japan caused by reassortant (h1n2) influenza viruses: its epizootic background and characterization of the causative viruses.in the winter of 1989 and the spring of 1990, there were large outbreaks of respiratory disease in two swine herds in nagasaki prefecture, southern japan. serological surveillance indicated that the majority of swine possessed antibodies to swine influenza virus h1 haemagglutinin and neuraminidase of early h3n2 influenza virus strains. eight viruses were isolated from swine that showed typical clinical symptoms of influenza. the haemagglutinin and neuraminidase of these isolates were closely rel ...19968760422
type- and subtype-specific detection of influenza viruses in clinical specimens by rapid culture assay.a rapid culture assay which allows for the simultaneous typing and subtyping of currently circulating influenza a(h1n1), a(h3n2), and b viruses in clinical specimens was developed. pools of monoclonal antibodies (mabs) against influenza a and b viruses and mabs ha1-71 and ha2-76, obtained by immunizing mice with the denatured hemagglutinin subfragments ha1 and ha2 of influenza virus a/victoria/3/75, were used for immunoperoxidase staining of antigens in infected mdck cells. mab ha1-71 reacted ex ...19957714186
an epidemiological study of influenza viruses among chinese farm families with household ducks and pigs.to examine the possibility of interspecies transmission and genetic reassortment of influenza viruses on farms in southern china, we surveyed 20 farm families living outside the city of nanchang who raised pigs and ducks in their homes. weekly interviews of family members and virus isolation studies of throat swabs and faecal samples, collected from september 1992 to september 1993, established the seasonal pattern of respiratory tract infections in these families and identified 11 influenza vir ...19968760967
two evolutionary strategies of influenza viruses to escape host non-specific inhibitors: alteration of hemagglutinin or neuraminidase specificity.the porcine serum inhibitor alpha 2-macroglobulin prevents influenza virus from entering host cells by competing for the sa alpha 2, 6gal-binding site of the hemagglutinin (ha). we studied a series of inhibitor-sensitive and inhibitor-resistant human and porcine influenza virus isolates of the h3n2 subtype, all of which contained has, which initially bound only to sa alpha 2, 6gal oligosaccharides. when their neuraminidase was inhibited, the naturally resistant viruses, as a result of no longer ...19968806180
alpha 2-macroglobulin is the major neutralizing inhibitor of influenza a virus in pig serum.horse, pig, and rabbit sera contain distinct glycoprotein inhibitors of influenza a viruses that inhibit hemagglutinating activity and neutralize viral infectivity. although alpha 2-macroglobulin has been identified as the inhibitor in horse serum, the inhibitors in pig and rabbit sera have not been identified. as an initial step in elucidating the structural differences among inhibitor molecules, we sought to isolate the inhibitor in pig serum. the purified inhibitor decreased the hemagglutinat ...19937681613
multiple genetic reassortment of avian and human influenza a viruses in european pigs, resulting in the emergence of an h1n2 virus of novel genotype.novel h1n2 influenza a viruses which were first detected in pigs in great britain in 1994 were examined antigenically and genetically to determine their origins and establish the potential mechanisms for genetic reassortment. the haemagglutinin (ha) of all swine h 1 n2 viruses examined was most closely related to, but clearly distinguishable both antigenically and genetically from, the ha of human h1n1 viruses which circulated in the human population during the early 1 980s. phylogenetic analysi ...19989880008
evaluation of a protective immunity induced by an inactivated influenza h3n2 vaccine after an intratracheal challenge of pigs.a challenge study was conducted to evaluate the safety and efficacy of an inactivated influenza h3n2 virus vaccine combined with quil a/alhydrogel mixture under controlled conditions in piglets. twenty-four piglets from 12 sows were allocated to 2 groups; injected intramuscularly with 2 doses of the tested vaccine or with pbs at 2 wk intervals and challenged intratracheally with 105tcid50 of the h3n2 swine influenza virus 6 d after the 2nd immunization. clinical and virological parameters were r ...19968904668
prevalence of antibodies to type a influenza viruses in swine sera 1990-1994.a total of 3,120 swine sera collected for the years 1990-94 were tested for the presence of hemagglutination-inhibition (hi) antibodies against swine (h1n1) and human (h1n1 and h3n2) strains of influenza virus. no hi antibody against the swine strains was recognized during 18 months, though a slight prevalence (1.5-9.2%) of the antibodies was observed over the entire period. a wide variance in the incidence (0-26.3%) of antibodies against the human h3n2 strains was observed among the swine popul ...19958519918
a longitudinal study of serological patterns of respiratory infections in nine infected danish swine herds.sixteen litters of seven pigs from each of nine danish farrow-to-finish herds were followed to investigate the serological patterns caused by natural infection with mycoplasma hyopneumoniae, pasteurella multocida toxin and actinobacillus pleuropneumoniae serotypes 2, 5-7, 12. in seven of the herds, pigs were followed as two separate cohorts started 4 weeks apart, and in two herds only one cohort was followed.a total of 999 pigs were included in the study. the pigs were blood sampled at weaning a ...200010821962
infection of children with avian-human reassortant influenza virus from pigs in europe.pigs have been proposed to act as the intermediate hosts in the generation of pandemic human influenza strains by reassortment of genes from avian and human influenza virus strains. the circulation of avian-like h1n1 influenza viruses in european pigs since 1979 and the detection of human-avian reassortants in pigs raises the question of whether these viruses actually have the potential to transmit and cause disease in humans. we now report the serologic and genetic characterization of two human ...19948091678
antigenic and sequence analysis of h3 influenza virus haemagglutinins from pigs in italy.to investigate the possible mechanism of maintenance of old human influenza a (h3n2) viruses in pigs, the haemagglutinins (has) of seven isolates from swine were studied by analysis of nucleotide and deduced primary amino acid sequences, as well as reactivity of the ha molecule to chicken antisera and monoclonal antibodies. the swine has were closely similar to the ha of the a/victoria/3/75 human variant as regards antigenic and molecular characteristics. these findings are consistent with the h ...19948113758
genetic reassortment between avian and human influenza a viruses in italian pigs.pandemic strains of influenza a virus arise by genetic reassortment between avian and human viruses. to examine the possibility that pigs serve as "mixing vessels" for such reassortment events (scholtissek et al., virology 147, 287-294, 1985), we phylogenetically analyzed the internal protein genes of classic h1n1, avian-like h1n1, and human-like h3n2 viruses circulating among italian pigs. the results show that human-like h3n2 strains isolated from 1985 to 1989 contained the internal protein ge ...19938438586
antigenic and genetic analyses of the hemagglutinin of influenza viruses isolated from pigs in 1993.three strains of influenza a virus (h3n2) were isolated from pigs in hokkaido, japan in 1993. the hemagglutinin (ha) antigen of the three isolates was related to that of recent h3n2 viruses of human origin. the reactivity patterns of two of the isolates (a/sw/obihiro/1/93 and a/sw/obihiro/2/93) with monoclonal antibodies to the hemagglutinin of a/bangkok/1/79 strain were similar to that of the human h3n2 strain isolated in hokkaido in 1988, while that of the other one (a/sw/obihiro/3/93) was sim ...19958720040
systemic and mucosal isotype-specific antibody responses in pigs to experimental influenza virus infection.the immunoglobulin isotype-specific responses in serum and at the respiratory mucosa of pigs after a primary infection with influenza virus were studied. to do this, we developed an aerosol challenge model for influenza in specified pathogen-free (spf) pigs and isotype-specific enzyme-linked immunosorbent assays (elisas). ten-week-old pigs were inoculated without anesthesia in the nostrils with an aerosol of the field isolate influenza a/swine/neth/st. oedenrode/96 (h3n2). the infection caused a ...200010893003
influenza--a model of an emerging virus disease.influenza a viruses continue to emerge from the aquatic avian reservoir and cause pandemics. phylogenetic analysis of the nucleotide sequence of all eight influenza a virus rna segments indicate that all of the influenza viruses in mammalian hosts originate from the avian gene pool. in contrast to the rapid progressive changes in both the nucleotide and amino acid sequences of mammalian virus gene lineages, avian virus genes show far less variation and, in most cases, appear to be in evolutionar ...19938407243
herd factors associated with the seroprevalences of four major respiratory pathogens in slaughter pigs from farrow-to-finish pig herds.the objective of this study was to investigate sero-epidemiological aspects of mycoplasma hyopneumoniae (mh), influenza h1n1 and h3n2 viruses and aujeszky disease virus (adv) in fattening pigs from 150 randomly selected farrow-to-finish pig herds. different herd factors were examined as potential risk indicators for the percentage of pigs with antibodies against the 4 pathogens. the median within-herd seroprevalences of the pathogens were: mh 76%, h1n1 100%, h3n2 40% and adv 53%. there was a pos ...200010863948
genetic reassortment of avian, swine, and human influenza a viruses in american pigs.in late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of north carolina, texas, minnesota, and iowa. four viral isolates from outbreaks in different states were analyzed genetically. genotyping and phylogenetic analyses demonstrated that the four swine viruses had emerged through two different pathways. the north carolina isolate is the product of genetic reassortment between h3n2 human and classic swine h1n1 influenza viruses, while ...199910482643
a serological survey of influenza a antibody in human and pig sera in calcutta.a study was undertaken with a view to assess the distinct pattern of sero-prevalence of influenza a viruses in the city of calcutta population during the years of 1981-90. concurrently, based on the fact of increasing pig population, a study was carried out to establish the activity of the human influenza a virus among pigs with a view to the potential threat of emergence of a new strain of influenza a virus that may surface following co-infection with swine and human influenza a viruses. the pe ...19958919937
risk indicators for the seroprevalence of mycoplasma hyopneumoniae, porcine influenza viruses and aujeszky's disease virus in slaughter pigs from fattening pig herds.epidemiological aspects of mycoplasma hyopneumoniae (mh), influenza h1n1 and h3n2 viruses, and aujeszky's disease virus (adv) were investigated in slaughter pigs from 50 fattening pig herds. herd factors as potential risk indicators for respiratory disease were obtained by means of a questionnaire. at slaughter, blood samples were collected from each herd, and the proportion of seropositive pigs per herd was assessed for each of these pathogens. the median herd-level seroprevalence of the agents ...199910416368
continued evolution of h1n1 and h3n2 influenza viruses in pigs in italy.swine influenza viruses possessing avian genes were first detected in europe in 1979 (scholtissek et al., 1983, virology, 129, 521-523) and continue to circulate in pigs in that region of the world. to characterize the molecular epidemiology of swine influenza viruses currently circulating in europe, we used dot-blot hybridization and sequence analysis to determine the origin of the genes encoding the nonsurface proteins ("internal" genes) of 10 h1n1 and 11 h3n2 swine influenza viruses isolated ...19979191844
emergence of avian h1n1 influenza viruses in pigs in china.avian influenza a viruses from asia are recognized as the source of genes that reassorted with human viral genes to generate the asian/57 (h2n2) and hong kong/68 (h3n2) pandemic strains earlier in this century. here we report the genetic analysis of avian influenza a h1n1 viruses recently isolated from pigs in southern china, a host suspected to generate new pandemic strains through gene reassortment events. each of the eight gene segments was of avian origin. phylogenetic analysis indicates tha ...19968892928
inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (sambucus nigra l.) during an outbreak of influenza b panama.a standardized elderberry extract, sambucol (sam), reduced hemagglutination and inhibited replication of human influenza viruses type a/shangdong 9/93 (h3n2), a/beijing 32/92 (h3n2), a/texas 36/91 (h1n1), a/singapore 6/86 (h1n1), type b/panama 45/90, b/yamagata 16/88, b/ann arbor 1/86, and of animal strains from northern european swine and turkeys, a/sw/ger 2/81, a/tur/ger 3/91, and a/sw/ger 8533/91 in madin-darby canine kidney cells. a placebo-controlled, double blind study was carried out on a ...19959395631
influenza infection in humans and pigs in southeastern china.the three last pandemic strains of influenza a virus-asian/57, hong kong/68 and russian/77-are believed to have originated in china. the strains responsible for the 1957 and 1968 human pandemics were reassortants incorporating both human and avian influenza viruses, which may have arisen in pigs. we therefore undertook a population-based study in the nanchang region of central china to establish the prevalence, types and seasonal pattern of human influenza infection and to screen serum samples f ...19968645101
molecular mechanisms of serum resistance of human influenza h3n2 virus and their involvement in virus adaptation in a new host.h3n2 human influenza viruses that are resistant to horse, pig, or rabbit serum possess unique amino acid mutations in their hemagglutinin (ha) protein. to determine the molecular mechanisms of this resistance, we characterized the receptor-binding properties of these mutants by measuring their affinity for total serum protein inhibitors and for soluble receptor analogs. pig serum-resistant variants displayed a markedly decreased affinity for total pig serum sialylglycoproteins (which contain pre ...19989658077
perspectives on pandemics: a research agenda.during the 20th century, indisputable pandemics of influenza occurred in 1918, 1957, and 1968. the pandemics of 1957 (a/h2n2) and 1968 (a/h3n2) were associated with major antigenic changes in the virus, probably reflecting introduction by recombination of animal virus genes. the 1918 epidemic is beyond the reach of modern virology but, based on seroarcheology, appears to have been caused by a virus very similar to present swine (a/h1n1) influenza viruses. changes in both principal antigens of th ...19979240691
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