RESUMO
An indirect fluorescent antibody (IFA) technique was used to screen and quantify antibodies against African horse sickness virus (AHSV) in equine sera. Results obtained with the IFA assay were compared directly with those obtained with standard complement fixation (CF) and virus neutralisation (VN) tests using horse sera from experimental studies and samples from the field. Positive fluorescent antibody titres were detected from as early as 7 days after primary vaccination and persisted for at least six months. The IFA technique offers a clear advantage over CF tests, where the antibodies are often of shorter duration and where sera from donkeys and mules are frequently anticomplementary. The sensitivity and specificity of the IFA test compared with the VN test were 98% and 83.3%, respectively. The IFA test is rapid, relatively easy to perform and inexpensive, and can be recommended as an alternative assay for screening different species of equidae in AHSV control and surveillance programmes.
Assuntos
Vírus da Doença Equina Africana/imunologia , Doença Equina Africana/imunologia , Anticorpos Antivirais/sangue , Equidae , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Vacinas Virais/imunologia , Doença Equina Africana/prevenção & controle , Animais , Testes de Fixação de Complemento/veterinária , Imunização Secundária/veterinária , Testes de Neutralização/veterinária , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Vacinação/veterináriaRESUMO
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 recorded for 4 d after the challenge. The use of the tested vaccine produced high serum hemagglutination-inhibition titers against the swine H3N2 strain virus. This strong immune response suppressed all clinical signs and viral shedding and reduced pulmonary lesions due to the challenge in the vaccinated group, without causing any secondary effects. Our results suggest that the serum HI titers correlated with the degree of protection induced by an inactivated swine influenza H3N2 vaccine.
Assuntos
Imunidade Inata/imunologia , Vacinas contra Influenza/normas , Infecções por Orthomyxoviridae/veterinária , Doenças dos Suínos/imunologia , Doenças dos Suínos/prevenção & controle , Vacinas de Produtos Inativados/normas , Animais , Anticorpos Antivirais/análise , Feminino , Vírus da Influenza A Subtipo H3N2 , Vírus da Influenza A/imunologia , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/imunologia , Injeções Intramusculares , Modelos Lineares , Masculino , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/prevenção & controle , Análise de Regressão , Suínos , Doenças dos Suínos/patologia , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologiaRESUMO
Two antigenically distinct H1N1 influenza A viruses were isolated during an outbreak of respiratory disease in Quebec swine in 1990/91. Analysis of haemagglutinin and partial nucleoprotein sequences indicated that one was a variant of the swine H1N1 influenza virus circulating in the American Midwest whereas the other was very similar to virus isolated from swine in 1930. The existence of this latter isolate supports the concept that influenza viruses can be maintained for long periods in swine, perhaps in geographically limited pockets. Serological evidence indicates that these distinct strains continued to circulate widely in south-central Quebec until at least 1993.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Vírus da Influenza A/genética , Vírus da Influenza A/imunologia , Infecções por Orthomyxoviridae/veterinária , Filogenia , Doenças dos Suínos/virologia , Sequência de Aminoácidos , Animais , Variação Antigênica , Antígenos Virais/análise , Sequência de Bases , Capsídeo/genética , Surtos de Doenças , Glicoproteínas de Hemaglutininação de Vírus da Influenza , Hemaglutininas Virais/análise , Hemaglutininas Virais/genética , Dados de Sequência Molecular , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/virologia , Quebeque/epidemiologia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Suínos , Doenças dos Suínos/epidemiologia , Proteínas do Core Viral/genéticaRESUMO
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 in 1975. We have also found serological evidence that this virus is circulating extensively in Quebec swine herds. We propose that human-like H3N2 influenza A strains may remain invariant for long periods in swine, which may serve as a reservoir for human pandemics.
Assuntos
Variação Antigênica/genética , Genes Virais/genética , Hemaglutininas Virais/genética , Vírus da Influenza A Subtipo H3N2 , Vírus da Influenza A/genética , Nucleoproteínas/genética , Proteínas de Ligação a RNA , Proteínas do Core Viral/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Hemaglutininas Virais/química , Humanos , Vírus da Influenza A/química , Dados de Sequência Molecular , Proteínas do Nucleocapsídeo , Nucleoproteínas/química , Filogenia , Quebeque , Análise de Sequência de DNA , Suínos , Proteínas do Core Viral/químicaRESUMO
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 immunoprecipitation test was a useful alternative for determining the hemagglutinin of influenza A virus subtypes. The neuraminidase inhibition test demonstrated a reactivity between the A/Swine/Saint-Hyacinthe/150/90 and antiserum against a N2 subtype influenza virus. Our results indicate that this new strain isolated for the first time in the porcine population of Canada is related to A/Sw/Hong Kong/76 H3N2 swine influenza virus.
