RESUMO
BACKGROUND: The highly pathogenic H5N1 and H9N2 influenza viruses are endemic in many countries around the world and have caused considerable economic loss to the poultry industry. Objectives We aimed to study whether a live attenuated H5N1 vaccine comprising internal genes from a cold-adapted H9N2 influenza virus could protect chickens from infection by both H5N1 and H9N2 viruses. METHODS: We developed a cold-adapted H9N2 vaccine virus expressing hemagglutinin and neuraminidase derived from the highly pathogenic H5N1 influenza virus using reverse genetics. RESULTS AND CONCLUSIONS: Chickens immunized with the vaccine were protected from lethal infections with homologous and heterologous H5N1 or H9N2 influenza viruses. Specific antibody against H5N1 virus was detected up to 11 weeks after vaccination (the endpoint of this study). In vaccinated chickens, IgA and IgG antibody subtypes were induced in lung and intestinal tissue, and CD4+ and CD8+ T lymphocytes expressing interferon-gamma were induced in the splenocytes. These data suggest that a live attenuated H5N1 vaccine with cold-adapted H9N2 internal genes can protect chickens from infection with H5N1 and H9N2 influenza viruses by eliciting humoral and cellular immunity.
Assuntos
Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/imunologia , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/imunologia , Vacinas contra Influenza/imunologia , Infecções por Orthomyxoviridae/prevenção & controle , Animais , Anticorpos Antivirais/análise , Anticorpos Antivirais/sangue , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Galinhas , Expressão Gênica , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Imunoglobulina A/análise , Imunoglobulina A/sangue , Imunoglobulina G/análise , Imunoglobulina G/sangue , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/genética , Interferon gama/biossíntese , Intestinos/imunologia , Pulmão/imunologia , Neuraminidase/genética , Neuraminidase/imunologia , Doenças das Aves Domésticas/prevenção & controle , Genética Reversa/métodos , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologiaRESUMO
H9N2 influenza virus is endemic in many Asian countries and is regarded as a candidate for the next human pandemic. Knowledge of the induction of inflammatory responses and toll-like receptors (TLRs) in chickens infected with H9N2 is limited. Here, we show that H9N2 induces pro-inflammatory cytokines such as transforming growth factor-beta 3; tumor necrosis factor-alpha; interferon-alpha, -beta, and gamma; and TLR 1, 2, 3, 4, 5, 7, and 15 in trachea, lung, and intestine of infected chickens. In the lung, TLR-15 was dominantly induced. Taken together, it seems that H9N2 infections efficiently induce inflammatory cytokines and TLRs in trachea, lung and intestine of chickens.
