RESUMO
The H9N2 influenza viruses that have become established in Bangladeshi live poultry markets possess five gene segments of the highly pathogenic H7N3 avian influenza virus. We assessed the replication, transmission, and disease potential of three H9N2 viruses in chickens and New World quail. Each virus replicated to high titers and transmitted by the airborne route to contacts in both species. Infected chickens showed no disease signs, and the viruses differed in their disease potential in New World quail. New World quail were more susceptible than chickens to H9N2 viruses and shed virus after airborne transmission for 10 days. Consequently, New World quail are a potential threat in the maintenance and spread of influenza virus in live poultry markets.
Assuntos
Galinhas , Vírus da Influenza A Subtipo H9N2/isolamento & purificação , Influenza Aviária/virologia , Codorniz , Animais , Bangladesh , Suscetibilidade a Doenças , Transmissão de Doença Infecciosa , Vírus da Influenza A Subtipo H9N2/patogenicidade , Vírus da Influenza A Subtipo H9N2/fisiologia , Influenza Aviária/patologia , Infecções por Orthomyxoviridae , Replicação ViralRESUMO
Avian influenza A(H9N2) is an agricultural and public health threat. We characterized an H9N2 virus from a pet market in Bangladesh and demonstrated replication in samples from pet birds, swine tissues, human airway and ocular cells, and ferrets. Results implicated pet birds in the potential dissemination and zoonotic transmission of this virus.
Assuntos
Vírus da Influenza A Subtipo H9N2/patogenicidade , Influenza Aviária/patologia , Influenza Humana/transmissão , Animais , Animais Exóticos/genética , Animais Exóticos/virologia , Bangladesh , Galinhas/genética , Galinhas/virologia , Surtos de Doenças , Furões/genética , Furões/virologia , Humanos , Vírus da Influenza A Subtipo H9N2/genética , Influenza Aviária/genética , Influenza Aviária/transmissão , Influenza Humana/patologia , Filogenia , Pardais/genética , Pardais/virologia , Suínos/genética , Suínos/virologiaRESUMO
Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011. Surveillance for influenza viruses in apparently healthy poultry in live-bird markets in Bangladesh during 2008-2011 showed that subtype H9N2 viruses are isolated year-round, whereas highly pathogenic subtype H5N1 viruses are co-isolated with subtype H9N2 primarily during the winter months. Phylogenetic analysis of the subtype H9N2 viruses showed that they are reassortants possessing 3 gene segments related to subtype H7N3; the remaining gene segments were from the subtype H9N2 G1 clade. We detected no reassortment with subtype H5N1 viruses. Serologic analyses of subtype H9N2 viruses from chickens revealed antigenic conservation, whereas analyses of viruses from quail showed antigenic drift. Molecular analysis showed that multiple mammalian-specific mutations have become fixed in the subtype H9N2 viruses, including changes in the hemagglutinin, matrix, and polymerase proteins. Our results indicate that these viruses could mutate to be transmissible from birds to mammals, including humans.
Assuntos
Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/imunologia , Influenza Aviária/epidemiologia , Influenza Humana/epidemiologia , Animais , Antígenos Virais/imunologia , Bangladesh/epidemiologia , Galinhas , Genes Virais , Humanos , Vírus da Influenza A Subtipo H9N2/classificação , Influenza Aviária/virologia , Influenza Humana/virologia , Dados de Sequência Molecular , Filogenia , Prevalência , CodornizRESUMO
Avian influenza surveillance in Bangladesh has been passive, relying on poultry farmers to report suspected outbreaks of highly pathogenic H5N1 influenza. Here, the results of an active surveillance effort focusing on the live-bird markets are presented. Prevalence of influenza infection in the birds of the live bird markets is 23.0%, which is similar to that in poultry markets in other countries. Nearly all of the isolates (94%) were of the non-pathogenic H9N2 subtype, but viruses of the H1N2, H1N3, H3N6, H4N2, H5N1, and H10N7 subtypes were also observed. The highly pathogenic H5N1-subtype virus was observed at extremely low prevalence in the surveillance samples (0.08%), and we suggest that the current risk of infection for humans in the retail poultry markets in Bangladesh is negligible. However, the high prevalence of the H9 subtype and its potential for interaction with the highly pathogenic H5N1-subtype, i.e., reassortment and attenuation of host morbidity, highlight the importance of active surveillance of the poultry markets.
