RESUMO
Three highly pathogenic H5N5 avian influenza viruses (HPAI), A/duck/Guangdong/wy11/2008 (WY11), A/duck/Guangdong/wy19/2008 (WY19), and A/duck/Guangdong/wy24/2008 (WY24) were isolated from ducks in southern China in April 2008. Here, we characterized these viruses by performing sequencing and phylogenetic analyses of their viral genes, assessing their virulence in ducks and mice, and performing cross-protection experiments in chickens. Sequence analysis revealed that the HA genes of these H5N5 viruses showed 97.1-97.8% homology to A/wild duck/Hunan/211/2005 (H5N1) influenza virus and that their NA genes showed 96.4-96.8% nucleotide identity to the NA gene of A/duck/Hunan/5613/2003 (H6N5) influenza virus, which belongs to the Eurasian lineage. Genotypic analysis indicated that these H5N5 viruses were multiple reassortants among H5N1, H5N2, H6N2, and H6N5 viruses. The analysis of HA clade showed that these H5N5 viruses are clustering into clade 2.3.4. In animal experiments, these H5N5 viruses caused 50% mortality in ducks and 100% mortality in chickens. In cross-protection experiments, the clade 2.3.2 avian influenza vaccine could provide only 75% protection with chickens against H5N5 virus challenge. Moreover, the H5N5 virus replicated efficiently in the lungs of mice, which suggested that the H5N5 viruses have the potential to infect mammalian hosts. Since ducks have served as reassortant vessels, playing pivotal roles in the generation of new subtypes of influenza viruses, it is important to monitor the emergence of this novel subtype of influenza viruses in waterfowl to understand their ecology and evolution and to control the spread of new viruses.
Assuntos
Patos/virologia , Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Influenza Aviária/virologia , Filogenia , Vírus Reordenados/genética , Animais , Galinhas/imunologia , Galinhas/virologia , China , Proteção Cruzada/imunologia , Genótipo , Hemaglutininas Virais/genética , Vírus da Influenza A/imunologia , Vacinas contra Influenza/imunologia , Influenza Aviária/imunologia , Influenza Aviária/mortalidade , Pulmão/patologia , Camundongos , Dados de Sequência Molecular , Infecções por Orthomyxoviridae/patologia , Infecções por Orthomyxoviridae/virologia , Homologia de Sequência do Ácido NucleicoRESUMO
A new emerging flavivirus caused severe egg-drop in poultry and spread quickly across most duck-producing regions of China in 2010. Complete genome sequencing indicated that the virus genome is 10,989 nucleotides in length and possesses typical flavivirus genome organization, 5' untranslated region (UTR)-Cv-Ci-prM-M-E-NS1-NS2A-NS2B-NS3-NS4A-2K-NS4B-NS5-3'-UTR. The long open reading frame (ORF) encodes 3,425 amino acids (95-10,372 nt). The 94-nucleotide 5'-UTR is of intermediate size and the 617-nucleotide 3'-UTR is quite long relative to those of other flaviviruses. The polyprotein cleavage sites, potential glycosylation sites, distribution of cysteine residues, and 3'-UTR secondary structure were characterized. Phylogenetic analysis of the polyprotein sequences indicates that the HN isolate is closely related to Tembusu viruses of the Ntaya virus group.
Assuntos
Infecções por Flavivirus/veterinária , Flavivirus/genética , Flavivirus/isolamento & purificação , Doenças das Aves Domésticas/virologia , Regiões 3' não Traduzidas , Regiões 5' não Traduzidas , Animais , China , Patos , Flavivirus/química , Flavivirus/classificação , Infecções por Flavivirus/virologia , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Filogenia , RNA Viral/química , RNA Viral/genética , Proteínas Virais/química , Proteínas Virais/genéticaRESUMO
We developed an enzyme-linked immunosorbent assay (ELISA) using eukaryotically expressed E protein as the antigen (termed E-ELISA) to detect antibodies to tembusu virus (TMUV) in ducks. The E-ELISA did not react with antisera to other known pathogens, indicating the E protein is specific for recognizing anti-TMUV antibodies. Compared to the serum neutralization test, the specificity and sensitivity of the E-ELISA was 93.2 and 97.8%, respectively. Therefore, this E-ELISA is a sensitive and rapid method for detecting antibodies against TMUV in ducks.
