Molecular Analysis Of The Entire Genes Of An Avian Influenza Virus Isolate A/Goose/Guangdong/1/96(H5N1)

Avian influenza is an infection and / or disease syndrome caused by any subtype of influenza A virus, a number of the Orthomyxoviridae family. Influenza A viruses are responsible for major disease problem in bird, as well as in humans and lower mammals. Literally thousands of viruses, belong to many different antigen subtypes based on hemagglutinin(HA) and numaminidae(NA) surface antigens, have been recovered from domestic and wild avian species throughout the world. Infection among domestic or canfined birds have been associated with a variety of disease syndromes ranging from subclinical to mild upper respiratory disease, loss of egg production to acute generalized fatal disease. Influenza A virus are divided into subtype according to the antigen nature of the HA and NA. So far there are 15 subtype of antigen of 1-IA a~ 9 subtype of NA antigen, in which avian influenza viruses of H5 and H7 subtypes have been associated with severe disease in chicken, turkey, domestic duck and tern. The highly pathogenic isolates have caused severe disease with morbidity and mortality reaching 100%. With the development of economics and exchange of poultry and its products, avian influenza has occurred in Southeneast China. And a few highly pathogenic influenza viruses were isolated from goose and duck. In this report, an avian influenza virus (AIV) isolate A/Goose/Guangdongll/96(H5N1) (GD 1/96) was propagated in specific pathogen free chicken embryo. The viral RNAs were extracted and used in reverse transcription-polymerase chain reaction for ampliIng the eight full-length cDNAs of the virus genes. The cDNAs were then cloned into Sma I site of pUC 119 and sequenced. The results show that each of 8 gene cDNA fragments contains the whole open reading frame of each gene. High homology exists among the hemagglutinins (HAs) of 001/96 and other 4 influenza virus isolated from human, chicken, duck and goose during ?997 Hong Kong Avian Flu? which implys that all the viruses can be classified into Eurasian lineage of HS subtype AIVs. However, very low homology associated with the non-structural (NS) proteins between GD 1/96 and the Hong Kong flu viruses indicated that GD 1/96 comes from different genetic groups. Furthermore, lower homology (63.9%-98. 1%) 80 of the entire genes exists between GDl/96 and the Hong Kong isolates when compared to thehomology (96.5%-l00%) among the Hong Kong viruses. In addition, deletion of 57 nucIeotides(or l9 amino acids) occurred within the NA molecule of all Hong Kong viruses instead ofGDl /96. The data above suggests that GD l/96 is not the pathogen and even not the gene donorof the Hong Kong viruses in "l997 Hong Kong Avian Flu". In order to demonsttate phylogeneticrelationships between GD1/96 and the other influenza viruses in the world, of phylogeneticrelationships were drew by ClustaI V method. The results conformed the above conclusion andshowed that HA. NA' M and NS genes of isolate GDl/96 are closely rel8ted those of isolatesfrom Hong Kong, and NS. PA. PB l and PB2 genes of isolate GDl/96 formed a unique branch,indicating that isolate GD l/96 envolving in separate route.