| An H5N1 avian influenza virus was isolated from China in a certain area at 2006 (named as A/CHICKEN/LF3/06, LAB No. AI0624) was studied the biological characteristics and the infection in this paper. After preliminary identified by HA and HI,virus isolation,50% egg infections dose (EID50), mean death test (MDT) in eggs and Intravenous patho-genicity index (IVPI) determine, its virulence was understanded. In order to demostrate the phylogenetic relationships between the A/CHICKEN/LF3/06 strain and the other isolates reported in the world, especially strains isolated from chickens and human in HongKong and in Southeast-Asian countries outbreak of AIV, Then the HA,NA and NS genes of the A/CHICKEN/LF3/06 strain was sequenced, molecular evolutionarily analyzed and drawed Phylogenetic tree, finally we determine its pathogenicity to mammiferous.EID50, IVPI, MDT were10-7.625/0.lml,3and 50.4h respectively, and the mortality is 100%. Accordingly, this virus is a H5N1 High Pathogenic Avian Influenza Virus.4 primers was designed based on genes of the HA,NA and NS genes of AIV reported at Genbank, then the genes of this virus was RT-PCR, cloned, sequenced and molecular evolutionarily analyzed, the result showed:the cleavage site of HA gene is PLRERRRK-R*G that is the sign of High Pathogenic Avian Influenza Virus and its same with the result of IVPI.Virus in this study was closely related with A/duck/Fujian/1734/05,A/human/Zhejiang/16/06 and A/chicken/Malaysia/5223/07 which isolated from duck in Fujian, China in 2005,from human in Zhejiang,China in 2006 and from chicken in Malaysia in 2007.But, it was comparatively far related with A/chicken/Hong Kong/220/97 and A/goose/Guangdong/1/96, which isolated from chickens in HongKong during the 1997 outbreak of AIV and from gooses in Guangdong, China in 1996.Therefore, I suppose that A/CHICKEN/LF3/06 in this study possibly has same ancestor with A/duck/Fujian/1734/05 and A/human/Zhejiang/16/06.The virus intranasal inoculated BALB/c mice experiment showed:in the high-dose infection, the mice had larger affection on weight loss, in the medium-dose to low-dose infection, the mice had less affection on weight loss.But during the experiment, there were mice dead, So this virus is a H5N1 higher pathogenic to mice. Through respiratory tract infections, the virus showed certain tropism on the lung tissue, the brain tissue. In addition, Mice infected intranasally with high-dose have produced antibody, with medium-dose to low-dose have no produced antibody. The experiment has proved the virus has significant dose effect.Concluded that after the strain reproduce in the mammalian, there is a certain pathogenicity on mammals, the strain might be directly infected mammalian. Therefore, It can be speculated this strain has potential infection possibility to people.At the same time,Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to amplify the six major encoding structure protein of an A goose paramyxovirus typeâ… (G).The cDNAs were then cloned to PMD18-T vector and sequenced. These sequences were compared with paramyxovirus typeâ… home and abroad reported. The results show that the F gene was comparatively far related with La Sota, Rate of homologous was 99.1%,and other genetic homology of the strains were low.In conclusion, the research is good for the further study of the molecular evolution, structure, and function and pathogenicity mechanism of H5N1 AIV.
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