Research Of H6N1Avian Influenza Virus Horizontal Transmission Capacity Between The Guinea Pig Model And H9N2Avian Influenza Virus Pathogenic Ability In The Mouse Model

The natural reservoir of avian influenza virus is waterfowl, which usually can infect chickens, turkeys, ducks, geese and wild birds. It is difficult to break through the host barrier to infect mammals and humans, because of the host species-specific. However, in recent years, more and more events have shown that low pathogenic avian influenza virus can infect mammals, it is a threat to the security of mankind. Therefore, like the H6and H9subtypes of low pathogenic avian influenza virus has drawn increasing attention. The results of this experiment can help us to know the molecular mechanisms of low pathogenic avian influenza virus across species barriers, pathogenic to mammals, and underlying the spread between mammals.In this study, we use the guinea pig model to evaluate the H6N1subtype contact transmission capacity. A/mallard/Sanjiang/275/2007can binding to both SAa-2,3Gal receptor and SAa-2,6Gal receptor; M-275can replicate in the guinea pig’s upper airway, and have the strongest replication ability in turbinate as the average titer is from1.5LogEID5o/mL to2.5LogEID5o/mL. The liver, spleen, brain, gut, lung and kidney have not detected any virus; M-275can cause the lung have some lesions which are difficult to observe with the naked eye, and during the14days observation the guinea pig did not show any clinical symptoms; This strain M-275can not be in contact transmission between the guinea pig.The result of adaptive passage in guinea pigs for M-275strain showed that the seventh adaptive strain and the18th adaptive strain still can not spread between in guinea pigs; the18th adaptive strain M-275-P18-M2has a high virulence for mice, its MLD50is105.25EID50,106EID50the ratio is100%lethal in mice, the primary strains is not lethal in mice; according to the passage virus M-275-P2-E1, M-275-P7-M1, M-275-P16-M1and M-275-P18-M2gene sequencing results, the six mutation sites PB2D701N, PB1Q687R, HA G122E, NA W233C, M1D94N, M1Q211R may not related to enhanced the disseminative capability in mammalian; the PB2D701N mutations, may be the pathogenicity relatedness amino acid sites.An H9N2subtype AIV was serial passage in the lung of mice to acquire the variant strains JN-P9-2-M1; JN-P9-2-M1has high pathogenicity to mice, its MLD50is103.5EID50, when has a106EID50、105EID50、104EID50dose in mice, its survival rate is0, at least1000times higher than JN, the JN in mice is not lethal; JN-P9-2-M1can spread between the guinea pig by chance, but JN can not; according to the genome sequencing results of JN-P5-2-M1and JN-P9-2-M1, this three amino acid sites PB2E627K, HA N313D, HA N496S may be the reasons of preliminary improve the virus virulence in mouse, and PA L342I, NA N218T this two amino acid sites, is possible to further improve the virus virulence in mice. Successfully constructed H9N2virulent strain JN-P9-2-M1reverse genetics operation system, the virus rJN-P9-2-Ml has been rescued in vitro.The bionomics of rJN-P9-2-Ml and JN-P9-2-M1are same. this platform will be used to research the molecular mechanism of variation of JN-P9-2-M1, and have the conditions for the further study of the molecular mechanisms of H9N2subtype avian influenza virus pathogenicity variation.