Molecular mechanisms of infection and pathogenesis of viruses

从西伯利亚鸭巢区的鸭粪便样品中分离出不同亚型的甲型流感病毒。对西伯利亚分离株和日本北海道分离株秋季从西伯利亚向南迁徙途中分离的NP基因进行系统发育分析，结果表明它们属于欧亚系禽流感病毒。据悉，西伯利亚分离株的基因与1997年在香港从鸡只和人类身上分离出的H5 N1流感病毒株，以及从华南家禽身上分离出的病毒株的基因有密切关系。结果表明，在香港出现的H5 N1病毒与西伯利亚鸭群中存在的流感病毒基因有关，用无毒力的A/ duck/北海道/ 4/ 96（H5 N3）流感病毒制备的疫苗能够保护小鼠免受致死剂量的致病性H5 N1病毒的攻击。因此，加强对水禽特别是西伯利亚水禽的监测研究，是为了提供有关未来大流行性流感病毒株的信息和疫苗的制备。血清学监测显示，至少自1977年以来，中国南方的猪只就发生了H5流感病毒感染。研究亦显示，H9病毒在一九八三年后已在这些地区传播。

Influenza A viruses of different subtypes were isolated from fecal samples of ducks in their nesting areas in Siberia. Phylogenetic analysis of the NP genes of the isolates in Siberia and those in Hokkaido, Japan on their flyway of migration from Siberia to the south in autumn revealed that they belong to the Eurasian lineage of avian influenza viruses. It is noted that the genes of the isolates in Siberia are closely related to those of H5N1 influenza virus strains isolated from chickens and humans in Hong Kong in 1997 as well as to those of isolates from domestic birds in southern China. The results indicate that influenza viruses perpetuated in ducks nesting in Siberia should have contributed genes in the emergence of the H5N1 virus in Hong Kong.Vaccine prepared from avirulent A/ duck/ Hokkaido/ 4/ 96 (H5N3) influenza virus was potent enough to protect mice from challenge with leathal dose of the pathogenic H5N1 virus. Intensive surveillance study of aquatic birds especially in Siberia is, therefore, stressed to provide information on the future pandemic influenza virus strains and for vaccine preparation.Serological surveillance revealed that H5 influenza virus infections had occurred in pigs in southern China since at least 1977. It is also shown that H9 viruses have circulated among them after 1983.