[Biological significance of amino acids deletion in NA stalk of H5N1 avian influenza virus].

It has been reported that NA gene of some H1N1 Influenza A virus strains isolated since 1933 is characterized by a deletion of 11 to 16 amino acids in the stalk. The spontaneous mutant in NA stalk of H1N1 virus lacks enzyme activity with large substrate (fetuin) but not with small substrate (sialyllactose). Recently, H5N1 virus also has been found that NA has the same unique mutation in the stalk, a deletion of 15 to 20 amino acids.

[Establishment of reverse genetics system for H5N1 subtype AI].

H5N1 subtype influenza virus A/Duck/Shandong/093/2004 (A/SD/04) strain was chosen as the master strain for rescue research. 11 sets of primers for 8 plasmids construction were designed base on the sequencing of the full-length of A/SD/04. Eleven fragments of A/SD/04 were amplified by the designed primers and were ligated with PHW2000 for rescue plasmid construction.

[Cloning of full-length genes of H5N1 subtype Avian influenza virus strain A/duck/Shandong/093/2004 and analysis of the sequences].

The eight full-length genes, including the 5' and 3' ends of H5N1 subtype Avian influenza virus (A/duck/ Shandong/093/2004) were amplified by using the universal primers and H5 specific primers. The method used for the amplification of Avian influenza virus's full-length sequence was more easily and rapidly than that of rapid amplification of cDNA ends assay (RACE). The amplified segments were cloned into the T vector PCR 2.