Abstract:

The polyadenylation signal site at the 5' end of the NA gene vRNA of H9N2 subtype avian influenza virus is diverse. When mutated, this site loses its binding effect with polymerase or leads to weakened binding ability, it blocks the polyadenylation process and affects the transcription process of viral mRNA.To explore the effect of 5-terminal polyadenylation signal sites (five or six uracil bases, U₅ or U₆ ) of NA gene on the H9N2 subtype of avian influenza virus rescue, a series of mutants were constructed with a reverse genetic technology based on a A/Chicken/China/Sichuan/CQY/2014 (H9N2) strain which was isolated in Sichuan Province. The results showed that both of the hemagglutination titer, TCID₅₀ and EID₅₀ of rCQYU₅-H9N2 strain were higher than those of rCQYU₆-H9N2 strain, while the growth curve had no significant difference. The results indicated that the structure of U₅ and U₆ at the 5' terminal of the H9N2 NA gene had no effect on the rescue of the virus, while the five consecutive uracil bases were more favorable for the titer of the H9N2 AIV on MDCK cells and chicken embryo. The results of this experimental study provided a certain reference for the research on the replication mechanism of H9N2 subtype avian influenza virus.

Key words: influenza virus, reverse genetic technology, polyadenylation