Characterization Of H5N1Reassortant Bearing NS Gene Of2009/H1N1Virus

The Mexico Flu breaking out in2009swept the world in a short time and caused a global panic.Although the pandemic2009/H1N1transmits well among humans, it is of low pathogenicity, so itbrought us no great loss. The H5N1highly pathogenic avian influenza virus(HPAIV) which exists inChina for a long time broke out sporadically in recent years and the avian industry is with a great loss. IfH5N1HPAIV reassorts with pandemic H1N1, it will have incalculable impact on humanity and avianindustry.To study the role of NS on the pathogenicity and transmission of influenza A virus, we generated areassorrtant virus DK/35-SC/01-NS containing the NS gene from the first2009H1N1isolate in China,A/Sichuan/01/2009(SC/01), in the background of a H5N1avian influenza virus,A/duck/Guangxi/35/2001(H5N1; DK/35), using reverse genetics. Mouse experiment showed that SC/01NS gene reduced the virulence of DK/35. The50%mouse lethal dose of DK/35is2.6log10EID50whilethat of DK/35-SC/01-NS is5.9log10EID50, the virulence of DK/35is2000fold of DK/35-SC/01-NS. Wespeculated that SC/01NS gene attenuated the pathogenicity of DK/35by influencing interferonproduction. Next, we detected the expression of type I IFN. The VSV-GFP propagated well in A549cellwhich was processed with supernatant from A549infected by DK/35. On the contrary, VSV-GFP waslimited in A549because of DK/35-SC/01-NS supernatant. Our data indicates that the NS gene formSC/01decreases the virulence of DK/35. In another study, we evaluated the transmission of DK/35andDK/35-SC/01-NS in Guinea pigs. DK/35doesn’t transmit in Guinea pigs while DK/35-SC/01-NStransmits100%in Guinea pigs.The data indicates that the NS gene influences both the pathogenicity and transmission of influenza Avirus.