Recognition mechanism of the RNA segments of influenza virus by the NS2 protein at the virion assembly step.

本研究利用产生大量DI颗粒的流感病毒NS2突变体，研究了(1)基因组RNA进入病毒粒子的包装是否受到DI-RNA种类的抑制，(2)是否存在能够识别每个RNA片段的信号序列；(3) NS2蛋白在基因组RNA片段组装过程中的作用。我们发现(1)PA DI-RNA物种选择性地抑制了仅祖先PA基因的掺入，(2)在片段特异性非编码区3‘和5’端分别有7个和3个核苷酸作为每个RNA片段的识别信号，(3)NS2蛋白下调了DI-RNA的包装，导致正常基因组RNA优先掺入。

In the present research using NS2 mutant of influenza virus that produces a large amount of DI particles, we have studied (1) whether genomic RNA packaging into virion is suppressed by DI-RNA species, (2) whether there is a signal sequence which can recognize each RNA segment ; and (3) what is the function of NS2 protein during assembly of genome RNA segments.We found (1) that PA DI-RNA species selectively suppressed the incorporation of only the progenitor PA gene, (2) that 7 and 3 nucleotides at the 3' and 5' terminal ends, respectively, in the segment-specific noncoding regions functioned as the recognition signals of each RNA segment, and (3) that NS2 protein down-regulated the DI-RNA packaging, resulting in preferential incorporation of normal genomic RNAs.