Analysis of the function of hPIV2 V protein by using reverse genetics.

点击翻译按钮获取中文摘要

1.The V protein of human parainfluenza virus type 2 (hPIV2) inhibits interferon (IFN) -induced innate antiviral responses through STAT protein degradation. I identified hPIV2 V protein residues essential for STAT2 protein degradation in human cells, that are conserved seven cysteine residues, tryptophan-rich-motif, and aa 207 phenylalanine in the C-terminal V-unique domain, and aa 143 phenylalanine in the P/V common domain.2.To conform the function for virus growth of the V protein, I made the recombinant virus which completely lacks expression of the V protein by inactivating the P gene mRNA-editing signal (rPIV2/P-edit). The growth rate of rPIV2/P-edit is very limited even in the Vero cells that cannot induce IFN. Thus, these results suggest that the V protein is essential not only for STAT protein degradation but also for promoting virus growth. The rhPIV2s which have the mutation in the V-specific domain also grew lower, but rPIV2 which has the mutation in the P/V common domain grew similar to wt.3.I investigated whether the V protein of human parainfluenza virus type 4 (hPIV4) has the function to evade the IFN-induced antiviral responses. The hPIV4 V protein has the conserved seven cysteine residues and tryptophan-rich-motif, and can bind to DDB1 and Cul4A that are important for STAT protein degradation. However, the hPIV4 V protein has no function to inhibit IFN signaling. I show that the only paramyxovirus that can't evade the IFN-induced antiviral responses to data is hPIV4.4.I identified that the V-specific region of hPIV2 binds to the N-terminal 80 amino acids on the NP protein, and is critical for self-association. Furthermore, I have identified a host protein, AIP1/Alix, involved in apoptosis and efficient budding of several enveloped viruses, as an interacting partner of the V and NP proteins. My data also suggest that the transiently binding between V and AIP1 is important for virus growth.