Gharakhanian Editte, Muñoz Luz, Mayorca Luz
Department of Biological Sciences, California State University at Long Beach, 1250 Bellflower Blvd, Long Beach, CA 90840-3702, USA.
J Gen Virol. 2003 Aug;84(Pt 8):2111-2116. doi: 10.1099/vir.0.19287-0.
The SV40 capsid is composed of pentameric capsomeres of the major structural protein Vp1. The two minor structural proteins, Vp2 and Vp3, interact with the capsid. Here, the roles of Vp2 and Vp3 were explored during the course of SV40 infection. Start codons of Vp2, Vp3, or both Vp2 and Vp3, were destroyed by site-directed mutagenesis, and mutant genomes were transfected into CV-1 cells. SV40DeltaVp2 produced plaques and infectious virion particles with titres indistinguishable from wild-type. SV40DeltaVp3 and SV40 DeltaVp2/Vp3 were defective in plaque formation and rendered no infectious particles. All three mutants showed normal nuclear localization of T-Ag and Vp1; they also showed packaging of SV40 DNA by nuclease digestion assays. Thus, Vp3 is essential for formation of infectious SV40 particles, whereas Vp2 is not. One critical role of full-length Vp3 appears to be in virus-cell interactions at post-packaging steps of a permissive infection.
SV40 衣壳由主要结构蛋白 Vp1 的五聚体壳粒组成。另外两种次要结构蛋白 Vp2 和 Vp3 与衣壳相互作用。在此，对 Vp2 和 Vp3 在 SV40 感染过程中的作用进行了探索。通过定点诱变破坏 Vp2、Vp3 或 Vp2 和 Vp3 两者的起始密码子，并将突变基因组转染到 CV - 1 细胞中。SV40DeltaVp2 产生的噬菌斑和感染性病毒粒子滴度与野生型无明显差异。SV40DeltaVp3 和 SV40 DeltaVp2/Vp3 在噬菌斑形成方面存在缺陷，且未产生感染性颗粒。所有三种突变体的 T - Ag 和 Vp1 均表现出正常的核定位；通过核酸酶消化试验也表明它们对 SV40 DNA 进行了包装。因此，Vp3 对于感染性 SV40 颗粒的形成至关重要，而 Vp2 并非如此。全长 Vp3 的一个关键作用似乎在于在允许性感染的包装后步骤中病毒与细胞的相互作用。
