Rice stripe virus (RSV) infects rice and is transmitted in a propagative manner by the small brown planthopper.How RSV enters an insect cell to initiate the infection cycle is poorly understood.Sequence analysis revealed that the RSV NSvc2 protein was similar to the membrane glycoproteins of several members in the family Bunyaviridae and might induce cell membrane fusion.To conveniently study the membrane fusion activity of NSvc2,we constructed cell surface display vectors for expressing Nsvc2 on the insect cell surface as the membrane glycoproteins of the enveloped viruses.Our results showed that NSvc2 was successfully expressed and displayed on the surface of insect Sf9 cells.When induced by low pH,the membrane fusion was not observed in the cells that expressed NSvc2.Additionally,the membrane fusion was also not detected when co-expressing Nsvc2 and the viral capsid protein on insect cell surface.Thus,RSV NSvc2 is probably different from the phlebovirus counterparts,which could suggest different functions.RSV might enter insect cells other than by fusion with plasma or endosome membrane.

The human immunodeficiency virus type 1 (HIV - 1 ) envelope glycoprotein gp41 plays a critical role in the fusion of viral and target cell membranes. The gp41 extracellular domain, which contains fusion peptide (FP), N - and C - terminal hydrophobic heptad repeats (NHR and CHR, respectively). Peptides derived from NHR and CHR regions,designated N- and C- peptides, respectively, can interact with each other to form a six - stranded coiled - coil domain, representing the fusion-active gp41 core. Our previous studies demonstrated that the C- peptides have potent inhibitory activity against HIV- 1 infection.These peptides inhibit HIV- 1 -mediated membrane fusion by binding to NHR regions for preventing the formation of fusion- active gp41 core. One of the C - peptides, T - 20, which is in the phase Ⅲ clinical trails, is expected to become the first peptide HIV fusion inhibitory drug in the near future. However, this peptide HIV fusion inhibitor lacks oral availability and is sensitive to the proteolytic digestion.Therefore, it is essential to develop small molecular non -peptide HIV fusion inhibitors having similar mechanism of action as the C- peptides. We have established an ELISA- based screening assay using a unique monoclonal antibody, NC- 1, which can specifically bind to a conformational epitope on the gp41 core domain. Using this screening assay, we have identified a small molecular anti- HIV- 1 compound,named ADS-Jl, which inhibits HIV- 1- mediated membrane fusion by blocking the interaction between the NHR and CHR regions to form the fusion - active gp41 core. This compound will be used as a lead to design and develop novel HIV fusion inhibitors as new drugs for the treatment of HIV infection and/or AIDS.