Heineman T C, Krudwig N, Hall S L
Heineman T C, Krudwig N, Hall S L. fusion with VZV gE-gB coexpression was comparable to that observed with VZV gH-gL: in both cases, 80% of the cells in a monolayer were fused. Thus, these studies established that VZV gE-gB coexpression greatly enhanced the fusogenic properties of gB. Control experiments documented that this fusion assay required a balance between the fusogenic potential of the VZV glycoproteins and the fusion-inhibitory effect of the VV contamination itself. Varicella-zoster computer virus (VZV) is usually a highly fusogenic computer virus, but the degree of fusion is dependent around the cell substrate in which the computer virus is usually propagated (20). In human fibroblast cells, fusion formation is limited to a small number of nuclei per syncytium. In contrast, in human melanoma cells, all VZV strains examined to date exhibit fusion formation in which the entire monolayer is usually eventually involved. Polykaryon formation also occurs during main VZV contamination in human epidermal cells. Therefore, fusion formation appears to be related to cells of ectodermal origin (20). The question of which glycoproteins are involved in VZV-induced fusion was resolved in two earlier reports in which transfection studies were carried out with the VZV gH and gL genes (13, 14). Transfection with gH alone caused little or no syncytium formation. In contrast, cotransfection with gH and gL genes led to multiple foci of fusion within the monolayer, where syncytia from 6 to 25 nuclei were very easily detected. This set of experiments also documented the power of confocal microscopy as an instrument to detect syncytium formation and glycoprotein expression within a polykaryon. Of interest, the VZV results differed markedly from your herpes simplex virus type 1 (HSV-1) data, which Morinidazole showed that cotransfection with four glycoprotein genes, namely those of gH, gL, gB, and gD, was required for syncytium formation (42, 55). In the latter case, each syncytium often included 10 to 20 nuclei but rarely larger foci. While VZV gH is usually very easily NAK-1 detected in the plasma membrane, VZV gL is not detected on the surface of the transfected cell monolayer. The above data suggest that VZV gH is usually a more fusogenic molecule than HSV-1 gH; however, the precise fusion domains have not been mapped in either VZV gH or HSV-1 gH. The degree of genetic identity between VZV gH and HSV gH is usually 25% (31). VZV has the smallest genome (125 kbp) among the human alphaherpesviruses. Because no gD homologous open reading frame (ORF) is present in the VZV Us segment (9), gD cannot play a role in VZV-induced fusion. It has been postulated that Morinidazole some functions of gD may be transferred to another VZV glycoprotein, but no obvious regions of homology between HSV gD and a VZV glycoprotein have been identified (7). Given the results obtained with VZV gH and gL, the unanswered question is the role of VZV gB in fusion. Prior studies have demonstrated that a murine monoclonal antibody (MAb) to VZV gH inhibits fusion formation in cell culture (33, 45). In a similar analysis, antibody to VZV gB was shown to reduce fusion formation (32). By analogy, therefore, the hypothesis was set forward that VZV gB was involved in fusion. The gB molecule is one of the most highly conserved genes in the herpesvirus genome. VZV gB, which is usually encoded by ORF 31, was shown to have a 49% degree of genetic identity with HSV gB (9, 16). The mature VZV gB is usually a highly glycosylated disulfide-linked heterodimer (19). Trafficking domains from your endoplasmic reticulum to the Golgi body within the cytoplasmic tail have been defined (21). Our preliminary studies with an individually expressed VZV gB gene failed to demonstrate a strong fusogenic property. The possibility was entertained that this gB gene in the particular laboratory strain may have undergone mutation and thereby lost its fusogenic Morinidazole domain name (44). However, sequencing of 10 VZV strains, including the most commonly used laboratory strains, did not detect an obvious mutation which could account for the loss of fusogenic potential (17, 47). Finally, a more detailed investigation including individual VZV glycoprotein genes came to the surprising discovery that gB required the.