Receptor properties of two varicella-zoster virus glycoproteins, gpI and gpIV, homologous to herpes simplex virus gE and gI

Abstract

The varicella-zoster virus (VZV) genome contains 70 reading frames (ORF), 5 of which encode the glycoproteins gpl, gpII, gpIII, gprV, and gpV. ORF 67 and 68 lie adjacent to each other in the unique short region of the VZV genome and code for gpIV and gpl, respectively. These two genes, which are contained within the HindIII C fragment of the VZV genome, were subcloned in the correct orientation downstream from the promoter regions of the eukaryotic expression vectors pCMV5 and pBJ. After transfection, 5 to 20% of the Cos cells bound antibody specific for the given glycoprotein. In this study, it was shown that only the cells transfected with the gpI construct bound to the Fc fragment of human immunoglobulin G. Neither the transfected gpIV gene product nor the vector only bound to the Fc fragment. Thus, VZV gpI is confirmed to be the VZV-encoded Fc-binding glycoprotein. Like the wild-type form of gpI expressed in VZV-infected cells, gpl precipitated from transfected cells contained both N-linked and 0-linked glycans and was heavily sialated. In addition, the transfected gpl gene product was phosphorylated both in cell culture and in protein kinase assays by mammalian casein kinases I and II. Extensive computer-assisted analyses of the VZV gpl sequence, as well as those of alphaherpesviral homolog glycoproteins, disclosed properties similar to those of other cell surface receptors; these included (i) exocytoplasmic regions rich in cysteine residues, (ii) membrane-proximal regions with potential 0-linked glycosylation sites, and (iii) cytoplasmic domains with consensus phosphorylation sites.

Herpesviral Fcγ receptors: culprits attenuating antiviral IgG?

“…1) [89], which are encoded by the HSV genes US (unique short) 7/US8 and are dispensable for HSV infection and replication in vitro. Homologous molecules to gE and gI are found in HSV-2 [84], VZV [90], PRV [91] and MDV [87]. gE and gI are exposed on the surface of infected cells and represent also the most abundant structural glycoproteins within the virus envelope.…”

UL13 Protein Kinase of Herpes Simplex Virus 1 Complexes with Glycoprotein E and Mediates the Phosphorylation of the Viral Fc Receptor: Glycoproteins E and I

“…The homolog of HSV-1 gE in VZV was reported to be phosphorylated by CKII in vitro (Litwin et al, 1992). Both the HSV-1 and VZV gE have CKII recognition sequences in the cytoplasmic domains of the proteins (Litwin et al, 1992).…”

“…The homolog of HSV-1 gI encoded by VZV has also been reported to be phosphorylated (Yao and Grose, 1994). The identities of the protein kinases responsible for the phosphorylation of these two glycoproteins are largely unknown, although the cytoplasmic domain of gE contains several casein kinase II (CKII) recognition sequences and CKII had been shown to phosphorylate VZV gE in vitro (Litwin et al, 1992;Yao et al, 1993).…”

The herpes simplex virus type 1 Fc receptor discriminates between IgG1 allotypes

“…The HSV-1 FcR is of biological interest for a number of reasons. First, FcR are found in widely divergent members of the human herpesviruses [7][8][9][10] and other human pathogens possess IgG binding proteins, e.g. staphylococcal protein A [11] and streptococcal protein G [12].…”