Pseudorabies virus gene encoding glycoprotein gIII is not essential for growth in tissue culture

510

274

The purpose of this study was to identify the herpes simplex virus glycoprotein(s) that mediates the adsorption of virions to cells. Because heparan sulfate moieties of cell surface proteoglycans serve as the receptors for herpes simplex virus adsorption, we tested whether any of the viral glycoproteins could bind to heparin-Sepharose in affinity chromatography experiments. Two glycoproteins, gB and gC, bound to heparin-Sepharose and could be eluted with soluble heparin. In order to determine whether virions devoid of gC or gB were impaired for adsorption, we quantitated the binding of wild-type and mutant virions to cells. We found that at equivalent input concentrations of purified virions, significantly fewer gC-negative virions bound to cells than did wild-type or gB-negative virions. In addition, the gC-negative virions that bound to cells showed a significant delay in penetration compared with wild-type virus. The impairments in adsorption and penetration of the gC-negative virions can account for their reduced PFU/particle ratios, which were found to be about 5 to 10% that of wild-type virions, depending on the host cell. Although gC is dispensable for replication of herpes simplex virus in cell culture, it clearly facilitates virion adsorption and enhances infectivity by about a factor of 10.

supporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Glycoprotein C of herpes simplex virus type 1 plays a principal role in the adsorption of virus to cells and in infectivity

Herold

WuDunn

Soltys

et al. 1991

510

274

“…Southern blot analysis. To identify correct recombinant viruses, a Southern blot analysis was performed on viral DNAs as previously described (23). Viral DNAs were digested with PstI and probed with [ 32 P]pGBe4.3.…”

Section: Methodsmentioning

confidence: 99%

“…The initial step for many herpesviruses has been shown to include an electrostatic binding of virus particles to negatively charged cell surface heparan sulfate (17,18,20,32). This attachment is mediated principally by glycoprotein gC but has been found to be unnecessary, at least in cell culture, in that strains lacking their gC homolog are still infectious (10,19,23). Additionally, biochemical studies on several herpesviruses have demonstrated that gC and a second envelope glycoprotein, gB, are capable of binding to heparin, a species closely related to heparan sulfate (10,17,27).…”

mentioning

confidence: 99%

A heterologous heparin-binding domain can promote functional attachment of a pseudorabies virus gC mutant to cell surfaces

Flynn

Ryan

1995

The efficient attachment of pseudorabies virus to cultured cells is dependent on an electrostatic interaction between negatively charged cell surface heparan sulfate and the viral envelope glycoprotein gC. Deletion of the first one-third of gC severely impairs virus attachment, but the mutant virions are still capable of entering cells and establishing an infection via a gC-independent pathway. This region of gC contains three clusters of positively charged amino acids that exactly or nearly conform to proposed consensus motifs for heparinbinding domains (HBDs), and the loss of one or more of these potential HBDs may be responsible for the observed attachment defect. To more directly show the involvement of HBDs in pseudorabies virus attachment to cells, we replaced the first one-third of gC with a single, biochemically defined HBD from apolipoprotein B-100. On the basis of the results of attachment, penetration, and heparin competition assays, the heterologous HBD mediated heparan sulfate-dependent virus attachment, but not to fully wild-type levels. Although the intermediate phenotype is not understood, the apolipoprotein B-100 HBD may represent the smallest defined amino acid sequence that promotes functional herpesvirus attachment to cultured cells.

“…Pseudorabies virus (PrV), a herpesvirus of swine, encodes at least four glycoproteins that are not essential for growth in cell culture (2,12,18,21,22,26). Primary isolates of PrV, however, do express these glycoproteins; consequently, they must play a role in virus replication, at least in vivo.…”

mentioning

confidence: 99%

Complex between glycoproteins gI and gp63 of pseudorabies virus: its effect on virus replication

Zuckermann

Mettenleiter

Schreurs

et al. 1988

114

To ascertain the biological functions of different glycoproteins that are nonessential for pseudorabies virus growth in vitro, we have constructed mutants defective in one (or a combination) of these glycoproteins and have examined various aspects of their role in the infective process. We made the following two observations. (i) Glycoproteins gI and gp63 are noncovalently complexed to each other. They are coprecipitated by antisera against either one of these glycoproteins but do not share antigenic determinants: monoclonal antibodies against gp63 do not immunoprecipitate gI from extracts of gp63mutant-infected cells, and monoclonal antibodies against gI do not immunoprecipitate gp63 from extracts of glmutant-infected cells. (ii) Mutants unable to synthesize either gI or gp63 have some common biological characteristics; they have a growth advantage in primary chicken embryo fibroblasts. Furthermore, we have shown previously that in conjunction with glycoprotein gIII, gI and gp63 are necessary for the expression of virulence (T. C. Mettenleiter, C.