Biomedical subjects

P E Pertel

Publications and source records attributed to P E Pertel.

4 recordsLinked to original sources

PubMed2001

Cell fusion induced by herpes simplex virus glycoproteins gB, gD, and gH-gL requires a gD receptor but not necessarily heparan sulfate.

To characterize cellular factors required for herpes simplex virus type 1 (HSV-1)-induced cell fusion, we used an efficient and quantitative assay relying on expression of HSV-1 glycoproteins in transfected cells. We showed the following: (1) Cell fusion depended not only on expression of four viral glycoproteins (gB, gD, and gH-gL), as previously shown, but also on expression of cell surface entry receptors specific for gD. (2) Cell fusion required expression of all four glycoproteins in the same cell. (3) Heparan sulfate was not required for cell fusion. (4) Coexpression of receptor with the four glycoproteins in the same cell reduced fusion activity, indicating that interaction of gD and receptor can limit polykaryocyte formation. Overall, the viral and cellular determinants of HSV-1-induced cell fusion are similar to those for viral entry, except that HSV-1 entry is significantly enhanced by binding of virus to cell surface heparan sulfate.

Animals↗

PubMed1998

Human herpesvirus-8 glycoprotein B interacts with Epstein-Barr virus (EBV) glycoprotein 110 but fails to complement the infectivity of EBV mutants.

To characterize human herpesvirus 8 (HHV-8) gB, the open reading frame was PCR amplified from the HHV-8-infected cell line BCBL-1 and cloned into an expression vector. To facilitate detection of expressed HHV-8 gB, the cytoplasmic tail of the glycoprotein was tagged with the influenza hemagglutinin (HA) epitope. Expression of tagged HHV-8 gB (gB-HA), as well as the untagged form, was readily detected in CHO-K1 cells and several lymphoblastoid cell lines (LCLs). HHV-8 gB-HA was sensitive to endoglycosidase H treatment, and immunofluorescence revealed that HHV-8 gB-HA was detectable in the perinuclear region of CHO-K1 cells. These observations suggest that HHV-8 gB is not processed in the Golgi and localizes to the endoplasmic reticulum or nuclear membrane. Because both HHV-8 and EBV are gamma-herpesviruses, the ability of HHV-8 gB to interact with and functionally complement EBV gp110 was examined. HHV-8 gB-HA and EBV gp110 co-immunoprecipitated, indicating formation of hetero-oligomers. However, HHV-8 gB-HA and HHV-8 gB failed to restore the infectivity of gp110-negative EBV mutants. These findings indicate that although HHV-8 gB and EBV gp110 have similar patterns of intracellular localization and can interact, there is not sufficient functional homology to allow efficient complementation.

Amino Acid Sequence↗

PubMed1997

Partial resistance to gD-mediated interference conferred by mutations affecting herpes simplex virus type 1 gC and gK.

Cells expressing herpes simplex virus (HSV) gD can be resistant to HSV entry as a result of gD-mediated interference. HSV strains differ in sensitivity to this interference, which blocks viral penetration but not binding. Previous studies have shown that mutations or variations in virion-associated gD can confer resistance to gD-mediated interference. Here we show that HSV-1 mutants selected for enhanced ability to bind and penetrate in the presence of inhibitory concentrations of heparin were partially resistant to gD-mediated interference. The resistance was largely due to the presence of two mutations: one in gC (the major heparin-binding glycoprotein) resulting in the absence of gC expression and the other in gK resulting in a syncytial phenotype. The results imply that heparin selected for mutants with altered postbinding requirements for entry. Resistance to gD-mediated interference conferred by mutations affecting gC and gK has not been previously described.

Animals↗

PubMed1996

Modified entry and syncytium formation by herpes simplex virus type 1 mutants selected for resistance to heparin inhibition.

Herpes simplex virus type 1 (HSV-1) mutants were selected by passage of HSV-1 (KOS) in HEp-2 cells such that binding and penetration occurred in the presence of heparin. Analysis of selected uncloned virus pools revealed that approximately 95% of virus formed syncytia and greater than 58% were gC-negative. Plaque-purified gC-negative syncytial mutants were more resistant than HSV-1 (KOS) to heparin inhibition, as was an engineered nonsyncytial recombinant deleted for gC, delta gC6. Thus, absence of gC was sufficient to explain the enrichment for gC-negative mutants. The syncytial phenotype of most mutants mapped to a mutation in gK. Transfer of this mutation to HSV-1 (KOS) resulted in a recombinant that induced fusion of Vero cells but not HEp-2 cells and was more sensitive to heparin inhibition of entry, revealing a previously undescribed phenotype of mutations in gK. Engineered gC-negative virus containing the gK syncytial mutation induced fusion of both cell lines and was as resistant to heparin inhibition as was delta gC6. Because deletion of gC reduces infectivity of HSV-1 in the absence of heparin, mutations in gC combined with the syncytial mutation could have provided a selective advantage. Thus, absence of gC reduced heparin inhibition of binding and penetration while the combination of the gC and gK mutations enhanced spread through the HEp-2 cell monolayer by cell fusion. Because extreme selective pressure was required to favor these mutations and such mutations are rare in clinical isolates, the wild-type forms of gC and gK must provide for optimal viral replication and propagation in cell culture as well as in vivo, despite the view that gC is dispensable in cultured cells.

Amino Acid Sequence↗