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 infl uenza 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 SE-HA was sensitiv e to endoglycosidase H treatment, and immunofluorescence revealed that HHV-8 SE-HA was detectable in the perinuclear region of CHO-K1 cells. These observations suggest that HHV-8 gB is not processed in the Golg i and localizes to the endoplasmic reticulum or nuclear membrane. Beca use both HHV-8 and EBV are gamma-herpesviruses, the ability of HHV-8 g B to interact with and functionally complement EBV gp110 was examined. HHV-8 SE-HA and EBV gp110 co-immunoprecipitated, indicating formation of hetero-oligomers. However, HHV-8 SE-HA and HHV-8 gB failed to rest ore the infectivity of gp110-negative EBV mutants. These findings indi cate that although HHV-8 gB and EBV gp110 have similar patterns of int racellular localization and can interact, there is not sufficient func tional homology to allow efficient complementation. (C) 1998 Academic Press.