Identification and Characterization of a Bovine Herpesvirus-1 (BHV-1) Glycoprotein gL Which Is Required for Proper Antigenicity, Processing, and Transport of BHV-1 Glycoprotein gH

Abstract

DNA sequence analysis of the bovine herpesvirus-1 (BHV-1) genome revealed the presence of an open reading frame named UL1 which exhibited limited homology to glycoprotein gL of herpes simplex virus-1 (S. K. Khattar, S. van Drunen Littel-van den Hurk, L. A. Babiuk, and S. K. Tikoo, Virology 213, 28-37). To identify the BHV-1 UL1 protein, rabbit antisera were prepared against two synthetic peptides that were predicted by computer analysis to encompass antigenic epitopes. Sera against both peptides immunoprecipitated a 16- to 17-kDa protein from in vitro translated in vitro transcribed mRNA, BHV-1-infected MDBK cells, and purified virions. Enzymatic deglycosylation and lectin binding assays confirmed that the BHV-1 UL1 protein contains only O-linked oligosaccharides and was named glycoprotein gL. Sera against UL22 protein immunoprecipitated a protein of 108 kDa from BHV-1-infected MDBK cells and purified virions, which was modified only by N-linked oligosaccharides and was named glycoprotein gH. Glycoprotein gL expressed by recombinant vaccinia virus was properly processed and secreted into the medium. In contrast glycoprotein gH expressed by recombinant vaccinia virus was found to be retained in the rough endoplasmic reticulum. However, gH coexpressed with gL by recombinant vaccinia viruses was properly processed and transported to the cell surface, suggesting that complex formation between gH and gL is necessary for the proper processing and transport of gH but not gL. In addition gH--gL complex formation is also required for induction of neutralizing antibody response and anchoring of gL to the plasma membrane.

Identification of a variant B-specific neutralizing epitope on glycoprotein H of human herpesvirus-6.

“…Glycoprotein H (gH) is highly conserved among human and animal herpesviruses (McGeoch & Davison, 1986 ;Keller et al, 1987 ;Gompels et al, 1988 ;Pachl et al, 1989 ;Josephs et al, 1991 ;Klupp & Mettenleiter, 1991 ;Xu et al, 1992 ;Maeda et al, 1993 ;Scott et al, 1993 ;Mukai et al, 1997 ;Pepper et al, 1996). It functions in the penetration step and in cell-to-cell spread, but not in the attachment step (Keller et al, 1987 ;Forrester et al, 1992 ;Peeters et al, 1992 ;Wilson et al, 1994 ;van Drunen Littel-van den Hurk et al, 1996 ;Babic et al, 1996). In addition, gH elicits antibodies which can neutralize Author for correspondence : Koichi Yamanishi.…”

“…infectivity in the absence of complement and is thus a target of the host immune response (Ghiasi et al, 1992 ;Liu et al, 1993 b ;Qian et al, 1993 ;Rapp et al, 1994 ;Khattar et al, 1996 ;Urban et al, 1996 ;Nemeckova et al, 1996). It also forms a complex with a smaller glycoprotein, glycoprotein L (gL), which is required for normal processing and transport of gH to the cell membrane and thus acts as a molecular chaperone (Hutchinson et al, 1992 ;Kaye et al, 1992 ;Klupp et al, 1994 ;Pulford et al, 1995 ;Duus et al, 1995 ;Duus & Grose, 1996 ;Khattar et al, 1996 ;Mukai et al, 1997 ;Stokes et al, 1996).…”

“…It also forms a complex with a smaller glycoprotein, glycoprotein L (gL), which is required for normal processing and transport of gH to the cell membrane and thus acts as a molecular chaperone (Hutchinson et al, 1992 ;Kaye et al, 1992 ;Klupp et al, 1994 ;Pulford et al, 1995 ;Duus et al, 1995 ;Duus & Grose, 1996 ;Khattar et al, 1996 ;Mukai et al, 1997 ;Stokes et al, 1996). In the case of Epstein-Barr virus (EBV), a third viral glycoprotein, which is encoded by the BZLF2 open reading frame, associates with the gH-gL complex (Li et al, 1995).…”

Bovine herpesvirus type 1 glycoprotein H is essential for penetration and propagation in cell culture.

“…BHV-1 gH forms a complex with another glycoprotein, gL, which is necessary for the proper processing and transport of gH but not gL (Khattar et al, 1996). In addition, the BHV-1 gH-gL complex is required for induction of a neutralizing antibody response and anchoring of gL to the plasma membrane (Khattar et al, 1996).…”

“…BHV-1 gH forms a complex with another glycoprotein, gL, which is necessary for the proper processing and transport of gH but not gL (Khattar et al, 1996). In addition, the BHV-1 gH-gL complex is required for induction of a neutralizing antibody response and anchoring of gL to the plasma membrane (Khattar et al, 1996). Characterization of PrV and HSV-1 gH null mutants has indicated that gH of these viruses is an essential glycoprotein which is involved in both fusion between virion and cellular membranes during virus entry and in cell-to-cell spread of the virus (Forrester et al, 1992 ;Babic et al, 1996).…”