
Herpes Simplex Virus Glycoproteins gB and gD Function in a Redundant Fashion To Promote Secondary Envelopment
Author(s) -
David C. Johnson,
Todd W. Wisner,
Catherine C. Wright
Publication year - 2011
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.00011-11
Subject(s) - herpes simplex virus , envelopment , viral tegument , herpesvirus glycoprotein b , glycoprotein , cytoplasm , biology , viral envelope , lipid bilayer fusion , virology , golgi apparatus , microbiology and biotechnology , capsid , mutant , cell fusion , virus , inner membrane , viral entry , cell , viral replication , biochemistry , endoplasmic reticulum , gene , mathematical optimization , mathematics , mitochondrion , data envelopment analysis
Egress of herpes simplex virus (HSV) and other herpesviruses from cells involves extensive modification of cellular membranes and sequential envelopment and deenvelopment steps. HSV glycoproteins are important in these processes, and frequently two or more glycoproteins can largely suffice in any step. Capsids in the nucleus undergo primary envelopment at the inner nuclear membrane (INM), and then enveloped virus particles undergo deenvelopment by fusing with the outer nuclear membrane (ONM). Capsids delivered into the cytoplasm then undergo secondary envelopment, involvingtrans -Golgi network (TGN) membranes. The deenvelopment step involves HSV glycoproteins gB and gH/gL acting in a redundant fashion. This fusion has features common to the fusion that occurs between the virion envelope and cellular membranes when HSV enters cells, a process requiring gB, gD, and gH/gL. Whether HSV gD also participates (in a redundant fashion with gB or gH/gL) in deenvelopment has not been characterized. Secondary envelopment in the cytoplasm is known to involve HSV gD and gE/gI, also acting in a redundant fashion. Whether gB might also contribute to secondary envelopment, collaborating with gD and gE/gI, is also not clear. To address these questions, we constructed an HSV double mutant lacking gB and gD. The HSV gB− /gD− mutant exhibited no substantial defects in nuclear egress. In contrast, secondary envelopment was markedly reduced, and there were numerous unenveloped capsids that accumulated in the cytoplasm, as well as increased numbers of partially enveloped capsids and morphologically aberrant enveloped particles with thicker, oblong tegument layers. These defects were different from those observed with HSV gD− /gE− /gI− mutants, which accumulated capsids in large, aggregated masses in the cytoplasm. Our results suggest that HSV gB functions in secondary envelopment, apparently acting downstream of gE/gI.