Glycoprotein L sets the neutralization profile of murid herpesvirus 4

J Gen Virol. 2009 May;90(Pt 5):1202-1214. doi: 10.1099/vir.0.008755-0. Epub 2009 Mar 4.

Abstract

Antibodies readily neutralize acute, epidemic viruses, but are less effective against more indolent pathogens such as herpesviruses. Murid herpesvirus 4 (MuHV-4) provides an accessible model for tracking the fate of antibody-exposed gammaherpesvirus virions. Glycoprotein L (gL) plays a central role in MuHV-4 entry: it allows gH to bind heparan sulfate and regulates fusion-associated conformation changes in gH and gB. However, gL is non-essential: heparan sulfate binding can also occur via gp70, and the gB-gH complex alone seems to be sufficient for membrane fusion. Here, we investigated how gL affects the susceptibility of MuHV-4 to neutralization. Immune sera neutralized gL(-) virions more readily than gL(+) virions, chiefly because heparan sulfate binding now depended on gp70 and was therefore easier to block. However, there were also post-binding effects. First, the downstream, gL-independent conformation of gH became a neutralization target; gL normally prevents this by holding gH in an antigenically distinct heterodimer until after endocytosis. Second, gL(-) virions were more vulnerable to gB-directed neutralization. This covered multiple epitopes and thus seemed to reflect a general opening up of the gH-gB entry complex, which gL again normally restricts to late endosomes. gL therefore limits MuHV-4 neutralization by providing redundancy in cell binding and by keeping key elements of the virion fusion machinery hidden until after endocytosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / immunology*
  • CHO Cells
  • Cell Line
  • Cricetinae
  • Cricetulus
  • Epithelial Cells
  • Female
  • Fibroblasts
  • Glycoproteins / immunology*
  • Macrophages
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Protein Binding
  • Rhadinovirus / immunology*
  • Rhadinovirus / metabolism*
  • Viral Envelope Proteins / immunology*

Substances

  • Antibodies, Viral
  • Glycoproteins
  • Viral Envelope Proteins