N-linked oligosaccharides on herpes simplex virus glycoprotein gD are not essential for establishment of viral latency or reactivation in the mouse eye model.

Glycoprotein D (gD) is an essential component of the herpes simplex virus (HSV) envelope. It is essential for viral penetration and for cell to cell spread of virus in vitro, and is also important for neuroinvasiveness. We investigated the contribution of N-linked oligosaccharides (N-CHO) on gD to viral pathogenesis. We used F-gD(QAA), a mutant virus derived from strain F of HSV-1. This virus contains three mutations in the gD gene which eliminate all signals for addition of N-CHO. These mutations affect the antigenic structure of gD and also lead to a small plaque phenotype. Otherwise the virus appears normal in in vitro assays. We used the mouse eye model of HSV latency to examine whether the mutations alter the phenotype of the virus in vivo. At 4 days postinfection similar amounts of F-gD(QAA) and F-gD(WT), its wild-type parent, were found in either eyes or trigeminal ganglia (TG) of infected mice. Moreover, both mutant and wild-type viruses exhibited the same ability to establish, maintain, and be reactivated from latency. We conclude that N-CHO on gD are not essential for HSV-1 pathogenesis in this model.