Anterograde Spread of Herpes Simplex Virus Type 1 Requires Glycoprotein E and Glycoprotein I but Not Us9

Abstract

Anterograde neuronal spread (i.e., spread from the neuron cell body toward the axon terminus) is a critical component of the alphaherpesvirus life cycle. Three viral proteins, gE, gI, and Us9, have been implicated in alphaherpesvirus anterograde spread in several animal models and neuron culture systems. We sought to better define the roles of gE, gI, and Us9 in herpes simplex virus type 1 (HSV-1) anterograde spread using a compartmentalized primary neuron culture system. We found that no anterograde spread occurred in the absence of gE or gI, indicating that these proteins are essential for HSV-1 anterograde spread. However, we did detect anterograde spread in the absence of Us9 using two independent Us9-deleted viruses. We confirmed the Us9 finding in different murine models of neuronal spread. We examined viral transport into the optic nerve and spread to the brain after retinal infection; the production of zosteriform disease after flank inoculation; and viral spread to the spinal cord after flank inoculation. In all models, anterograde spread occurred in the absence of Us9, although in some cases at reduced levels. This finding contrasts with gE-and gI-deleted viruses, which displayed no anterograde spread in any animal model. Thus, gE and gI are essential for HSV-1 anterograde spread, while Us9 is dispensable.

Herpes simplex virus type 1 strain KOS carries a defective US9 and a mutated US8A gene

“…The described attenuation of certain KOS isolates has been mapped to genome regions other than the US9 gene (Thompson et al, 1986). This might indicate a limited functional relevance of pUS9, which would be in line with the inconspicuous phenotypes of engineered US9 deletion mutants of HSV-1 and other alphaherpesviruses in vitro (Brideau et al, 2000;Chowdhury et al, 2002;Polcicova et al, 2005), and partly also in vivo (Klopfleisch et al, 2006;McGraw et al, 2009;Nishiyama et al, 1993).…”

“…Conservation of pUS9 function was proven by complementation of US9-deleted PrV by the homologous proteins of equine herpesvirus 1 and BoHV-1, as well as of US9-deleted BoHV-5 by the BoHV-1 protein (Chowdhury et al, 2006;Lyman et al, 2009). However, pUS9 of HSV-1 or varicella-zoster virus (VZV) failed to compensate functionally for the PrV protein (Lyman et al, 2009), and recent studies indicate that pUS9 is dispensable for anterograde axonal transport of HSV-1 particles, whereas the product of the US8 gene, gE, is required (McGraw et al, 2009).…”

“…Since different results regarding the relevance of pUS9 for axonal transport of HSV-1 have been obtained using strains F (Snyder et al, 2008) and NS (McGraw et al, 2009), we attempted to investigate the role of this protein for HSV-1 strains KOS (Smith, 1964) and 17 (Brown et al 1973). The latter two HSV-1 strains were originally isolated from human labial lesions, and are frequently used as parental wild-type strains for the generation of virus mutants and investigation of viral gene functions (Brown et al, 1973;Schaffer et al, 1973).…”

Glycoproteins gE and gI Are Required for Efficient KIF1A-Dependent Anterograde Axonal Transport of Alphaherpesvirus Particles in Neurons

“…Compared to the 67 wild-type protein-coding regions, PRV Bartha has missense or silent mutations in at least 46 proteins as well as a deletion in the unique short region of the PRV genome that removes the coding sequences for gI (Us7), gE (Us8), Us9, and Us2. Since both gE and gI have a well-established role in anterograde spread in neurons (13)(14)(15)(17)(18)(19), the function of the heterodimer formed by these two proteins may be required for mediating the interaction between Us9 and KIF1A. However, since the Us2 protein is also mutated in Bartha and, like gE, copurifies with Us9 (6) we also assessed whether it is required for anterograde spread of infection using a previously described compartmentalized neuronal culture system ( Fig.…”

“…Newly replicated progeny virions are assembled in the cell body and may be sorted into axons and transported back out toward the periphery (anterograde-directed spread) (10,11). Three highly conserved viral membrane proteins are important for anterograde-directed spread of infection in vivo and in vitro, including Us9 and the glycoproteins gE and gI (13)(14)(15)(16)(17)(18)(19)(20)(21).…”