Purchase this article with an account.
JH LaVail, AN Tauscher, E Aghaian; Viral Envelope and Capsid Proteins are Transported as Separate Components in Herpes Simplex Virus Infected Neurons In Vivo . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4315.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To test the hypothesis that newly synthesized Herpes simplex virus (HSV) is transported as separable components in infected neurons in vivo. After reactivation from latency, new virus is made and spreads from the infected neuron' s cell soma to the axon and terminal. In non-polarized cells in vitro viral particles are transported as fully assembled virions in host cell transport vesicles for delivery to the cell surface. In neurons in vitro, however, envelope proteins are transported separately from capsid proteins in the axon. What has been needed to study anterograde transport of HSV in an animal model is a way to synchronize viral synthesis in the neurons and limit viral replication in associated glial cells. We have used Valacyclovir to satisfy these requirements. Methods: HSV (F strain) was injected intravitreally into the eyes of mice. Valacyclovir (1 mg/ml) was introduced into the drinking water of mice 24 hrs later. Two, 3, 4 or 5 days after infection, the animals were killed, and the 15 mm long optic pathway was divided into 4 segments, (the proximal and distal optic nerve, optic chiasm and optic tract). The transport of a major capsid protein (VP5) and a major envelope protein, glycoprotein D (gD) in retinal ganglion cell axons was assayed using SDS PAGE and Western blots. Results: Valacyclovir treatment significantly reduced the spread of HSV from axons to astrocytes in the optic pathway at all survival times. Two days after infection, there were low levels of gD antigen in the optic nerve, but no detectable gD antigen in the optic chiasm or tract. By 3 days, there was distinct bands of gD immunostaining in the optic nerve segments, and by day 4 the gD immunostaining extended throughout the pathway. In contrast, we found no evidence of VP5 staining until day 4 when there was faint immunoreactivity throughout the optic pathway. By day 5 VP5 immunostaining was found throughout the optic pathway. Conclusions: Valacyclovir can be used to "pulse infect" retinal ganglion cells and restrict infection in astrocytes. The gD (and presumably other envelope proteins) accumulate in the optic pathway about 2 days before VP5 (and presumably other capsid proteins) can be identified in the optic pathway. This supports the hypothesis that new HSV virus is transported within the axon as unassembled components in vivo. Furthermore, the transport of gD is not dependent on simultaneous transport of VP5 in infected neurons.
This PDF is available to Subscribers Only