Purchase this article with an account.
J.H. LaVail, A.N. Tauscher, O. Harrabi, C. Duffy, J.D. Baines, R. Brandimarti; A Comparison of the Roles of HSV Tegument Proteins VP22 and US9 in Corneal Cell–Cell Spread and Retinal Anterograde Transport . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4305.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The anterograde axonal transport of newly–synthesized Herpes simplex virus type 1 (HSV) in trigeminal neurons is an essential step in the pathogenesis of herpetic keratitis. Our goal is to define host and viral proteins that collaborate in the delivery of HSV to the corneal epithelium. We have infected scarified cornea and retinal ganglion cells to model infected trigeminal neurons and cornea.
Murine corneas were scarified and inoculated with equivalent titers of each of 10 strains of HSV, including those encoding mutant proteins required for normal replication (ICP8), tegument (VP22 and US9) and envelope (gD and gE). Based on these results, we focused on the roles of US9 and VP22 in axonal transport. We injected equivalent titers of VP22–deficient (VP22–), VP22 rescued (VP22R), US9–, US9R and wild–type (wt) strains of virus into the vitreal chamber of mice. Three or 5 days dpi the optic pathways were collected for western blots, DNA analysis, or immunohistochemistry.
There was no significant difference in the titers of virus produced by any of the strains. After scarification, VP22– spread only ∼60% the distance spread by the wt or VP22R viruses. Both VP22– and US9– demonstrated impaired axonal transport. By 3 dpi of retinal ganglion cells, we found that the VP22– infected mice had transported <17% of the amount of DNA transported by the VP22R or wt strains infected mice. By 3 dpi, we found that the US9– infected mice had transported <7% of the amount of DNA transported by the US9R or wt strain infected mice. Although gD and VP5 were detectable in the optic tracts of VP22–, VP22R and wt infected mice by 5 dpi, the amount of both proteins was significantly reduced in VP22– infected mice. We could detect gD in the optic tracts of US9– and US9R mice by 5 dpi, but VP5 was significantly reduced or absent in the tracts of mice infected with US9– virus. Preliminary results indicate that VP5 co–immunoprecipitates with US9.
VP22 is necessary for effective cell–cell spread between corneal epithelial cells and delivery of virus for axonal transport. The US9 protein is necessary for the efficient anterograde transport of HSV capsid and DNA, but is not necessary for transport of the envelope component of the virus. Since US9 is not necessary for cell–cell spread of HSV between corneal epithelial cells, this suggests that HSV is delivered by different mechanisms in neurons and epithelial cells in vivo.
This PDF is available to Subscribers Only