Differential anterograde transport of HSV type 1 viral strains in the murine optic pathway

Active anterograde transport of herpes simplex virus Type 1 (HSV-I) in neur ons is often assumed based on early appearance of infection in postsynaptic target cells of a primary infected cell, and is further logically inferred by good evidence of microtubule-motor based mechanisms of retrograde trans port. However, direct evidence of mechanisms of anterograde movement of new ly synthesized virus in CNS neurons actually has yet to be obtained. In eff orts to investigate the latter, we will be greatly aided by viral strains t hat exhibit differences in their ability to move in an anterograde directio n. We compared the anterograde axonal transport of three HSV strains (F str ain, H129, and MacIntyre B) in the murine visual system. Equivalent titers of virus were injected intraocularly in BALB/c mice. From 2-6 days after in oculation, segments of the infected optic pathway were harvested and Wester n blots using an anti-HSV polyclonal antibody performed. H129 traveled very rapidly towards the terminals (3 days post-inoculation). F strain spread m ore slowly than H129, but also reached terminal regions by 4 days, MacIntyr e B accumulated only in the most proximal optic nerve, and was seen only ve ry faintly in distal optic pathway after 5 days. Coincidentally, a single v iral protein appeared to be greatly reduced in expression in MacIntyre B. O ur results suggest that different viral strains display variability in thei r capacity to spread anterogradely, and that further comparison of these st rains may reveal how virus engages the host cell transport machinery.