To determine whether viral antigen is transported all the way to the RGC cell bodies, whole eyes were isolated and sectioned. Viral antigen immunostaining of retinal sections demonstrated no viral antigen in cells of the RGC layer of RSMHV2-infected mice (Fig. 6A) , whereas RSA59 viral antigen was detected in some cells within the RGC layer (Figs. 6B, C) at day 6 pi. Overall, viral antigen staining was detected in 60% of eyes from RSA59-infected mice, with 15 serial cross sections examined from each of 5 eyes. The timing of viral antigen spread and relative levels of antigen in retina and optic nerve were determined in protein extracts isolated at days 3 and 6 pi. Western blot analysis demonstrated presence of viral antigen in retinal tissue from RSA59infected mice at day 6 pi but not at day 3 and no viral antigen was detected in RSMHV2-infected mice (Fig. 6D ). Viral antigen was detected in protein extracts from optic nerves of RSA59-infected mice earlier than it was detected in retina. Antigen was detected on Western blots at both days 3 and 6 pi (Fig. 6E) . These results suggest that the viral antigen was able to enter the RGC axons and was transported retrograde to the cell bodies within the eye.