SPECIFIC PSEUDORABIES VIRUS-INFECTION OF THE RAT VISUAL-SYSTEM REQUIRES BOTH GI AND GP63 GLYCOPROTEINS

Transneuronal transport of pseudorabies virus (PRV) from the retina to visual centers that mediate visual discrimination and reflexes requir es specific genes in the unique short region of the PRV genome. In con trast, these same viral genes are not required to infect retinorecipie nt areas of the brain involved in circadian rhythm regulation. In this report, we demonstrate that viral mutants carrying defined deletions of the genes encoding glycoprotein gI or gp63, or both, result in the same dramatic transport defect. Efficient export of either gI or gp63 from the endoplasmic reticulum to the Golgi apparatus in a fibroblast cell line requires the presence of both proteins. We also show that gI and gp63 physically interact, as demonstrated by pulse-chase and sucr ose gradient sedimentation experiments. Complex formation is rapid com pared with homodimerization of PRV glycoprotein gII. We suggest that g I and gp63 function in concert to affect neurotropism in the rat visua l circuitry and that a heterodimer is likely to be the unit of functio n.