We have isolated a number of plaque-morphology mutants from a strain of herpes simplex virus type I which, unlike the wild type, cause extensive cell fusion during a productive viral infection. After the onset of fusion, there is an exponential decrease in the number of single cells as a function of time after infection. At a multiplicity of infection (MOI) of 3.8 plaque-forming units per cell, fusion begins 5.3 h after infection with the number of single cells decreasing to 10% of the original number 10.2 h after infection. As the MOI is gradually increased from 0.4 to 8, the onset of fusion occurs earlier during infection. However, when the MOI is increased from 8 to 86, the onset of fusion does not occur any earlier. The rate of fusion is independent of the MOI for an MOI greater than 1. The rate of fusion varies linearly with initial cell density up to 3.5

2-Deoxyglucose and glucosamine were found to inhibit cell fusion caused by a syncytial mutant of herpes simplex virus and to inhibit the glycosylation of viral glycoproteins in the infected cells. The inhibition of fusion and the inhibition of glycosylation caused by 2-deoxyglucose were substantially prevented when mannose was also present during infection. When glycosylation was inhibited, three new bands were found in the major glycoprotein region on sodium dodecyl sulfate-polyacrylamide gels. These bands may be precursors to the normal glycoproteins. The correlation between fusion and glycosylation in the presence of 2-deoxyglucose, glucosamine, and mannose suggests that the cells cannot fuse if their glycoproteins have a considerably reduced carbohydrate content.

We have previously identified a monoclonal antibody, T8/2T8‐5H7, which clustered serologically with CD8 monoclonal antibodies, but lacked reactivity with L cell transfectants expressing the human CD8 molecule (Lyt‐2 homologue). Based on these observations, we postulated that T8/2T8‐5H7 might recognize the human Lyt‐3 gene product. To test this hypothesis, we have isolated a full‐length cDNA encoding the human Lyt‐3 molecule and have characterized its product in additional transfection experiments. The results of these studies indicate that the human Lyt‐3 cDNA encodes a product recognized by the antibody T8/2T8‐5H7. Interestingly, the human Lyt‐3 molecule cannot be expressed alone, but requires the human Lyt‐2 homologue for efficient cell surface expression. A heterodimer composed of the human Lyt‐2 and Lyt‐3 molecules may have importance in T cell‐target cell interactions.

No abstract

No abstract