CELL-TYPE DEPENDENT SENSITIVITY OF HERPES-SIMPLEX-VIRUS-1 MUTANTS TO PLAQUE DEVELOPMENT INHIBITION BY AN ANTI-GD MONOCLONAL-ANTIBODY

Herpes simplex virus 1 (HSV-1) mutants selected in Vero cells either f or resistance to plaque development inhibition (PDI) (P1, P2 and P3) o r for resistance to neutralization (N1, N2, and N3) against an anti-gl ycoprotein D (gD) monoclonal antibody (mAb) were characterized both in Vero and BHK cells. In Vero cells P mutants were completely resistant to PDI, while N mutants showed from moderate to good resistance. In B HK cells P mutants lost their resistance to PDI, while N mutants becam e fully resistant. Cell type influenced the plaque size of the mutants as well. In Vero cells P mutant plaques were larger, and N mutant pla ques smaller than wild type virus plaques. In BHK cells all plaques we re comparable. With one exception (N2 in BHK) resistance to neutraliza tion could be clearly appreciated at high but not at low mAb : virus p articles ratio. For most of the mutants the neutralization values rema ined approximately the same in Vero and BHK cells. P2 and N2 mutants w ere more resistant to neutralization in BHK than in Vero cells. Howeve r, only for N2 mutant did the change in neutralization resistance go i n the same direction as the change in PDI resistance. The results show that it is possible to dissociate the neutralizing and the PDI activi ties of a mAb and that the sensitivity of a virus to plaque inhibition by an anti-gD mAb is cell-type dependent.