EXPRESSION OF SYN-GENE OF HERPES-SIMPLEX VIRUS TYPE-1 .1. MORPHOLOGY OF INFECTED-CELLS

The morphological response of cells infected with fusion-inducing (syn-) strains of herpes simplex virus type 1 (HSV-1) was altered by the presence of the syn+ allele. When [baby hamster kidney BHK-21 and human epidermoid carcinoma HEp-2] cells are simultaneously infected with syn+ and syn- strains of HSV-1, the morphology of the syn+ strain is dominant. When syn--infected cells are superinfected with syn+ virus 2 h after the initial infection, the morphological response of the syn- genome is expressed. Regardless of the order used in the delayed infection, both virus genotypes are replicated and found in the progeny in approximately equal amounts. The basis for the dominance of the syn- allele in the delayed infection is not known. Although cells infected with syn- virus fuse with uninfected cells or cells infected with syn- virus, they do not fuse with cells infected with syn- virus. The membranes of syn+ virus-infected cells are probably altered in such a way that precludes participation in cell fusion.