A HERPES-SIMPLEX VIRUS-1 U(S)11-EXPRESSING CELL-LINE IS RESISTANT TO HERPES-SIMPLEX VIRUS-INFECTION AT A STEP IN VIRAL ENTRY MEDIATED BY GLYCOPROTEIN-D

A baby hamster kidney BHK(tk(-)) cell line (U(s)11c119) which stably expresses the U(s)11 and alpha 4 genes of herpes simplex virus 1 stra in F HSV-1(F) was found to be resistant to infection with HSV-1, Alt hough wild-type HSV-1(F) attached with normal kinetics to the surface of U(s)11C119 cells, most cells showed no evidence of infection and fa iled to accumulate detectable amounts of a mRNAs. The relationship bet ween the expression of U(L)11 and resistance to HSV infection in U(s)1 1c119 cells has not been defined, but the block to infection with wild -type HSV-1 was overcome by exposing cells with attached virus on thei r surface to the fusogen polyethylene glycol, suggesting that the bloc k to infection preceded the fusion of viral and cellular membranes. An escape mutant of HSV-1(F), designated R5000, that forms plaques on U( s)11c119 cells was selected. This mutant was found to contain a mutati on in the glycoprotein D (gD) coding sequence that results in the subs titution of the serine at position 140 in the mature protein to aspara gine. A recombinant virus, designated R5001, was constructed in which the wild-type go gene was replaced with the R5000 go gene. The recombi nant formed plaques on U(s)11c119 cells with an efficiency comparable to that of the escape mutant R5000, suggesting that the mutation in go determines the ability of the mutant R5000 to grow on U(s)11c119 cell s. The observation that the U(s)11c119 cells were slightly more resist ant to fusion by polyethylene glycol than parental BHK(tk(-)) cells le d to the selection and testing of clonal lines from unselected and pol yethylene glycol-selected BHK(tk(-)) cells. The results were that 16% of unselected to as much as 36% of the clones selected for relative re sistance to polyethylene glycol fusion exhibited various degrees of re sistance to infection. The exact step at which the infection was block ed is not known, but the results illustrate the ease of selection of c ell clones with one or more sites at which infection could be blocked.