THE OPEN READING FRAMES UL3, UL4, UL10, AND UL16 ARE DISPENSABLE FOR THE REPLICATION OF HERPES-SIMPLEX VIRUS 1 IN CELL-CULTURE

By means of insertion and deletion mutagenesis, we have constructed four herpes simplex virus 1 recombinants, each lacking most sequences encoding a different open reading frame. The deleted genes are located in the unique sequences of the long component and include those designated U(L)3, U(L)4, U(L)10, and U(L)16. The recombinant virus R7211 lacks 579 of the 696 bp of U(L)3. The recombinant virus R7217 lacks 307 of the 597 bp of the U(L)4 open reading frame. R7216 contains a 972-bp deletion within the 1,419-bp open reading frame of U(L)10, whereas R7210 lacks 988 bp of the 1,119-bp U(L)16 open reading frame. Growth curves indicated that the yields of these viruses in Vero and BHK cell cultures were only slightly reduced from or in some instances equivalent to that of the parent virus. The function of the gene products is not known. It is of interest to note that (i) the U(L)16 open reading frame maps entirely within the single intron of U(L)15 and (ii) on the basis of the extent and size of hydrophobic domains, the U(L)3 and U(L)10 gene products were predicted to be membrane proteins.