Isolation of a viable herpesvirus (pseudorabies virus) mutant specifically lacking all four known nonessential glycoproteins.

Recently we described the isolation and characterization of a pseudorabies virus (PrV) mutant lacking the nonessential glycoproteins gI, gp63, and gIII. Using insertional mutagenesis with a functional gX-beta-galactosidase fusion gene we describe here the isolation of a PrV mutant specifically lacking all four known nonessential glycoproteins, gI, gp63, gIII, and gX. The quadruple mutant did not show any significant alterations in the vitro growth characteristics compared to its triple mutant parent. These results prove that PrV nonessential glycoproteins are dispensable for viral replication in cell culture altogether.