Analysis of conserved domains of UL41 of herpes simplex virus type 1 in virion host shutoff and pathogenesis.

The herpes simplex virus type 1 virion host shutoff protein has four domains whose sequences are conserved only among neurotropic herpesviruses. Mutant viruses with 29- and 31-amino-acid deletions in domains III and IV but outside of the domain required for interaction with VP16 were generated. The mutants failed to induce cellular RNA degradation and showed impaired virulence in mice. Domains III and IV are therefore required for both shutoff and virulence.