Inhibition of pseudorabies virus replication by vesicular stomicles virus I. Activity of infectious and inactivated B particles

Infectious B particles of vesicular stomatitis virus (VSV) are capable of inhibiting the replication of pseudorabies virus (PSR) in a variety of cell lines. Even under conditions of an abortive infection in a continuous line of rabbit cornea cells (RC-6O), B particles interfere with the replication of PSR with high efficiency. Particle per cell dose-response analysis of B particle populations revealed that the number of VSV particles capable of inhibiting PSR replication exceeds the number of PFU by a factor of 32 to 64. When B particles are treated with UV irradiation, a drastic increase in the multiplicity of infection is required to inhibit PSR replication. Whereas one infective B particles per cell is sufficient to prevent replication of PSR, 800 to 1,000 VSV particles rendered noninfective by UV irradiation are required to compensate for the loss of VSV synthetic activity that results from irradiation. Temperature-sensitive mutants representing five complementation groups of VSV were tested at low multiplicities of infection for their effect on PSR replication at the nonpermissive temperature. Generally, the ability of the different complementation groups to amplify virion products at the nonpermissive temperature is associated with their ability to inhibit PSR replication. These results imply that at low multiplicities of infection, amplification of infecting VSV components is necessary for inhibition of PSR replication., but at high multiplicities of infection with VSV, a virion component can prevent PSR replication in the absence of de novo VSV RNA or protein synthesis.