The ability of two strains of herpes simplex virus type 1 (HSZP and KOS) to shut off the host protein synthesis in the presence of Actinomycin D was investigated. The HSZP strain proved to be defective with respect to the so-called early shutoff function. In superinfection experiments, the HSZP was effective at interfering with the early shutoff function of the KOS strain provided that the HSZP infection preceded KOS superinfection. Heat inactivation of the HSZP did not lead to the loss of its interfering ability. Evidence was given that this interference was neither due to the hindrance of the KOS by HSZP at adsorption nor due its exclusion during penetration.

Institute of Virology Slovak Academy of Sciences Bratislava Czechoslovakia