REACTIVATION OF PROTEASE-INACTIVATED VACCINIA VIRUS BY HOMOLOGOUS AND MUTANT VIRUSES^*

Abstract

In a previous publication from this laboratory (Nishimura & Tagaya, 1960) it was reported that a bacterial protease “Nagarse” inactivated vaccinia virus by log 2.0 to 3.0 at 37°C, beyond which no further inactivation could be obtained by further incubation or repeated treatments with the enzyme. An attempt to isolate enzyme-resistant variants by serial passages of the survivors after Nagarse-treatment failed, giving an unaltered survival rate by the enzyme treatment after 10 selective passages. The phenomenon suggested an intervention of the reactivation of virus particles with differently impaired surface structures, and investigations on the reactivation of Nagarse-inactivated vaccinia virus by a simultaneous inoculation of ultraviolet (UV) -inactivated virus of the homologous or its mutant strain were carried out. A part of this work was puplished recently (Kitamura, 1963) and the present paper deals with the full description of the experimental results.