Survival of Vaccine Virus Separated from Living Host Cells by Collodion Membranes.

Abstract

The fact that vaccine virus is capable of multiplication in the presence of living host cells 1 , 2 cultivated in vitro has been known for a number of years. Reports concerning the growth of the virus on lifeless media have not been substantiated. Although it has, as yet, been impossible to cultivate the virus of vaccinia in the absence of living cells, no one definitely knows what function these cells serve in the cultures. Recently, Maitland and Maitland 3 demonstrated that vaccine virus increased in a medium consisting of minced kidney suspended in a mixture of serum and Tyrode's solution. The development of this fluid medium, in which living cells persist for at least 5 days, 4 has made possible experiments designed for an intensive study of the relation of vaccine virus to host cells.

Collodion sacs, prepared according to the method of Northrop and Kunitz, 5 were placed over the lower ends of small open tubes that fitted into larger test tubes. The small inner tubes with their attached sacs and the larger outer tubes were sterilized separately in an autoclave, after which the former were placed in the latter, thus forming 2 compartments separated at the lower level by the membrane alone.

Levaditi neurovaccine prepared in the testicles of rabbits was used. Emulsions of the infected testicles, from which cells were thoroughly removed, were diluted with rabbit serum and Tyrode's solution and then placed on one side of the collodion membrane, while a mixture of minced normal kidney, normal serum, and Tyrode's solution was placed on the other side. Vaccine virus under these conditions, although separated from living cells, survived a 4-day incubation at 37°C., while the virus in controls—a mixture of virus, serum, and Tyrode's solution incubated alone in test tubes—became inactive.