Attempt to Propagate Poliomyelitis Virus Through Serial Passage in Cotton Rats by “Spreading Factor of Duran-Reynals.”

Abstract

Numerous attempts have been made to “adapt” poliomyelitis virus to passage in the eastern cotton rat since Armstrong 1 reported that a strain of virus isolated from one of a number of cases occurring during an outbreak of poliomyelitis in Lansing, Michigan, could be propagated in the variety Sigmodon hispidus hispidus. These attempts, including those of Armstrong, to obtain takes with other strains of poliomyelitis virus have failed. Toomey 2 has recently reported unsuccessful attempts to propagate 9 other monkey adapted strains of this virus. He inoculated 9 groups of Sigmodon hispidus littoralis rats, each with one of 9 strains of virus and later when symptoms failed to develop, these animals were shown to be susceptible to the Lansing strain.

Duran-Reynals 3 , 4 has shown that testicular extract (“spreading factor”) added to the virus of vaccinia increased the extent of the lesions in the rabbit, and Hoffman and Duran-Reynals 5 showed that it had similar enhancing effects on the viruses of herpes, vesicular stomatitis and Borna disease. In this laboratory several experiments have been made recently to further investigate the effects of testicular extract on the pathogenesis of a number of filterable viruses. Our unreported and incomplete experiments, although of a slightly different character, tend to confirm those reported for the virus of herpes and also suggest that a somewhat similar effect is obtained when the spreading factor is combined with minimal doses of the virus of lymphocytic choriomeningitis given to mice intracerebrally.

It was decided to attempt to adapt a strain of poliomyelitis virus to the cotton rat by suspending the virus in testicular extract, in the hope that this factor might enable the virus to propagate in a tissue that presented conditions which possibly were partially though not entirely suitable for its growth.