The recovery of polyoma virus from infected mouse cells: relevance to virus purification

The desire to obtain maximum yields of polyoma virus from infected mouse tissue culture lysates prompted us to examine more closely the interaction between virus and cell fragments. The objective was to find the best and most economical means of alleviating this interaction, and allow quantitative recovery of the virus for further purification. Sonication of polyoma virus infected mouse-kidney cultures sufficed to release the virus in a form amenable to hemagglutinin assay. In contrast infected mouse embryo lysates required neuraminidase to effect maximum release. A variety of other enzymes and treatments were tested and found to be completely ineffective, or less effective than neuraminidase. However, in spite of the ability to effect release of virus at this stage, subsequent centrifugation to pellet the cell fragments always resulted in reattachment of the virus to these fragments. Complete elution of the virus then required several cycles of neuraminidase, trypsin, pH 8.5 treatments. It was shown that full and empty viral capsids behaved similarly.