Propagation of MM Virus in Continuous Cell Lines

Abstract

Baby hamster kidney (BHK), McCoy, and L cell lines were found to be suitable for isolation of MM virus from infected mouse brain tissue. The virus was recovered in high titer in the first passage in BHK and McCoy cells, with concomitant cytopathic effect (CPE). In L cells, virus yield was lower than in the other two cell lines and CPE was incomplete. Adaptation of the virus to BHK and McCoy cells by serial passages was evidenced by accelerated development of the CPE and increase in the virus titer. Plaques were obtained in all three cell lines when inoculated with infected mouse brain or with the tissue culture-propagated virus. In the BHK cells, the virus release preceded the appearance of CPE and maximal yield of virus was obtained after 1 to 3 days of incubation, depending on the size of inoculum. The BHK-propagated virus had the same lethality for mice as did the mouse brainpropagated stock, and there was no difference in the course of the disease caused by the two preparations.

Role of Interferon in the Propagation of MM Virus in L Cells

“…Since its discovery, MM virus has been almost exclusively propagated by mouse brain passage because of the apparent failure of the virus to grow in continuous cell lines (4). Recently, however, propagation of MM virus in several continuous cell lines has been reported (1,8). In L cells, mouse brain-grown MM virus replicated to relatively low titers [average yield of less than 1 plaque-forming units (PFU) /cell] without cytopathic effect (CPE).…”