Studies on the propagation in vitro of poliomyelitis viruses. I. Viral multiplications in tissue cultures employing monkey and human testicular cells.

Poliomyelitis virus was propagated in vitro successfully in extraneural tissues. Suspended tissue fragment cultures and combined plasma clot-suspended tissue fragment cultures of monkey or human testicular tissues were employed. Five strains representative of poliomyelitis virus were maintained for from 36 to 263 days in the suspended tissue fragment type of culture. The dilution factors calculated by tissue replacements for the eight serial passages ranged from 10(7.8) to 10(44.5) and when assessed by fluid replacements, from 10(15) to 10(95.3). The LD(50) for each strain of Type 2 virus was determined for selected transfers. The identify of each strain of virus was established by neutralization tests and histopathological findings in monkeys dead from the injection of tissue culture virus. Control experiments and other tests made known that propagation of poliomyelitis virus did not occur in the absence of viable testicular cells and that an extraneous virus was not inadvertently acquired during the course of these studies.