Propagation of Rabies Virus in Tissue Culture. ∗

Abstract

Summary and Conclusions

(1) The rabies virus has been propagated for as long as 57 passages (transfers) in cultures of chopped mouse embryo brain suspended in rabbit serum and buffered salt solutions. Under conditions developed in shorter, more recent experiments, the virus multiplied to the extent that mice were killed regularly by the culture material in dilutions as high as 10^-6 (1:1,000,- 000); and it was possible to produce typical rabies in mice with 1/33,000,000 cc of the culture virus. When ox serum ultrafiltrate was substituted for rabbit serum, the virus titer was somewhat less. (2) Comparative experiments showed the importance of grinding the culture material for mouse titrations. But no significant increase in virus output was ever obtained by subjecting the cultures to continuous gassing with mixtures of O₂, CO₂ and N₂. (3) A duplicate series of cultures incubated for 9 passages at 35°C and at 37.5°C, respectively, showed no consistent difference in the amount of virus produced. (4) Attempts to cultivate the rabies virus in chick embryo brain cultures were unsuccessful even when the virus had been adapted to chick tissue by serial intracerebral passage in embryonated eggs. (5) Rabies virus from a mouse brain frozen at −60°C for 60 days has been cultivated for 24 successive passages in cultures of brain tissue from embryo mice (5 passages), 1 day old mice (3 passages), 3 day old mice (2 passages), 5 day old mice (10 passages) and 14 day old mice (4 passages), respectively. Culture virus developed in brain material from 5 day old mice, failed to multiply in cultures of brain tissue from 48 day old mice.