Immunity in Guinea Pigs to the Virus of Vesicular Stomatitis.

Abstract

It is known that the injection of immune serum into guinea pigs prevents generalization of the lesions but not the primary vesicles of foot-and-mouth disease. In studying a strain of the virus of vesicular stomatitis, a disease of horses closely related to foot-and-mouth disease of cattle, 1 we have found that the virus, when injected into guinea pigs, loses its original feeble power to produce the characteristic secondary lesions in the pad, and that only primary lesions arise after pad inoculation. Notwithstanding this fact, the virus receives a general distribution since it can be recovered, 48 hours after pad inoculation into guinea pigs, from the apparently normal tongue. On the other hand, when the virus is injected into the muscles or the skin (intradermal) elsewhere than in the pad, no local lesion whatever follows, and 10 days after the inoculation it is found that the pigs are immune to reinoculation.

In the preliminary experiments, no attempt was made to titrate the strength of the virus, because present methods are crude, and once the infectivity of a given sample of virus has been determined, it is impossible to estimate the rate of its deterioration. Guinea pig pad vesicle fluid, obtained 24 to 48 hours after inoculation, diluted 1:10 and 1:20 with phosphate buffer at a pH of 7.5; and filtered through a Berkefeld “V” candle, was employed in the following experiments. The immune serum was obtained from guinea pigs 10 to 14 days after inoculation.

Neutralization of the virus in vitro was first undertaken. 1 cc. of a 1:10 dilution of the virus was added to 1 cc. of immune serum and the contents of the tubes thoroughly mixed. The tubes were kept a room temperature for one minute, one hour, and 24 hours respectively, at which times the virus-serum mixture was injected into the pads of normal guinea pigs.