On the Prophylactic and Therapeutic Value of Specific Immune Serum in Experimental Poliomyelitis

Abstract

Comparatively few studies have been reported on the protective and therapeutic value of immune serum in experimental poliomyelitis in monkeys. The results vary somewhat, but indicate in the main that specific immune serum, while of doubtful therapeutic value, is of definite prophylactic value. We report observations on M. rhesus monkeys injected with immune serum either shortly before or at varying periods of time after inoculation with virus, the latter being administered in most of the experiments by the intranasal route, the normal route of infection in man. The method of inoculating the experimental animals with virus by the intranasal route has already been reported by us. The method described has yielded infection in about 95% of animals so inoculated. The immune serum employed in most of the experiments was one produced by injecting a horse with poliomyelitis virus over a period of nearly 2 years, at the end of which time its potency was such that 1 cc. of the serum contained sufficient immune substance to inactivate in vitro at least 25,000 minimum infecting doses of virus. Thus far we have carried out 11 experiments on the prophylactic value of immune serum, involving a total of 18 controls and 59 . test animals. Convalescent monkey serum was employed in 2 of the experiments and immune horse serum in the remainder. The serums were administered by different routes; the amounts injected varying from a total of 1.75 cc. in one of the experiments to more than 30 cc. in other experiments. In most instances the serum was administered 24 hours prior to the inoculation of the animal with virus. The results obtained in the individual experiments vary considerably, the percent survivors in the serum inoculated group ranging from 0% in one experiment (1.75 cc. of serum intracranially) to 100% in 3 of the experiments. Out of the total number of 58 serum treated animals 20 (or 34%) failed to develop the disease, while among the 18 controls all but one (or 94%) developed poliomyelitis. The average protection is somewhat below that realized in more limited studies by other investigators. Our results do not lead us to believe that pooled convalescent monkey serum is any more or any less effective as a prophylactic agent than the immune horse serum.