An Attempt to Infect Vitamin-Deficient Animals with Poliomyelitis Virus

Abstract

The great need for further experimental work in poliomyelitis and the fact that the monkey has been the only responsive experimental animal have evoked numerous attempts 1 to adapt the virus to smaller laboratory animals. The most recent of these was made by Brodie and associates, 2 who claimed that mice were successfully infected following reduction of their natural resistance to the virus by means of X-ray radiation.

We have approached the problem by using rats, mice and guinea pigs which were kept on a diet deficient in vitamins B and C. The diet consisted of casein (Harris Vitamin-B free) 20 parts, starch (Harris Vitamin-B free) 60 parts, purified butter fat 10 parts, agar-agar (Merck) 4 parts, and Osborne-Mendel Salt Mixture 4 parts. Young recently weaned animals were kept on this diet for a period of 10 to 25 days before inoculation and were maintained on the diet during the experimental period. They manifested marked symptoms of vitamin deficiency, such as weakness, shaggy fur, failure to gain weight or loss of weight, and sometimes cutaneous and mucous membrane lesions. Occasionally it was necessary to revert to a more complete diet for short periods (addition of yeast) to maintain life. Rats tolerated the management fairly well, mice not quite so well, and guinea pigs poorly.

Two preparations of virus were used: a chemically purified product, and a suspension of monkey cord which had been preserved in glycerin. Both were infectious for monkeys in the amounts used experimentally. The animals were inoculated under anesthesia, the rats and guinea pigs with 0.1 to 0.2 cc. intracerebrally and 1.0 cc. intraperitoneally, the mice with 0.05 cc. intracerebrally and 0.5 cc. intraperitoneally. Subinoculations were made in the same manner, brain and cord serving as the source of the subinoculation material.