Etiology of Poliomyelitis

Abstract

Bacteriological cultivation experiments were attempted with Berkefeld N filtrates prepared from the nervous tissues of monkeys inoculated with poliomyelitis virus and developing typical experimental poliomyelitis. Seven strains of virus were studied in a special culture medium designated as VB medium and containing essentially minced sheep brain in a veal infusion broth free from peptone. The use of fresh living tissue and ascitic fluid such as characterize the Noguchi medium or its modifications was avoided. No attempt was made to obtain strict anerobiosis by means of the recognized methods. The reduced oxygen tension developed in the culture medium was found satisfactory. The use of brain tissue suggested itself as a suitable culture medium for a virus that is known to exhibit a marked affinity for the nervous system.

The culture medium was prepared as follows: Blood and membranes were carefully removed at autopsy from fresh sheep brain. One kilogram of tissue was added to one liter of veal infusion broth, pH 8.0, free from peptone. The mixture was coagulated thoroughly by boiling for 2 to 3 minutes and 0.2% glucose by volume was added. The cooled material was then passed 2 or 3 times through a meat chopper. The culture medium was placed in test tubes measuring 1.5 by 15 cm. to a depth of approximately 6 cm. (about 10 cc. by volume) and sterilized in the autoclave at 15 pounds pressure for 20 minutes. The final pH was adjusted (if necessary) to 7.6 Rigorous tests for sterility of the material were made before use to rule out all possible sources of contamination.

The inoculum, consisting of Berkefeld filtrates as already described, was added to a series of tubes of culture medium and incubated at 37.5 to 38.0°C. for a period of 3 to 4 weeks during which time samples were withdrawn every week or 10 days by means of a platinum loop or capillary pipette for subplants and film preparations.