Cultivation of Poliomyelitis Virus in vitro in Human Embryonic Nervous Tissue

Abstract

The current opinion of many investigators is that there is no unequivocal evidence that the virus of poliomyelitis has as yet been successfully cultivated outside the body. The recent demonstration that the virus is of very minute size (8 to 12 mμ 1 ; 12 to 17 mμ 2 ) emphasized the improbability that certain minute, visible microorganisms, which have been cultivated from poliomyelitic tissue, are etiologically related to the disease, while a critical analysis of presumably successful multiplication in chick embryo media 3 , 4 indicates that insufficient care was taken to rule out contamination with other viruses. Investigations by workers at this Institute and elsewhere are in accord that no propagation of the virus has been demonstrated by methods which have proved successful for the cultivation of most of the other viruses. 5

The problem of cultivating the virus of poliomyelitis is being pursued not only for the further elucidation of the nature of the virus but also in the hope that successful in vitro propagation may facilitate attempts at adaptation to new hosts and tissues and provide new material for further experimentation on active immunization.

A new approach was made by the use of 3- to 4-months-old human embryos, obtained aseptically by Cesarean section. (The authors are indebted to Dr. Lance Monroe, of Bellevue Hospital, for the 2 human embryos used in this investigation.) The brain and cord, the lungs, kidneys, liver, and spleen were stored in the refrigerator, fragments of these tissues being taken for the preparation of media at 3-day intervals. The media were prepared by suspending approximately 100 mg. of one or another of the tissues, thoroughly washed and minced, in 4.5 cc. of Tyrode's solution contained in a 50 cc. Erlenmeyer flask; each flask was inoculated with 0.5 cc. of a Berkefeld N filtrate of a 5% suspension of poliomyelitis cords (M.V. strain) which, by titration, was found to be equivalent to approximately 50 minimal infective doses.