Significance of Early Appearance of Neutralizing Substances in Poliomyelitis of Man. ∗

Abstract

Although it has long been known that the serum of patients convalescent from acute anterior poliomyelitis contains an antiviral substance, the fact that a similar substance is present in the blood of the majority of normal adults has been recognized only in recent years. 1 , 2 By analogy to the known subclinical acquisition of immunity against diphtheria, the assumption has been made that a similar mechanism is operative in poliomyelitis. Such a belief postulates wide dissemination of the virus with a minor incidence of actual paralysis. Endocrine factors have been suggested in certain recent experiments. 3 However, another group of investigators 4 has been unable to reproduce the data of the first group. Further, the exact role that the poliocidal substances play in preventing infection under natural conditions and in recovery from the disease has not been elucidated, it having been assumed that these substances are the humoral expression of the immune state. One of us, 1 in collaboration with others, showed that occasional samples of convalescent human serum were devoid of neutralizing substances, while Howitt 5 found 80 of 141 samples taken weeks or months after an acute attack to be likewise without these substances. She attributed her findings to the fact that many of her patients received convalescent serum therapy.

In an effort to obtain further information upon the behavior of the poliocidal substances following an acute attack of the disease, we have titrated the serums from patients obtained as soon as possible after the onset of the acute disease and again after several months. Each of these serums has been mixed in vitro in several dilutions with 10 paralyzing doses of the virus (PMV) contained in a one percent centrifuged emulsion of glycerolated spinal cord removed from monkeys (Macaca mulatta) at the height of paralysis. Injection of the serum-virus mixtures intracerebrally into unused rhesus monkeys was the indicator of unneutralized virus.