LEVELS OF HOMOTYPIC NEUTRALIZING ANTIBODY IN HUMAN POLIOMYELITIS THREE YEARS AFTER INFECTION

Abstract

Quantitative neutralization testes in monkeys were carried out on sera obtained from 7 patients, 3 mos., and 3 yrs. after an attack of poliomyelitis. The serum specimens were tested against 100 to 1000 PD50 of the patient''s own strain of virus, recovered during the acute phase of the illness; all the strains were Type 1. The 6 patients, aged 6 mos. to 13 yrs., who had a paralytic attack of the disease, all exhibited very high levels of neutralizing antibody at 3 yrs. as well as at 3 mos. after onset. The 50% serum dilution titers ranged from about 1180 to at least 1:860. Since the max. titers were not established, it is not known to what extent, if any, the level of antibody may have dropped over the 3 yr. period. One of the patients, with a diagnosis of non-paralytic poliomyelitis, had a negligible or questionable antibody response during convalescence and no demonstrable antibody at 3 yrs.; there is justifiable doubt as to whether the Type 1 poliomyelitis virus recovered from this patient had actually caused infection. Tests for Lansing neutralizing antibody indicated that the 5 patients who had no evidence of previous infection with Type 2 poliomyelitis virus had not become infected with it during the 3-yr. period. This suggested that these patients did not live in an environment in which infection with poliomyelitis virus is frequent. It is concluded, therefore, that in human beings, paralytic infections due to Type 1 poliomyelitis virus produce large amounts of homotypic neutralizing antibody, which persists at high levels for a period of at least 3 yrs.