Studies on the Relationship Between Virulence of Polioviruses and Their Antigenicity

Within the past several years, at least six markers of poliovirus have been described which can be determined by tissue culture, physical property and serological method and which tend to discriminate between neurovirulent and attenuated strains. In this communication a report is made on the relationship between the virulence of polioviruses and their antigenicity. The results are summarized as follows: Three known virulent and nine known attenuated strains of poliovirus were used. Rabbits received a single intramuscular injection of 5 ml of virus-adjuvant mixture and two intravenous injections of 5 ml of polioviruses. The rabbits were then examined 15 days after the last injection to determine the production of homo and hetero strainic antibody in theis sera. The injected dose of the virus contained 106 TCD50 per ml. A linear relationship was found to exist between the virulence of poliovirus and its antigenicity in the animal experiment. It is suggested that the immunizing capacity test might serve as a useful test for the virulence of poliovirus. The correlation between in vitro markers of excreted poliovirus and antibody titer of serum in the patient was examined. A linear relationship was found to exist between the virulence of excreted poliovirus and serum antibody titer in the patient.