Homotypic complement-fixing antibody in monkeys infected with type 2 poliomyelitis virus by the oral route.

CF tests with Type 2 poliomyelitis antigen (MEF1) were performed on the pre- and postinfection sera of 20 cynomolgus monkeys which developed paralytic, non-paralytic, or inapparent infection following oral administration of a Type 2 strain of virus (Y-SK). All the monkeys developed neutralizing antibody, and 17 developed CF antibody in an original serum dilution titer of 1:4 or greater. The 3 monkeys which did not develop this level of CF antibody were in a group of 7 which died within 8 days after onset of paralysis. The CF titers were as high at 2 to 6 days after onset of paralysis in the other 4 moribund or dead monkeys as in the surviving animals tested 4 weeks after the first dose of virus and the CF titers were of the same order of magnitude in the groups with paralytic, non-paralytic, or inapparent infection. The Type 2 poliomyelitis CF titers developed in monkeys as a result of infection with homotypic virus were not greater than those found in human beings infected with heterotypic Type 1 poliomyelitis strains.