Studies on immunity in poliomyelitis

Summary

The mouse-adapted AK strain, which had previously shown avirulent for rhesus monkeys, appeared to possess a low pathogenicity for cynomolgus monkeys. In cynomolgus monkeys, which had been immunized either by feeding or by intramuscular inoculation with living virus, no significant immunity against type 1 and type 3 poliomyelitis virus developed, which is in contrast with earlier experiments in rheusus monkeys. Four out of 9 monkeys, which had survived the intracerebral inoculation with the mouse-line of the AK strain, proved resistant to intracerebral challenge with Brunhilde virus. In the immunized monkeys, antibodies neutralizing both type 2 poliomyelitis virus and columbia SK virus developed, which is in agreement with earlier results. A discrepancy was observed in typing of the rodent non-pathogenic simian AK strain by the method of neutralization. The strain could be classified as type 2 in rhesus monkeys, but it was untypable in cynomolgus monkeys. In the latter, the strain was neutralized only by a mixture of Lansing and Columbia SK antiserum. This phenomenon is explained by the view, that the AK strain possesses a Lansing and a Columbia SK component, which could not be separated by neutralization of a limiting dilution of the virus with Lansing immune serum. In one monkey of the 17th passage, however, a spontaneous dissociation has occurred, from which a mouse-line, possessing the characteristics of the Columbia SK group has been derived.