Immunological Studies on Intestinal Theiler's Virus,and Its Relation to Poliomyelitic Virus. ∗

Abstract

Discussion and Summary

Attempts at transmission of Theiler's virus to rhesus monkeys by means of intracerebral inoculation and, further, by consecutive passage in monkeys, failed; the virus, moreover, was not demonstrable in the CNS of monkeys 24 hours after inoculation. Thus, Theiler's virus has its own traits in monkeys, which fact conforms with Theiler's original conclusion 3 that the mouse virus is not identical with that of human poliomyelitis. Further proof of this finding can be deduced from results of immuno-logical studies. In the foregoing experiments two standard strains of poliomyelitic virus were used, the MV and Philadelphia, both monkey-passaged for several years; what would have been the outcome had strains freshly isolated from human cases of poliomyelitis been studied is, of course, unknown. It is apparent, however, that by the methods here used, such monkey-passaged strains are not only non-pathogenic in the type of mouse which is susceptible to Theiler's virus and which carries the latter in its intestines for a good part of its life, but also fail to produce serum-neutralizing antibodies in such mice against the homologous poliomyelitic viruses and against Theil-er's virus. Moreover, antipoliomyelitic sera of human and monkey origin that are capable of neutralizing homologous and other strains of poliomyelitic virus fail to inactivate Theiler's virus. Conversely, serum from mice harboring Theiler's virus does not neutralize the poliomyelitic viruses. On the other hand, serum from normal mice of certain adult age has antiviral bodies against Theiler's virus. In this latter relation, a similarity exists between the virus of Theiler's disease—a natural malady of mice—and that of poliomyelitis of man in that neutralizing antibodies against the latter virus develop with time in man in the absence of clinically apparent disease.