Anti-soluble substance antibodies and neutralizing substances, which develop following infection with the virus of lymphocytic choriomeningitis, appear to be separate entities. The times of appearance and regression of the two antibodies are different in both man and the guinea pig; the antisoluble substance antibodies appear earlier and remain a shorter time. Moreover, mice develop them but no demonstrable neutralizing substances.
Injection of formalin-treated, virus-free extracts containing considerable amounts of soluble antigen fails to elicit anti-soluble substance antibodies and to induce immunity in normal guinea pigs; administration of such preparations to immune pigs, however, is followed by a marked increase in the titer of anti-soluble substance antibodies in their serum. On the other hand, suspensions of formolized washed virus are effective in normal guinea pigs in stimulating both anti-soluble substance antibodies and protective substances, and in inducing immunity to infection.