Interference with eastern equine encephalomyelitis (EEE) virus in the brains of mice immune to lymphocytic choriomeningitis (LCM)

Abstract

It has long been suspected that neutralizing antibodies are not the sole immunity factor in mice immunized against LCM as mature animals (5). Although such mice are not tolerant immunologically, they form neutralizing antibodies rather poorly (4, 10). Since many of them do not carry demonstrable amounts of infectious virus in their brains and other organs (5, 4), there w~s at first no reason to suppose that their immunity might be correlated with the interference phenomenon, which appears to be responsible for the strong immunity of tolerant mice (virus carriers) infected congenitally with LCM virus (7,11).It is the purpose of this communication to show that slight but definite interference with EEE virus occurs in the brains of both categories of LCM-immune mice and that the persistence of detectable quantities of infectious LCM virus is not a prerequisite for such interference in nontolerant animals. Materials and Methods Viruses:As in previous experiments reported in this journal (10, ll), strain W of LCM virus and strain S 18888 of EEE virus were used.Mice: The tolerant animals came from our infected stock mentioned previously (11) in which all mice, young or old, are carriers of strain W of LCM virus. The mice immunized as mature animals and the controls were obtained from stock III of the Institute (ill from which the ancestors of the infected colony originated.Immunization of mature mice with LCM virus: The attribute "mature" is used here for animals beyond the age at which the "carrier state", based on immunological tolerance, frequently develops upon artificial infection Archly f. Virusforschung, Bd, XI, l~. 3 28