The Long Persistence of Rickettsia Orientalis in the Blood and Tissues of Infected Animals

[摘要] The ready demonstration of R. orientalis in the blood and tissues (liver, brain, and kidney) of albino Swiss mice at intervals up to 610 days after infection has been reported. These mice survived in a few cases (not tested for virus beyond the 62nd day) because primary infection was by the subcutaneous route. For the most part, they survived because of treatment with toluidine blue or methylene blue. During this period the serum antibody (complement fixing) was high and the mice were resistant to reinfection. The greatest concentration of infectivity appeared to be in the kidney, and the least, perhaps because of the presence of antibody, in the blood. No infectivity was demonstrated, in two attempts, in bladder urine or, in one attempt, in day-old mice from an infected mother. Parallel observations made in the cotton rat, terminated at 269 days after infection, revealed a similar persistence of infectivity except in the brain (not infective at 269 days) and blood (infective at 102 days but not at 154 or 269 days.) Serum antibody was also demonstrated.These observations suggest that of all the rickettsiae, with the possible exception of the immunologically similar Canadian vole agent, which was not sought in animals beyond 75 days after infection (13), R. orientalis is the most persistent in the tissues of rodent hosts. The equilibrium observed in the mouse most nearly parallels that observed in mouse carriers of lymphocytic choriomeningitis (2), with the interesting difference that the latter animals had little or no demonstrable serum antibody (of the neutralizing type), although they remained resistant to reinfection. Unpublished results of neutralization tests with sera from guinea pigs convalescent from infection with R. orientalis have revealed peculiar zonal effects (neutralization of large and of small but not of intermediate amounts of virus) which may help to explain the interesting simultaneous demonstration of infectivity and antibody in the same blood specimens. The significance of these observations to the problem of the rodent reservoir in Tsutsugamushi disease is obvious.

[学科分类] 生物科学（综合）