1 Palo Alto Medical Research Foundation and Stanford University School of Medicine, Palo Alto, California 94301, California Primate Research Center, University of California, Davis. and University of California Medical School, Davis, California 95616
The experiments reported in this paper were performed in order to develop a nonhuman primate model for the study of toxoplasmosis. Forty-eight Macaca arctoides monkeys were tested by the Sabin-Feldman dye test and 9 (18.7%) were positive (≥1:4). Eight had a titer of 1:4 and one a titer of 1:2,048. Eight seronegative animals were experimentally infected with either cysts or trophozoites of Toxoplasma gondii using subcutaneous. intravenous and oral routes of inoculation. The immune response was monitored by the dye and IgM-fluorescent antibody tests and the skin test. Serological responses varied with size of inoculum, form of the parasite inoculated and route of inoculation. The skin test was positive in all animals 15 weeks after infection. Parasitemia was demonstrated by mouse inoculation in four animals during the first 10 days after infection but not thereafter. T. gondii was demonstrated in mice which had been inoculated with brain and heart of one monkey sacrificed 10 weeks after infection and from another which died of unrelated causes 30 weeks following infection, indicating that the serological response observed was due to active invasion and multiplication of the parasite. Since the response of this species to infection with Toxoplasma is not dissimilar to that of man, this model may be useful to study various aspects of toxoplasmosis.
Palo Alto Medical Research Foundation and Stanford University School of Medicine, Palo Alto, California.
California Primate Research Center, University of California, Davis.