Geophagy as a therapeutic mediator of endoparasitism in a free-ranging group of rhesus macaques (Macaca mulatta).

Parasite levels were determined for 141 members of a naturally formed social group of rhesus macaques living under free-ranging conditions. Results indicate that group members harbor Trichuris trichiura, Balantidium coli, and large numbers of Strongyloides fuelleborni. Parasite counts decrease significantly with age in this population. Females have significantly fewer parasites than males and a significantly lower prevalence of multiple infections. There were no rank effects regarding parasitosis. While 89% of the animals examined are infected with one or more species of enteric parasite, the prevalence of diarrhea is negligible (2%). The low prevalence of diarrhea in the presence of high parasite loads may be due to the practice of geophagy, which is engaged in by 76% of group members. Soil eaten by these monkeys contains large amounts of kaolinitic clays. Kaolin-based pharmaceuticals (i.e. Kaopectate) are commonly used in human populations to treat diarrhea and intestinal upsets. The mechanical and pharmaceutical properties of the natural kaolinite-based clays may counteract the effects of parasitosis in this free-ranging population.

Vaccine evaluation studies of replication-defective SIVsmB7.

Non-infectious virus-like particles of SIVsmB7 that expresses env and gag gene products but are defective in pol and vpx/vpr were assessed for their ability to induce protective immunity against infection with pathogenic SIVsmE660 in rhesus macaques. Animals were immunized in three groups: group A was primed with cell-associated SIVsmB7 and boosted with cell-free SIVsmB7; group B was primed with cell-free SIVsmB7 and boosted with cell-free SIVsmB7 conjugated to iron oxide microbeads; group C was primed with cell-free SIVsmB7 mixed with Titer Max adjuvant and boosted with cell-free SIVsmB7 mixed with SAF-M adjuvant followed by secondary boosting with cell-free SIVsmB7 conjugated to microbeads. Animals were challenged intravenously with 20 animal infectious doses of SIVsmE660 grown in rhesus peripheral blood mononuclear cells 3 weeks after final boosting. All animals became infected as evidenced by quantitative virus cultivation. Sera from immunized animals contained low-titer antibodies by ELISA and low or undetectable neutralizing antibodies on the day of challenge but strong anamnestic antibody responses were observed following challenge. Interestingly, 2 of 3 animals in group A showed evidence of transient viremia and more stable CD4 counts following challenge as compared to the other immunized animals and to non-immunized controls. Thus, immunization with cell-associated SIVsmB7 did not provide sterilizing immunity against challenge with a highly pathogenic SIV strain but might have caused virus clearance later in infection.