Calomys callosus, Rengger 1830 (Rodentia, Cricetidae), a wild rodent found
in Central Brazil, was studied to investigate its susceptibility to
Toxoplasma gondii experimental infection and its humoral immune response
against this protozoa. The electrophoretic profile of the serum proteins of
C. callosus showed that IgG, which shows no affinity to Protein A, has
higher cross reactivity with rat IgG than with IgG from other rodents. The
susceptibility assay was performed by inoculation groups of animals with
various suspensions of T. gondii tachyzoites from 10^2 to 10^6 parasites.
All animals died between 3 and 9 days after infection and the kinetics of
antibody synthesis was determined. Basically, they recognized predominantly
the immunodominant antigen SAG-1 (P30). The immunohistochemistry assays
revealed that the liver was the most heavily infected organ, followed by
the spleen, lungs, intestine, brain and kidneys. It can be concluded that
C. callosus is an excellent experimental model for acute phase of
Toxoplasma infection.
