Parasitological, Pathological, and Immunological Parameters Associated with Schistosoma mansoni Infection and Reinfection in BALB/c AND C57BL/6 Mice.

Schistosome-host interaction is influenced by multiple factors, such as the type of immune response developed by the host, host genetic background, intensity, and number of infections. Those factors not only affect the development and elimination of Schistosoma mansoni , but also the pathology triggered by infection with this parasite. In the present study, we assessed the parasitological, pathological, and immunological aspects elicited by infection and reinfection in 2 different mouse strains commonly used as models in studies on schistosomiasis: BALB/c and C57BL/6. No differences in worm burden recovery or in the number of eggs per gram of intestine or feces were observed between the strains or between infected and reinfected mice from the same strain. However, the number of eggs trapped in the liver of the reinfected mice was significantly higher than the number of eggs in the liver of the infected animals. But, the granulomatous area was significantly lower in reinfected animals than in infected ones. Additionally, granuloma in the infected BALB/c mice was greater than in infected C57BL/6 animals. Regarding the cytokine profile, spleen cells from the infected/reinfected C57BL/6 mice produced higher interleukin 10 (IL-10) levels against egg antigens than BALB/c-infected/reinfected mice. BALB/c mice, in contrast, produced significantly higher IL-4 and IL-13 cytokines after infection/reinfection than the C57BL/6 mice, with the highest levels of IL-13 being observed after reinfection. Our results demonstrate that, although different host backgrounds did not impact resistance to S. mansoni , they result in different immunological profiles that suggest different pathological impacts on the liver.