Different routes of infection with Encephalitozoon intestinalis affect the development of immune response in immunocompetent and immunodeficient mice

The development of an immune response of immunocompetent BALB/c and C57BL/6 mice with different levels of resistance to microsporidial infection and immunodeficient SCID mice was analysed in relation to the route of infection with Encephalitozoon intestinalis. Cell-mediated immune responses were characterised by measurement of IFN-γ and quantification of CD4+, CD8+ and NK cells. Intraperitoneal (i.p.) infection induced higher levels of IFN-γ in ex vivo cultures of peritoneal exudate cells or splenocytes than peroral (p.o.) infection. Numbers of CD4+ and CD8+ T lymphocytes in the spleen increased markedly at later time points (14 and 21 DPI) after i.p. infection of BALB/c mice, whereas in C57BL/6 mice the highest increase was after p.o. infection. Considerable IFN-γ production in ex vivo cultures of Peyer's patch lymphocytes of both mouse strains was observed after p.o. infection. Intraperitoneal infection of SCID mice induced marked influx of inflammatory cells into the peritoneum with NK cells. The results contribute to the development of an animal model of microsporidiosis caused by E. intestinalis.