Susceptibility to re-infection in C57BL/6 mice with recombinant strains of Toxoplasma gondii.

This work reports results of re-infection of BALB/c and C57BL/6 mice with different recombinant strains of Toxoplasma gondii. Mice were prime-infected with the non-virulent D8 strain and challenged with virulent strains. PCR-RFLP of cS10-A6 genetic marker of T. gondii demonstrated that BALB/c mice were re-infected with the EGS strain, while C57BL/6 mice were re-infected with the EGS and CH3 strains. Levels of IFN-γ and IL-10 after D8 prime-infection were lower in C57BL/6 than in BALB/c mice. Brain inflammation after D8 prime-infection was more intense in C57BL/6 than in BALB/c mice. It was shown that re-infection depends on mice lineage and genotype of the strain used in the challenge.