To assess reinfection of BALB/c mice with different
Toxoplasma gondii
strains, the animals were prime infected
with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain
cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction
and PCR-RFLP analysis to distinguish the different
T. gondii strains present in possible co-infections. Anti-
Toxoplasma immune responses were evaluated in D8-primed BALB/c mice by detecting IFN-γ and IL-10 produced
by T cells and measuring immunoglobulin levels in serum samples. PCR-RFLP demonstrated that BALB/c mice
were reinfected with the EGS strain at 45 days post prime infection (dpi) and with the EGS and CH3 strains at 180
dpi. High levels of IFN-γ were detected after D8 infection, with no significant difference between 45 and 180-day
intervals. However, higher IL-10 levels and higher plasmatic IgG1 and IgA were detected from samples obtained 180
days after infection. BALB/c mice were susceptible to reinfection with different recombinant
T. gondii strains and
this susceptibility correlated with enhancement of IL-10 production.
