Early kinetics of intestinal infection and immune responses to two Toxoplasma gondii strains in pigs

Toxoplasma gondiiis an obligate intracellular parasite, able to infect all homeothermicanimals mostly through ingestion of (oo)cysts contaminated food or water. Recently,we observed aT. gondiistrain-specific clearance from tissues upon infection in pigs:while the swine-adapted LR strain persisted in porcine tissues, a subsequent infectionwith the human-isolated Gangji strain cleared parasites from several tissues. Wehypothesized that intestinal immune responses shortly after infection might play a rolein this strain-specific clearance. To assess this possibility, the parasite load in smallintestinal lymph node cells and blood immune cells as well asthe IFNγsecretion bythese cells were evaluated at 2, 4, 8, 14, and 28 days post oralinoculation of pigs withtissue cysts of both strains. Interestingly, at day 4 post inoculation with the LR strainthe parasite was detected by qPCR only in the duodenal lymph node cells, while in thejejunal and ileal lymph node cells and PBMCs the parasite wasdetected from day 8post inoculation onwards. Although we observed a similar profile upon inoculation withthe Gangji strain, the parasite load in the examined cells was much lower. This wasreflected in a significantly higherT. gondii-specific serum IgG response in LR comparedto Gangji infected pigs at day 28 post inoculation. Unexpectedly, this was not reflected inthe IFNγsecretion upon re-stimulation of the cells where almost equal IFNγsecretion wasobserved in both groups. In conclusion, our results show thatT. gondiifirst enters thehost at the duodenum and then probably disseminates from this site to the other tissues.How the early immune response influences the clearance of parasite from tissues needsfurther study.

Jaar van publicatie:2020

Toegankelijkheid:Open