Benefits and costs of immune memory in Rhodnius prolixus against Trypanosoma cruzi

There is increasing evidence supporting the immune memory in invertebrates, but the studies are relatively neglected in insect vectors other than mosquitoes. Therefore, we tested two hypotheses: 1) Rhodnius prolixus insects possess immune memory against Trypanosoma cruzi, and 2) their immune memory is costly. The Dm28c and Y strains of T. cruzi were used, the former being more infective than the latter. On the one hand, the triatomines subjected to dual challenges with the Dm28c strain did not show significant differences in survival than those of the heterologous challenge groups control-Dm28c and Y-Dm28c. On the other hand, the insects survived longer after a dual Y-Y challenge than after the corresponding heterologous challenge (control-Y). The Y-Y, Dm28c-Y, and naive groups showed similar survival. There was more prolonged survival following the Y-Y versus Dm28c-Dm28c dual challenge. The Dm28c-Dm28c group exhibited moulting sooner than the controlDm28c or naive group. In contrast, there were no differences in the probability of moulting between the Y-Y and naive groups. The results suggest that triatomines have immune memory against the Y but not the Dm28c strain. Further investigation on triatomine and T. cruzi interaction is needed to determine if infectivity accelerates or delay growth due to innate immune memory.

Automated summary

The study found that the insect vectors have immune memory against the Y strain of Trypanosoma cruzi, but not the Dm28c strain. It also suggests that immune memory affects the survival and molting process of the insects.