Trypanosoma rangeli: a new perspective for studying the modulation of immune reactions of Rhodnius prolixus

Abstract

Insects are exposed to a wide range of microorganisms (bacteria, fungi, parasites and viruses) and have interconnected powerful immune reactions. Although insects lack an acquired immune system they have well-developed innate immune defences that allow a general and rapid response to infectious agents.Over the last few decades we have observed a dramatic increase in the knowledge of insect innate immunity, which relies on both humoral and cellular responses. However, innate reactions to natural insect pathogens and insect-transmitted pathogens, such as parasites, still remain poorly understood.In this review, we briefly introduce the general immune system of insects and highlight our current knowledge of these reactions focusing on the interactions of Trypanosoma rangeli with Rhodnius prolixus, an important model for innate immunity investigation.

Antimicrobial peptides play a functional role in bumblebee anti-trypanosome defense

“…This seems to contradict recent findings that found a central role for gut microbiota in the bumblebee's defense against Crithidia (Koch and Schmid-Hempel, 2011). It is clear that the outcome of a Crithidia infection is not the result of the immune system or the gut microbiota but rather the interaction between the parasite, the gut microbiota and the host immune system (Castro et al, 2012;Garcia et al, 2009;Weiss et al, 2013). This interaction will be the focus of much future research.…”

Overexpression of Trypanosoma rangeli trypanothione reductase increases parasite survival under oxidative stress

“…Epimastigotes from T. cruzi multiply and colonize the entire gut (oxidative environment), whereas T. rangeli epimastigotes rapidly cross the gut epithelium and invade the haemolymph. The haemolymph of Rhodnius prolixus has been described to have ten times more urate than human plasma (Souza et al 1997;Graça-Souza et al 2006). Urate is considered as one of the most important antioxidants in human plasma.…”

“…However, Paiva et al (2012) and Goes et al (2016) have demonstrated that oxidative stress actually enhances infection by the protozoan T. cruzi. In others words, T. cruzi seems to thrive in an oxidative environment, and antioxidant responses suppress infections by this protozoan parasite.…”

Microbial symbiosis and the control of vector-borne pathogens in tsetse flies, human lice, and triatomine bugs

“…64 The triatomine are fundamental in the life cycle of the parasite, both for their vector capability through their blood-feeding habits, and for the interaction they establish with the Trypanosoma, at the physiological and at the biochemical level. [65][66][67] Triatomine usually consume their blood meal at night, while the host is sleeping and, if they feed on infected hosts, they are likely to acquire T. cruzi, allowing it to complete its life-cycle and to be released with the feces. Furthermore triatomine bugs tend to defecate during the blood meal, contaminating host's skin and hair.…”