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Physalin B inhibits Trypanosoma cruzi infection in the gut of Rhodnius prolixus by affecting the immune system and microbiota

Castro, Daniele P., Moraes, Caroline S., Gonzalez, Marcelo S., Ribeiro, Ivone M., Tomassini, Therezinha C.B., Azambuja, Patrícia, Garcia, Eloi S.
Journal of insect physiology 2012 v.58 no.12 pp. 1620-1625
intestinal microorganisms, insect development, parasites, Rhodnius prolixus, immunomodulators, blood meal, epimastigotes, insect vectors, immune system, Physalis angulata, Trypanosoma cruzi, oral administration, digestive system, nitrates, antibacterial properties
Physalin B is a natural secosteroidal, extracted from the Solanaceae plant, Physalis angulata, and it presents immune-modulator effects on the bloodsucking bug, Rhodnius prolixus. In this work, R. prolixus was treated with physalin B at a concentration of 1mg/ml of blood meal (oral application), or 20ng/insect (applied topically) or 57ng/cm² of filter paper (contact treatment), and infected with Trypanosoma cruzi Dm28c clone (2×10⁶ epimastigotes/insect). The three types of applications significantly decreased the number of T. cruzi Dm28c in the gut comparing with the non-treated infected insects (controls). All groups of infected insects treated with physalin B had higher numbers of bacterial microbiota in the gut than the non-treated controls infected with T. cruzi. We observed that the infected physalin B insects with topical and contact treatments had a lower antibacterial activity in the gut when compared with control infected insects. Furthermore, infected insects with the physalin B oral treatment produced higher levels of nitrite and nitrate in the gut than control infected insects. These results demonstrate that physalin B decreases the T. cruzi transmission by inhibiting the parasite development in the insect vector R. prolixus. Herein the importance of physalin B modulation on the immune system and microbiota population in terms of parasite development and transmission are discussed.