Involvement of lipophorin in the immune response of Rhodnius prolixus (Hemiptera: Reduviidae): challenge with the plant-derived entomotoxin jaburetox

MOYETTA, NATALIA R.; CANAVOSO, LILIAN E.; FRUTTERO, LEONARDO L.

La Plata

Congreso; II Congress of the Latin American Society for Vector Ecology; 2022

Latin American Society for Vector Ecology

Lipophorin is the main lipoprotein circulating in insects. One of it its most thoroughlycharacterized function is the transport and transfer of lipids among target tissues. However,lipophorin also participates in insect immunity processes, changing the expression levels inresponse to pathogen challenges and neutralizing toxins in the hemolymph. On the otherhand, ureases (urea amidohydrolases, E.C. 3.5.1.5.) are enzymes that catalyze thebreakdown of urea in carbon dioxide and ammonia. In plants, besides generatingbioavailable nitrogen, ureases fulfill a role in defense against phytophagous insects, thusexhibiting biotechnological potential for the rational control of pest species. Previous works intriatomines reported that the treatment with jaburetox, a recombinant peptide derived of the leguminous Canavalia ensiformis, induced toxic effects and the activation of the immuneresponse. Even though the insecticidal effect of jaburetox was reported 15 years ago,several aspects of its mechanism of action are unknown. In this work, we employed theChagas disease vector Rhodnius prolixus as a model to study the participation of lipophorinin the jaburetox-induced immune response. Analytical ultracentrifugation assays wereconducted in order to assess lipophorin-jaburetox interaction in vitro. At 6 h after injection,lipophorin expression in the fat body, as well as its circulating levels in the hemolymph, wereevaluated by biochemical, molecular and cellular approaches. The sedimentation rateobtained by analytical ultracentrifugation assays indicated a direct binding betweenlipophorin and jaburetox, reinforcing the implication of this mechanism of peptidedetoxification in vivo. The results also show that, under our experimental conditions,treatment with jaburetox did not induce significant modifications neither in the expression oflipophorin in the fat body, nor in its circulating levels in the hemolymph. However, theinjection of jaburetox impaired the association of lipophorin with the hemocytes, the maincells involved in insect immunity. Taken together, these findings support the involvement oflipophorin in the jaburetox-induced immune response of R. prolixus, providing valuableinformation to unravel the mechanisms of action of this toxin.