Trypanosoma rangeli: effects of physalin B on the immune reactions of the infected larvae of Rhodnius prolixus.
Physalins are seco-steroids obtained from plants of the family Solanaceae. Herein, we tested Physalis angulata L purified physalin B as an immunomodulatory compound in 5th-instar larvae of Rhodnius prolixus, which were systemically infected with the H14 Trypanosoma rangeli strain protozoan. In uninfected insects, the effective concentration of physalin B, which inhibited 50% of the blood ingested (ED(50)) volume, was 15.2+/-1.6 microg/ml of the meal. Ecdysis processes and mortality in uninfected larvae, treated orally with physalin B in concentrations ranging from 1 to 10 microg/ml, was similar to that observed in insects not treated with physalin B. However, R. prolixus larvae previously fed on blood containing 1.0, 0.1, and 0.01 microg of physalin B/ml exhibited mortality rates of 78.1, 54.3, and 12.7%, respectively, 6 days after inoculation of T. rangeli (1 x 10(3) parasites/insect), whereas only 7.2% mortality was observed in the control group, injected with sterile culture medium. The insects treated with physalin B (0.1 microg/ml) and inoculated with T. rangeli did not modify the phenoloxidase (PO) activity and total hemocyte count in the hemolymph. However, physalin B treatment caused a reduction in hemocyte micro-aggregation and nitric oxide production and enhanced the parasitemia in the hemolymph. These results demonstrate that physalin B from P. angulata is a potent immunomodulatory substance for the bloodsucking insect, R. prolixus.
Garcia
Eloi S
ES
Departamento de Bioquímica e Biologia Molecular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (Fiocruz), Av. Brazil 4365, Rio de Janeiro 21045-900, RJ, Brazil.
Castro
Daniele P
DP
Ribeiro
Ivone M
IM
Tomassini
Therezinha C B
TC
Azambuja
Patrícia
P
D000818:Animals; D004156:Catechol Oxidase / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects; D002452:Cell Count; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000378:metabolism; D006434:Hemocytes / Q000166:cytology / Q000187:drug effects; D007783:Lactones / Q000737:chemistry / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000276:immunology / Q000469:parasitology; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D012239:Rhodnius / Q000187:drug effects / Q000276:immunology* / Q000469:parasitology; D012632:Secosteroids; D013256:Steroids / Q000737:chemistry / Q000494:pharmacology*; D014345:Trypanosoma / Q000276:immunology*
D004792:Enzyme Precursors; D007783:Lactones; D009566:Nitrates; D009573:Nitrites; D012632:Secosteroids; D013256:Steroids; C033270:physalin B; C038451:pro-phenoloxidase; D004156:Catechol Oxidase