Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus

Protease activities in the haemolymph and fat body in a bloodsucking insect , Rhodnius prolixus, infected with Trypanosoma rangeli, were investigated A fter SDS-polyacrylamide gel electrophoresis containing gelatin as substrate , analysis of zymograms performed on samples of different tissues of contro ls and insects inoculated or or-ally infected with short or long epimastigo tes of T rangeli, demonstrated distinct patterns of protease activities: (i ) proteases were detected in the haemolymph of insects which were fed on, o r inoculated with, short epimastigotes of T. rangeli (39 kDa and 33 kDa, re spectively), but they were not observed in the fat body taken from these in sects; (ii) protease was also presented in the fat bodies derived from naiv e insects or controls inoculated with sterile phosphate-saline buffer (49 k Da), but it was not detected in the haemolymph of these insects; (iii) no p rotease activity was observed in both haemolymph and fat bodies taken from insects inoculated with, or fed on, long epimastigotes of T. rangeli. Furth ermore, in short epimastigotes of T. rangeli extracts, three bands of the p rotease activities with apparent molecular weights of 297, 198 and 95 kDa w ere detected while long epimastigotes preparation presented only two bands of protease activities with molecular weigh ts of 297 and 198 kDa. The prot eases front the insect infected with T. rangeli and controls belong ro the class of either metalloproteases or metal-activated enzymes since they are inhibited by 1,10-phenanthroline. The significance of these proteases in th e insects infected with short epimastigotes of T. rangeli is discussed in r elation to the success of the establishment of infection of these parasites in ifs vector R. prolixus.