[No Title Available]

Abstract

Rhodnius prolixus is an insect that has been used as a model in studies of parasite-vector interactions by our laboratory. The interaction protozoan parasites with vectors may be modulated by a complex reactions. Several trypanosomes contain proteases that may be released into their invertebrate hosts. Previously published data demonstrated metalloproteases activities in the haemolymph of R. prolixus infected with Enterobacter cloacae (Feder et al., 1998) and T. rangeli (Feder et al., in press). Based in these facts, we decided to investigate proteases of R. prolixus infected with T. cruzi.Using SDS-polyacrylamida gel electroforesis containing gelatin as substrate, analysis of zimograms performed on samples of different tissues of controls and insects inoculated or orally infected. We observed protease activities in the haemolymph and fat body in a bloodsuking insect, R. prolixus, infected with T. cruzi (Dm28c). These proteases demonstrated distinct patterns of activities: (i) proteases were detected in the haemolymph of insects which were fed on, or inoculated with T. cruzi (Dm28c), but they were not observed in fat body of insects; (ii) protease was also presented in the fat bodies derived from naive insects or controls inoculated with sterile phosphate-saline buffer (49 KDa), as previously described with other microorganisms but it was not detected in the haemolymph of these insects. These proteases from the insect with T. cruzi will be characterized. The significance of these proteases will be discussed in relation to the success of the establishment of infection of these parasites in vector, R. prolixus.