Expression of schistosomal cathepsin L1 in Escherichia coli and evaluation of its protective capacity in an animal challenge

Schistosomes use proteinases to accomplish some tasks such as tissue penetration, tissue digestion for nutrition and evasion of host immune responses. The Cathepsin L is a cysteine proteinase of the papain superfamily detected in the gut lumen indicating that this enzyme contributes to the proteolysis of ingested hemoglobin. Due to these roles they play in the schistosome biology, proteolytic enzymes are considered potential targets to develop and direct anti-schistosomal therapies. In this work, the cDNA coding Cathepsin L1 of Schistosoma mansoni was cloned into the pAE vector that provides high-level expression of heterologous proteins in Escherichia coli. The recombinant protein was expressed as inclusion bodies, purified under denaturing conditions through nickel charged chromatography and used for experimental animal vaccination. ELISA was performed with the pooled sera. Although this protein showed to be immunogenic, mice immunized with three doses of recombinant protein plus aluminum hydroxide as adjuvant did not protect against S. mansoni infection.

Effects of the desiccation on Biomphalaria tenagophila (Orbigny, 1835) (Mollusca) infected by Schistosoma mansoni Sambon, 1907

Specimens of Biomphalaria tenagophila exposed to miracidia of Schistosoma mansoni were submitted to different desiccation periods as follows: group I: 24 h after exposure, desiccated for 28 days; group II: after cercariae elimination, desiccated for 7 days; group III: 21 days after exposure, desiccated for 7 days; group IV: 14 days after exposure, desiccated for 14 days; group V: 7 days after exposure, desiccated for 21 days. From the obtained data it was verified that desiccation was not capable of interrupting the development of larvae of S. mansoni in mollusks. A delay in the development of S. mansoni larvae in groups I, III, IV and V was observed. A pause was verified in the development of S. mansoni larvae in groups II, III, IV and V. Some larvae, in groups I, III, IV and V, did not suffer as a result of desiccation and continued their development. Larvae in the cercariae stage were shown to be more sensitive to desiccation. It was possible to obtain clearing of mollusks infected by sporocysts II and cercariae using a period of 7 days of desiccation

Effect of 60CO gamma radiation on Biomphalaria glabrata (Mollusca, Gastropoda) embryos: mortality, malformation and hatching

A study was carried out on the radiosensitivity of Biomphalaria glabrata embryos submitted to doses of 5, 10, 15, 20 and 25 Gy of 60Co during the cleavage, blastula, gastrula, young trochophore and trochophore stages. Mortality, malformation and hatching were the parameters used to evaluate the damage induced by ionizing radiation. Estimated LD(50) values (15 days) showed that the cleavage stage (4.3 Gy) was approximately four times more radiosensitive than the trochophore stage (l7.0 Gy). Susceptibility to malformation induction was higher in the blastula, gastrula and young trochophore stages. Several types of morphogenetic malformations were observed, such as head malformations, exogastrulas, shell malformations, and embryos with everted stomodeum, with nonspecific malformations being the most frequent. The types of malformation induced by radiation probably are not radiation-specific and do not depend on the dose applied. The dose of 15 Gy was sufficient to greatly reduce the number of hatching snails regardless of the embryonic stage irradiated. We conclude that the effect of (60)Co gamma radiation on B.glabrata embryos presented a specific pattern.