Biochemical and functional characterization of the glutathione S-transferase from Trichinella spiralis

Glutathione-S-transferase (GST) is a family of multifunctional enzymes catalyzing detoxification reactions. Our previous study showed that Trichinella spiralis GST (TsGST) gene is an up-regulated gene in intestinal infective larvae (IIL) compared to muscle larvae (ML) and vaccination of mice with rTsGST displayed a partial protection against challenge infection. The purified rTsGST showed the maximum enzymatic activity at pH 6.5 and 40 °C. The enzymatic K m values for GSH and CDNB were 457 and 123 μM, respectively. An in vitro invasion assay showed that when anti-rTsGST serum of mice infected with T. spiralis and normal mouse serum were added to the medium, and the invasion rate of the infective larvae in an intestinal epithelial cell (IEC) monolayer was 31.0, 11.36, and 78.96%, respectively (P < 0.05), which indicates that anti-rTsGST antibodies partially inhibited the larval invasion of IEC. ADCC assay showed that anti-rTsGST serum induced significant death of larvae (70% cytotoxicity) compared to the larvae incubated with pre-immune serum (12% cytotoxicity, P < 0.001) and was dose dependent.