Lymphoproliferative response to the 30-kDa protein and a crude lysate from Salmonella typhimurium in patients with ankylosing spondylitis.

OBJECTIVES: To determine the lymphoproliferative response to the 30-kDa protein (p30) of Salmonella typhimurium in patients with ankylosing spondylitis (AS). METHOD: Lymphoproliferative response was determined in peripheral blood mononuclear cells (PBMCs) from 30 patients with AS and 40 healthy subjects. Cells were cultured with concanavalin A (Con A), a crude lysate of S. typhimurium (StCL), or p30. Lymphoproliferation was measured by the MTT assay. RESULTS: Our data show that the mitogenic response to Con A was similar in both groups studied; however, the lymphoproliferative response to StCL and p30 was statistically higher in AS patients than in healthy subjects. CONCLUSIONS: Our data strongly suggest that S. typhimurium, and particularly p30, are associated with AS.

Crassostrea gigas oysters as a shrimp farm bioindicator of white spot syndrome virus.

This study explored whether Crassostrea gigas oysters can be used as a bioindicator of white spot syndrome virus (WSSV) in shrimp farm water canals. Bioassays showed that C. gigas can accumulate WSSV in their gills and digestive glands but do not become infected, either by exposure to seawater containing WSSV or by cohabitation with infected shrimp. The use of a WSSV nested PCR to screen oysters placed in water canals at the entry of a shrimp farm allowed WSSV to be detected 16 d prior to the disease occurring. The finding that C. gigas can concentrate small amounts of WSSV present in seawater without being harmed makes it an ideal sentinel species at shrimp farms.

Cloning, expression and characterisation of a recombinant triosephosphate isomerase from Taenia solium.

We isolated and characterised the cDNA that encodes the glycolytic enzyme, triosephosphate isomerase from Taenia solium. A 450 bp DNA fragment was obtained by the polymerase chain reaction using a cDNA from larval stage as template and degenerate oligonucleotides designed from conserved polypeptide sequences from TPIs of several organisms. The fragment was used to screen a T. solium larval stage cDNA library. The isolated cDNA, encoding a protein of 250 amino acids shares 44.8-59.6% positional identity with other known TPIs, in which the catalytic enzyme residues were conserved. The complete coding sequence of the T. solium TPI cDNA was cloned into the expression vector pRSET and expressed as a fusion protein with an N-terminal tail of six histidine residues. The catalytic activity of the purified protein was similar to other TPI enzymes. Northern and Southern blot analysis suggest that in T. solium, single gene exists for triosephosphate isomerase and that the gene is expressed in all stages of the parasite.

Characterization of glutathione S-transferase of Taenia solium.

A Taenia solium glutathione-S-transferase fraction (SGSTF) was isolated from a metacestode crude extract by affinity chromatography on reduced glutathione (GSH)-sepharose. The purified fraction displayed a specific glutathione S-transferase (GST) activity of 2.8 micromol/min/mg and glutathione peroxidase selenium-independent activity of 0.22 micromol/min/mg. Enzymatic characterization of the fraction suggested that the activity was closer to the mammalian mu-class GSTs. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration, and enzyme activity analysis showed that the fraction was composed of a major band of Mr = 26 kd and that the active enzyme was dimeric. Immunohistochemical studies using specific antibodies against the major 26-kd band of the SGSTF indicated that GST protein was present in the tegument, parenchyma, protonephridial, and tegumentary cytons of the T. solium metacestode. Antibodies generated against the SGSTF tested in western blot showed cross-reactivity against GSTs purified from Taenia saginata, T. taeniaeformis, and T. crassiceps, but did not react with GSTs from Schistosoma mansoni, or mice, rabbit, and pig liver tissue. Furthermore, immunization of mice with SGSTF reduced the metacestode burden up to 74.2%. Our findings argue in favor of GST having an important role in the survival of T. solium in its hosts.

Glutathione S-transferase in helminth parasites.

Glutathione S-transferases (GSTs; EC 2.5.1.18) are a large family of multifunctional dimeric enzymes that conjugate reduced glutathione to electrophilic centers in hydrophobic organic compounds. The GST enzymatic activity has been described in the adult and larval stages of helminths. Several forms and isoforms of the enzyme have been purified and GST genes have also been isolated and expressed as recombinant proteins. The helminth GSTs participate in detoxification of lipid hydroperoxides and carbonyl cytotoxics produced by oxygen-reactive intermediates (ORI). The ORIs can come from the endogenous parasite metabolism or from the host immune system. The helminth GSTs are able to conjugate glutathione to xenobiotic compounds or to bind to anthelminth drugs. GST is usually localized near to host-parasite interface. This enzyme has been identified as a potentially vulnerable target in immunotherapy and chemotherapy. The present review compiles current knowledge about the biochemical characteristics of the enzyme, its presence, localization, induction, structural heterogeneity, relationship with mammalian GSTs, detoxification capacity and ability to induce protection in several animal models.

Characterization of a recombinant mu-class glutathione S-transferase from Taenia solium.

A Taenia solium larval glutathione S-transferase fraction (SGSTF), composed of two proteins with Mr 25,500 (SGSTM1) and 26,500 (SGSTM2), was purified by GSH-sepharose. Its N-terminal sequence analysis revealed that both proteins are related to mammalian mu-class GST enzymes. A cDNA clone coding for SGSTM1 was isolated and the amino acid sequence analysis showed close identity with two Echinococcus GSTs and also high identity with several mu-class GSTs that have been reported. In addition, SGSTM1 presents a similar structure to mu-class GSTs, including the mu loop. The recombinant SGSTM1 is a dimeric protein with enzymatic properties clearly related to mammalian mu-class GSTs. Western blot studies indicated that SGSTM1 is not antigenically related to SGSTM2 or mammalian GSTs from rabbit, pig and rat livers. Immunization with SGSTF and SGSTM2 was highly effective in reducing cysticerci load in murine cysticercosis. In contrast, no protection was obtained using native SGSTM1 and recombinant SGSTM1 as immunogens.