O-glycosylation in Echinococcus granulosus: identification and characterization of the carcinoma-associated Tn antigen.

In the present work we demonstrate that the cancer-associated O-glycosylated Tn antigen (GalNAc-O-Ser/Thr) is expressed by the cestode Echinococcus granulosus. This antigen was detected in both larval and adult worm extracts, with the highest specific activity observed in the adult excretion/secretion preparation. Histochemical analysis showed that Tn is preferentially expressed in the parenchyma in both parasite stages and the external part of tegument in adult worms. A similar pattern was observed for sialyl-Tn, a related O-linked antigen. Tn glycoproteins from protoscoleces were resolved by SDS-PAGE in two main components of 43 and 49 kDa. After purification, this material was reactive with lectins which bind GlcNAc/sialic acid, GalNAc, and T antigen. In a preliminary evaluation, high levels of Tn antigen were detected in serum samples from patients with hydatid cyst, suggesting that the measure of Tn in serum could be a biomarker of this disease, although extensive work is necessary in order to determine the clinical usefulness of this assay. The results reported here, the first evidence of O-glycosylation pathways in E. granulosus and the presence of Tn antigen in cestodes, suggest that the evaluation of O-glycosylated antigens might give new insights in the host-parasite relationship.

A new nematode, Ansiruptodera scapteromi sp.nov. (Nematoda: Aspidoderidae), recovered from the Argentinean water rat Scapteromys tumidis (Waterhouse, 1837) in Uruguay.

This report describes a new species of aspidoderid nematode, Ansiruptodera scapteromi sp. nov., the second species to be reported in the genus Ansiruptodera Skrjabin and Shikhobalova, 1947. The A. scapteromi sp. nov. is the first species of the genus to be recorded from a rodent host. The new species is clearly different from the only other species, A. ansiruipta (Proença, 1937) Skrjabin and Shikhobalova, 1947, in that it possesses short lateral alae that terminate before the midbody; a smaller cephalic extremity; a shorter esophagus, pharynx, tail, and tail appendage; a smaller sucker; and longer spicules. The two species also differ in the numbers and arrangements of caudal papillae. A. scapteromi appears to be a parasite of capture and the water rats seem to have been infected from Edentata in Uruguay.

Coproantigen detection in dogs experimentally and naturally infected with Echinococcus granulosus by a monoclonal antibody-based enzyme-linked immunosorbent assay.

A sandwich ELISA for the detection of Echinococcus granulosus coproantigen in formalin and heat-treated faecal supernatants of dogs was developed. The assay used affinity-purified polyclonal antibodies obtained from rabbits hyperimmunised with E. granulosus excretory/secretory antigens and biotinylated monoclonal antibody EmA9 produced against adult E. multilocularis somatic extract. The test was sensitive to 7 ng and 2.3 ng of E. granulosus protein and carbohydrate/ml of faecal supernatant, respectively. Thirteen helminth-free dogs were infected with different amounts of E. granulosus protoscoleces and the presence of coproantigen was monitored during the prepatent period until day 35 post-infection, when they were necropsied. Faecal antigen levels started to rise above the normal range between days 10 and 20 post-infection, and typically peaked at the end of the experiment. All the dogs, bearing from 3 to 67,700 worms, showed positive values in the ELISA during the prepatent period. One dog experimentally infected with Taenia hydatigena metacestode and harbouring three worms, tested positive only after the prepatent period at day 52. The test was applied to 98 stray dogs. The ELISA detected all of four dogs naturally infected with E. granulosus, two dogs with patent infections of T. hydatigena and two dogs with no cestode infections, showing a sensitivity of 100% and a specificity of 96%.

High prevalence of Ancylostoma spp. infection in dogs, associated with endemic focus of human cutaneous larva migrans, in Tacuarembo, Uruguay.

A helminthological survey of the intestinal parasites in stray dogs was conducted in urban and suburban area of Tacuarembó, Uruguay, during winter time. Eighty stray dogs captured in the city were necropsied. Seventy nine dogs (98.8%) were positive for helminth infection. Seventy seven (96.3%) were parasitized by hookworms. Two species of hookworms were found: Ancylostoma caninum 96.3% and A. braziliense 49.4%. This is the first report of the prevalence of A. braziliense in Uruguay. Considering that incidences of human cutaneous larva migrans caused by the migration of hookworms larvae were restricted mainly to the northern part of Uruguay and that only A. caninum were reported to be prevalent in the southern part, it is supposed that A. braziliense is the primary causative agent of human cutaneous larva migrans in Uruguay.

Partial characterization of antigens in circulating immune complexes in cystic hydatid patients treated with albendazole.

Immune complexes were precipitated by 3% polyethylene glycol (PEG) from 4 sera from albendazole-treated hydatid patients from Uruguay, and together with sheep hydatid cyst fluid were analysed by ion-exchange fast protein liquid chromatography (FPLC). FPLC-eluted fractions of serum preparations and cyst fluid were tested in an enzyme-linked immunosorbent assay for the detection of specific Echinococcus granulosus antigens and also for presence of specific immunoglobulin (Ig) M and IgG in the serum samples. Two peaks (nos 13 and 25) were found to have antigenic activity. Antigens were identified in both serum and cyst fluid preparation (fraction 25) after sodium dodecyl sulphate-polyacrylamide gel electrophoresis immunoblotting analysis, with approximate molecular masses 50 kDa and 62 kDa. Specific IgM antibody was also detected in the same FPLC fraction (no. 25) of PEG-precipitated serum complexes.

Seroprevalence of Echinococcus granulosus infection in a Uruguayan rural human population.

Serological tests using hydatid cyst fluid (HCF) are useful as a primary screen for detecting asymptomatic infections due to Echinococcus granulosus in human populations. An enzyme-linked immunosorbent assay (ELISA) performed with whole sheep HCF was used to determine the prevalence of hydatid antibodies in a rural human population in Uruguay. In order to eliminate cross-reactions with sheep proteins in HCF, 1% normal sheep serum was added to each human serum before testing. ELISA seropositives were further tested using the double diffusion test (DD5) and confirmed where possible by ultrasound and X-ray examination. Serum samples were obtained from 420 individuals inhabiting rural areas in the Department of Paysandu (160), Rivera (21) and San José (239). An overall seroprevalence of 1.24% was obtained. Two of 17 seroreactors were subsequently proven to have hydatidosis. These results confirm and extend previous studies indicating an unusually high prevalence of E. granulosus infection in the Uruguayan population.