Distribution of Taenia solium Diagnostic Glycoproteins in the Different Developmental Stages of the Parasite

Taenia solium is a helminth parasite that causes 2 diseases in humans: cysticercosis and taeniasis. The establishment of T. solium metacestodes in the central nervous system causes neurocysticercosis, while development of the adult tapeworm in the small intestine causes taeniasis. Serological diagnosis of neurocysticercosis is performed by Western blot with an enriched fraction of glycoproteins that has been extensively used for clinical diagnosis and epidemiological surveys. The lectin-bound fraction that is used for this assay contains 7 antigenic glycoproteins. These antigenic proteins are considered to be highly specific for cysticercosis when tested with heterologous parasitic diseases. However, recent studies show that people with taeniasis have cross-reactive antibodies against the neurocysticercosis diagnostic glycoproteins and vice versa. Nevertheless, it is not known if these diagnostic proteins are expressed in the adult stage of the parasite. In this paper, we describe the location of 3 of these glycoproteins in T. solium adults and cysticerci using polyclonal antibodies raised against a synthetic peptide based on the amino acid sequence of TS14, a recombinant protein T24H, and the native GP50. The glycoproteins' distribution was different in invaginated and evaginated cysticerci as well as in adult tapeworms. Specifically, the 3 glycoproteins studied were differentially expressed during embryogenesis. Our findings indicate that expression of the diagnostic glycoproteins is developmentally regulated; this is noteworthy since these glycoproteins are considered specific for the diagnosis of neurocysticercosis but nevertheless are present in different structures throughout the development of T. solium. Here we describe the glycoprotein expression and localization, which can be important in understanding their biological functions. In addition, our results help clarify the cross-reaction observed between people with neurocysticercosis and taeniasis to TS14, T24H, and GP50, which are used as diagnostic antigens for neurocysticercosis.

Evaluation of cross-reactivity to Taenia hydatigena and Echinococcus granulosus in the enzyme-linked immunoelectrotransfer blot assay for the diagnosis of porcine cysticercosis

BACKGROUND

Taenia solium is an important zoonotic parasite that infects humans as definitive host (taeniasis) and pigs as intermediate host (cysticercosis). Serological diagnosis of porcine cysticercosis is limited to antigen detection using ELISA, which is known to cross-react with other Taenia species, and antibody detection using the lentil-lectin glycoprotein enzyme-linked immunoelectrotransfer blot (LLGP EITB), which has not been adequately evaluated for cross-reactivity to other parasites. Field studies suggest that the GP50 diagnostic band of the LLGP EITB may cross-react to Taenia hydatigena, a common non-zoonotic parasitic infection of pigs. The objective of this study was to evaluate the specificity of the LLGP EITB assay in pigs infected experimentally with T. hydatigena and Echinococcus granulosus.

RESULTS

Twelve three-month-old seronegative were divided into two groups; six were each given an oral challenge with a single gravid proglottid of T. hydatigena and the other six were each given an oral challenge with 50 gravid proglottids of E. granulosus. Serum samples were collected biweekly until 14 weeks when all pigs underwent a detailed necropsy. Taenia hydatigena cysticerci were found in two of six pigs from the first group. Four T. hydatigena-exposed pigs were seropositive at the GP50-band only on EITB LLGP; two of these had cysts at necropsy while no seronegative pigs had cysts. One E. granulosus-exposed pig was positive to EITB LLGP, again with reactivity only to GP50; all six pigs had hepatic echinococcosis on necropsy.

CONCLUSION

These results provide definitive evidence that the GP50 diagnostic band in pigs cross-reacts with T. hydatigena. Evidence of cross-reaction with E. granulosus was not conclusive.

GP50 as a promising early diagnostic antigen for Taenia multiceps infection in goats by indirect ELISA

Background

Coenurosis is caused by coenurus, the metacestode of Taenia multiceps, which mainly parasitizes the brain and spinal cord of cattle, sheep and goats. To date, no widely-approved methods are available to identify early coenurus infection.

Methods

In this study, we identified a full-length cDNA that encodes GP50 (TmGP50) from the transcriptome of T. multiceps, and then cloned and expressed in E. coli. The native proteins in adult stage and coenurus were located via immunofluorescence assays, while the potential of recombinant TmGP50 protein (rTmGP50) for indirect ELISA-based serodiagnostics was assessed using native goat sera. In addition, we orally infected 20 goats with mature T. multiceps eggs. Praziquantel (10%) was given to 10 of the goats 45 days post-infection (p.i.). Blood samples were collected for 17 weeks p.i. from the 20 goats and anti-rTmGP50 antibodies were evaluated using the indirect ELISA established here.

Results

The TmGP50 contains an 897 bp open reading frame, in which signal sequence resides in 1 ~ 48 sites and mature polypeptide consists of 282 amino acid residues. Immunofluorescence staining showed that native TmGP50 was localized to the microthrix and parenchymatous zone of the adult parasite and coenurus, and the coenurus cystic wall. The indirect ELISA based on rTmGP50 exhibited a sensitivity of 95.0% and a specificity of 92.6% when detecting GP50 antibodies in sera of naturally infected goats and sheep. In goats experimentally infected with T. multiceps, anti-TmGP50 antibody was detectable from 2 to 17 weeks p.i. in the control group, while the antibody fell below the cut-off value about 3 weeks after praziquantel treatment.

Conclusion

Our results indicate that recombinant TmGP50 is a suitable early diagnostic antigen for coenurus infection in goats.