Taenia saginata Metacestode Antigenic Fractions without Affinity to Concanavalin A Are an Important Source of Specific Antigens for the Diagnosis of Human Neurocysticercosis

Abstract

Taenia saginata metacestode antigens have been constituted a useful alternative antigen for neurocysticercosis (NC) serodiagnosis, particularly due to an increasing difficulty to obtain Taenia solium homologous antigen. Cross-reactivity with Echinococcus granulosus infection occurs in homologous and heterologous antigens and could be avoided by using different purified methods. The present study evaluated antigen fractions obtained from saline extracts of T. saginata metacestodes purified by affinity chromatography with jacalin or concanavalin A (ConA) lectins to detect IgG antibodies by enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis to diagnose human NC. Serum samples were collected from 142 individuals: 40 of them were diagnosed with NC, 62 presented Taenia sp. and other parasites, and 40 were apparently healthy individuals. The jacalin-and ConA-unbound fractions demonstrated sensitivity and specificity higher than those of bound fractions. Among unbound fractions, ConA demonstrated statistically higher sensitivity and specificity by ELISA (90% and 93.1%, respectively). By immunoblot assay, the 64-to 68-kDa component from the ConA-unbound fraction showed 100% sensitivity and specificity, making this component suitable for use as a specific antigen for diagnosis of NC. To our knowledge, this is the first report showing the relevance of using the unbound ConA fraction of T. saginata metacestodes to diagnose NC. In conclusion, the results obtained herein clearly demonstrate that antigenic fractions without affinity to ConA, obtained from T. saginata metacestodes, are an important source of specific peptides and are efficient in the diagnosis of NC when tested by immunoblot assay.Taenia solium is a parasite whose larvae (metacestodes) may be located in the central nervous system of humans, causing neurocysticercosis (NC). Clinical manifestations are nonspecific and vary in severity, ranging from headaches, dizziness, and occasional seizures to a very severe neurological condition with intracranial hypertension or dementia (39,40,42).The diagnosis of NC is given by the combined analysis of clinical data and neuroimaging (computerized tomography and magnetic resonance imaging) as well as immunological and epidemiological data (10). From the neuroimaging findings of NC, only the presence of cystic lesions demonstrating the scolex should be considered pathognomonic (4). In many countries where T. solium is endemic, neuroimaging methods could be inaccessible and/or too expensive for the population at risk, often rural. Under these conditions, serology may provide a viable tool for diagnosis of the infection (6,16,18,35).As NC immunodiagnosis continues to be a challenge because of the increasing difficulty in obtaining parasites from naturally infected pigs for the preparation of T. solium homologous antigen (33), alternative antigens, including heterologous antigens from Taenia saginata, have also been used with satisfactory results to diagnose human NC (29,31,32). T. saginata cysticerci in the cysti...

Taeniosis and Cysticercosis

“…T. saginata (Harrison and Parkhouse 1989;Oliveira et al 2010), T. crassiceps (Larralde et al 1990;Espíndola et al 2002;Suzuki et al 2007), and T. hydatigena (Hayunga et al 1991) have been used for detection of human cysticercosis.…”

Use of heterologous antigens for the immunodiagnosis of abdominal angiostrongyliasis by an enzyme-linked immunosorbent assay

“…The feasibility of this congeneric species approach has already been demonstrated by the diagnoses of patients who are infected with parasites that share epitopes, such as S. stercoralis and Strongyloides venezuelensis (Feliciano et al 2010) or Strongyloides ratti (Rodrigues et al 2007). This approach has been particularly promising in the development of alternative methods for the diagnoses of cisticercosis, strongyloidiasis and hidatidosis (Vaz et al 1997, Sako et al 2006, Feliciano et al 2010, Oliveira et al 2010, da S Ribeiro et al 2010). In addition, Dekumyoy et al (2000) studied the use of a crude antigen preparation that was derived from A. costaricensis as a heterologous target for the detection of antibodies in patients with eosinophilic meningitis.…”

Wormy surprise!

“…Surgical complications like colonic perforation,2 intestinal obstruction3 and appendicitis4 due to tapeworms have been reported. The diagnosis can be made by investigations like stool microscopy, detecting Taenia eggs in the perianal region and immunoblot assay to detect IgG anticysticercal antibodies in serum, cerebrospinal fluid and saliva 5. Antihelmintics like praziquantel and niclosamide are effective for treating intestinal tapeworm infestation 6 7.…”