Application of Taenia saginata metacestodes as an alternative antigen for the serological diagnosis of human neurocysticercosis

Abstract

Serological tests are an important tool for the diagnosis of neurocysticercosis (NCC), the disease caused by Taenia solium metacestodes. The aim of the present research was to test the application of Taenia saginata metacestodes as an alternative antigen for use in the immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), and Western blotting (WB) tests compared with the metacestodes antigen of T. solium in serum samples. The samples were obtained from 130 individuals: 20 from patients with definitive NCC, Group 1; 18 from individuals infected by Taenia sp., Group 2; 40 from individuals infected by various parasites, Group 3; and 40 from healthy individuals, Group 4. The sensitivity of IFAT, ELISA, and WB using antigen obtained from T. solium applied to the patients of Group 1 yielded results of 85, 95, and 95%, respectively, for the three tests. When the tests were conducted using T. saginata metacestodes, results were 75, 80, and 85%, respectively. The specificity of IFAT, ELISA, and WB using antigen obtained from T. solium yielded results of 94.9, 88.8, and 93.9%. When the tests were conducted using T. saginata metacestodes, results were 95.9, 88.8, and 93.6%, respectively. No statistical differences for sensitivity or specificity among the antigens were found. In conclusion, the results indicated that T. saginata metacestodes can be used as an alternative antigen for NCC diagnosis.

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

“…Fresh T. saginata metacestodes were collected from naturally infected bovine muscle and were carefully dissected from the host tissues, washed repeatedly, and stored at Ϫ20°C. A saline extract was prepared as described previously by Oliveira et al (31).…”

“…(i) ELISA. An ELISA using a saline extract and fractions was carried out according to the method of Oliveira et al (31). Briefly, polystyrene microplates (Interlab, Brazil) were coated with each extract at concentrations of 10 g/ml in 0.06 M carbonate bicarbonate buffer, pH 9.6.…”

“…The immunoblot assay was performed according to the method of Oliveira et al (31). Antigen preparations were subjected to electrophoresis and transferred to nitrocellulose membranes (0.45 m; Sigma) by using a transfer apparatus (Omniphor, England).…”

“…Although heterologous antigens from T. saginata metacestodes have been used with satisfactory results, there has been no research to test their purification with the purpose of selecting antigens present in this helminth that are able to react with antibodies induced by T. solium-infected individuals. Although our previous study has demonstrated high sensitivity and specificity with heterologous antigens but residual crossreactivity between heterologous and homologous antigens (31), no research has been conducted so far to test the efficiency of purified fractions of saline antigen from T. saginata metacestodes for NC diagnosis.…”

“…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 cystic stage may be obtained in considerable amounts, because the eating habits in many countries, including Brazil, are based mainly on cattle meat consumption.…”