Estudo das frações hidrofóbica e hidrofílica de metacestódeos de Taenia saginata no diagnóstico sorológico da neurocisticercose humana

Abstract

Neurocysticercosis (NC) caused by the Taenia solium metacestodes usually affects the central nervous system and can be confused with other brain pathologies, which present similar clinical and image findings. This parasitose is endemic in Brazil and the serological diagnosis of NC is of great importance in routine clinical management of patients. The search for alternative antigens for NC immunodiagnosis is importance because of the difficulty of obtaining parasites from naturally infected pigs for the preparation of metacestodes T. solium homologous antigen. Once that purified antigen is more sensitive and specific than crude saline extracts, the objective of this study was to evaluate the performance of enzyme linked immunosorbent assay (ELISA) and Immunoblotting (IB) for the serological diagnosis of human NC, using the crude saline extract (Crude) obtained from T. saginata metacestodes and two fractions of this extract, hydrophobic or detergent fraction (D) and hydrophilic or aqueous fraction (A), purified by extraction with Triton X-114 as alternative purified antigens for the diagnosis of human NC. Serum samples were obtained from 115 individuals: 40 patients with a definitive diagnosis of NC, 45 patients with Taenia sp. and with other parasitic diseases and 30 apparently healthy individuals. The serum samples were diluted 1:200 for ELISA but only the samples positives were diluted 1:100 and evaluated in IB. ELISA sensitivity and specificity were 95% and 73.3% when using Crude, 95% and 82.6% for D phase and 65% and 61.3% for A phase, respectively. The diagnostic efficiency and Youden index were: 83.9% and 0.74 (Crude), 88.5% and 0.80 (D phase) and 72.8 % and 0.46 (A phase), respectively. IB of the antigens confirmed the results obtained by ELISA, and the D phase antigen proved to be more specific than other extracts, showing only one immunodominant protein of 70-64 kDa that was the most frequent (92.5%) among patients with NC. Our results suggest that the D phase obtained with Triton X-114 can be used as heterologous purified antigen for the serological diagnosis of human NC in the IB.