PADRONIZAÇÃO DE UM ENSAIO IMUNOENZIMÁTICO (ELISA) UTILIZANDO UMA PROTEÍNA MULTIEPÍTOPO RECOMBINANTE PARA PRODUÇÃO DE KIT PARA DIAGNÓSTICO DA HEPATITE C

Abstract

Hepatitis C virus (HCV), described in 1989, belongs to the Hepacivirus genus and the Flaviviridae family and possess a genomic RNA contend 9,600 nucleotides approximately. Due to its high genetic variability was classified in genotypes (1-6) and subtypes (a, b, c etc.). The genotypes 1a, 1b, 2a, 2b and 3a, have cosmopolitan distribution; whereas in Brazil, genotypes 1 and 3 are the most prevalent. The incubation period for acute hepatitis C varies around 6 to 10 weeks and approximately 80% of the acute infections are asymptomatic. Between 10 and 20 years, about 20% of the chronic infections evolve for cirrhosis and these can evolve for death due to complications. In accordance with the World Organization of Health, 3% of the world-wide population (about 180 million individuals) is infected for the HCV. Hepatitis C can be diagnosed by means of serological tests and analyses-based techniques of Molecular Biology. The assay more commonly used for detention of antibodies anti-HCV is ELISA. This test consists of antigens fixed in the wells of a microtiter plate. Specific antibodies against these antigens will adhere to the plate and will be detected by antibodies anti-human immunoglobulin colorimetric markers. This study aims the confection of ELISA using a multiepitope protein (MEHCV). The samples used in the assays are from blood banks. Tests with nickel resin-purified MEHCV and column-purified MEHCV (desalting and non-desalting) had been carried through. The tests aimed standardize the concentration of the protein for well and the dilutions of the serum; to evaluate unspecific reactions through tests with positive serum for other infections (positive anti- HBV and HAV) and with negative serum; and to compare ELISA in house with commercial ELISA. In accordance with the standardization results tests, how much bigger the protein pureness degree biggest was the protein concentration necessary in the microplates sensitization to evaluate possible crossed-reactions. The tests to evaluate unspecific reactions using the resinpurified MEHCV had presented higher sensitivity (92.86%) and specificity (82.89%) than the column-purified MEHCV (Sensitivity = 80%; Specificity = 47.5%). In contrast of ELISA in house, commercial ELISA only presented a result false-positive for sample 5 (anti-HBV positive). To evaluate the interference of other proteins, it was carried through, an assay using microplates sensitized with unspecific proteins. These results suggest that MEHCV protein don t possess yet the ideal pureness degree to be used as antigen and that possibly, the false-positive reactions occurred had been caused by unspecific proteins present with the recombinant protein MEHCV.