Detecção de autoanticorpos em soros com padrão indeterminado a técnica Western Blot para HIV1 e HIVZ

Abstract

The serological tests used for the laboiatorial diagnosis of the infection by the HIV virus (Human Immunodeficiency Virus), are initially tested by the ELISA technique (Enzyme-Linked Immunosorbent Assay), and, presenting a positive result, are later analysed by a confirmation test called Western Blot. This test is based on the identification of specific antibodies to each of the yjral antigenic components, prepared from cultured cells and transferred to nitrocellulose strips by electrophoresis, with which the serum to be tested is incubated. The presence of specific antibodies directed against the virus in the serum of the individual leads to the binding of these with the viral antigens. The addition of an enzyme-linked anti-human immunoglobulin conjugate and the addition of specific substrate to the enzyme reveals a pattern of coloured bands at the sites where the specific antibodies bind to the viral antigens. This technique confirms exposure to virus proteins when all viral protein bands appear on the test strip that meet the established criteria for positivity or no such exposure when no banding pattern is seen. However, there have often been "indeterminate or "non-conclusive" results, which are referred to as such because they show reactivity to viral protein bands that do not meet the established criteria for positivity. These results remain to date without any meaning, although several hypotheses have been put forward to explain them. It has been described by other authors that they may be due to the stage of the disease in which the infected individual is, to non-specific reactions caused by the existence of high levels of immunogiobulins in the serum of the individuals or to the presence of autoantibodies. Autoantibodies are considered to be a possible cause of indeterminate results due either to the existence of homology of certain HIV proteins with normal body proteins, or to the possible reaction of autoantibodies present in the serum of the individual with cellular proteins present on the Western blot test strips. One of the major problems faced in HIV serology is the occurrence of these indeterminate results in the pchy Western Blot confirmation tests, which have been very frequent in the sera of Mozambican individuals. The consequences of this situation are negative for HIV screening at blood banks, for the surveillance of