RESUMO
The objective of the study was to determine the diagnostic value of the parallel detection of the avidity index of the IgG to Toxoplasma gondii in the blood and cerebrospinal fluid by a three-step solid-phase enzyme immunoassay using T. gondii antigen, protein dissociating agent and monoclonal antibodies against human IgG at HIV-infected individuals with a focal damage of the brain. The results of the study showed that conducting of the enzyme-linked immunosorbent assay by a direct and dissociated method makes it possible to detect specific intrathecal and serum immunoglobulins, which is proposed in terms of improving diagnosis of cerebral toxoplasmosis in HIV-infected individuals. The high informative ability of the test system for detecting the avidity index of IgG antibodies to T. gondii allows the possibility to apply it in the algorithm for diagnosing an etiological factor of neuroinfection in HIV-infected individuals.