Advanced laboratory techniques for diagnosing Toxoplasma gondii encephalitis in AIDS patients: significance of intrathecal production and comparison with PCR and ECL-western blotting

The polymerase chain reaction (PCR) for detection of cerebral spinal fluid (CSF) Toxoplasma gondii DNA was combined with the study of intrathecal anti body synthesis by antibody specific index calculation (ASI) and the detecti on of specific oligoclonal IgG bands (OCB) by affinity mediated immunoblott ing (AMI) in 11 AIDS patients with T. gondii encephalitis (TE) and in 20 co ntrol patients with or without neurological disorders. Enhanced chemilumine scence (ECL) western-blot technique was employed to evaluate the antigenic specificity of CSF-IgG towards individual T. gondii antigens. PCR was posit ive in all TE patients which displayed brain-derived or blood-derived speci fic OCB, even when comparative ASI failed. Four TE patients had a unique an ti-T. gondii OCB restricted to the CSF and a strong antibody response towar d the 29 kDa band by ECL western blot. This response could be an important marker to discriminate TE from other opportunistic central nervous system ( CNS) infections in the course of AIDS. (C) 1998 Elsevier Science B.V. All r ights reserved.