QUANTITATION OF HUMAN CYTOMEGALOVIRUS GENOMES IN THE BRAIN OF AIDS PATIENTS

Human cytomegalovirus (HCMV) is one of the major pathogens causing neu rologic disease in the immunocompromised host. A competitive nested po lymerase chain reaction (PCR) was used to determine DNA load, distribu tion, and sequence variability of HCMV genomes in the brain of AIDS pa tients with and without HCMV encephalitis confirmed by histology and i mmunocytochemistry. By quantitative PCR, HCMV genomes were found to be distributed diffusely in the central nervous system (CNS) of all five patients with histologically proven HCMV encephalitis, but also in th e brain of five of eight AIDS patients without neuropathological evide nce of HCMV encephalitis. The viral DNA load in cases with HCMV enceph alitis was increased 10- to 1,000-fold as compared to patients without evidence of encephalitis. A viral load above 6,000 copies HCMV/10(6) copies beta-globin was found to be highly suggestive for HCMV encephal itis. Characterization of PCR products by temperature gradient gel ele ctrophoresis (TGGE) and direct sequencing allowed us to detect a seque nce variability of the amplified fragment of HCMV glycoprotein B (gB) among different patients, but also among different HCMV foci within th e same patient. Furthermore, two of five AIDS patients with HCMV encep halitis most likely experienced double infections with different HCMV strains. The experimental procedure described in this study should als o be applicable to the detection of significant HCMV DNA levels in bio psy samples. (C) 1995 Wiley-Liss, Inc.