CIRCULAR FORMS OF UNINTEGRATED HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 DNA AND HIGH-LEVELS OF VIRAL PROTEIN EXPRESSION - ASSOCIATION WITH DEMENTIA AND MULTINUCLEATED GIANT-CELLS IN THE BRAINS OF PATIENTS WITH AIDS

Thirty-one histologically abnormal brains from patients with AIDS were studied in order to establish the relationship between multinucleated giant cells, viral protein expression, the various forms of human imm unodeficiency virus type 1 (HIV-1) DNA, and clinical evidence of demen tia. Unintegrated HIV-1 DNA of 2 to 8 kb was found in 22 of the 31 bra ins. Multinucleated giant cells without any other pathology were found in 14 cases; unintegrated 1-long terminal repeat (1-LTR) circular for ms of HIV-1 DNA and strongly positive immunohistochemistry for gp41 an d p24 were found in most of these brains. Most of these patients had a clinical diagnosis of HIV-1-associated dementia and cerebral atrophy. In all the other brains studied, 1-LTR circles were absent and immuno histochemistry for gp41 and p24 was usually negative. Very few of thes e patients had a clinical diagnosis of dementia. Sequence comparison o f the LTR region from integrated HIV-1 DNA with that from unintegrated 1-LTR circular forms of HIV-1 DNA in 12 cases showed no significant d ifferences. A further comparison of these brain-derived LTR sequences with LTR sequences derived directly from lymphoid tissue also showed s trong sequence conservation. The V3 loop of the virus from the brain w as sequenced in 6 cases and had a non-syncytium inducing-macrophage-tr opic genotype. Our results show that (i) although unintegrated HIV-1 D NA was present in most brains from patients with AIDS, molecular evide nce of high levels of viral replication was associated with the presen ce of multinucleated giant cells and dementia, and that (II) the HIV-1 LTR is not a determinant of neurotropism. These observations suggest that replication of HIV-1 and not just the presence of HIV-1 DNA withi n giant cells makes the important contribution to central nervous syst em damage.