PCR IDENTIFICATION OF HIV-1 DNA-SEQUENCES IN BRAIN-TISSUE OF PATIENTSWITH AIDS ENCEPHALOPATHY

We analyzed brain tissue from 39 patients for the presence of proviral HIV-1 sequences, using the polymerase chain reaction (PCR) for the am plification of segments of the viral LTR and gag genes. A novel primer extension procedure allowed the detection of a single HIV-1 copy in 1 mug DNA. We detected proviral HIV-1 DNA in 16 of 25 brain samples fro m AIDS patients. Semiquantitative evaluation of the amplified DNAs ind icated considerable variation in viral load. Highest levels of provira l DNA were present in brain samples from six patients with clinical ev idence of HIV-associated cognitive/motor complex and the histopatholog ic correlate of HIV leukoencephalopathy or HIV encephalitis. An additi onal 11 brain samples contained smaller amounts of proviral DNA. ln th ese patients, clinical data were inconclusive regarding the diagnosis of HIV-1 encephalopathy and histopathologically there was no evidence of HIV-1-induced tissue lesions. In nine of 25 seropositive patients w ith AIDS (36%), brain samples scored negative or did not contain an un equivocal signal indicating the presence of proviral DNA. HIV-1 sequen ces were not detected in any of 14 control brain samples from HIV-1 se ronegative patients. Our data indicate that HIV-1 is present in the ce ntral nervous system of the majority (two thirds) of AIDS patients and that the highest levels of proviral DNA in brain tissue are associate d with HIV encephalopathy.