PCR detection of HIV proviral DNA (gag) in the brains of patients with AIDS: comparison between results using fresh frozen and paraffin wax embedded specimens.

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Abstract
To adapt the polymerase chain reaction (PCR) technique of HIV detection to paraffin wax embedded brain tissue and to compare the results with those obtained using frozen tissue. HIV antigen and HIV proviral DNA were detected in specimens of frontal lobe using immunohistochemistry and PCR, respectively. DNA was extracted from fresh tissue using standard methods whereas the technique for extracting DNA from paraffin wax embedded tissue was partly modified. Twenty cases were examined. HIV DNA was detected in 16 cases in frozen specimens. Of these, 15 were also positive when paraffin wax embedded material was analysed. This study shows that HIV proviral DNA can be detected in formalin fixed, paraffin wax embedded brain tissue by PCR. The results obtained from paraffin wax embedded specimens showed a similar degree of reliability to those from fresh frozen brain. Factors such as fixative, fixation time, and delay in performing post mortem examinations did not seem to influence PCR amplification as positive results were obtained with specimens left in fixative for up to eight months, as well as in cases where post mortem examinations had been delayed for up to four days.