NESTED PCR ASSAYS WITH NOVEL PRIMERS YIELD GREATER SENSITIVITY TO TANZANIAN HIV-1 SAMPLES THAN A COMMERCIAL PCR DETECTION KIT

To investigate the efficacy of the SK431/SK145 primer pair and two nes ted primer assays in amplifying African HIV-1 samples, a total of 35 T anzanian PBMC samples were examined. These were assayed by two HIV-1 s pecific nested in-house PCR assays and a commercial HIV-1 PCR kit (Gen eAmp(TM)) using SK431/SK145 as the primer pair. One of the nested PCR assays has been evaluated previously (old assay), whereas the modified assay was constructed from the HIV-1 sequence alignment released in A ugust 1993. The modified nested primer assay showed increased sensitiv ity in the gag and env regions compared to the old nested primer assay . However, both the old and the modified nested primer assays displaye d higher sensitivity for the detection of Tanzanian HIV-1 proviruses t han the GeneAmp(TM) assay. When two regions were used (gag and env) as targets for the amplification, the modified nested primer assay detec ted 97.1% (34/35) of the proteinase K lysed samples, compared to 68.6% (24/35) using the SK431/SK145 primer pair (P < 0.01*). The results i ndicate that the SK431/SK145 primer pair may be less suitable when HIV -1 samples from Africa are analysed. The results also show that contin uous modification of primer sequences can improve and maintain high se nsitivity for the detection of highly divergent HIV-1 strains.