Abstract: Objective To establish a multiple nested polymerase chain reaction(nPCR) and RT-PCR diagnosis assay system for human immunodeficiency virus-1(HIV-1) and to compare the sensitivity,specificity and other features of the method with those of a marketed assay,nucleic acid sequence-based amplification(NASBA).Methods The authors established an nPCR for detection of HIV DNA and RT-PCR for HIV RNA detection system with three sets of primers which target gag,pol and gp41 districts in HIV-1 gene.A total of 119 HIV seropositive patients were tested by the PCR methods and NASBA separately,the sensitivity was compared.The sensitivity of PCR detection in patients with different viral load were compared.Ten cases of suspected acute infection patients were tested by using the established PCR methods.The C2-C3 district in HIV-1 membrane was amplified in 43 positive DNA to identify their subtype.Results Sensitivity of nPCR was 97.5%(116/119).Sensitivity of RT-PCR was 78.2%(93/119).Specificities of both assay systems were 100%(50/50).The positive predictive values are 97.5%(116/119) and 78.2%(93/119) respectively,and the negative predictive values of both were 100%(50/50).The accuracies were 98.2% and 84.6%.The nPCR assay systems showed higher sensitivity than NASBA(97.5% vs 73.1%).The sensitivity of nPCR was markedly higher than that of RT-PCT in patients with viral load<10³ copy/mL,but the sensitivities of nPCR and RT-PCT were close to each other(nearly 100%) in patients with viral load 10³～10⁴ copy/mL and ≥10⁴ copy/mL viral load.Five of the 10 cases of suspected acute infection were tested positive by the PCR,and had a seropositive conversion afterwards during the follow up,therefore they were confirmed to have acute HIV infection.The 43 DNA samples belong to subtype B'(37cases),AE subtype(5 cases) and BC subtype(1 case).Conclusion The established PCR detective methods were highly effective in detection of HIV subtypes B',AE and BC,and showed a higher detective sensitivity than NASBA.The plasma RNA level has smaller influence on the sensitivity of nPCR than on RT-PCR.The HIV PCR diagnostic assay can be used for early diagnosis of HIV acute infection.

Key words: human immunodeficiency virus(HIV), nucleic acid test, polymerase chain reaction(PCR), diagnosis assay