[The diagnosis of HIV infection by detecting specific nucleotide sequence]

There are several methods to detect human immunodeficiency virus (HIV) infection; the detection of antibodies against HIV, the detection of HIV particles, and the detection of HIV infected cells. The detection of anti-HIV antibodies is practical, but the antibodies are undetectable both on a seronegative person at the superacute phase, and the new-born baby from a seropositive mother. No other method is ideal for all purposes. Thus the detection of the HIV-specific nucleotide sequence especially using the PCR method has been expected. We developed a quantitational PCR method to assay HIV-infected PBMC cell number, and the result correlated with that of the quantitational culture method, and also correlated with the CD4 count, that is inversely related to the clinical stage of HIV infection. Our quantitational PCR method must be improved before application to a practical routine test. A new PCR kit to detect HIV infected cells qualitatively has been developed and purchased in Europe. This kit is especially workable to test specimens where the antibody detection method cannot be used. PCR can be used on other specimens and can be applied to HIV infection. HIV RNA (both genomic RNA and viral mRNA) can be detected by a combination with the reverse transcriptase reaction. This method (RT-PCR) will be ideal to detect HIV particles. With PCR, the sequence-differentiation between each clinical virus strain may be detected, thus the characterization of a virus strain such as drug resistance, latency, or the prognosis may be recognized. PCR is indeed a valuable method to detect HIV-infection, provided its limits are properly understood.