Quantitation of plasma human immunodeficiency virus type 1 RNA by competitive polymerase chain reaction

Clinical measures of human immunodeficiency virus (HIV) type 1 activity in vivo are limited and hinder the assessment of antiretroviral therapies. Reported here is a method for quantitating HIV-1 RNA in human plasma using the polymerase chain reaction (PCR). This method uses an internal cRNA standard generated from a cloned 113-bp deletion mutation of a highly conserved HIV-1 gag region sequence. The mutant cRNA (K4) was shown to amplify with efficiency equivalent to that of wild-type HIV-1. Known quantities of K4 cRNA added to wild-type HIV-1 in a competitive PCR strategy using a radiolabeled primer permitted quantitation of wild-type HIV-1 RNA over four orders of magnitude (10(3)-10(6) RNA copies). RNA isolated from plasma from AIDS patients yielded 10(3) to 8 x 10(4) HIV-1 RNA copies/ml of plasma with an average intrasample coefficient of variation of .26. This method offers a sensitive assay with a broad dynamic range for monitoring HIV-1 activity in the plasma of AIDS patients. It may provide a useful tool for assessing the effects of antiretroviral therapy.