QUANTIFICATION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 RNA FROM DRIED PLASMA SPOTS COLLECTED ON FILTER-PAPER

To assess dried plasma spots (DPSs) as a source of material for virus quantification, human immunodeficiency virus type 1 (HIV-1) RNA levels were quantified in matched DPS and liquid plasma samples from 73 infe cted patients, including 5 neonates and 4 adult patients with acute HI V-1 infection, Quantifications were performed by commercially availabl e assays (NASBA [nucleic acid sequence-based amplification] or Amplico r, or both). There was a strong correlation between HIV-1 RNA levels i n plasma and DPSs, More importantly, there was no decline in HIV-1 RNA levels in DPSs stored for as long as 2 weeks at 20 degrees C, Similar ly, storage of DPSs for 3 days at 37 degrees C resulted in no decrease in viral RNA levels, For patients with primary infection, the DPS met hod allowed for the measurement of RNA levels in plasma during the ini tial spike in the level of viremia and in the subsequent period of sup pressed viral replication, DPS quantification was equally informative in the neonatal setting, with all five newborns showing HIV-1 RNA load s of greater than 4.991 log(10) copies/ml, We conclude that the viral RNA levels in DPSs are equivalent to those measured in fresh-frozen pl asma, The ease and economy of DPS sampling, the minute volumes require d, and the unexpected stability of dried RNA suggest that the use of D PSs will be particularly valuable for small-volume neonatal samples an d large, population-based studies in which cold storage and transporta tion present special problems, as is often the case in developing coun tries, The ability to measure viral changes during primary infection s uggests that the method will be useful for assessing vaccine efficacy in large field trials.