Dried blood spots for the diagnosis and quantitation of HIV-1: Stability studies and evaluation of sensitivity and specificity for the diagnosis of infant HIV-1 infection in Thailand ◊◊◊

Molecular methods for HIV-1 infection using dried blood-spot (DBS) for HIV-1 CRF01_AE subtypes have not been fully optimized. In this study assays for HIV-1 diagnosis or quantitation were evaluated using infant DBS from Thailand. Paired DBS and whole blood samples from 56 HIV-1 CRF01_AE or B’-infected infants were tested for infant diagnosis using modified Amplicor DNA PCR and NucliSens RNA NASBA and an in-house real-time PCR assay. The Amplicor Monitor viral load (VL) assay, with modifications for DBS, was also evaluated. DBS VL were hematocrit corrected. Stability studies were done on DBS stored at −70 °C to 37 °C for up to 1 year.The DBS diagnostic assays were 96–100% sensitive and 100% specific for HIV-1 diagnosis. DBS HIV-1 VL were highly correlated with plasma VL when corrected using the actual or an assumed hematocrit factor (rc = 0.88 or 0.93, respectively). HIV-1 DNA in DBS appeared to be more stable than RNA and could be detected after up to 9 months at most temperatures. DBS VL could be consistently determined when stored frozen.These results show that DBS can be used accurately instead of whole blood for the diagnosis of HIV-1 infection and VL quantitation, particularly if samples are appropriately stored.