Example of the experimental testing of HIV-1 specific primer set targeting gag gene (NP3/4) for its sensitivity with DNA analytical standards is shown in Figure S1 . Serial dilutions of a plasmid DNA corresponding to 5-10 4 HIV-1 genome copies spiked into 50 ng of normal human DNA, HIV-1 infected cells (H9/IIIB) (''positive'' control DNA) and uninfected human PBMC (''negative'' control DNA) are used in the experiment. Only a single melting peak Tm = 72.5uC corresponding to HIV-1 specific product was observed and no unspecific amplification was registered. Figure S1B revealed a standard curve showing the correlation between copy number of the target gene and Ct values with a slope = 23.77. The limit of sensitivity was determined in this assay to be 10 viral genome copies/PCR.