Long-term stability of human immunodeficiency virus viral load and infectivity in whole blood

BACKGROUND: We intended to evaluate the stability of human immunodeficiency virus (HIV) type 1 virions in whole blood and in culture medium. MATERIALS AND METHOD: EDTA whole-blood samples taken from 12 patients were left at room temperature for up to 7 days, and aliquots of a laboratory virus stock spiked in EDTA, in heparinized or in citrated whole blood, with or without the addition of Triton X-100, or spiked in culture medium were left at room temperature for up to 120 days before plasma was separated and frozen at -80 degrees C. Viral load was measured for all frozen plasma samples using different viral load assays. p24 antigen and infectivity were also measured in the spiked samples. RESULTS: The patient whole-blood samples did not show any decrease in viral load during this 7-day period. The spiked samples decayed by not more than 1 log after 120 days (about 4 months), with the fastest decay in medium. Virus infectivity decayed very slowly from 20,000 units mL-1 to undetectable amounts after 56 days. CONCLUSIONS: These results indicate that HIV-1 virions in whole blood possess a long-term stability in terms of viral load, p24 antigen level and infectivity, which is not sufficiently recognized by laboratory and health care workers.