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 l eft at room temperature for up to 7 days, and aliquots of a laboratory viru s 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 fro zen at -80 degrees C. Viral load was measured for all frozen plasma samples using different viral load assays. p24 antigen and infectivity were also m easured 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. Vi rus infectivity decayed very slowly from 20 000 units mL(-1) to undetectabl e amounts after 56 days. Conclusions These results indicate that HIV-1 virions in whole blood posses s a long-term stability in terms of viral load, p24 antigen level and infec tivity, which is not sufficiently recognized by laboratory and health care workers.