Determining The Stability Of Hiv-1 Rna In Plasma Samples Stored At Various Temperatures In Primary Tubes Of Centrifuged Whole Blood

Abstract

INTRODUCTION

Lesotho is a developing country faced with challenges of limited resources. Majority of Basotho live in remote areas that are miles and miles from health care facilities.HIV-1 RNA quantification is mainly performed at the Reference Laboratory and a few laboratories where the assay has been decentralized to. Patient’s samples often take a long time to reach the laboratory. The study is aimed to evaluate the HIV-1 RNA stability of un-separated plasma stored for one week at different temperatures.

METHODOLODY

Ethylenediaminetetraacetic acid (EDTA) whole blood samples were collected. HIV-1 RNA quantification test was performed within 24 hours of collection on Roche Cobas Ampliprep-Cobas Taqman analyser. This was done to determine samples with detectable values, thereafter three samples with equal volumes were mixed together to make a mini pooling sample. A large volume was obtained and aliquots of four sample batches made and samples at; 25-30⁰C (a fresh sample analysed within 24 hours), 2-8⁰C, -20⁰C and -80⁰C. Results of a fresh sample were compared to matching HIV-1 RNA concentrations determined from un-separated plasma stored at above mentioned temperatures for a week.

RESULTS AND DISCUSSION

Results in number of copies did not show a significant decrease in HIV-1 RNA copies, for samples that were stored at 2-8⁰ C (difference A) a greater percentage of 57% samples, showed the difference in number of copies that was less than 50%. Only 21 % were above 50% difference and the other 21% of the batches stored at this temperature had failed. Ginocchio et.al 2006, Bruistein et.al 1997 and Amellal et.al 2008 in their studies also indicated that samples that were stored at 4⁰ C for 14 days, 24 hours and 1 week respectively, did not show a significant decline in number of RNA copies.

Samples stored at -20⁰ C and – 80⁰ C did not indicate significant decline in RNA copies as 7% and 14% respectively of the samples showed a difference of above 50% number of copies from their initial values.

A log difference of ≥ 0.5 log in HIV-1 RNA viral load testing is said to be clinically significant. The results of this study were below 0.5 log therefore a significant change or decline was not noted.

CONCLUSION

The study showed that there is loss of HIV-1 RNA copies when EDTA samples are stored beyond 24 hours of sample collection, with plasma un-separated from RBCs. However, this loss is significantly shown by the number of HIV-1 RNA copies, logs shows that there is no statistically significant difference.