Indian Journal of Sexually Transmitted Diseases and AIDS
: 2022  |  Volume : 43  |  Issue : 1  |  Page : 97--99

Stability of HIV-1 in human plasma samples at 37°C for up to 6 days

Manoj Kumar Rajput, Anoop Kumar, Deepika Paliwal, Aftab Ansari 
 Molecular Diagnostic Lab, National Institute of Biologicals, Noida, Uttar Pradesh, India

Correspondence Address:
Dr. Manoj Kumar Rajput
National Institute of Biologicals, A-32, Sector-62, Noida, Uttar Pradesh

How to cite this article:
Rajput MK, Kumar A, Paliwal D, Ansari A. Stability of HIV-1 in human plasma samples at 37°C for up to 6 days.Indian J Sex Transm Dis 2022;43:97-99

How to cite this URL:
Rajput MK, Kumar A, Paliwal D, Ansari A. Stability of HIV-1 in human plasma samples at 37°C for up to 6 days. Indian J Sex Transm Dis [serial online] 2022 [cited 2023 Jan 31 ];43:97-99
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Viral load monitoring is an important factor to access the effectiveness of antiviral therapy in HIV-1 patients. This is directly dependent on reliable procedure followed for processing of samples prior to quantification. In most of the countries, the laboratories which carry out viral quantification are stationed at distant places from the rural areas. Preprocedure and logistic factors such as storage and transport conditions can affect the quality of results. It is recommended that samples should be tested within 24 h of their collection. However, it is not feasible in resource-limited areas and samples may take more than 24 h to reach the testing laboratory. During this time period, samples are stored in cooled gel packs. Viral RNA decay has been reported in simulation studies.[1] The degree of decay due to these preprocedural factors is not known. The whole-blood samples collected in ethylenediaminetetraacetic acid did not reveal any change in viral load at room temperature up to 7 days. However, whole-blood samples spiked in culture medium showed 1 log viral load decay after 120 days at room temperature.[2] The present study was conducted to find out decay in HIV-1 load in human plasma samples at 37°C for up to 6 days. Five HIV-1 RNA-positive human plasma samples were taken for this study. Eight aliquots of each sample were prepared. Two aliquots of each sample were separately incubated at 37°C in a water bath for 2 days, 4 days, and 6 days and two aliquots of each sample were reserved for controls. After incubation, isolation of HIV-1 RNA and viral load determination was carried out using Cobas TaqMan HIV-1 test, version 2.0 and Cobas TaqMan 48 (m/s Roche molecular systems, Inc., South Branchburg, New Jersey, USA), respectively. The values of viral load determined are summarized in [Table 1]. Two samples, HI-21 and HI-24, showed 0.58 log10 copies/ml and 0.55 log10 copies/ml decrease in viral load, respectively, after incubation for 6 days. However, the difference was less than clinical cutoff after incubating HI-21 and HI-24 for 2 and 4 days. In all other cases, viral load decrease or difference was less than the clinical cutoff of ±0.5 log10 copies/ml. The differences of less than ±0.5 log10 copies/ml are clinically insignificant[3] which indicates that HIV-1 is quite stable in human plasma samples at 37°C for up to 6 days. In other studies, the stability of HIV RNA in whole blood reported is up to 7 days at 4°C and 3 days at 25°C.[4] Less than 0.5 log10 copies/ml decrease in HIV RNA at 25°C in 1 day has been shown by a study conducted in the year 1997.[5] Similar results were obtained in our study. In three different studies, the decrease in HIV RNA at 4°C was 0.04 log copies/ml after 7 days and 0.01 log copies/mL after 14 days. At 30°C, it showed insignificant decline of 0.12 log after 2 days and after 7 days the decline was 0.74 log copies/ml. It further declined to 1.6 log copies/ml after 14 days.[1],[3],[6] The reported decrease in viral load at 37°C after 7 days was 0.92 log copies/ml. However, it was negligible (0.03 log copies/ml) at 22°C after 7 days.[6] In our study, most of the samples showed <0.5 log copies/ml decrease after incubation at 37°C for 6 days. Two samples showed a decrease little over clinical cutoff after 6 days.{Table 1}

Although the sample size is small, the results of this study indicate that storage and transportation of samples at ≤37°C for a limited duration may not have much effect on test results and their clinical correlation. Therefore, in Indian setup in winters, the samples can be transported without cool/gel pack or any cooling device. Furthermore, there are many areas in India where the temperature remains below 37°C throughout the year. However, in areas where the temperature exceeds 37°C in summers, the temperature of samples during the transport should be maintained at least at 37°C. Further, the study could not be performed with large sample size due to their unavailability; therefore, the outcome of this pilot study needs to be tested with large sample size for better statistical interpretation to draw a final decision.

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