Rapid decline in the efficiency of HIV drug resistance genotyping from dried blood spots (DBS) and dried plasma spots (DPS) stored at 37°C and high humidity

Abstract

Objectives: Dried blood spots (DBS) and dried plasma spots (DPS) are considered convenient alternatives to serum and plasma for HIV drug resistance testing in resource-limited settings. We sought to investigate how extreme conditions could affect the short-term ability to amplify and genotype HIV from DBS. Methods: A panel of six matched DPS/DBS was generated using blood collected from HIV-infected donors. Replicate cards were prepared in 903 filter paper using 50 μL of blood and stored at either -20°C or at 37°C/100% humidity. Nucleic acids were extracted at baseline and after 1, 2, 8 and 16 weeks of storage and were amplified and sequenced using an in-house RT-nested PCR method or the ViroSeq assay. Results: HIV-1 pol was successfully amplified in all DBS/DPS at baseline and in those stored for up to 16 weeks at -20°C by the in-house assay. In contrast, amplification was rapidly lost during storage at 37°C/100% humidity with only 6/6 and 4/6 DBS specimens amplifiable by the in-house assay at weeks 1 and 2, respectively. Similarly, only two DPS stored at 37°C/100% humidity were amplified by the in-house assay at week 1. Conclusions: We show that resistance testing from DBS and DPS is severely compromised after 2 and 1 weeks of storage at 37°C/100% humidity with desiccant, respectively. These findings underscore the importance of temperature and humidity for the efficient genotyping of HIV-1 from DBS and DPS, and reiterate the need to rapidly transport specimens from collection sites to locations that have appropriate storage conditions such as -20°C. © Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.