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

The Journal of antimicrobial chemotherapy

PubMedID: 19403653

García-Lerma JG, McNulty A, Jennings C, Huang D, Heneine W, Bremer JW. Rapid decline in the efficiency of HIV drug resistance genotyping from dried blood spots (DBS) and dried plasma spots (DPS) stored at 37 degrees C and high humidity. J Antimicrob Chemother. 2009;64(1):33-6.
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 microL of blood and stored at either -20 degrees C or at 37 degrees 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 degrees C by the in-house assay. In contrast, amplification was rapidly lost during storage at 37 degrees 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 degrees 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 degrees 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 degrees C.