Field Study of Dried Blood Spot Specimens for HIV-1 Drug Resistance Genotyping.

Parry CM1, Parkin N2, Diallo K3, Mwebaza S4, Batamwita R4, DeVos J3, Bbosa N5, Lyagoba F6, Magambo B6, Jordan MR7, Downing R5, Zhang G3, Kaleebu P6, Yang C8, Bertagnolio S9.

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Abstract

Dried blood spots (DBS) are an alternative specimen type for HIV drug resistance genotyping in resource-limited settings. Data relating to the impact of DBS storage and shipment conditions on genotyping efficiency under field conditions are limited. We compared genotyping efficiency and resistance profiles of DBS stored and shipped at different temperatures to plasma specimens collected in parallel from patients receiving antiretroviral therapy in Uganda. Plasma and four DBS cards from anti-coagulated venous blood, and a 5th card from finger-prick blood were prepared from 103 HIV-patients with a median VL of 56,795 copies/ml (range 1,081 - 2,964,191). DBS were stored at ambient temperature for 2 or 4 weeks or frozen at -80°C, and shipped from Uganda to the United States, at ambient temperature or frozen on dry ice, for genotyping using a broadly sensitive in-house method. Plasma (97.1%) and DBS (98.1%) stored and shipped frozen had similar genotyping efficiency. DBS stored frozen (97.1%) or at ambient temperature for 2 weeks (93.2%) and shipped at ambient temperature also had similar genotyping efficiency. Genotyping efficiency was reduced for DBS stored at ambient temperature for 4 weeks (89.3%, P=0.03) or prepared from finger-prick blood and stored at ambient temperature for 2 weeks (77.7%, P<0.001) compared to DBS prepared from venous blood and handled similarly. Resistance profiles were similar between plasma and DBS specimens. This study delineates the optimal DBS collection, storage and shipping conditions and opens a new avenue for cost-saving ambient temperature DBS specimen shipments for HIVDR surveillances in resource-limited settings.