Long term stability of HBsAg,anti-HBc and anti-HCV in dried blood spot samples and eluates

BackgroundDried blood spots (DBS) are a useful specimen collection tool in situations where venous access is problematic, however, detection of biomarkers from this specimen type is subject to variation depending on storage conditions and storage time.ObjectivesThe objective of this study is to assess the detection of HBsAg, anti-HBc and anti-HCV from DBS after storage.Study designDBS specimens were stored at ?70 °C, ?20 °C, 4 °C, 22 to 28 °C and 37 °C either with or without desiccant. Eluates were also prepared from DBS specimens and stored at ?20 °C and ?70 °C. DBS cards and eluates were tested for HBsAg, anti-HBc and anti-HCV at baseline on day 0 and thereafter at intervals of 14, 70 and 200 days.ResultsLoss of detection of both HBsAg and anti-HBc was evident by the first time point (14 days) in all storage conditions except for the samples (DBS and eluates) stored at ?20 °C or ?70 °C. Both HBsAg and anti-HBc stored under these conditions showed minimal variation up to the final time point (200 days) of storage. The detection of anti-HCV did not differ between the 22 to 28 °C, 4 °C, ?20 °C and ?70 °C DBS nor the ?20 °C or the ?70 °C stored eluates over the 200 day time period.ConclusionWe suggest that extended storage of DBS intended for downstream testing is best carried out by freezing either the DBS, or eluate, at ?20 °C or ?70 °C as soon as possible following collection for optimal detection of HBsAg, anti-HBc and anti-HCV.