Evaluation of the Abbott m2000 system for dried blood spot detection of hepatitis C virus RNA.

ABSTRACT

BACKGROUND: Hepatitis C virus RNA testing using dried blood spots (DBS) offers a method for detecting ongoing HCV infection in "hard to reach" populations. Abbott Molecular have developed a quantitative HCV RNA DBS protocol (currently for research use only) for extraction and real-time PCR amplification using them2000sp and m2000rt system. METHODS: A panel of seventy "mock" DBS were made from patient whole blood; who were known to be either HCV RNA negative or positive. This panel compared the "mock" DBS and the plasma viral load results. A further dilution panel of "mock" DBS made from one HCV positive patient was used to estimate the detection limit of the assay. Abbott was then compared with an in-house real-time Taqman PCR using patient DBS samples. RESULTS: All "mock" DBS samples with a viral load >1000IU/ml were detected by Abbott, with only 1/8 detected at <1000 IU/ml. The dilution panel suggested the limit of detection to be between 178 to 1779 IU/ml. There were two false positive samples detected at low level <282 IU/ml, both samples were from patients who had been previously positive. The overall sensitivity of the Abbott RUO DBS protocol when compared to plasma was 86% (95 CI 73.76%-74.18%) increasing to 100% (CI 91.59%-100%) when the viral load was >1000IU/ml. Abbott compared well with the in-house assay with sensitivity of 97.5% (95% CI 86.84%-99.94%) and specificity of 100% (95% CI 91.19%-100%). CONCLUSIONS: The Abbott system is an automated platform which can be used for DBS HCV RNA extraction and amplification. The preliminary data presented here showed a high sensitivity and specificity for DBS with viral loads greater than 1000IU/ml and compared well with a published in-house method.