A hepatitis C avidity test for determining recent and past infections in both plasma and dried blood spots

作者：Shepherd Samantha J^*; Kean Joy; Hutchinson Sharon J; Cameron Sheila O; Goldberg David J; Carman William F; Gunson Rory N; Aitken Celia

来源：Journal of Clinical Virology, 2013, 57(1): 29-35.

DOI：10.1016/j.jcv.2013.01.002

• Avidity
• HCV
• DBS
• Recent
• Chronic
• Resolved

Background: DBS testing has been used successfully to detect HCV antibody positive individuals. Determining how long someone has been infected is important for surveillance initiatives. Antibody avidity is a method that can be used to calculate recency of infection. %26lt;br%26gt;Objectives: A HCV avidity assay was evaluated for both plasma and DBS. %26lt;br%26gt;Study design: To measure antibody avidity a commercial HCV ELISA was modified using 7 M urea. The plasma samples were split into: group 1 (recently infected N = 19), group 2 (chronic carrier N = 300) and group 3 (resolved infection N = 82). Mock DBS made from group 1 (N = 12), group 2 (N = 50), group 3 (N = 25) and two seroconverter panels were evaluated. 133 DBS taken from patients known to have a resolved infection or be a chronic carrier were also tested. %26lt;br%26gt;Results: The avidity assay cut-off was set at AI %26lt;= 30 for a recent infection. Using sequential samples the assay could detect a recent infection in the first 4-5 months from the point of infection. Most of the false positive results (AI %26lt;= 30 among cases known not to have had recent infection) were detected among known resolved infections, in both the plasma and DBS; as a result, a testing algorithm has been designed incorporating both PCR and two dilution factors. The sensitivity and specificity of the assay on plasma was 100% and 99.3%, respectively, while DBS had 100% sensitivity and 98.3% specificity. %26lt;br%26gt;Conclusion: The HCV avidity assay can be used to distinguish between chronic and recent infection using either plasma or DBS as the sample type.

• 出版日期2013-5