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. OBJECTIVES: A HCV avidity assay was evaluated for both plasma and DBS. 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. RESULTS: The avidity assay cut-off was set at AI≤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 < 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. CONCLUSION: The HCV avidity assay can be used to distinguish between chronic and recent infection using either plasma or DBS as the sample type.
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. OBJECTIVES: A HCV avidity assay was evaluated for both plasma and DBS. 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. RESULTS: The avidity assay cut-off was set at AI≤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 < 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. CONCLUSION: The HCV avidity assay can be used to distinguish between chronic and recent infection using either plasma or DBS as the sample type.
Authors: Eshan U Patel; Andrea L Cox; Shruti H Mehta; Denali Boon; Caroline E Mullis; Jacquie Astemborski; William O Osburn; Jeffrey Quinn; Andrew D Redd; Gregory D Kirk; David L Thomas; Thomas C Quinn; Oliver Laeyendecker Journal: J Infect Dis Date: 2016-01-14 Impact factor: 5.226
Authors: L Leon; S Kasereka; F Barin; C Larsen; L Weill-Barillet; X Pascal; S Chevaliez; J Pillonel; M Jauffret-Roustide; Y LE Strat Journal: Epidemiol Infect Date: 2016-12-22 Impact factor: 4.434
Authors: Hong-Van Tieu; Oliver Laeyendecker; Vijay Nandi; Rebecca Rose; Reinaldo Fernandez; Briana Lynch; Donald R Hoover; Victoria Frye; Beryl A Koblin Journal: PLoS One Date: 2018-07-18 Impact factor: 3.240