title: Development of an avidity assay for detection of recent HIV infections.
abstract: HIV avidity can measure the incidence of recent infections within the population. The aim of this study was to evaluate an HIV avidity assay, initially from a clinically defined group of patients and then apply the assay to a prospective study to determine the false recency rate and mean duration of recency for the assay. The assay is a commercial ELISA modified with 7 M urea. The validation of the assay used plasma from patients split into Group 1 (recently infected N=25) and group 2 (established infection N=301). The prospective study tested 178 newly diagnosed HIV patients for avidity. A total of 326 retrospective samples of known HIV status were collected and tested. The initial evaluation gave a sensitivity 100% (CI 86.16-100%) and specificity of 98.65% (95% CI 97.05-99.78%). The prospective study incorporating 178 newly diagnosed patients found 22 patients with low avidity. Follow-up samples obtained from low avidity patients determined the estimated mean duration of recency to be between 3 and 4 months with a false recency rate of 0.89% (CI: 0.24-2.3%). The assay described here compares well in sensitivity, specificity and false recency rate with that of other published avidity assays.
authors.affiliation: West of Scotland Specialist Virology Centre, Level 5, New Lister Building, Glasgow Royal Infirmary, 10-16 Alexandra Parade, Glasgow G31 2ER, United Kingdom. Electronic address: Samantha.Shepherd@ggc.scot.nhs.uk.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Shepherd
authors.affiliation: Edinburgh Specialist Virology Centre, Royal Infirmary Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, United Kingdom.
authors.forename: Georgina
authors.initials: G
authors.lastname: McAllister
authors.affiliation: West of Scotland Specialist Virology Centre, Level 5, New Lister Building, Glasgow Royal Infirmary, 10-16 Alexandra Parade, Glasgow G31 2ER, United Kingdom.
authors.forename: Joy
authors.initials: J
authors.lastname: Kean
authors.affiliation: Health Protection Scotland, NHS National Services Scotland, Meridian Court, 5 Cadogan Street, Glasgow, United Kingdom.
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Wallace
authors.affiliation: Edinburgh Specialist Virology Centre, Royal Infirmary Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, United Kingdom.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Templeton
authors.affiliation: Health Protection Scotland, NHS National Services Scotland, Meridian Court, 5 Cadogan Street, Glasgow, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Goldberg
authors.affiliation: West of Scotland Specialist Virology Centre, Level 5, New Lister Building, Glasgow Royal Infirmary, 10-16 Alexandra Parade, Glasgow G31 2ER, United Kingdom.
authors.forename: Rory N
authors.initials: RN
authors.lastname: Gunson
authors.affiliation: West of Scotland Specialist Virology Centre, Level 5, New Lister Building, Glasgow Royal Infirmary, 10-16 Alexandra Parade, Glasgow G31 2ER, United Kingdom.
authors.forename: Celia
authors.initials: C
authors.lastname: Aitken
mesh_terms: D000915:Antibody Affinity; D003951:Diagnostic Errors; D003955:Diagnostic Tests, Routine / Q000379:methods*; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D007118:Immunoassay / Q000379:methods; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015483:HIV Antibodies
keywords: Avidity; ELISA; HIV; Incidence; Recent; Urea