Assessment of Recent HIV-1 Infection by a Line Immunoassay for HIV-1/2 Confirmation

Abstract

BackgroundKnowledge of the number of recent HIV infections is important for epidemiologic surveillance. Over the past decade approaches have been developed to estimate this number by testing HIV-seropositive specimens with assays that discriminate the lower concentration and avidity of HIV antibodies in early infection. We have investigated whether this “recency” information can also be gained from an HIV confirmatory assay.Methods and FindingsThe ability of a line immunoassay (INNO-LIA HIV I/II Score, Innogenetics) to distinguish recent from older HIV-1 infection was evaluated in comparison with the Calypte HIV-1 BED Incidence enzyme immunoassay (BED-EIA). Both tests were conducted prospectively in all HIV infections newly diagnosed in Switzerland from July 2005 to June 2006. Clinical and laboratory information indicative of recent or older infection was obtained from physicians at the time of HIV diagnosis and used as the reference standard. BED-EIA and various recency algorithms utilizing the antibody reaction to INNO-LIA's five HIV-1 antigen bands were evaluated by logistic regression analysis. A total of 765 HIV-1 infections, 748 (97.8%) with complete test results, were newly diagnosed during the study. A negative or indeterminate HIV antibody assay at diagnosis, symptoms of primary HIV infection, or a negative HIV test during the past 12 mo classified 195 infections (26.1%) as recent (≤ 12 mo). Symptoms of CDC stages B or C classified 161 infections as older (21.5%), and 392 patients with no symptoms remained unclassified. BED-EIA ruled 65% of the 195 recent infections as recent and 80% of the 161 older infections as older. Two INNO-LIA algorithms showed 50% and 40% sensitivity combined with 95% and 99% specificity, respectively. Estimation of recent infection in the entire study population, based on actual results of the three tests and adjusted for a test's sensitivity and specificity, yielded 37% for BED-EIA compared to 35% and 33% for the two INNO-LIA algorithms. Window-based estimation with BED-EIA yielded 41% (95% confidence interval 36%–46%).ConclusionsRecency information can be extracted from INNO-LIA-based confirmatory testing at no additional costs. This method should improve epidemiologic surveillance in countries that routinely use INNO-LIA for HIV confirmation.

Decreased Specificity of an Assay for Recent Infection in HIV-1-Infected Patients on Highly Active Antiretroviral Treatment: Implications for Incidence Estimates

“…The concept of immunoassays for recent infections, named serological testing algorithm for recent HIV seroconversion (STARHS), was introduced more than 10 years ago by Janssen et al (9) and, since then, has been considered a major tool allowing the estimation of HIV incidence in cross-sectional studies (for recent reviews, see references 4, 6, and 16). Although several technical approaches have been used, the shared rationale for recent infection testing algorithms (RITA) is to discriminate recent from long-standing infections based on maturation of HIV-specific antibody responses, predominantly using the measurement of antibody levels or antibody avidity toward major antigenic proteins or epitopes of HIV-1 (2,9,18,20,24,28,31). Several limitations of the RITA have been reported regularly, and there have been debates about their real validity and, hence, their value for incidence measurements (6).…”

Estimates of HIV-1 incidence based on serological methods: a brief methodological review

“…16 , including additional data from Bush et al 12 , Chawla et al 34 , Barrin et al 38 and Schüpbach et al 41 . of the HIV infection over time paved the way for all subsequent assessments of HIV incidence based on cross-sectional studies, always profiting from the fact that incidence can be approximately deduced from available data on prevalence and the duration of a given infection (or non-transmissible medical condition).…”

“…More recently, the ability of an HIV confirmatory line immunoassay (INNO-LIA HIVI/II) was tested to distinguish recent from long-term HIV infection 41 . The authors evaluated the performance of various algorithms for detecting recent infections, based on reactivity, and classified them into one of six possible intensity scores of reaction to five HIV antigens measured in the western blot.…”

An old enzyme for current needs: adenosine deaminase and a dendritic cell vaccine for HIV

“…The national epidemiological picture developed by CDC included the first-ever estimates of incident infections by race/ethnicity, age, gender and mode of transmission. In recent years, epidemiologists have applied various laboratory tests to estimate HIV incidence in testing facility settings (Schüpbach et al, 2007;Suligoi et al, 2007).…”