Improved HIV-1 incidence estimates using the BED capture enzyme immunoassay

Objective:To validate the BED capture enzyme immunoassay for HIV-1 subtype C and to derive adjustments facilitating estimation of HIV-1 incidence from cross-sectional surveys. Design:Laboratory analysis of archived plasma samples collected in Zimbabwe. Methods:Serial plasma samples from 85 women who seroconverted to HIV-1 during the postpartum year were assayed by BED and used to estimate the window period between seroconversion and the attainment of a specified BED absorbance. HIV-1 incidences for the year prior to recruitment and for the postpartum year were calculated by applying the BED technique to HIV-1-positive samples collected at baseline and at 12 months. Results:The mean window for an absorbance cut-off of 0.8 was 187 days. Among women who were HIV-1 positive at baseline and retested at 12 months, a proportion (ϵ) 5.2% (142/2749) had a BED absorbance < 0.8 at 12 months and were falsely identified as recent seroconverters. Consequently, the estimated BED annual incidence at 12 months postpartum (7.6%) was 2.2 times the contemporary prospective estimate. BED incidence adjusted for ϵ was 3.5% [95% confidence interval (CI), 2.6–4.5], close to the 3.4% estimated prospectively. Adjusted BED incidence at baseline was 6.0% (95% CI, 5.2–6.9) and, like the prospective estimates, declined with maternal age. Unadjusted BED incidence estimates were largely independent of age; the pooled estimate was 58% higher than adjusted incidence. Conclusion:The BED method can be used in an African setting, but further estimates of ϵ and of the window period are required, using large samples in a variety of circumstances, before its general utility can be gauged.

[1]  B. Branson,et al.  Comparison of HIV type 1 incidence observed during longitudinal follow-up with incidence estimated by cross-sectional analysis using the BED capture enzyme immunoassay. , 2006, AIDS research and human retroviruses.

[2]  L. Moulton,et al.  Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival , 2005, AIDS.

[3]  R. Byers,et al.  Quantitative detection of increasing HIV type 1 antibodies after seroconversion: a simple assay for detecting recent HIV infection and estimating incidence. , 2002, AIDS research and human retroviruses.

[4]  J. Hargrove,et al.  Mortality and Morbidity Among Postpartum HIV-Positive and HIV-Negative Women in Zimbabwe: Risk Factors, Causes, and Impact of Single-Dose Postpartum Vitamin A Supplementation , 2006, Journal of acquired immune deficiency syndromes.

[5]  A. Kamali,et al.  Investigating the utility of the HIV-1 BED capture enzyme immunoassay using cross-sectional and longitudinal seroconverter specimens from Africa , 2007, AIDS.

[6]  J. Hargrove,et al.  HIV incidence among post-partum women in Zimbabwe: risk factors and the effect of vitamin A supplementation , 2006, AIDS.

[7]  N. Sewankambo,et al.  Increased risk of incident HIV during pregnancy in Rakai, Uganda: a prospective study , 2005, The Lancet.

[8]  UNAIDS Reference Group on estimates, modelling and projections--statement on the use of the BED assay for the estimation of HIV-1 incidence for surveillance or epidemic monitoring. , 2006, Releve epidemiologique hebdomadaire.

[9]  J. Mcdougal,et al.  New Approaches For Detecting Recent HIV-1 Infection , 2002 .

[10]  K. Sullivan,et al.  Temporal trends in HIV Type 1 incidence among inner-city childbearing women in Atlanta: use of the IgG-capture BED-enzyme immunoassay. , 2005, AIDS research and human retroviruses.

[11]  A. Puren,et al.  National HIV incidence measures--new insights into the South African epidemic. , 2007, South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde.

[12]  R. Salamon,et al.  Do Tests Devised to Detect Recent HIV-1 Infection Provide Reliable Estimates of Incidence in Africa? , 2007, Journal of acquired immune deficiency syndromes.

[13]  L. Moulton,et al.  Effects of a single large dose of vitamin A, given during the postpartum period to HIV-positive women and their infants, on child HIV infection, HIV-free survival, and mortality. , 2006, The Journal of infectious diseases.

[14]  B. Branson,et al.  Surveillance for HIV-1 incidence using tests for recent infection in resource-constrained countries , 2005, AIDS.