title: Prevalence and incidence estimation of HSV-2 by two IgG ELISA methods among South African women at high risk of HIV.
abstract: BACKGROUND
  Previous comparison studies of the Kalon and HerpeSelect 2 ELISA IgG assays on sub-Saharan samples have found differences in the sensitivity and specificity of these assays. Using longitudinal samples from an HIV prevention study, we compared both assays and determined the HSV-2 prevalence and incidence in a South African young female population at elevated risk of acquiring HIV.
  
  
  METHODS
  Samples at baseline were tested in both assays using the manufacturers' guidelines (cut-off > 1.10). When non-reactive in one assay, the final visit samples were tested to determine the incidence rate. Using correlation and regression analyses, the intra- and inter-assay variabilities were assessed.
  
  
  RESULTS
  The prevalence rate was 41.1% and 44.9% for Kalon and HerpeSelect using the manufacturer guidelines, respectively. Agreement between the two tests were high (kappa = 0.92). The original optical density values of both assays were highly correlated (R = 0.94), but the calibrator and correspondingly cut-off index values differed between the assays. Lowering the index value cut-off for the Kalon assay by 40% (to 0.66) resulted in a HSV-2 prevalence of 43.2%, and increased agreement between the assays (to kappa = 0.96). The incidence rate was 16.3/100 Person Years using the lower cut-off for the Kalon assay.
  
  
  CONCLUSIONS
  In this longitudinal study, we showed that the performance of the two assays was very similar. After lowering the cut-off for the Kalon assay to 0.66 early infections were detected without impairing its specificity. The prevalence and incidence rates are in line with previously described rates for sub-Saharan African cohorts.
authors: Institute of Tropical Medicine, Antwerp, Belgium.
authors: Irith
authors: I
authors: De Baetselier
authors: Institute of Tropical Medicine, Antwerp, Belgium.
authors: Joris
authors: J
authors: Menten
authors: Institute of Tropical Medicine, Antwerp, Belgium.
authors: Vicky
authors: V
authors: Cuylaerts
authors: Setshaba Research Center, Soshanguve, Pretoria, South Africa.
authors: Khatija
authors: K
authors: Ahmed
authors: FHI-360, Durham, North Carolina, United States of America.
authors: Jennifer
authors: J
authors: Deese
authors: FHI-360, Durham, North Carolina, United States of America; Bill and Melinda Gates Foundation, Seattle, Washington, United States of America.
authors: Lut
authors: L
authors: Van Damme
authors: Institute of Tropical Medicine, Antwerp, Belgium.
authors: Tania
authors: T
authors: Crucitti
mesh_terms: D060085:Coinfection / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000150:complications; D006558:Herpes Genitalis / Q000150:complications / Q000453:epidemiology* / Q000821:virology*; D018258:Herpesvirus 2, Human / Q000302:isolation & purification* / Q000502:physiology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D015994:Incidence; D008137:Longitudinal Studies; D015995:Prevalence; D012189:Retrospective Studies; D012306:Risk; D013019:South Africa / Q000453:epidemiology
chemical_list: D007074:Immunoglobulin G