title: Importance of the cutoff ratio for detecting antibodies against hepatitis A virus in oral fluids by enzyme immunoassay.
abstract: Multiple studies have examined the use of oral fluids in modified serum-based assays aiming to replace serum in antibody detection for hepatitis A. However, the reliable detection of HAV immunity in oral fluid requires an extremely sensitive assay; most immunoassays designed for serum antibody determination lack sufficient sensitivity for this purpose. Consequently, an "in-house" competitive enzyme immunoassay (EIA) designed specifically for use with oral samples collected using a ChemBio(®) device was developed to detect total anti-HAV antibodies (IgG and IgM). This system was compared to an in-house competitive EIA and a commercial EIA considered to be the "gold standard" using corresponding serum samples (n=225) to determine the accuracy of the assay and to evaluate the importance of the cutoff ratio for the detection of anti-HAV antibodies in oral fluids. When the median serum cutoff and the optimal oral fluid cutoff (ROC analysis) obtained from the in-house competitive EIA were compared, the oral fluid cutoff was found to be 28.8% higher than the serum cutoff. When different oral fluid cutoff values were compared, a reduction of about 17% was shown to be essential to increase test accuracy. At an oral fluid cutoff value of 0.351, sensitivity and specificity were higher, reaching 91.7% and 86.2% (p<0.001, AUROC=0.915), respectively. The convenience, accuracy and non-invasive nature of the developed method make it a useful alternative to serum-based assays for discriminating between HAV-immune and non-immune individuals.
authors.affiliation: Laboratório de Desenvolvimento Tecnológico em Virologia, Instituto Oswaldo Cruz - FIOCRUZ, Cx Postal 926, Av. Brasil 4365, CEP: 21360-040, Rio de Janeiro, RJ, Brazil. renatats@ioc.fiocruz.br
authors.forename: Renata Santos
authors.initials: RS
authors.lastname: Tourinho
authors.forename: Luciane Almeida
authors.initials: LA
authors.lastname: Amado
authors.forename: Livia Melo
authors.initials: LM
authors.lastname: Villar
authors.forename: Daniela Vieira
authors.initials: DV
authors.lastname: Sampaio
authors.forename: Alyne Costa
authors.initials: AC
authors.lastname: Moraes
authors.forename: Kicia Maria
authors.initials: KM
authors.lastname: Rodrigues do Ó
authors.forename: Ana Maria Coimbra
authors.initials: AM
authors.lastname: Gaspar
authors.forename: Vanessa Salete
authors.initials: VS
authors.lastname: de Paula
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D006506:Hepatitis A / Q000175:diagnosis*; D035922:Hepatitis A Antibodies / Q000032:analysis*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000276:immunology*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M