title: Accuracy assessment and screening of a dairy herd with paratuberculosis by three different ELISAs.
abstract: Although the culture of Mycobacterium avium subsp. paratuberculosisis is the gold standard for the diagnosis of paratuberculosis, this bacterium is difficult to grow. In contrast, serological tests like ELISAs are inexpensive, rapid, and easy to perform. The aims of this study were to evaluate the accuracy of three different ELISAs: one with the commercial antigen PPA-3, another one with L5P (a recently described lipopentapeptide), and a third one with an in-house antigen whole cell lysates (WCL) of M. avium (MAA) strain D4ER (Study 1), and to compare them with other tests for paratuberculosis (PTB) diagnosis (Study 2). In Study 1, the sensitivities of the three ELISAs tested were 74.1%, 37% and 74.1%, respectively, whereas their specificities were 98.9%, 100% and 100%, respectively. In Study 2, we compared the three above-mentioned ELISAs with the intradermal reaction test using Avian PPD (PPDa) and fecal culture associated with Ziehl-Neelsen stain and PCR tests, in a dairy herd with 4.6% of cows with clinical signs of PTB. The results showed that fecal samples from 14 cows (16%) were culture-positive and that fecal samples from nine cows (10%) were PPDa-positive. Most of these animals (culture-positive and PPDa-positive) were detected as positive with any of the three ELISAs tested. Serological results showed that 31% of the animals were positive to ELISA-PPA-3, 17% to ELISA-L5P and 42.5% to ELISA-WCL. The combination of these three ELISAs identified 50.6% of the animals as positive in the infected herd. In particular, the results show that the locally developed ELISA seems to be useful for identifying many infected animals in a herd.
authors.affiliation: Instituto de Biotecnología, Centro de Investigaciones Veterinarias y Agronómicas (CICVyA), Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Buenos Aires, Argentina.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Costanzo
authors.forename: Fiorella Alvarado
authors.initials: FA
authors.lastname: Pinedo
authors.forename: María Laura
authors.initials: ML
authors.lastname: Mon
authors.forename: Mariana
authors.initials: M
authors.lastname: Viale
authors.forename: Andrés
authors.initials: A
authors.lastname: Gil
authors.forename: Mariano Carrica
authors.initials: MC
authors.lastname: Illia
authors.forename: Andrea
authors.initials: A
authors.lastname: Gioffré
authors.forename: Alicia
authors.initials: A
authors.lastname: Arese
authors.forename: Gabriel
authors.initials: G
authors.lastname: Travería
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Romano
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000379:methods* / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D005260:Female; D016927:Mycobacterium avium subsp. paratuberculosis / Q000235:genetics / Q000276:immunology; D010283:Paratuberculosis / Q000175:diagnosis* / Q000382:microbiology; D011897:Random Allocation; D012680:Sensitivity and Specificity