A Bacterial Glycoengineered Antigen for Improved Serodiagnosis of Porcine Brucellosis

MARÍA EUGENIA CORTINA; BALZANO PARODI R.; REY SERANTES D.A.; CAILLAVA AJ; ELENA S.; SÁ M I; NICOLA A.M.; FELDMAN M. F.; JUAN E. UGALDE; CIOCCHINI A. E.; COMERCI D. J

Chicago

Conferencia; 68th Annual Brucellosis Research Conference; 2015

Brucellosis International Research Association

Brucella suis is the etiological agent of porcine brucellosis and one of the major human brucellosis pathogens together with B. melitensis and B. abortus. In the absence of an affective porcine brucellosis vaccine, control of the disease in pigs depends exclusively on detection of infected animals and slaughter. Diagnosis of the disease based only on Brucella isolation presents many limitations and serology is the most cost effective means of detecting brucellosis. Infection with smooth Brucella strains leads to the induction of high antibody titres against the immunodominant O-polysaccharide section of sLPS. Additionally, it has been widely demonstrated that serological assays based on the detection of such antibodies are the most sensitive tests for diagnosis of brucellosis. Our group have developed a recombinant glycoprotein called Oag-AcrA composed of the N-formylperosamine O-polysaccharide present in smooth brucelae species, linked to an acceptor protein (AcrA). The recombinant OAg-AcrA antigen demonstrated an excellent diagnostic performance for the diagnosis of bovine and humans brucellosis caused by B. abortus, B. melitensis and B. suis. For that reason, we decided to evaluate this antigen for the diagnosis of porcine brucellosis. An indirect immunoassay based on the detection of anti O-polysaccharide IgG antibodies was developed coupling OAg-AcrA to ELISA plates (Glyco-iELISA). To validate the assay, more than 560 serum samples obtained from experimentally infected and immunized pigs as well as naturally infected animals with B. suis biovar 1 and 2 were tested and a receiver-operating characteristic (ROC) analysis was performed. Based on this analysis, the area under the ROC curve for the test was 0.9999 (95% CI, 0.9997?1.000) and the optimum cutoff value was 0.56, which resulted in a diagnostic sensitivity and specificity of 100 and 99.7 %, respectively. A cutoff value of 0.78 resulted in a test sensitivity of 98.4% and a test specificity of 100%. Overall, our results demonstrate that the Glyco-iELISA is highly accurate for diagnosis of porcine brucellosis improving the diagnostic performance of currently serological tests. The recombinant glycoprotein OAg-AcrA can be produce in lager homogenous batches in a standardized way making it an ideal candidate for further validation as a universal antigen for diagnosis of ?smooth? brucellosis.