Recombinant antigens rLipL21, rLoa22, rLipL32 and rLigACon4-8 for serological diagnosis of leptospirosis by enzyme-linked immunosorbent assays in dogs.

Animal leptospirosis is one of the most common zoonotic diseases in the United States and around the world. In a previous study, we applied four recombinant antigens, rLipL21, rLoa22, rLipL32 and rLigACon4-8 of Leptospira interrogans (L. interrogans) for the serological diagnosis of equine leptospirosis (Ye et al, Serodiagnosis of equine leptospirosis by ELISA using four recombinant protein markers, Clin. Vaccine. Immunol. 21:478-483). In this study, the same four recombinant antigens were evaluated for their potential to diagnose canine leptospirosis by ELISA. A total of 305 canine sera that were Leptospira microscopic agglutination test (MAT)-negative (n = 102) and MAT-positive (n = 203) to 5 serovars (Pomona, Grippotyphosa, Icterohaemorrhagiae, Canicola and Hardjo) were tested. When individual recombinant antigens were used, the sensitivity and specificity of ELISA were 97.5% and 84.3% for rLigACon4-8; 89.7% and 81.4% for rLoa22; 92.6% and 84.3% for rLipL32 and 99.5% and 84.3% for rLipL21, respectively compared to the MAT. The sensitivity and specificity of ELISA were, 92.6% and 91.2% for rLigACon4-8 and rLipL32, 97.5% and 84.3% for rLigACon4-8 and rLipL21, 89.7% and 87.3% for rLigACon4-8 and rLoa22, 89.7% and 87.3% to rLipL21 and rLoa22, 92.6% and 91.2% for rLipL21 and rLipL32 and 89.2% and 94.1% for rLoa22 and rLipL32 when one of the two antigens was test positive. The use of all four antigens in the ELISA assay was found to be sensitive and specific, easy to perform, and agreed with the results of the standard Leptospira Microscopic Agglutination test (MAT) for the diagnosis of canine leptospirosis.