Development of antibody ELISA specific of Leptospira interrogans serovar Grippotyphosa, Canicola, and Icterohaemorrhagiae to monitor vaccine immunogenicity.

The antibody response after primary vaccination and annual revaccination with a multivalent DAPPi-L vaccine was assessed respectively in SPF dogs and in client owned dogs against the Grippotyphosa (Lg), Canicola (Lc) and Icterohaemorrhagiae (Li) Leptospira serovars. To overcome limitations of the microscopic agglutination test (MAT), we developed serovar-specific and sensitive blocking ELISA assays. Serovar-specific antibodies against Lg, Lc and Li were detected in 100%, 45% and 91% of dogs, respectively, after the first dose of vaccine, and in 100% of dogs for all serovars after the second dose. In addition, mean ELISA antibody titers increased 14 days after annual revaccination with most dogs remaining ELISA antibody positive against Lg (85.3%), Lc (90%) and Li (100%). Parallel testing of sera from the annual revaccination study in the MAT and ELISA assays resulted in an overall agreement of 72%, 67%, 77% of samples for Lg, Lc and Li serovars, respectively. More sera tested positive by ELISA than by MAT, suggesting that the ELISA assay is more sensitive than the MAT. These three new antibody-based assays are the first suitable and reliable ELISA assays for the assessment of the canine antibody response following vaccination and an attractive alternative to the MAT.