Introduction

Canine leishmaniosis is a severe disease affecting dogs especially around the Mediterranean basin. It is transmitted by small biting insects (sandflies) of the Phlebotomus spp. The recent availability in Europe of a vaccine against Leishmania infantum constitutes a new approach in leishmaniosis prevention. However, more information is needed to evaluate the evolution of the immune response after vaccination and to discriminate antibodies induced by vaccination from those due to infection. The aim of this study was to evaluate the humoral immune response following vaccination with IFAT, ELISA and a rapid test.

Material and Methods

Twelve Beagle dogs were included in the study. The dogs were divided into two groups: a control group (n = 2) and a vaccinated group (n = 10) which was given three injections of LiESP/QA-21 (CaniLeish®; Virbac, France), a vaccine composed of purified excreted/secreted proteins (ESP) from Leishmania infantum. Regular serological monitoring was performed for 4 months after vaccination to follow the humoral immune response with an ELISA test to quantify anti-ESP antibodies, an IFAT to detect the evolution of total anti-Leishmania antibody titers, and an immunochromatographic rapid test (Speed Leish K^TM; BVT Groupe Virbac, France), to detect Leishmania-specific anti-kinesin antibodies. Vaccinations and tests were performed in accordance with the manufacturers' instructions.

Results

Before vaccination, whatever the serological method used, no anti-Leishmania antibodies were detected in the 2 groups. In the control group, dogs remained free of anti-Leishmania antibodies throughout the study. In the vaccinated group, dogs seroconverted with anti-ESP antibodies which were detectable by both ELISA and IFAT. The maximum antibody titer was reached 2 weeks after the third vaccine injection. Titers then gradually declined to become negative for almost all dogs after 4 months. Dogs of the vaccinated group remained negative throughout the study with the Leishmania-specific anti-kinesin antibody rapid test.

Conclusion

Antibodies induced by vaccination with LiESP/ QA-21 are detected by IFAT for 4 months after vaccination, but are not detected by the anti-kinesin antibody test. The fact that this rapid diagnostic tool does not detect antibodies induced by vaccination makes it suitable for first-line use in a vaccinated animal with symptoms suggestive of leishmaniosis: a positive result indicates the presence of antibodies due to a contact with the parasite.