Antibody responses induced by Leish-Tec®, an A2-basedvaccine for visceral leishmaniasis, in a heterogeneous caninepopulation.

Abstract

Zoonotic visceral leishmaniasis (VL) is a widespread disease, and dogs are the main reser-voirs for human parasite transmission. Hence, development of an effective vaccine thatprevents disease and reduces the transmission of VL is required. As euthanasia of seropos-itive dogs is recommended in Brazil for VL epidemiological control, to include anti-VLcanine vaccines as a mass control measure it is necessary to characterize the humoralresponses induced by vaccination and if they interfere with the reactivity of vaccinateddogs in serological diagnostic tests. Leish-Tec®is an amastigote-specific A2 recombinantprotein vaccine against canine visceral leishmaniasis (CVL) that is commercially availablein Brazil. Here, we tested the immunogenicity of Leish-Tec®in a heterogeneous dog popula-tion by measuring A2-specific antibody responses. Healthy dogs (n = 140) of various breedswere allocated to two groups: one group received Leish-Tec®(n = 70), and the other groupreceived a placebo (n = 70). Anti-A2 or anti-Leishmania promastigote antigen (LPA) antibodylevels were measured by ELISA in serum samples collected before and after vaccination.An immunochromatographic test (DPP) based on the recombinant K28 antigen was alsoused for serodiagnosis of CVL. Vaccinated animals, except one, remained seronegative foranti-LPA total IgG and anti-K28 antibodies. Conversely, seropositivity for anti-A2 total IgGantibodies was found in 98% of animals after vaccination. This value decreased to 81.13% at6 months before rising again (98%), after the vaccination boost. Anti-A2 IgG2 and IgG1 titers.