Potency and Efficacy of a Novel Leptospira Vaccine in Pregnant Mares

The aim of the proposed research is·to evaluate the ability of a novel vaccine to protect pregnant mares against experimental challenge with Leptospira interrogans serovar Pomona type kennewicki (Lk) the most frequently encountered cause ofleptospira abortion in 'Kentucky. The vaccine is novel because it will contain three leptospira proteins produced only during infection of the horse and therefore missing from commercial vaccines prepared from cultured leptospira. These proteins will be produced by recombinant DNA technology in the Gluck Center and combined with heat inactivated Lk from a case of equine abortion and with QuilA as adjuvant to enhance immune responsiveness. The vaccine will be tested in late stage pregnant mares for safety and immunogenicity. Given expected proof of safety and potency, efficacy of the vaccine will be tested in Spring 2014 by challenging groups of vaccinated and non-vaccinated mares with intravenously inoculated Lk. Quantitative PCR will be performed on blood samples to evaluate growth of the inoculated leptospira in the bloodstream. Abortion rates in vaccinates and control mares will be compared. An effective vaccine will prevent leptospiremia, placental damage and abortion.