Immune Response of Horses to Inactivated African Horse Sickness Vaccines Using Different Adjuvants

Abstract

Six groups, each comprising 10 African horse sickness (AHS) naïve horses were immunized with an inactivated AHS vaccine named “Duequivac” containing all nine AHS serotypes combined with either of four different experimental adjuvants. The serum antibody levels after each immunization as assessed by ELISA, were compared with the results achieved with Imject Alum which is commonly used as an adjuvant in equine vaccines. The vaccine Duequivac vaccine was well tolerated with only minor local injection site reactions in some horses. None of the four adjuvants performed better than Imject Alum with the antibody level after a primary and booster immunization, as serum anti-AHS antibody titers receded rapidly after 108 days of booster immunization and became undetectable between 141 and 170 days. In conclusion, Imject Alum was a superior adjuvant compared to 4 different adjuvants as its serum anti-AHS antibody titers remained high at least for 1 year.