Multivalent Disabled Infectious Single Animal (DISA)-DIVA vaccine for all nine serotypes of African horse sickness virus (AHSV) is broadly protective in IFNAR (-/-) mice

African horse sickness (AHS) is a highly severe, midge-borne disease of equids showing a mortality rate of > 90% in naive domestic horses. Outbreaks are caused by AHS virus (AHSV) and result in devastating economic losses in developing countries as equids play a crucial role in the agricultural industry and many households. The AHSV species encompasses nine serotypes showing no or limited cross protection, which is challenging regarding AHS vaccine development. Recently, and like bluetongue virus (BTV), the AHS Disabled Infectious Single Animal (DISA)-DIVA vaccine platform was developed and applied for all nine AHSV serotypes. The vaccine platform is based on a single deletion crucial for vaccine safety and affording differentiation of infected from vaccinated individuals (DIVA) testing. Before considering ethically debatable and expensive experiments in equids, DISA-DIVA vaccine candidates were evaluated here in the previously validated IFNAR (-/-) mouse model for AHS. A multivalent AHS DISA-DIVA vaccine containing DISA constructs for each of the nine serotypes was studied. This "DISA cocktail" was safe and protected mice against two virulent AHSV serotypes used in challenge infection studies. DISA multivalent vaccine induced serotype-specific neutralizing antibodies (nAbs) against all AHSV serotypes suggesting broad protection, as correlates of protection (CoP) based on nAb titers for studied serotypes can be extrapolated to others. These results now justify further experiments in horses to study safety, efficacy and DIVA by DISA cocktail vaccine. Importantly, the presented results for IFNAR (-/-) mice indicate that broad protection of equines by vaccination with DISA cocktail vaccine can be feasible.