A novel Schmallenberg virus subunit vaccine candidate protects IFNAR-/- mice against virulent SBV challenge

9 Pág.Schmallenberg virus (SBV), an arthropod-transmitted pathogenic bunyavirus, continues to be a threat to the European livestock industry, causing morbidity and mortality among young ruminant livestock. Here, we describe a novel SBV subunit vaccine, based on bacterially expressed SBV nucleoprotein (SBV-N) administered with a veterinary-grade Saponin adjuvant. When assayed in an IFNAR-/- mouse model, SBV-N with Saponin induced strong non-neutralizing broadly virus-reactive antibodies, decreased clinical signs, as well as significantly reduced viremia. Vaccination assays also suggest that this level of immune protection is cell mediated, as evidenced by the lack of neutralizing antibodies, as well as interferon-γ secretion observed in vitro. Therefore, based on these results, bacterially expressed SBV-N, co-administered with veterinary-grade Saponin adjuvant may serve as a promising economical alternative to current SBV vaccines, and warrant further evaluation in large ruminant animal models. Moreover, we propose that this strategy may be applicable to other bunyaviruses.This work was supported by the Marie Sklodowska Curie Actions programme number MSCAIF-EF-ST-660155 (H.B. and N.G.A.A.), the Spanish Ministerio de Ciencia, Innovación y Universidades RTI2018-095700-B-I00 (N.G.A.A.), AGL2017-83226R (A.B.), the Basque Departamento de Desarrollo Económico e Infraestructura 37-2017-00036 (N.G.A.A.) and “La Caixa” Foundation (ID 100010434) INPhINIT “La Caixa” fellowship LCF/BQ/DI19/11730041 (G.S.G. and N.G.A.A.). MICINN is also thanked for the Severo Ochoa Excellence Accreditation to the CIC bioGUNE (SEV-2016-0644).Peer reviewe