Evaluation of Poly(I:C) and combination of CpG ODN plus Montanide ISA adjuvants to enhance the efficacy of outer membrane vesicles as an acellular vaccine against Brucella melitensis infection in mice

•The OMVs vaccine in both adjuvant formulations induces vigorous humoral and Th1-biased cellular responses.•OMVs in both adjuvant formulations confer protection levels higher than REV.1 live vaccine against B. melitensis infection.•OMVs in CpG ODN 1826+ Montanide ISA 70VG adjuvants elicits higher protective immunity than OMVs in Poly(I:C).