Abstract

This study was conducted to evaluate the immunogenicity and protective efficacy of a DNA vaccine encoding Brucella abortus Cu,Zn superoxide dismutase (SOD) using the Toll-like receptor 2/6 agonist S-[2,3-bispalmitoyiloxy-(2R)-propyl]-R-cysteinyl-amido-monomethoxy polyethylene glycol (BPPcysMPEG) as an adjuvant. Intranasal coadministration of BPPcysMPEG with a plasmid carrying the SOD-encoding gene (pcDNA-SOD) into BALB/c mice elicited antigen-specific humoral and cellular immune responses. Humoral responses were characterized by the stimulation of IgG2a and IgG1 and by the presence of SOD-specific secretory IgA in nasal and bronchoalveolar lavage fluids. Furthermore, T-cell proliferative responses and increased production of gamma interferon were also observed upon splenocyte restimulation with recombinant SOD. Cytotoxic responses were also stimulated, as demonstrated by the lysis of RB51-SOD-infected J774. A1 macrophages by cells recovered from immunized mice. The pcDNA-SOD/BPPcysMPEG formulation induced improved protection against challenge with the virulent strain B. abortus 2308 in BALB/c mice over that provided by pcDNA-SOD, suggesting the potential of this vaccination strategy against Brucella infection.