Abstract
As an alternative brucellosis prevention method, we evaluated the immunogenicity induced by new multivalent DNA vaccines in BALB/c mice. We constructed the vaccines by fusion of BAB1_0273 and/or BAB1_0278 open reading frames (ORFs) from genomic island 3 (GI-3) and the Brucella abortus 2308 sodC gene with a link based on prolines and alanines (pV273-sod, pV278-sod, and pV273-278-sod, resp.). Results show that immunization with all tested multivalent DNA vaccines induced a specific humoral and cellular immune response. These novel multivalent vaccines significantly increased the production of IgM, IgG, and IgG2a antibodies as well as IFN-γ levels and the lymphoproliferative response of splenocytes. Although immunization with these multivalent vaccines induced a typical T-helper 1- (Th1-) dominated immune response, such immunogenicity conferred low protection levels in mice challenged with the B. abortus 2308 pathogenic strain. Our results demonstrated that the expression of BAB1_0273 and/or BABl_0278 antigens conjugated to SOD protein can polarize mice immunity to a Th1-type phenotype, conferring low levels of protection.
Highlights
Brucella spp. cause brucellosis, a globally distributed zoonosis infecting more than half a million people worldwide every year [1]
In order to obtain a safer vaccine against brucellosis, immunization with DNA vectors has been implemented due to their ability to induce the generation of a T-helper 1- (Th1-)type immune response, which is protective against B. abortus [14, 27, 28]
DNA immunization using BAB1 0278 open reading frames (ORFs) [19, 20], immunodominant epitopes of BAB1 0273 ORF [21], and Cu-Zn superoxide dismutase gene [17] appeared to be highly immunogenic and capable of conferring high levels of protection in mice challenged with pathogenic strain B. abortus 2308
Summary
Brucella spp. cause brucellosis, a globally distributed zoonosis infecting more than half a million people worldwide every year [1] This genus is constituted by Gram-negative, coccobacillary, microaerophilic, non-spore-forming, immotile, intracellular facultative, and slow-growing bacteria [2]. Such pathogens are found in a wide range of mammalian hosts, such as B. abortus (bovine), B. melitensis (goats), and B. suis (pigs) which are the most pathogenic species within the genus for humans [2, 3]. This GI in B. abortus 2308 includes the ORF BAB1 0250 to BAB1 0279 and contains 25 genes, many of which have unknown function, and several pseudogenes [11]
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