Purpose: To investigate the efficacy of a double DNA vaccine encoding of
Brucella melitensis
omp31
gene and of Escherichia coli eae gene in inducing protective immune response in a mouse model.
Methods: After performing PCR assays and cloning both the eae and omp31 genes, the generated
DNA vaccines were intramuscularly injected into BALB/c mice. Purified proteins and transformed cell
lysates were identified by western blot and sodium dodecyl sulfate-polyacrylamide gel electrophoresis
(SDS-PAGE) and analyzed by enzyme-linked immunosorbent assay (ELISA).
Results: pcDNA3-omp31-eae provokes a significant, high level of protection in BALB/c mice against
challenges with E. coli and B. melitensis. Titers ranging from 90:160 to 2,570:5,110 were detected 60
days after vaccination. Notably, rOmp31 and rEae proteins significantly induced the production of IFN-γ
in cells from pcDNA3-omp31-eae-immunized mice (p < 0.05 in both groups) and only low levels of IL-10
were found in all groups. The lymphocytes from mice immunized with pcDNA3-omp31-eae had an
apparent T cell proliferative response to rOmp31 and rEae proteins (p < 0.01) with a stimulation index of
14.90.
Conclusion: The novel pcDNA3-omp31-eae construct can be used as a DNA vaccine to prevent E. coli
and B. melitensis infections in future studies.
