DNA prime-protein boost increased the titer, avidity and persistence of anti-Abeta antibodies in wild-type mice.

Recently, we reported that a DNA vaccine, composed of three copies of a self B cell epitope of amyloid-beta (Abeta(42)) and the foreign T-cell epitope, Pan DR epitope (PADRE), generated strong anti-Abeta immune responses in wild-type and amyloid precursor protein transgenic animals. Although DNA vaccines have several advantages over peptide-protein vaccines, they induce lower immune responses in large animals and humans compared with those in mice. The focus of this study was to further enhance anti-Abeta(11) immune responses by developing an improved DNA vaccination protocol of the prime-boost regimen, in which the priming step would use DNA and the boosting step would use recombinant protein. Accordingly, we generated DNA and recombinant protein-based epitope vaccines and showed that priming with DNA followed by boosting with a homologous recombinant protein vaccine significantly increases the anti-Abeta antibody responses and do not change the immunoglobulin G1 (IgG1) profile of humoral immune responses. Furthermore, the antibodies generated by this prime-boost regimen were long-lasting and possessed a higher avidity for binding with an Abeta(42) peptide. Thus, we showed that a heterologous prime-boost regimen could be an effective protocol for developing a potent Alzheimer's disease (AD) vaccine.

DNA, but not protein vaccine based on mutated BORIS antigen significantly inhibits tumor growth and prolongs the survival of mice.

The ideal immunological target for cancer vaccine development would meet the criteria of tumor specificity, immunogenicity and vital dependency of the tumor on the functional activities of the antigenic target so as to avoid antigenic loss by mutation. Given that at face value the brother of regulator of imprinted sites (BORIS) transcription factor meets these criteria, we have developed a mutant variant of this molecule (mBORIS) that lacks tumorigenic ability, while retaining immunogenic epitopes that elicits responses against histologically irrelevant tumor cells. Here we compared vaccine strategies employing as an immunogen either mBORIS recombinant protein formulated in a strong Th1-type adjuvant, QuilA or DNA encoding this immunogen along with plasmids expressing interleukin (IL)12/IL18 molecular adjuvants. In both groups of vaccinated mice induction of tumor-specific immunity (antibody response, T-cell proliferation, cytokine production, T-cell cytotoxicity) as well as ability to inhibit growth of the aggressive breast cancer cell line and to prolong survival of vaccinated animals have been tested. We determined that DNA, but not recombinant protein vaccine, induced potent Th1-like T-cell recall responses that significantly inhibited tumor growth and prolongs the survival of vaccinated mice. These studies demonstrate that DNA immunization is superior to recombinant protein strategy and provide a clear guidance for clinical development of a cancer vaccine targeting what appears to be a universal tumor antigen.