| Nucleic acid vaccine (NAV), uses expression vectors encoding one or more antigen genes to transfect host cells, inducing both humoral and cellular immunity against the target antigen. Because the bacterial plasmid DNA backbone of NAVs, specifically the unmethylated CpG dinucleotides, has immune stimulatory function and NAVs are derived from bacteria, the use of NAVs also has the potential to eliminate the use of harmful adjuvants. Thus, bacterial-like CpG oligodeoxynucleotides (ODNs) can also serve as adjuvant for protein vaccines. The aim of this study is to examine NAVs and CpG ODN's protective role against both viral and bacterial infection.; This study shows that a plasmid DNA (pGT36VP1) encoding the full length VP1 region of canine parvovirus (CPV) induces immunity that protects dogs against challenge with virulent virus. All results showed that pGT36VP1 can generate protective anti-CPV IgG antibody titers in dogs. The addition of E. coli DNA resulted in a more rapid and more consistent antibody response compared to dogs receiving the same dose of pGT36VP1 alone, suggesting a possible role for unmethylated CpG as an adjuvant. A single dose of pGT36VP1 was also protective, even when anti-CPV IgG antibody was not detectable, suggesting a possible functional cell mediated immune response. Doses of pGT36VP1 as low as 200 μg may protect dogs against CPV challenge.; Most infections originate at the mucosal site, and mucosal immunity generally requires vaccination at the mucosal site. Systemic injection of NAVs expressing Helicobacter pylori (H. pylori) genes failed to induce serum antibody responses. Thus, CpG ODN was used to examine its adjuvant activity in protein vaccination and more importantly protection. Mucosal administration of CpG ODN with whole lysate can induce mucosal and systemic immune responses. The combination of CpG and cholera toxin (CT) induced an even better immune response than either one alone. Intranasal (i.n.) immunization generated a better mucosal response than intragastric (i.g.) immunization, suggesting the nasal mucosal site is a better immune induction site. In this study, a powerful and precise SYBR Green® quantitative PCR, was used to measure H. felis colonization in mouse stomach. Immunization of whole lysate with CpG adjuvant alone showed no significant decrease of colonization when compared to unimmunized-challenged control mice. The combination of CpG ODN and CT adjuvants with antigen decreased H. felis colonization levels to background levels. This suggested that the mucosal immune response induced by CpG ODN in this study was not effective in preventing H. felis colonization; however, CpG ODN in combination with CT may provide “sterile immunity” against Helicobacter. |
