The efficacy of CpG oligodinucleotides, in combination with conventional adjuvants, as immunological adjuvants to swine streptococcic septicemia vaccine in piglets in vivo.

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, the immunostimulatory effects of CpG in combination with aluminum hydroxide (alum) or Emulsigen (Em) were investigated in cattle, rabbits or mice, but not piglets. In this report, using the swine streptococcus as model bacteria, the efficacy of CpG ODN as an adjuvant for piglets was assessed alone and in combination with alum (CpG/alum) or Em (CpG/Em). The CpG/alum or CpG/Em combination elicited greater immune responses to swine streptococcic septicemia killed vaccine (SSSK vaccine) compared with CpG alone, or alum or Em. A GpC/alum or GpC/Em combination did not have the same effects as CpG/alum or CpG/Em suggesting that the adjuvanticity was related to the CpG motifs. In addition, we also found that the 10% Em in combination with CpG ODN had similar immunological effects as 30% Em combination. Our results demonstrate that the addition of CpG ODN to alum or to Em significantly improves the efficiency of the adjuvants in piglets.