CpG oligodinucleotides induce strong humoral and cellular responses to swine streptococcic septicemia vaccine in piglets in vivo

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, but data on humoral and cellular immune responses in piglets are scarce. In this report, using the swine streptococcus as model bacteria, CpG ODN was used as immunoadjuvants to enhance the immune responses of the piglets to swine streptococcic septicemia killed vaccine (SSSK vaccine). The titre of specific antibodies to SSSK vaccine, the proliferation of lymphocytes, SSSK-specific interferon-gamma(IFN-gamma) and IL-6, the expression of major histocompatibility complex class II (MHC-II) and CD14 of peripheral blood mononuclear cells (PBMCs) were examined to identify the immune responses of the piglets. The results were found that the above-mentioned immune responses of the piglets with CpG ODN were significantly stronger than standard immunization protocols. All these data suggested that immunostimulatory CpG ODN was promising immune enhancers for vaccination against SSSK vaccine.