In vivo effects of oligodeoxynucleotides containing synthetic immunostimulatory motifs in weaned piglets

The innate immunostimulatory effects of CpG ODN have been demonstrated in mouse, monkey, sheep and chicken in some reports. Unfortunately, little work has been carried out with regard to their effects on the innate immune system of weaned piglets. In this study, the proportion of CD4+, CD8+ T lymphocytes subpopulations and interferon-γ (IFN-γ) and IL-4 in serum, proliferation of peripheral blood mononuclear cells (PBMCs) were tested at different time-points. The results suggested that, the CD4+/CD8+ ratio decreased significantly in weaned piglets inoculated with phosphate buffer saline (PBS) alone, however, it was stable in CpG ODN-inoculated piglets. Proliferation of PBMCs and IFN-γ levels of CpG ODN-injected piglets were significantly higher than those of PBS-injected piglets. The ODN-induced responses were stronger in animals injected with CpG ODN formulated in 30% emulsigen than in PBS and alum. The innate immunostimulatory activity of CpG ODN appeared to be in dose-dependent manner. These in vivo data demonstrate for the first time that CpG ODN can stimulate innate immune system in weaned piglets.