Beschreibung:
<jats:title>Summary</jats:title><jats:p>Examples exist in the literature that demonstrate that treatment with immunostimulatory cytosine–phosphate–guanosine (CpG)‐DNA can protect mice against infection by intracellular pathogens. There are, however, few studies reporting that CpG‐DNA offers similar disease protection in other species. In this study, we assessed the potential of a class A and class B CpG oligodeoxynucleotide (ODN) to induce innate immune responses in sheep, an outbred species. Using peripheral blood mononuclear cells, we have for the first time demonstrated CpG‐ODN‐induced innate immune responses, including natural‐killer‐like activity [non‐major histocompatibility complex (MHC)‐restricted cytotoxicity], interferon‐α secretion and 2′‐5′A oligoadenylate synthetase activity, that could contribute to immune protection in sheep. The type and magnitude of these responses were dependent on ODN class and non‐MHC‐restricted killing was not associated with interferon‐γ production. The latter observation is in contrast with observations reported for mice and humans. These observations support the conclusion that differences in CpG‐ODN‐induced responses exist among species and that specific ODN sequences can significantly influence innate immune responses.</jats:p>