The cloning and sequencing of cervine interleukin 10

Immunoregulatory cytokines are associated with protection from immunopathology following Mycobacterium avium subspecies paratuberculosis infection in red deer

Although the causative agent of Johne's disease, Mycobacterium avium subsp. paratuberculosis, is well known, the etiology of disease and the immune responses generated in response to infection are still poorly understood. Knowledge of definitive markers of protective immunity, infection, and the establishment of chronic granulomatous Johne's disease is necessary to advance vaccine and diagnostic development. We sought to profile the immune responses occurring within jejunal lymph nodes of experimentally challenged red deer (Cervus elaphus). Quantitative PCR was utilized to measure a range of cytokines, signaling molecules, and transcription factors involved in Th1, Th2, Treg, and Th17 immune responses. Significant differences in gene expression were observed between control, minimally diseased, and severely diseased animals, with severely diseased animals showing elevated proinflammatory transcripts and reduced anti-inflammatory transcripts. We identified a proinflammatory cytokine milieu of gamma interferon, interleukin-1α (IL-1α), and IL-17, which may contribute to the immunopathology observed during clinical Johne's disease and suggest that Th2 and Treg immune responses may play an important role in controlling the development of immunopathology in infected animals.

The production and biological assessment of cervine interferon gamma

Cervine interferon gamma (IFN-gamma) was cloned and expressed using an Escherichia coli expression system pET-32. The expressed protein contained a 6 histidine purification tag and an 11 kDa thioredoxin fusion partner 5' to the IFN-gamma molecule. The ability of IFN-gamma to inhibit the killing of Madin-Darby bovine kidney cells by Semliki forest virus was used as a measure of the bioactivity of the recombinant cervine IFN-gamma (rIFN-gamma). It was shown that the presence of the thioredoxin fusion partner 5' to the IFN-gamma molecule did not affect its biological activity. As in the mouse model, it was shown that cervine rIFN-gamma was able to down-regulate the transcription of interleukin 10 mRNA while up-regulating the transcription of interleukin 12 mRNA in lipopolysaccharide-sensitized, peripheral blood mononuclear cells. A prototype ELISA was tested for its ability to detect both recombinant and native IFN-gamma. The ELISA was able to detect rIFN-gamma at concentrations greater than 100 pg/ml. It was also used to detect native IFN-gamma produced by peripheral blood lymphocytes from Mycobacterium bovis infected or vaccinated deer after in vitro restimulation with antigen. The rIFN-gamma and the cervine IFN-gamma specific ELISA provide valuable tools with which to study important zoonotic infections in farmed and wild deer.

In vitro responses of cervine macrophages to bacterial stimulants

The function of cervine (deer) mononuclear phagocytes is poorly defined. In the present study, the potential of cervine macrophages to generate phagocytic and immunoregulatory responses following stimulation with bacterial products was investigated. Blood-derived macrophages of red deer were cultured in vitro with particulate stimulants (Mycobacterium bovis BCG and Staphylococcus aureus SAC) or soluble stimulants (M. bovis PPD and Escherichia coli LPS), prior to assessment of phagocytic responses, prostaglandin secretion and cytokine production. Particulate stimulants induced vigorous phagocytic responses (superoxide anion generation, lysosomal enzyme release), secretion of prostaglandin E2 and transcription of mRNA specific for the cytokines IL-1 beta, IL-10 and TNF alpha, while soluble products invoked weaker responses. These results are discussed in relation to the role of cervine mononuclear phagocytes in regulating and participating in inflammatory and immune processes relevant to bacterial challenge.