Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 1/10/2006
Publication Date: 1/26/2006
Citation: Stabel, J.R. 2006. JDIP Core 4 - Animal Models and Facilities Core [abstract]. 2nd Annual JDIP Conference. p. 20. Interpretive Summary:
Technical Abstract: Responsibilities for this core include the maintenance of a current list of institutions that are willing to provide BL-2 housing for JDIP researchers on a fee-for-use basis, and to provide access to current and developing animal infection models for MAP. Development of a calf infection model that will transition to clinical disease in a short period of time (1-2 years) is a major priority of this core. Several experimental methods of infection are currently being evaluated in a chronic calf infection model. Treatment groups (n =4) are: 1) control (C) group; 2) oral inoculation (Oral) – live MAP (10**10 cfu) in milk replacer, 2 x times per day for 14 consecutive days; 3) oral inoculation with dexamethazone (Oral/DXM) – same as above but calves were pre-treated with DXM for 3 days prior to inoculation and on days 28 and 56 of infection; 4) intraperitoneal inoculation (IP) – inoculation of MAP (10**10 per ml; 1 ml) directly into the peritoneal cavity; 5) oral/mucosal (Oral/M) – live MAP from macerated mucosa from ileal tissue of clinical cow (20 g per dose; 2 doses 7 days apart). Blood and fecal samples are being obtained throughout the study on a monthly basis until 12 months of age. During the study period fecal samples are being processed for culture and PCR to determine shedding status of infected animals. Light and intermittent shedding has been observed in Oral and Oral/DXM calves by 3 months post-infection. Peripheral blood mononuclear cells are being isolated from blood samples monthly and processed for flow cytometric analysis, cytokine secretion, and lymphocyte proliferation. As an early indicator to MAP infection, IFN-gamma responses were assessed and within 2 months post-infection, IFN-gamma was significantly higher for IP and Oral/M calves compared to the other groups after stimulation of PBMC with MAP. By 4 months post-infection, infected calves, regardless of treatment group, had significantly higher antigen-specific IFN-gamma responses than C calves (Mean Abs650nm values: 0.11, 1.6, 0.72, 1.4, 0.77 for C, Oral, Oral/DXM, IP, and Oral/M calves, respectively). Further data on immune cell function obtained to this point will be summarized at the meeting.