Local and systemic immune parameters were investigated following subcutaneous immunisation of cattle with a gamma-irradiated M. avium subsp. paratuberculosis (Map) inactivated vaccine. The ATCC 19698 strain was exposed to 0.5 megarad and a single dosis of 4 mg dry weight was administered subcutaneously (SC) in a non-mineral Montanide ISA775~R water in oil suspension to five 2-week old Friesian-Holstein male calves. Animals were monitored fortnighly and sacrificed 7 months post-immunisation together with 3 non-immunised controls. Lymphocytes prepared from peripheral blood, spleen, the SC draining lymph node (LN), ileocecal lymph nodes, lamina propria (LP) and intraepithelial lymphocytes (IEL), were stimulated in vitro and antigen-specific IFN-gamma responses measured in 20-h and 5-day cultures along with proliferative responses. Strong systemic IFN-gamma responses were recorded at 20h in immunised animals versus no response in ileocecal, LP and IEL preparations, whereas IFN-gamma was detected in 5-day cultures from LP, IEL and ileocecal LN together with enhanced systemic responses. Results are discussed in terms of induction of mucosal CD4 Th1 immunity, of effector and memory T cell functions, and of systemic vaccine potency.
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