Project Number: 3625-32000-110-00
Project Type: Appropriated

Start Date: Oct 06, 2011
End Date: Oct 05, 2016

Objective:
Objective 1: Characterize unique MAP proteins using previously cloned and expressed proteins for their effect on immune cells and to determine potential antigenicity by evaluating humoral and cellular immune responses and evaluate their use as new diagnostic tools. Subobjective 1.1: Construct 96-spot protein arrays and use them to probe sera from healthy and infected cattle. Subobjective 1.2: Screen recombinant proteins in a gamma-interferon (IFN-') microassay. Subobjective 1.3: Characterize a new protein that is expressed uniquely in MAP as well as other promising proteins from our initial screen. Subobjective 1.4: Develop a Luminex bead assay incorporating the most promising 10 MAP antigens and validate this test using 35 well-characterized cattle at different stages of Johne’s disease. Objective 2: Develop an infection model that allows the evaluation of the host immune response to MAP in early and late infection by defining the factors that induce the shift of a T helper 1 to a T helper 2 response resulting in clinical disease. Subobjective 2.1: Compare methods of MAP inocula preparation on tissue infectivity in a calf model. Subobjective 2.2: Compare neonatal calves, sheep and goats as host animals for MAP challenge model. Subobjective 2.3: Evaluate host immunity in naturally infected dairy cows to identify markers associated with subclinical and clinical infection. Objective 3: Develop new vaccines using novel vaccine platforms, adjuvants and strategies to control MAP based on the antigenic and genetic findings using various animal models. Subobjective 3.1: Determine immune responses elicited by vaccination with a commercial vaccine for MAP as well as effects of vaccination on the interpretation of M. bovis diagnostic tests. Subobjective 3.2: Evaluate cloned MAP proteins as potential vaccine candidates. Subobjective 3.3: Evaluate genomic DNA clones as potential vaccine candidates.

Approach:
Within Objective 1 unique antigens of MAP will be evaluated as immunogens with particular emphasis on their utility as diagnostic reagents or vaccine candidates. In Objective 2, ruminant models of infection will be developed and compared for efficacy in establishing infection in the host with the goal of characterizing a model that will progress from asymptomatic subclinical infection to a more clinical state within a 12-month period. These infection challenge models will be useful for evaluating potential vaccine candidates characterized in Objective 3. Cloned MAP proteins that are antigenic in the ruminant host and genomic DNA clones arrayed in pools will be evaluated as potential vaccines to protect against infection under Objective 3. The 3 major objectives outlined within this project plan will work in an interactive manner to provide us with tools to control this disease.