Animal challenge models are critical to evaluate potential vaccine candidates and to study host immune responses to Mycobacterium avium subsp. paratuberculosis(MAP) infection. Virtually all researchers have developed their MAP challenge model independently of others, resulting in a high degree of variability. The need to standardize challenge models for vaccine efficacy studies was a conclusion reached in August 2005 at the International Colloquium for Paratuberculosis "Role of Vaccination" workshop, held in Copenhagen, Denmark.

An international expert committee of Johne's Disease (JD) researchers was convened to review and develop guidelines for JD challenge studies in multiple animal species. Members of the committee included Murray E. Hines II, Judith R. Stabel, Raymond W. Sweeney, Frank Griffin, Adel M. Talaat, Douwe Bakker, Geart Benedictus, William C. Davis, Geoffrey W. de Lisle, Ian A. Gardner, Ramon A. Juste , Vivek Kapur, Ad Koets, Jim McNair, Greg Pruitt, Robert H. Whitlock.

Parameters essential for the development of long term and acute infection models were outlined and harmonized to provide a template JD challenge model for cattle, goats, sheep, cervids, and mice. The intent was to develop and propose international standard guidelines for models that would gain acceptance worldwide. The consensus guidelines for models developed by this committee included recommendations for experimental challenge studies listed by animal species for strains of Mycobacterium avium subsp. paratuberculosis used, challenge dose, dose frequency, age of challenge, route of challenge, preparation of inoculum, method of quantifying MAP in the inoculum, experimental animal selection, quality control and minimal experimental endpoints.

These models will be useful to study host-pathogen interactions, host immunity at the local and systemic level, and for evaluating vaccine candidates and therapeutics