Field performance of six  Mycobacterium avium  subsp.  paratuberculosis  antigens in a 20  h interferon gamma release assay in Belgium, Dernivoix, Kathy, Roupie Virginie, Welby Sarah, Roelandt Sophie, Viart Sophie, Letesson Jean-Jacques, Wattiez Ruddy, Huygen Kris, and Govaerts Marc , Veterinary Immunology and Immunopathology, Jan-07-2017, Volume 189, (2017)