[Pathogenesis and immune reactions of paratuberculosis]

Mycobacterium avium subspecies paratuberculosis (M. ptb) is known as the cause of paratuberculosis for over a century but the knowledge on biology of the organism and pathogenesis of the disease is still limited. There are several reasons for the present lack of progress, these are (i) the extremely slow growth of the bacterium, a feature which has also protected the organism against researchers, (ii) confusion over its taxonomy and identification, (iii) limited possibilities for the application of molecular biology techniques, and (iv) the extremely long incubation period in natural infection for which no suitable laboratory model exists. Despite these discouraging facts, recent research efforts have led to important findings, which have shown that a better understanding of the disease may contribute to the improvement of control strategies. This presentation focuses mainly on the unique nature of M. ptb within the mycobacteria and the central role of the macrophage in pathogenesis and immune response. More details can be found in a number of excellent recent reviews (see list of references).