THE KINETICS OF SERUM ANTIBODY-RESPONSES TO NATURAL INFECTIONS WITH MYCOBACTERIUM-BOVIS IN ONE BADGER SOCIAL GROUP

Bovine tuberculosis remains a significant problem in some parts of Gre at Britain and Ireland largely because of a reservoir of infection in badgers. Little is currently known about the immunopathology of Mycoba cterium bovis infection in the badger. Badgers, from 31 social groups, in a study area of the Cotswold escarpment, have been trapped and sam pled from 1981 to 1995. Serum antibody responses directed against the 25 kDa antigen (MPB83) of M. bovis have been studied in detail in a se lected social group (JM) which has endemic infection. Sequential sera from 44 badgers were studied and results compared with culture from fa eces, urine, tracheal aspirates. bite wound swabs and at post mortem. The results indicate that some badgers (about 10%) remain uninfected d espite exposure to endemic M. bovis infection within the social group. In culture-positive animals active excretion of organisms is not nece ssarily concomitant with seropositivity. Conversely, seropositivity is not an indicator that culture positivity is present or imminent. This is particularly true in cubs when a transient seropositivity can occu r within the first 6-8 months of life but these animals can remain cul ture-negative for up to 5 years. Western blotting confirms that at lea st some of these antibodies, detectable by ELISA in the culture-negati ve cubs, are directed against the 25 kDa M. bovis antigen. In contrast antibodies detectable in the culture-positive animals do not Western blot prior to a positive culture. Thus, differential reactivity in Wes tern blotting may distinguish between serum antibodies indicative of p otentially culture-positive animals and animals which will remain cult ure-negative.