Serologic survey for antibodies against Mycobacterium a vium subsp. paratuberculosis in free-ranging cervids from Norway

Affinity between protein-G and immunoglobulins from red deer (Cervus elaphus), moose (Alces alces), roe deer (Capreolus capreolus), and reindeer (Rangifer tarandus tarandus) was tested in a competition binding assay. Sera from red deer, reindeer, and moose inhibited the assay less than sera from cattle (less affinity), whereas sera from roe deer showed a slightly higher affinity to protein-G than did sera from cattle. The conclusion was made that protein-G could be used instead of anti-species antibodies for these cervid species, where the aim of the screening was to look for exposure or lack of exposure to mycobacteria in the tested populations. Serologic screening of 1,373 free-ranging cervids for antibodies against Mycobacterium avium subsp. paratuberculosis was conducted. All sera were tested by a protein-G-based antigen-absorbed enzyme-linked immunosorbent assay (ELISA). Seropositive moose (10/537; 1.9%), red deer (14/371; 3.8%), roe deer (6/49; 12.2%), and semidomesticated reindeer (11/325; 3.4%) were found, whereas wild reindeer (n = 91) were seronegative. In addition, the red deer sera were tested with a commercial ELISA, by which two animals tested positive and nine were suspicious of having M. avium subsp. paratuberculosis antibodies. Tissue samples and feces from 10 moose originating from a population with a clustering of seropositive animals were investigated by histology and bacteriology with negative results. Paratuberculosis has never been diagnosed in free-ranging or farmed cervid species in Norway. Thus, further studies are indicated to prove that the present findings reflect an infection with M. avium subsp. paratuberculosis.