High spoligotype diversity within a Mycobacterium bovis population: Clues to understanding the demography of the pathogen in Europe

Mycobacterium bovis is the main causative agent of bovine tuberculosis. This zoonotic disease produces important economic losses and must be considered a threat to endangered animal species and public health. This study was performed (1) to assess the degree of diversity of the Spanish M. bovis isolates and its effect on the epidemiology of the infection, and (2) to understand the connection of M. bovis populations within a European context. In this report we resume the DVR-spoligotyping results of 6215 M. bovis isolates collected between 1992 and 2007 from different hosts. The isolates clustered into 252 spoligotypes which varied largely in frequency, geographical distribution and appearance in different animal species. In general, the most frequent spoligotypes were found all over the country and in different animal species, though some were restricted to a geographical area. Among our most often isolated spoligotypes, SB0121 and SB0120 (BCG-like) are a common feature between mainland European countries, however, the spoligotypes differ with those found in the UK, the Republic of Ireland and abroad. A comparison of spoligotypes reported from other countries reveals hints for the M. bovis demography in Europe and suggests a common ancestor strain. This study gives insight into the usefulness of the standardized DVR-spoligotyping technique for epidemiological studies in a country with a high degree of strain diversity.