Genetic variations among Mycoplasma bovis strains isolated from Danish cattle

The genetic heterogeneity of Mycoplasma bovis strains isolated in Denmark o ver a 17-year period was investigated. Forty-two field strains isolated fro m different geographic locations and specimens, including strains from 21 h erds involved in two outbreaks of M. bovis-induced mastitis, and the type s train of M. bovis (PG45(T)) were assayed for variations in the BglII and Mf eI restriction sites in the chromosomal DNA by using the amplified fragment length polymorphism (AFLP) fingerprinting technique. The obtained genomic fingerprints consisted of 62-68 AFLP fragments in the size range of 50-500 bp. Among the analyzed strains, 18 different AFLP profiles were detected. T he similarity between individual fingerprints, calculated by Dice similarit y coefficient, ranged from 0.9 to 1.0. Twenty-five strains, including 23 wh ich were isolated during two outbreaks of M. bovis-induced mastitis which o ccurred 2 years apart; showed indistinguishable AFLP patterns. More genetic diversify was observed among the recent strains. The similarity of the gen otypes of the field strains to that of the M. bovis type strain (PG45(T)) w as 97.7%. The results of this study have demonstrated a remarkable genomic homogeneity of Danish strains of M. bovis that were probably epidemiologica lly related and which have remained stable for a considerable length of tim e. Furthermore; this study has demonstrated that AFLP can be used for genom ic fingerprinting and discrimination of M. bovis strains. (C) 2000 Federati on of European Microbiological Societies. Published by Elsevier Science B.V . All rights reserved.