Phylogeny of the Mycoplasma mycoides cluster as shown by sequencing of a putative membrane protein gene

The Mycoplasma mycoides cluster is made of six species that are closely rel ated both genetically and phenotypically. Two are of particular importance, M. mycoides subsp. mycoides SC causing contagious bovine pleuropneumonia a nd M. capricolum subsp. capripneumoniae causing contagious caprine pleuropn eumonia. The sequences of a putative membrane protein gene and partial flan king open reading frames have been obtained from various strains in this cl uster, including all reference strains. Sequence analysis showed this locus is present and fully conserved in all strains of M, mycoides subsp, mycoid es SC isolated from geographically most distant places worldwide. In M. cap ricolum subsp. capripneumoniae polymorphism in this locus has been found at seven positions and revealed that they can be used as epidemiological mark ers. Conserved regions were used to define a primer pair that enables the a mplification by PCR of two fragments 302 and 1298 bp long, respectively. Th e 302 bp long fragment contains an intergenic sequence that can be used for phylogenetic studies or for identification purposes. Parsimony analysis on an alignment of 49 DNA sequences show a subdivision of the M. mycoides clu ster into two subgroups that is in accordance with results obtained by phen otypic methods. Two lineages exist within the capricolum subgroup, one of t hem clustering strains identified as nl. capricolum subsp. capricolum, M. c apricolum subsp, capricolum and M. sp Bovine Group 7. However M. capricolum subsp. capripneumoniae strains can readily be identified by three specific nucleotide positions or by sequencing the 1298 bp long fragment. There is no clear subdivision within the mycoides subgroup, supporting the idea that hi, mycoides subsp. mycoides LC and M. mycoides subsp. capri should not be separated into two subspecies. Mycoplasma mycoides subsp. mycoides SC stra ins can easily be distinguished as they bear an insertion sequence 15 bp do wnstream from the stop codon of the membrane protein gene. (C) 2000 Elsevie r Science B.V. All rights reserved.