THE PHYLOGENY OF UREAPLASMA-UREALYTICUM BASED ON THE MBA GENE FRAGMENT

Sequencing of mba gene fragments of reference strains of Ureaplasma ur ealyticum serovars 1, 3, 6, 14 and 8, in addition to 33 clinical U. ur ealyticum isolates is reported. A phylogenetic tree deduced from align ment of these sequences clearly demonstrates two major clusters (confi dence limit 100%), which equate to the parvo and T960 biovars, and fiv e types, which have been designated mba 1, 3, 6, 8 and X. These relati onships are supported by bootstrap analysis. Polymorphisms within the mba fragment of types mba 1, 3 and 6 were used to define nine subtypes (mba 1a, 1b, 3a, 3b, 3c, 3d, 3e, 6a and 6b), thus facilitating high r esolution typing of U. urealyticum. Inclusion of reference strains for serovars 1, 3, 6 and 8 in the mba typing scheme showed that the resul ts of this analysis are broadly consistent with currently accepted ser otyping. In addition, a ure gene fragment from nine of the clinical is olates was amplified and sequenced. Comparisons of the sequences clear ly distinguished the two biovars of U. urealyticum; however, this frag ment was invariant within the parvo biovar. This study has shown that the mba sequence can reveal the fine details of the relationships betw een U. urealyticum isolates and also supports the significant evolutio nary gap between the two biovars.