Comparative analysis and serovar-specific identification of multiple-banded antigen genes of Ureaplasma urealyticum biovar 1

Ureaplasma urealyticum is a causative agent of nongonococcal urethritis and is implicated in the pathogenesis of several other diseases. The species i s divided into 14 serovars and two biovars, of which biovar 1 is most commo nly isolated from clinical specimens. Reported associations between individ ual serovars and diseases have been difficult to confirm because of practic al difficulties with serotyping. The multiple-banded antigen (MBA) is the p redominant U. urealyticum antigen recognized during infections in humans an d probably has a significant role in virulence. The 5' end of the MBA gene is relatively conserved but contains biovar, and possibly serovar, specific ity. The 5' ends of the MBA genes of standard strains of U, urealyticum bio var 1, consisting of serovars 1, 3, 6, and 1 1, Here amplified, cloned into pUC19, and sequenced to identify serovar-specific differences. The 5' end of the MBA gene sequence of serovar 3 was identical with the previously pub lished sequence and differed by only three bases from that of serovar 1 I. Significant differences between the MBA gene sequences allowed biovar 1 to be divided into two subgroups, containing serovars 3/14 and serovars 1 and 6, respectively, using primers UMS-125-UMA269 and UMS-125-UMA69'. Serovars 1 and 6 were distinguished by restriction enzyme analysis of the amplicon a nd/or by PCR specific for serovar 6. These methods were used to identify an d type Li. urealyticum in 185 (46.3%) of 400 genital specimens from women. Biovar 1 was detected in 89.2% and biovar 2 in 18.3% of positive specimens, Of 165 specimens containing U, urealyticum biovar 1, 22.2% contained more than one serovar and 46.7,46.1, and 25.5% contained serovars 1, 3/14, and 6 , respectively. U. urealyticum was found in a significantly higher proporti on of pregnant women than in sex workers and other women attending a sexual ly transmissible diseases clinic (P < 0.01), The methods described are rela tively rapid. practicable, and specific for serotyping isolates and for dir ect detection and identification of individual serovars in clinical specime ns containing U. urealyticum biovar 1.