Molecular genotyping of human Ureaplasma species based on multiple-banded antigen (MBA) gene sequences

Ureaplasma urealyticum has been divided into 14 serovars. Recently, subdivi sion of U. urealyticum into two species has been proposed: U. parvum (previ ously U. urealyticum parvo biovar), comprising four serovars (1, 3, 6, 14) and U, urealyticum (previously U. urealyticum T-960 biovar), 10 serovars (2 , 4, 5, 7-13). The multiple-banded antigen (MBA) genes of these species con tain both species and serovar/subtype specific sequences. Based on whole se quences of the 5'-ends of MBA genes of U. parvum serovars and partial seque nces of the 5'-ends of MBA genes of U, urealyticum serovars, we previously divided each of these species into three MBA genotypes. To further elucidat e the relationships between serovars, we sequenced the whole 5'-ends of MBA genes of all 10 U. urealyticum serovars and partial repetitive regions of these genes from all serovars of U. parvum and U. urealyticum. For the firs t time, all four serovars of U. parvum were clearly differentiated from eac h other. In addition, the 10 serovars of U. urealyticum were divided into f ive MBA genotypes, as follows: MBA genotype A comprises serovars 2, 5, 8; M BA genotype B, serovar 10 only; MBA genotype C, serovars 4, 12, 13; MBA gen otype D, serovar 9 only; and MBA genotype E comprises serovars 7 and 11. Th ere were no sequence differences between members within each MBA genotype. Further work is required to identify other genes or other regions of the MB A genes that may be used to differentiate U. urealyticum serovars within MB A genotypes A, C and E. A better understanding of the molecular basis of se rotype differentiation will help to improve subtyping methods for use in st udies of the pathogenesis and epidemiology of these organisms.