Epitope mapping of the variable repetitive region within the MB antigen of ureaplasma urealyticum

Xiaotian Zheng, Keith Lau, Monica Frazier, Gail H. Cassell, Harold L. Watson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


One of the major surface structures of Ureaplasma urealyticum recognized by antibodies of patients during infection is the MB antigen. Previously, we showed by Western blot (immunoblot) analysis that any one of the anti-MB monoclonal antibodies (MAbs) 3B1.5, 5B1.1, and 10C6.6 could block the binding of patient antibodies to MB. Subsequent DNA sequencing revealed that a unique six-amino-acid direct tandem repeat region composed the carboxy two-thirds of this antigen. In the present study, using antibody-reactive peptide scanning of this repeat region, we demonstrated that the amino acids defining the epitopes for MAbs 3B1.5, 5B1.1, and 10C6.6 are EQP, GK, and KEQPA, respectively. Peptide scanning analysis of an infected patient's serum antibody response showed that the dominant epitope was defined by the sequence PAGK. Mapping of these continuous epitopes revealed overlap between all MAb and patient polyclonal antibody binding sites, thus explaining the ability of a single MAb to apparently block all polyclonal antibody binding sites. We also show that a single amino acid difference in the sequence of the repeats of serovars 3 and 14 accounts for the lack of reactivity with serovar 14 of two of the serovar 3-specific MAbs. Finally, the data demonstrate the need to obtain the sequences of the mba genes of all serovars before an effective serovar-specific antibody detection method can be developed.

Original languageEnglish (US)
Pages (from-to)774-778
Number of pages5
JournalClinical and Diagnostic Laboratory Immunology
Issue number6
StatePublished - 1996

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Clinical Biochemistry
  • Microbiology (medical)


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