A mutation affecting expression of a major outer membrane protein of Moraxella catarrhalis alters serum resistance and survival in vivo

Merja E. Helminen, Isobel Maciver, Maria Paris, Jo L. Latimer, Sheryl L. Lumbley, Leslie D. Cope, George H. McCracken, Eric J. Hansen

Research output: Contribution to journalArticle

66 Scopus citations


A major outer membrane protein (CopB) of Moraxella catarrhalis is a target for antibodies that enhance clearance of this organism from the lungs of mice. A mini-Tn10kan transposon was inserted into the cloned copB gene from M. catarrhalis O35E, and an isogenic mutant unable to express the CopB protein was constructed by transforming this mutated gene into the wild-type strain. The mutant grew at the same rate as the wild-type parent strain in broth. Unlike the serum-resistant parent strain, this mutant was sensitive to killing by normal human serum, and its ability to survive and grow in the lungs of animals was impaired. Genetic restoration of CopB protein expression resulted in the simultaneous acquisition of wild-type levels of serum resistance and the ability to resist pulmonary clearance in vivo. Thus, the CopB protein of M. catarrhalis may be important in the interaction between this organism and the defense mechanisms of the respiratory tract.

Original languageEnglish (US)
Pages (from-to)1194-1201
Number of pages8
JournalJournal of Infectious Diseases
Issue number5
Publication statusPublished - Nov 1993


ASJC Scopus subject areas

  • Immunology
  • Public Health, Environmental and Occupational Health

Cite this