Immunoreactivity of the 60 kDa cysteine-rich proteins of Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae expressed in Escherichia coli

Microbiology (Reading). 1994 Aug;140 ( Pt 8):2003-11. doi: 10.1099/13500872-140-8-2003.


The 60 kDa cysteine-rich proteins (CrPs) of Chlamydia are developmentally regulated outer envelope proteins synthesized late in the chlamydial growth cycle. These proteins, found only on the extracellular infectious elementary bodies, elicit major antibody responses in chlamydial infection. We have cloned and expressed in Escherichia coli the complete 60 kDa CrP genes from Chlamydia trachomatis, C. psittaci and C. pneumoniae. The recombinant products were expressed as either 'native' proteins or as fusions with the bacteriophage T7 gene 10 protein. Electron microscopy showed that recombinant proteins were produced as insoluble inclusions within the E. coli host cells. The recombinant 60 kDa CrPs were purified and used to raise high titre polyclonal antisera. In immunoblot analysis these antisera reacted with the 60 kDa CrPs from purified elementary bodies of all three chlamydial species in a genus-specific manner. Further molecular analysis allowed the genus-specific cross-reacting epitopes to be localized by using overlapping synthetic peptides covering the C. trachomatis 60 kDa CrP. Immunogold labelling experiments, using purified infectious elementary bodies from the three chlamydial species indicated that the 60 kDa CrPs are not surface accessible to antibody binding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Bacterial / immunology*
  • Antibodies, Monoclonal / immunology
  • Antigens, Bacterial / biosynthesis
  • Antigens, Bacterial / immunology*
  • Antigens, Surface / immunology
  • Bacterial Outer Membrane Proteins / biosynthesis
  • Bacterial Outer Membrane Proteins / immunology*
  • Base Sequence
  • Chlamydia trachomatis / genetics
  • Chlamydia trachomatis / immunology*
  • Chlamydophila pneumoniae / genetics
  • Chlamydophila pneumoniae / immunology*
  • Chlamydophila psittaci / genetics
  • Chlamydophila psittaci / immunology*
  • Cloning, Molecular
  • Epitopes / immunology
  • Escherichia coli
  • Immune Sera
  • Molecular Sequence Data
  • Rabbits
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / immunology
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / immunology*


  • Antibodies, Bacterial
  • Antibodies, Monoclonal
  • Antigens, Bacterial
  • Antigens, Surface
  • Bacterial Outer Membrane Proteins
  • Epitopes
  • Immune Sera
  • Omp2 protein, bacteria
  • Recombinant Fusion Proteins
  • Recombinant Proteins