The present invention provides variant LcrE sequences and/or combinations of variant LcrE sequences across the Chlamydia trachomatis serovars. Such changes in LcrE genotypes across the Chlamydia trachomatis serovars are likely to correspond with changes in LcrE phenotypes, in particular, with changes in immunogenicity. The present invention also provides peptides surrounding or associated with the amino acid substitutions, in particular, peptides surrounding or associated with high frequency mutated amino acid positions or hypervariable regions, which are likely to be B and/or T cell epitopic regions capable of eliciting Chlamydia specific cell mediated immune responses. The variant LcrE sequences and/or combinations of the variant LcrE sequences and/or epitope regions associated with the variant LcrE sequences are useful as immunogens and/or in the preparation of immunogenic compositions for preventing and/or treating and/or, diagnosing Chlamydia infections.
