The present invention features peptides of a PorB polypeptide, which PorB peptides are useful in production of antibodies that bind the full-length PorB polypeptide and as a therapeutic agent. In specific embodiments the invention features a composition comprising one or more PorB peptides (other than a full-length PorB polypeptide), which peptides contain at least one epitope that can elicit Chlamydia-neutralizing antibodies. The invention also features methods for induction of a protective immune response against infection by Chlamydia and Chlamydiophila.