ABSTRACT
Chlamydiae are procaryotic organisms obligately restricted to an existence within susceptible eucaryotic cells due, at least in part, to their requirements for high energy intermediates of oxidative phosphorylation, which they must secure from preformed host cell stores. The genus shares a lipopolysaccharide antigen, similar in nature to an endotoxin lipopolysaccharide of gram-negative bacteria, but chlamydiae are set apart from gram-negative organisms by the lack of detectable peptidoglycan in their cell wall structure. Morphologic differentiation by chlamydiae involves conversion of a rigid, metabolically inert infectious form of the organism to a metabolically active, noninfectious intracellular form of the organism. The chlamydiae are ubiquitously distributed in a nature. Representatives of the genus are known to cause infections in molluscs, lower vertebrates, and avian species. A variety of animal models are available to study immune responses to chlamy-dial infection or an immunization protocols.
