The
lipopolysaccharide (LPS) of Chlamydia psittaci was extracted from yolk sac-grown elementary bodies, purified, and characterized chemically, immunochemically, and biologically. The LPS contained D-
galactosamine, D-
glucosamine,
phosphorus, long-chain
fatty acids, and
3-deoxy-D-manno-2-octulosonic acid in the molar ratio of approximately 1:2:2:6:5. The antigenic properties of the isolated LPS were compared with those of the LPS from Chlamydia trachomatis and Salmonella minnesota Re by the passive
hemolysis and passive
hemolysis inhibition tests, absorption, hydrolysis kinetics, and Western blot analysis with rabbit polyclonal
antisera against chlamydiae and with a mouse
monoclonal antibody recognizing a genus-specific
epitope of chlamydial LPS. Two
antigenic determinants were identified, one of which was chlamydia specific and the other of which was cross-reactive with Re LPS. Both determinants were destroyed during
acid hydrolysis, whereby a third
antigen specificity was exposed which was indistinguishable from the
lipid A antigenicity. In rabbit polyclonal
antisera prepared against
Formalin-killed elementary bodies or
detergent-solubilized membranes, two antibody specificities were differentiated. One of these was chlamydia specific, and the other was cross-reactive with Re LPS. The LPS of C. psittaci was inactive within typical
endotoxin parameters (lethal toxicity, pyrogenicity, local Shwartzman reactivity); it was, however, active in some in vitro assays, such as those testing for mouse B-cell mitogenicity and the induction of
prostaglandin E2 in mouse peritoneal macrophages.