LIPOPOLYSACCHARIDE SMOOTH-ROUGH PHASE VARIATION IN BACTERIA OF THE GENUS CHLAMYDIA

In two strains of Chylamydia psittaci and in Chlamydia trachomatis ser otype L(1), we have detected a so-far-unknown antigen which (i) is res istant to heat and proteolytic digestion, (ii) can be extracted with p henol-water into the water phase, (iii) gives a ladder-like banding pa ttern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (i v) is immunogenic in rabbits and mice, and (v) contains immunoreactivi ty of lipid A, a common and characteristic component of gram-negative lipopolysaccharides (LPS). Thus, chlamydiae contain, in addition to th e known rough-type LPS, another LPS type which is phenotypically smoot h (S-LPS). S-LPS was observed preferentially in chlamydiae grown in th e yolk sac of embryonated eggs; it was, however, also detected by immu nofluorescence in tissue culture-grown chlamydiae with a monoclonal an tibody against S-LPS.