Host Influence on the Density of Chlamydiae in Renografin Gradients

Egg-grown and L cell-grown C. psittaci 6BC strains formed two bands when centrifuged through preformed Renografin gradients. No additional bands were observed by extending the time of centrifugation. Particles present in the bands which were collected from the Renografin gradients were examined by electron microscopy. Purified elementary bodies from both egg- and L cell-grown sources were located in a lower, minor band; egg-derived elementary bodies showed a higher density (p < 0.01) than elementary bodies derived from L cells. Particles present in the major, upper band of both egg- and L cell-derived strains had similar densities and contained mixed populations of elementary bodies and polymorphic reticulate bodies.