CHANGES IN THE ULTRASTRUCTURE OF CHLAMYDIA-PSITTACI PRODUCED BY TREATMENT OF THE HOST-CELL WITH DEAE-DEXTRAN AND CYCLOHEXIMIDE

The ultrastructure of two Chlamydia psittaci serotypes was investigated in infected L-cell monolayers fixed and embedded in situ. This preparation preserved the relationship of the parasite to the internal structure of the host cells. Chlamydial inclusions in cells treated with diethylaminoethyl-dextran (DEAE-D) and cycloheximide were compared to inclusions in untreated cells. C. psittaci serotype 1 had the same or larger yields of infectious progeny per infected cell in treated cells as in untreated cells. This serotype developed normal inclusions following both treatments. C. psittaci serotype 2 had decreased infectivity yields per infected cell and developed aberrant chlamydial forms in treated cell monolayers. Serotype 2 inclusions contained pycnotic chlamydial forms and numerous miniature reticulate bodies in cycloheximide-treated cells. In DEAE-Dtreated cells, some serotype 2 reticulate bodies were abnormally pleomorphic and contained amorphous material of intermediate electron density. Other reticulate bodies had lost electron density, degenerated, and contained only fragments of the reticulum. Maturation of reticulate bodies into infectious elementary bodies was greatly decreased in serotype 2 inclusions that contained aberrant forms. © 1979 Academic Press, Inc.