Ultrastructure of Chlamydia pneumoniae in cell culture

Abstract

The electron microscopic appearance of Chlamydia pneumoniae elementary bodies with pear-shaped, loose outer membrane has been suggested as one criterion of its classification as a new chlamydial species. The study of the original strain TW 183 in LCL 929 and HL cells and a low-passage isolate of Kajaani-6 isolate in HL cells revealed spherical compact elementary bodies common to other chlamydia.

The morphology of Chlamydia pneumoniae

“…Carter et a1.22 demonstrated that the morphology of EBs of C. pneumoniae IOL-207 also appeared round in thin sections and were indistinguishable from those of the C. trachomatis and C. psittaci. Similarly, Popov et al 23 demonstrated round EBs in thin sections of C. pneumoniae Kajaani-6. These results, together with those presented here, strongly suggest that the " pear-shaped" profiles of EBs in thin sections are not common in C. pneumoniae and that the pear-shape is not a morphological criterion for recognising C. pneumoniae.…”

Evidence for Chlamydia pneumoniae of non-human origin

“…Other differences between N16 and TWAR are that N16 contains a plasmid and has normal EB morphology (Wills et al, 1990) whereas TWAR EBs were originally described as pear-shaped (Grayston et al, 19893). However not all TWAR isolates have abnormal EB morphology (Carter et al, 1991 ;Popov et al, 1991) and the presence or absence of a plasmid is not a reliable indicator of species. Studies on the plasmid of N16 (pCpnE) showed that it is similar in size (7.5 kb) and organization to the plasmids found in C. psittaci and C. trachomatis but that it has a unique restriction profile (Lusher et al, 1989).…”

“…known that not all TWAR isolates have pear-shaped EBs (Carter et al, 1991 ;Popov et al, 1991). All isolates recognized in 1989 were from humans and they comprised a single strain that was called W A R .…”

Emended description of the order Chlamydiales, proposal of Parachlamydiaceae fam. nov. and Simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family Chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms

“…The description of biovar TWAR is identical to the description of the prototypical TWAR serovar (Grayston et al, 1989), except that biovar TWAR EBs may have either of two distinct ultrastructural morphologies : the prototypical pear-shaped EB (Grayston et al, 1989) or the classic coccoid morphology of the Chlamydiaceae spp. (Carter et al, 1991 ;Miyashita et al, 1993;Popov et al, 1991). The name TWAR was formed by merging the first two letters of isolates TW-183 and AR-39 (Grayston et al, 1989).…”