Simkania negevensis may produce long-lasting infections in human pneumocytes and endometrial cells.

Simkania negevensis is a novel Chlamydia-related bacterium and the founding member of the Simkaniaceae family within the Chlamydiales order. Little is known about the biology and pathogenesis of this bacterium. So far, S. negevensis has been considered as an amoebal symbiont, but its natural host remains unknown. Moreover, evidence of human exposition has been reported worldwide and an association with pneumonia and bronchiolitis is suspected. Here, we evaluated the ability of S. negevensis to replicate in potential environmental reservoirs, namely amoebae and arthropods, as well as in mammalian cells (Vero cells, pneumocytes and endometrial cells) and further evaluated the characteristics of its replicative vacuole. We demonstrated that S. negevensis efficiently replicates in all cell lines tested, with the shortest doubling time and an increased adhesion observed in pneumocytes. Our work highlights the specificities of the Simkania-containing vacuole compared to other Chlamydiales; contrarily to Chlamydia trachomatis, S. negevensis does not disrupt the Golgi apparatus. Importantly, our work suggests that S. negevensis infection is associated with few cytopathic effects and might persist for a prolonged time in infected cells. Further evaluation of its implication in human diseases is required; an implication in chronic or subacute respiratory infections might be suspected.

Inclusion counter: a public domain image analysis system for measurement of Chlamydiaceae growth in vitro.

The traditional method of measuring chlamydial growth in vitro, counting Chlamydiaceae inclusions by eye, is time-consuming and error prone. This paper describes a novel automated image analysis system suitable for high-throughput screening of novel anti-Chlamydiaceae compounds. The software, Inclusion Counter v3.0, is freely available in the public domain (http://www.image-analysis.co.uk).

Bacteria-host relationships in the bivalve mollusc Loripes lucinalis.

Loripes lucinalis, a lucinid species found in reduced sediments, contains endosymbiotic bacteria within specialized gill cells which contribute to the bivalve's nutrition. An additional bivalve-bacteria association can be seen in the digestive gland where large inclusion bodies filled with rickettsia- or chlamydia-like organisms are observed in the duct and tubule cells. Despite indications of a possible energy parasitism on the part of these endocellular digestive gland bacteria, the digestive epithelium of the host is not significantly damaged by the infection suggesting that this is a generalized and normal bivalve-bacteria association in adults of this species.

Rickettsiaceae and Chlamydiaceae: comparative electron microscopic studies.

The structure and cytopathology of obligate intracellular bacteria belonging to families Rickettsiaceae and Chlamydiaceae and their interaction with eukaryotic host cells were compared in electron microscopic studies. "Rickettsia-like" and "chlamydia-like" types of organization of bacterial cells and their interaction with host cells are presented. The rickettsia-like type is characterized by short rod-shaped cells multiplying freely ( extravacuolarly ) in the cytoplasm or nucleoplasm of the host cell; the chlamydia-like type has spherical cells multiplying inside the cytoplasmic vacuole limited by the host membrane. The rickettsia-like type includes the genus Rickettsia and rod-shaped symbionts from genera Wolbachia and Symbiotes ; the chlamydia-like type falls into genera Chlamydia, Ehrlichia, Cowdria and Neorickettsia . The transitional types represented by Wolbachia persica (type 1), Coxiella and Rickettsiella (type 2) are also described. The possible evolutional relationships of the genera comprising both families are considered and their classification is proposed.

Comparison of the ultrastructure of small dense forms of chlamydiae and Coxiella burnetii.

In the course of passaging of Coxiella burnetii (C.b.) in Alveonasus lahorensis ticks, the haemocytes contained cell forms with electrondense cytoplasm, intracytoplasmic lamellar membranes, and a peculiar limiting membrane--25 to 30 nm thick "envelope complex". Similar small forms occurred when C.b. had been cultured in the yolk sack of chick embryos. The dense forms of C.b. were similar to those of Rickettsiella cells. Dense forms (elementary bodies) surrounded by an "envelope complex" were found also in some chlamydiae cultured in yolk sacs of chick embryos.