Chlamydophila abortus

• Domain: Eukaryota
•     Kingdom: Planctomycetes [kingdom]
•         Class: Planctomycetes [class]
•             Order: Chlamydiales
•                 Family: Chlamydiaceae
•                     Genus: Chlamydophila
•                         Species: Chlamydophila abortus

The Chlamydiales, thought to be viruses for a long time, are obligate intracellular bacterial pathogens of higher cells. The chlamydial elementary body (EB) is near the limit of light microscopic visibility with approximately 0.3 µm in diameter, round or occasionally pear-shaped, and contains electron-dense structures. It is the infectious stage of the chlamydial developmental cycle, and functions as a tough ‘spore-like’ body whose purpose is to permit chlamydial survival in the non-supportive environment outside the host cell. The ultrastructure of EB has been extensively studied (Eb et al., 1976; Louis et al., 1980; Matsumoto, 1982; 1988; Rockey et al., 2000; Solof et al., 1982).

The chlamydial reticulate body (RB) is the chlamydial developmental stage during intracellular replication, and it is non-infectious. Typically, the RB has a diameter of approximately 1 µm. The RB is metabolically active, the cytoplasm is rich in ribosomes, which are required for protein synthesis. As the RB begins to differentiate into an EB, sites of re-condensation of nucleic acid appear in its cytoplasm. In the maturing inclusion, chlamydial particles appear to be packed tightly in the inclusion membrane. Development of chlamydiae is highly dependent on nutrient supply and metabolic status of host cells. Nutrient deficiencies such as low glucose levels lead to delayed development and to a few, aberrant chlamydial organisms within the inclusions.

Chlamydial agents, classically have been propagated in the yolk sacs of chicken embryos (Storz, 1971). Cultivation in cell culture is now preferred, and the use of appropriate techniques is important for high-yield culture (Li, et al., 2005). Buffalo Green Monkey Kidney (BGMK) cells support chlamydial replication effectively, particularly when cultivated in Iscove’s Modified Dulbecco’s Medium. EBs are purified by sedimentation, separated from cellular nuclei by low-speed centrifugation, and separated from cell debris by step-gradient centrifugation in a 30% RenoCal-76 50% sucrose step-gradient. Extensive sonication increases yield and infectivity of chlamydial EBs.

Disease(s) associated with this pathogen is/are on the list of diseases notifiable to the World Organisation for Animal Health (OIE). The distribution section contains data from OIE's Handistatus database on disease occurrence. Please see the AHPC library for further information from OIE, including the International Animal Health Code and the Manual of Standards for Diagnostic Tests and Vaccines. Also see the website: www.oie.int.