Chlamydiae (see also http://www.chlamydiae.com/ ) belong to the few bacteria that grow only within a host cell, inside a cytoplasmic vacuole, and exist in 2 alternate forms, the infectious, rigid elementary body (EB) and the metabolically active, multiplying, non-infectious reticulate body (RB). These organisms are very successful pathogens infecting almost every animal, from arthropods to humans. The Chlamydia can cause inapparent, asymptomatic infections, acute infections, as well as most damaging chronic infections, which have highly diverse disease syndromes. Relatively little is known about the biology of these organisms and the ways they interact with the host and cause disease, as they are very difficult to work with. Although chlamydial plasmids and a bacteriophage were known for some time, a system for genetic manipulation is still missing. However, the completion of the sequencing of the first chlamydial genome in 1998 and the large application since of biomics (genomics and proteomics) as well as of novel cell biology tools have revolutionized chlamydial research. 
 
  Since the early 90’s our lab has been dedicated to the study of those chlamydial species that cause abortion in ruminants (pregnant farm workers are also at risk!), and infertility in cattle and sheep, and are therefore economically important. Indeed, the impact of the environmental presence of chlamydia in farming is only now beginning to be estimated. Earlier studies in collaboration with Olga Mangana (Ministry of Agriculture) Vicky Siarkou and Orestis Papadopoulos (University of Thessaloniki) focused on the typing and characterization of Greek field isolates. Unique variant placental strains and virulent intestinal strains from apparently healthy animals were characterized. Moreover, the use of proteomics led to the identification of the second known bacteriophage in chlamydia beard by one Greek strain. The group of Ian Clark (University of Southampton, UK) has determined the genome of this phage. Furthermore, a specific competitive ELISA has been developed, valuable for the serologic diagnosis of chlamydial abortion. This test is being broadly used by the group of Andreas Pospishil (University of Zurich, CH) to perform an epidemiological survey of chlamydial abortions in Switzerland.  More exciting, a project that had started in the recent years as the pursuit of a diagnostically important novel antigen, led to the identification of a new family of proteins, the polymorphic outer membrane proteins, the POMPs. Several protein members of this family were identified by proteomics analysis, in collaboration with Luca Bini (University of Siena, Italy). Though improved ELISAs with the novel antigens were developed and validated in collaboration with David Longbottom (The Moredun Research Institute, Scotland), these fascinating proteins are promising vaccine candidates, too.  Moreover, they are believed to be involved in chlamydial pathogenesis, acting as autotransporters. Study of this protein family is our main current research topic.