The family waddliaceae

Abstract

Members of the family Waddliaceae are obligate intracellular prokaryotes. The Waddliaceae have a unique biphasic developmental cycle that alternates between an infectious, metabolically inactive particle, the elementary body (EB), and a noninfectious, metabolically active, replicative form, the reticulate body (RB). Sometimes, a third form named aberrant body is observed and might be associated to persistence, with a potential of recurrence. The only one formally validated species is Waddlia chondrophila that is considered as an emerging pathogen for humans and animals. Indeed, W. chondrophila seems to be associated with bovine abortion as well as human respiratory diseases and miscarriage. This pathogenicity is intimately linked to the capability of Waddliaceae to grow rapidly in several cell lines and to evade the early innate immune system. The Waddliaceae are capable to synthetize their own macromolecules, so they exhibit a relative independence to the host even if they are intimately associated to host cell mitochondria and endoplasmic reticulum during infection. Outer envelope of the Waddliaceae shares some features with the envelopes of Gram-negative organisms, and it exhibits a complete family of OmpA proteins that might help Waddliaceae to escape the immune system. Waddlia chondrophila was first isolated by Dilbeck in 1990 and then by Henning in 2002. Because of the impossibility to genetically manipulate the Waddliaceae, very little is known about the biology and epidemiology of these bacteria.