Pneumocystis Species Co-evolution: State-of-the-Art Review

Abstract

At the end of the 20th century, the notion of a unique species in the genus Pneumocystis (i.e. Pneumocystis carinii) was challenged and our understanding of the natural history of pneumocystosis was drastically changed. It is now accepted that the Pneumocystis genus comprises multiple stenoxenic biological entities that are widely distributed in ecosystems, airborne transmitted and closely adapted to the mammalian species they colonize. This article provides an opportunity to review one of the atypical features of these fungal microorganisms, namely host specificity as well as their parallel history with the mammalian hosts in which they co-evolve. Pneumocystis organisms can be used as powerful tools for phylogenetic and phylogeographic studies in mammals. Finally, we propose to challenge the molecular lens historically used to study the genetic diversity of Pneumocystis spp. in order to improve our understanding of Pneumocystis co-evolution with their hosts.