Pneumocystis:: unraveling the cloak of obscurity

Organisms in the genus Pneumocystis are fungal pathogens of immunocompromised mammalian hosts where they cause a lethal pneumonia. This genus has been cloaked in obscurity for almost half a century following their discovery in 1912, and has remained poorly understood throughout the ensuing 40 years. Progress towards understanding their life cycle, metabolism and basic biology has been hindered owing to the inability to continuously propagate any species outside the lung. Sequencing of the genome of Pneumocystis carinii is helping to unveil some of the mystery surrounding these organisms. Unusual genomic structures and a myriad of genes encoding cell cycle proteins have been identified and further revelations are expected upon its completion.