NIH researchers have sequenced nearly the entire genome of Pneumocystis—the cause a deadly infection that helped identify the HIV/AIDS epidemic. Pneumocystis is still a significant risk for those patients as well as for transplant recipients and other immunosuppressed patients.
Pneumocystis has puzzled researchers for years—especially how it developed its “unique” mechanisms of adaptation to life in mammals. “Having the genome information helped us recognize the unusual biology of Pneumocystis and how it co-exists with its mammalian hosts,” said Liang Ma, MD, first author of the paper on the study. Through analysis, the researchers now better understand where the organism lives—it’s “highly adapted to existence in the host lung with strict dependence on the mammalian host for nutrients and a stable environment.” They can also get a better idea of how it avoids elimination by the host’s immune system.
The researchers say their study helps map out a clearer picture of the genomes, compared with prior studies, with high-quality, near chromosomal draft genomes—the “highest level of genomic mapping.” That high quality helped them identify metabolic pathways critical to the growth and survival of the organism, as well as pathways in other closely related fungi that Pneumocystis does not have. The pathways likely disappeared as Pneumocystis evolved to become highly dependent on its host to stay alive, the researchers say.
Their detailed description of genes that are present or missing should facilitate attempts to culture the organism, they note. Culturing could help speed drug development and allow for genetic manipulation to modify the genes involved.