Inside the genome of a deadly desert disease
Rhinocladiella mackenziei is a fungus that infects the human brain. It is the most common cause of neurological fungal infections in arid regions of the Middle East, and it is fatal in 70% of cases. However, little is understood about this lethal pathogen—not even its natural habitat.
To learn more about the biology of R. mackenziei, Moreno et al. turned to its genome. They resequenced the genome of two strains isolated from patients and compared them to known sequences from R. mackenziei, as well as other related fungi.
These comparisons gave clues about the natural lifestyle of the fungus. For example, R. mackenziei carries genes similar to fungi from habitats polluted by aromatic hydrocarbons, such as those found in gasoline. This suggests that R. mackenziei might flourish in oil-contaminated desert soil, where these genes would give it a competitive advantage over organisms that are unable to thrive in such a harsh environment.
The authors also identified a number of secreted virulence factors which could permit R. mackenziei to more easily establish itself in the brains of infected humans. The genomes harbor a wide array of genes involved in metabolism of diverse substrates, as well as nitrogen and iron uptake. This metabolic adaptability means that R. mackenziei probably isn’t a true pathogen; a pathogen would have lost some of these pathways because it could rely on its host for nutrients. Rather, this desert fungus is equipped to survive a number of harsh conditions, so its ability to infect human brains is most likely opportunistic.