The sequencing the genome of the fungus Pneumocystis jirovecii could help identify new targets for drugs to treat and prevent Pneumocystis pneumoniaScientists have sequenced the genome, according to new study results.

“Recognized first among malnourished infants, P. jirovecii pneumonia became a public issue with the advent of the HIV epidemic,” , said corresponding author Philippe Hauser of the Centre Hospitalier Universitaire Vaudois and University of Lausanne, in Switzerland. “It is obviously better to study [P. jirovecii’s] genes rather that those of Pneumocystis species from animal models. The genome has both medical and evolutionary interests for the scientific community.”

Pneumocystis pneumonia is an opportunistic infection that strikes most often in individuals with diminished immune systems.

Since they were unable to grow P. jirovecii cells for their genomic DNA, Hauser and colleagues took a sample of bronchoalveolar lavage fluid from an individual infected with Pneumocystis pneumonia, then concentrated the P. jirovecii cells using immuno-precipitation and created copies of the DNA in the sample using a technique called random DNA amplification. This mixture of DNA strands, from P. jirovecii, human, and other microbes from the lungs of the infected patient, was then sequenced using high throughput technologies.

Once the sorting task was accomplished, the researchers assembled the sequences into a genome and attempted to identify the functions of P. jirovecii’s genes. This is the first time scientists have assembled the genome of a fungus from a mixed pool of DNA from a single source, according to researchers. The analyses revealed a “surprising fact,” according to the team: P. jirovecii is a parasite that must live within the human body to survive.

“It implies that they need their host to provide these molecules. Thus, this has been quite an important finding which implied that human beings represent the reservoir of this pathogen,” said Hauser.

This finding indicates that people are the only significant source of the organism and that both infected people and healthy carriers represent the only control points for limiting the spread of the disease, said researchers, who note that because “the genome of P. jirovecii is assembled and available to researchers all over the world, scientists can tease out clues about the organism that will help identify targets for some badly needed new drugs.”