An Indiana University team of researchers has conducted the most in-depth and diverse genetic analysis of the defense systems that trillions of micro-organisms in the human body use to fend off viruses. The work is among a collection of 16 research papers released today by the Human Microbiome Project Consortium, a National Institutes of Health-led effort to map the normal microbial make-up of healthy humans.
Led by IU Bloomington assistant professor of informatics and computing Yuzhen Ye, the team of bioinformaticists and biologists reconstructed arrays of clusters of regularly interspaced short palindromic repeats -- CRISPRs -- which function as immune systems to the bacteria that play a vital role in human health. Between genomic repeats, CRISPR locations carry short strands of foreign DNA called spacers, which provide a history of past exposures to outside invaders like plasmids and bacteriophages (viruses that infect bacteria), and allow the bacteria to fight off viruses they have already encountered.
"By studying CRISPRs and their sequences, we ask the same types of questions we ask about viral infections in humans and other animals: Do individuals make antibodies to a particular virus? If they do, we then know they have been exposed to that virus," Ye said. "By examining CRISPR sequences, we learn about what viruses there have been infecting different species of bacteria in a particular environment."
Bacteriophages are the most abundant life form on the planet and are in a constant arms race with bacteria, which in the human body outnumber human cells by 10 to 1. Scientists want to better understand how microbes -- a group that contributes more genes responsible for human survival than humans themselves do -- battle the viruses that seek to infect them.
Using a targeted assembly strategy to reconstruct CRISPR arrays that otherwise are impossible to identify from whole metagenome assemblies, the team identified the
|Contact: Steve Chaplin|