Genomics Approach to Shigella and Chlamydia
These new genetic techniques could result in better therapies and safer vaccines.
Throughout history, more military personnel have died from infectious diseases than from combat. Dysentery remains a problem to this day, especially in developing areas. Though the disease is far more treatable, because of its high degree of contagion, dysentery still poses a significant threat to military readiness.
Investigating Shigella
One of the causes of dysentery is a bacteria called Shigella flexneri, which is becoming increasingly resistant to multiple antibiotics. Researchers working in the USU lab of Anthony Maurelli, Ph.D., are using a genomics approach to study the bacteria.
Shigella shares a non-pathogenic ancestor with Escherichia coli (E. coli). Though the two are very similar, a non-pathogenic strain of E. coli is normally present in the human body.
Searching for Black Holes
The traditional approach is to identify the genes that are present in Shigella and not E. coli. Instead, the group is taking the reverse tactic—examining the genes that are present in E. coli., but not Shigella. The theory is that Shigella has knocked out certain genetic traits because they are not compatible with pathogenicity.
Acting on this idea, researchers re-introduced some of those genes back into Shigella. The result was an attenuated form of the bacteria.
This research holds promise not only for new therapeutics and safer vaccines for dysentery, but also for other avenues of investigation. Conceivably, researchers can use this same reverse-analysis method to isolate deletions, or "black holes," in other pathogenic bacteria.
Applying New Methods to Chlamydia Research
Maurelli and colleagues are also examining Chlamydia trachomatis, a pathogen for which there is currently no genetic means of investigation. Chlamydia is the most common sexually transmitted infection in the U.S. and is a significant health threat in areas of Africa, where it is common as a respiratory pathogen and is one of the leading causes of blindness.
Scientists in the Maurelli lab have devised a plaque assay to grow a pure population of the bacteria and mutant variants. The group also is working to create specific mutations in Chlamydia bacteria to determine what it needs to grow and replicate.