Professor Shepherd's Research Explores How Parasites Switch to Survive without Oxygen

Study Raises Prospects for New Treatments

SPOKANE, Wash. — Scientists estimate that 1 billion people worldwide are infected with parasitic helminths, round worms that live in soil and colonize human guts through dirty water. Gonzaga University Professor Jennifer Shepherd, Ph.D., has co-led a study showing that the helminths are able to survive in the low-oxygen environment of the human gut due to a unique enzyme variant.

Shepherd, professor and chair of Gonzaga’s chemistry and biochemistry department, notes the study raises prospects for new treatments to slow increasing resistance of parasites to available medications. Infections from these worms are common in less developed countries and have significant chronic negative consequences for child development.

“Survival by helminths in low-oxygen environments requires an electron transporter molecule named rhodoquinone, and its biosynthesis has been the focus of my research for over a decade,” Professor Shepherd said. “The discovery of a gene variant in parasites, which allows them to synthesize rhodoquinone, is significant since mammalian hosts do not contain this variant and thus it is a new selective target for drug discovery.”

Seven of the 18 neglected diseases categorized by the World Health Organization are caused by helminths, according to the Centers for Disease Control and Prevention (CDC, 2019).
Scientists know that the parasites use an aerobic, or oxygen-dependent, metabolism to create energy. Once consumed, the parasitic helminths begin using a type of anaerobic, or oxygen-independent, metabolism. The researchers’ work is advancing their understanding of the mechanisms involved in how the parasites are able to make the switch.

Understanding how that switch works might allow scientists to interfere with that switch, and possibly kill the parasite in humans.

The study was co-led by Gustavo Salinas, a professor at Universidad de la República in Uruguay and Andrew Fraser, professor of molecular genetics at the University of Toronto’s Donnelly Centre for Cellular and Biomolecular Research. Funding from the Canadian Institutes for Health Research and Agencia Nacional para la Innovación y la Investigación ANII in Uruguay have supported the study.

The complete findings are published in e-Life, an online journal for life-sciences.