Iowa State University

Inside Iowa State
July 17, 1998

He's after a prevention instead of the cure

by Steve Jones

Veterinary medicine researchers soon will have more knowledge about little understood bacteria that harm livestock and poultry.

Veterinary microbiologist F. Chris Minion is leading a project to sequence the genome of two species of mycoplasmas, considered the smallest free-living organisms known.

Scientists have sequenced human mycoplasmas, uncovering valuable genetic information to help fight mycoplasmal diseases including pneumonia. But Minion, a researcher at ISU's Veterinary Medical Research Institute (VMRI), is thought to be the first to sequence animal mycoplasmas. His work should speed research that someday may lead to vaccines and other intervention strategies to control the microscopic pathogens.

Genome sequencing indicates the order, or sequence, of the chemical units making up an organism's DNA. The sequencing provides a "virtual blueprint" of the DNA, the chemical building block of all living things.

Minion's project will sequence two respiratory mycoplasmas in swine and poultry. The actual sequencing will take place this summer and fall at a special laboratory at the University of Washington, Seattle. The lengthy preparation work took place at ISU.

With the sequencing information in hand, scientists will be able to begin determining what genes are responsible for what functions. Someday, researchers hope to learn how to manipulate the genes to control the mycoplasmas.

"There's a lot that can be done when we have the gene sequence," Minion said.

Mycoplasmas are a diverse group of bacterial pathogens first studied some 40 years ago. They're different from other bacteria because they lack cell walls. Although they're primitive organisms, they can be costly to livestock and poultry producers because the bacteria can spread quickly throughout a herd or flock.

Minion's research is needed because little is known about how mycoplasmas over-throw an animal's immune response and cause chronic infections. The mycoplasmas don't directly kill their hosts, but allow other infections to become more severe.

"The main problem is that they predispose the host to other diseases," Minion explained. "Despite being genetically simple pathogens, they have complex virulence mechanisms."

Hard evidence is lacking, but Minion said scientists believe mycoplasmas contribute to other health problems. In humans, this may include arthritis and AIDs.

"The mycoplasmas alter the immune response in ways we don't understand," he said. "They can cause all kinds of problems in a host."

Applying the results of Minion's sequencing research will be neither simple nor quick. Some diagnostic tests soon may be developed, but new vaccines could be years away. Minion estimates about 40 percent of the genes will have unknown functions, which will require additional investigation.

Minion is a native of Memphis, Tenn., where his mother was a nurse. Because of her profession, he had an interest in medicine and considered going to medical school. Eventually he decided becoming a scientist had more appeal than becoming a clinician.

"I wanted to stop diseases before they started, as opposed to treating them," Minion explained.

He received his Ph.D. in microbiology in 1983 from the University of Alabama at Birmingham. Prior to coming to ISU in 1986, he spent three years as a National Institutes of Health (NIH) postdoctoral fellow at the University of Tennessee Health Sciences Center in Memphis. His mycoplasma research has been funded by the NIH, the U.S. Department of Agriculture and the state of Iowa.

"Chris has built up a significant level of expertise on this topic and is an international authority on these mycoplasmas," said Harley Moon, professor-in-charge at the VMRI.

Moon said Minion's work complements the research of fellow VMRI scientists Eileen Thacker, Ricardo Rosenbusch and veterinary medicine Dean Richard Ross, who also study mycoplasmas.

"They make a strong team," Moon said.

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