The Scales of Science

Investigators unlock wonders of immunity by studying channel catfish

Ask most anybody on the University of Mississippi Medical Center campus where to get catfish and they’ll point you to a cafeteria.

Ask Dr. Gregory Chinchar, professor of microbiology, and he’ll take you to a hospital basement room where 150 of them bottom feed in aerated plastic tanks.

Catfish, live in a hospital?

It might seem an unlikely place, but the Medical Center has housed generations of these slick siluriforms. The fish are partners in a study that marks its 30th anniversary this year.

Chinchar, along with Dr. Norman Miller, Dr. Mel Wilson, Dr. Eva Bengten and, over the years, a couple-dozen doctoral candidates study the immune system of the channel catfish. Some of this work involves understanding just how the fish immune system works; other studies focus on how pathogens such as channel catfish virus are controlled.

That pathogen is a relative of herpes simplex virus, a virus that causes cold sores in humans. It doesn’t affect humans but attacks and kills Mississippi’s finned friends.

As cafeterias, plate-lunch shacks and fine restaurants across the state attest, catfish is a major industry. With 427 farms, Mississippi is the country’s largest producer of catfish.

Counting direct and indirect jobs, Mississippi’s catfish industry employs several thousand people while providing one of the most efficient and environmentally sustainable sources of protein.

By converting roughly one pound of food into 0.8 pounds of fish, channel catfish have one of the highest conversion ratios of any animal. Beef cows, by comparison, run about 80:1.

“So any change that immunology brings to protect the species means greater efficiency,” said Dr. Melanie Wilson, professor of microbiology, who works on the study.

The researchers call what they do basic science: laboratory-intensive work analyzing the virus and cellular-level responses.

Dr. Norman Miller, a microbiology professor who’s spent nearly his whole career in the study, said the work adds to the basic-science knowledge and understanding of immune responses.

“It also gives insight into the way gene families have evolved in other animals,” Chinchar said.

Fact is, their findings are anything but basic. In three decades they’ve published in the neighborhood of 250 papers and articles on catfish-immune responses alone. Their work has produced lines of genetically identical fish used as control subjects in related studies, both at the Medical Center and around the country.

Catfish cell lines, originally isolated at the Medical Center by Miller, are supplied to research institutions throughout the world. The work is being used to help develop the catfish genome expression map.

The study launched the careers of several-dozen microbiologists. Many former students go on to study immune systems in mammals, including humans, Miller said.

“The techniques you learn here are broad enough to apply to many different systems,” he said.

For example, Wilson and Bengten helped identify the function of a mysterious immunogloblulin, IgD.

“Their work helped show that IgD was present in cows, pigs and other  mammals, when previously it was thought they were only present in mice and men,” said Bengten, associate professor of microbiology.

That kind of crossover is called comparative immunology. And the study continues to produce it in spades. That feeds researchers at other institutions working on herpes vaccinations.

The study started out in 1979 with a comparative-findings goal.

“Initially we thought that looking into how a simple (immune) system functions in a lower, or primary, organism would give us insights into how more advanced organisms function with their immune responses,” said Miller, who plans to retire from the Medical Center in June.

“In some cases, systems are similar, but in many ways they’re very different. Catfish have very highly developed and specific immune systems.”

Over the years, funding has come from various sources, including the National Institutes of Health – where the project once held a coveted MERIT Award – the U.S. Department of Agriculture and the National Science Foundation.

In the future, the catfish research could help other commercial fish species, such as trout, salmon and cod.

In addition to the antibody studies, the “catfish group” hopes to identify cells that kill virus-infected cells and to use this information to help develop vaccines for aquaculture.

Overall, the 30-year project suggests that all advances don’t necessarily have to come from translational science. Scientists understand that we just need to know more.

-Jack Mazurak

2009-03-31 00:00:00 18879