Veterinary College technician Joby Crispell poses with "Shadow."
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By Roger Segelken
Every Feb. 2 has a special significance for researchers at Cornell's College of Vet erinary Medicine, and it's not because scientists think a sleepy rodent on Groundhog Day can predict winter's end.
Rather, the groundhog (also known as the woodchuck) is honored at Cornell for its indispensable contributions to the study of liver disease in humans. For more than 15 years, animals born at the world's only scientific source of disease-free woodchucks have led researchers to discoveries in treatment and prevention of hepatitis B infection and the liver cancer it can cause.
"A percentage of the wild woodchuck population in the United States is infected with a virus very similar to HBV, the human hepatitis B virus. Humans don't get hepatitis from woodchucks with WHV, the woodchuck hepatitis virus, but the virus and its effect on their liver is similar enough to make the woodchuck the best system we have for studying viral hepatitis in humans," explained Bud C. Tennant, D.V.M., the James Law Professor of Comparative Medicine who heads the woodchuck-re search project.
Groundhogs in the Cornell program have been responsible for many advances in un derstanding liver disease (see accompanying chart), including the finding that immu nizing against hepatitis B virus can prevent liver cancer. Woodchucks are the best-avail able animal model for hepatitis B studies, Tennant said, because the woodchuck virus has a nearly identical effect on woodchuck livers as does human hepatitis B virus on human livers -- except that time is compressed. Disease processes that take 30 to 40 years in humans occur in three to four years in woodchucks. The only other animal model for HBV studies is the chimpanzee, an endangered species.
An estimated 250 to 300 million people, mainly in sub-Saharan Africa and Asia, are carriers of HBV, and about 40 percent of those infected will develop chronic liver damage or cancer. Many babies are born infected with the virus in those regions of the world, and they carry the infection throughout their lives.
Most of the woodchuck studies are conducted at Cornell, in collaboration with re searchers from the National Institutes of Health and from research centers supported by the NIH. The original woodchucks that formed the breeding stock for the Cornell colony were caught in the wilds of upstate New York, beginning in 1979.
Cornell raises the woodchucks indoors, under contract with the NIH, so the dis ease-free animals are essentially government employees. They must be consid
ered "essential" because they continued to work and receive their pay -- in woodchuck chow -- during the recent federal government furloughs.
Besides a reliable source of food, shelter and veterinary care, the Cornell groundhogs have one advantage that their outdoor cousins do not: an unfailing knack for predicting weather. Even the most celebrated of wild groundhogs -- which folklore credits with indicating another six weeks of winter if
they see their shadow on Groundhog Day -- are frequently and disappointingly wrong.
But not Shadow, the Cornell woodchuck colony mascot.
"By the time Shadow wakes up and comes out of her nestbox on Feb. 2, the indoor lights are on," Tennant revealed. "Not sur prisingly, she always sees her shadow.
"And we're never surprised if spring is months away," he said. "After all, this is Ithaca and upstate New York."