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Herpes virus is found to destroy oral tumors in mice, say researchers at the State University of New York Health Science Center at Syracuse

In the first study of its kind, a team of researchers has discovered that the herpes simplex virus type-1 (HSV-1) destroys oral tumors in mice. This discovery could have implications for improved treatment of oral cancers, scientists say.

The study was conducted by Edward Shillitoe, Ph.D., and Christopher Pellenz of the Department of Microbiology and Immunology in the College of Medicine at the State University of New York Health Science Center in Syracuse, and Eric Gilchrist and Valerie Murrah of the University of North Carolina School of Dentistry. The study appears in the March 1999 issue of Oral Oncology.

The scientists found that when the herpes simplex virus was injected into human oral cancer cells growing as tumors in nude mice, the virus spread quickly through the tumors and eliminated them. The virus also eliminated tumor cells in culture.

However, after destroying the tumors in mice, the herpes virus spread to the skin and nervous system, often causing significant health problems.

"We need to design a mutant virus that is toxic to the tumor, but safe for other tissues," Dr. Shillitoe said. "Although the herpes virus spreads to the brain it does not spread until after the virus has its effect on the tumor. It should be possible to separate the two effects."

The scientists selected the herpes virus for their work on oral cancer because it is highly toxic and its natural target tissue is the oral epithelium-the tissue of origin of most oral malignancies. Modified viruses used in previous experiments have been too weak to fight the cancer, Dr. Shillitoe reported.

"Now it's time to move onto more aggressive viruses even though there's a risk of side effects," he said. "Our data suggest that a mutant herpes virus that expresses the UL42 gene mainly in oral cancer cells could have the therapeutic effect, but not the undesired side effects of the herpes virus we used. We are now trying to construct such a mutant."

Oral cancer accounts for about 8 percent of all malignant growths. Men are affected twice as often as women, particularly men over 40 years old.

Approximately 50 percent of people with oral cancer will live for longer than five years. If the cancer is detected early, before it has spread to other tissues, the cure rate can be substantial. Unfortunately, over 50 percent of oral cancers are advanced at the time the cancer is detected. Most have spread to the throat or neck. Approximately 25 percent of people die from oral cancer because of delayed diagnosis and treatment. Current treatments include surgery and radiation therapy.

Dr. Shillitoe, who directs the Department of Microbiology and Immunology at the State University of New York Health Science Center, has studied oral cancers for more than 20 years. He is a member of numerous organizations and associations, including the American Association for the Advancement of Science and has authored more than 120 articles and abstracts.

The State University of New York Health Science Center at Syracuse is one of 125 academic medical centers in the United States. The Health Science Center consists of four colleges: Medicine, Nursing, Health Professions and Graduate Studies. Aside from its academic mission, the Health Science Center includes University Hospital, a 350-bed teaching hospital, which is Central New York's Level 1 trauma center.

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