EVMS research: Virus linked to hepatitis may have ocean origin

March 27, 2006

David O. Matson, M.D., Ph.D.

NORFOLK—Oceans and bays can benefit a community by providing food, waterborne transportation and ports for everything from shrimp boats to aircraft carriers. But a new study, published this month in the online Journal of Medical Virology, suggests the ocean may also harbor a virus linked to hepatitis.

Scientists from Eastern Virginia Medical School (EVMS) and Oregon State University (OSU) discovered the association by examining hundreds of blood samples from blood banks and also from patients who suffered hepatitis of unknown cause. The pathogen, known as vesivirus, showed up in patients suffering from hepatitis of an unknown origin at a higher rate than in the general population, the study showed.

While “it’s not hard-and-fast proof that the virus caused liver injury,” the elevated presence of vesivirus suggests it may play a part in the disease, said senior author David O. Matson, M.D., Ph.D., a professor of pediatrics at EVMS and a researcher at the EVMS Center for Pediatric Research.

The vesivirus is one of four strains in the caliciviridae family that affects humans and other animals. One strain, the norovirus, strikes cruise ship passengers. The vesivirus “first became known to humans in the 1930s with large outbreaks of disease in pigs,” said Matson. “We were the first to report that the vesivirus affects humans.”

The vesivirus strain studied is known to affect more than 20 species. This study suggests that vesivirus may play a role in a serious condition like hepatitis.

To conduct the study, researchers found antibodies to vesivirus in four groups.

• In blood donors whose blood was determined to be safe, research found that 12 percent showed antibodies to vesivirus, suggesting a previous infection.
• In donors who had evidence of liver damage based upon a liver enzyme test, and whose blood had been discarded as a result, 21 percent had antibodies to vesivirus.
• In blood samples from persons who had been diagnosed with clinical hepatitis, 29 percent had antibodies to vesivirus.
• In persons who previously had transfusions or dialysis, and who then developed hepatitis of unknown cause, 47 percent had antibodies to vesivirus.

After the antibody testing, the researchers tested for evidence of vesivirus itself in the blood and found about 10 percent of the blood samples from normal blood donors and from blood donors with evidence of liver damage to have vesivirus RNA, the virus's genetic material, in the blood.

“There is a broader potential for vesivirus infection and illness in humans than previously recognized,” said a principal investigator and coauthor Alvin Smith, a professor of veterinary medicine at OSU.

Researchers say that vesivirus has natural reservoirs in the marine community where it can replicate and recycle, infecting and sometimes causing health problems in seals, sea lions, whales, and perhaps fish, shellfish and other species. In general, the marine environment is “a relatively under-explored potential reservoir of human pathogens,” the researchers said in their study.

The vesivirus strain detected in the blood samples are similar to the strain in marine mammals.

This research was supported by the Oregon Agricultural Experiment Station; the OSU Foundation, Laboratory for Calicivirus Studies Fund; AVI BioPharma; and the EVMS Center for Pediatric Research.

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