"Our findings suggest that humans can acquire immunity that protects against the disease caused by hepatitis C virus."
Humans may be able to develop immunity to hepatitis C virus, according to a study by Hopkins researchers published in the April 26 issue of The Lancet, findings that add to a growing body of evidence that immunity to the virus can be acquired. The findings are important because no vaccines exist for preventing hepatitis C in humans although preliminary vaccine research in primates appears promising.
Other studies in chimpanzees demonstrate that although animals who were previously infected or vaccinated could be infected with hepatitis C virus, those infections were less likely to persist compared to animals infected for the first time, according to David L. Thomas, associate professor of medicine at Hopkins and lead author of the study.
"We found the same in humans, suggesting that humans can acquire immunity that protects against hepatitis C virus persistence," says Thomas. "If this is indeed the case, it suggests that vaccines can be used to protect us from the long-term complications of hepatitis C infection, like liver cirrhosis and liver cancer."
In their study of injecting drug users from Baltimore, Md., Thomas, co-author Shruti Mehta, M.P.H., and colleagues identified 164 people whose blood tests revealed no evidence of previous hepatitis C infection, and 98 people who had been infected in the past but were not currently infected with the virus. They compared the incidence and persistence of infection in these two groups over four consecutive six-month periods.
People previously infected were half as likely to develop new infections compared to those who had not been previously infected (12% compared to 21%, respectively). Among HIV-1-negative people, those previously infected were 12 times less likely to develop persistent infection than people infected for the first time .
"The medical consequences of hepatitis C virus are tremendous," says Thomas. "Our findings indicate that vaccines should be developed to reduce the burden of liver disease associated with hepatitis C infection."
Close to 4 million people in the United States and 170 million people worldwide have been infected with the hepatitis C virus. Eighty-five percent of those infected develop persistent infection and are at risk of serious complications such as liver cirrhosis and liver cancer, according to Thomas.
Other authors of the study are Stephanie Strathdee, Ph.D., Andrea Cox, M.D., Xiao-Hong Wang, M.D., Qing Mao, M.D., and Stuart Ray, M.D., all from Johns Hopkins; Donald Hoover, Ph.D., of Rutgers University, and David Vlahov, Ph.D., of the New York Academy of Medicine. The study was funded by the National Institute on Drug Abuse and the National Institute of Allergy and Infectious Disease.
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http://hopkins-id.edu/
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Journal
The Lancet