Immunity against persistent hepatitis C virus, or HCV, protection can be acquired, said researchers at Johns Hopkins School of Medicine.
According a press release from The Lancet, neither previous HCV infection nor vaccination protect against HCV reinfection. However, they have been shown in chimpanzees to reduce the magnitude and duration of HCV symptoms after reinfection. In the April 27 issue of The Lancet, researchers reported on a study they conducted to establish whether this type of adaptive immunity to HCV could be achieved in humans.
From a study of injecting drug users, researchers identified 164 subjects who had no evidence of previous HCV infection and 98 who previously had been infected with HCV, but no longer were. Researchers then compared the incidence and persistence of HCV infection in these two groups over four consecutive six-month periods.
The incidence of HCV infection was 12 percent for subjects who had been infected previously compared with 21 percent for those who had not been infected previously.
"The high rate of HCV infection in injecting drug users underscores the importance of preventing HCV infection," said researcher David L. Thomas, M.D., associate professor of medicine. "Since it appears that immunity can be acquired to protect against viral persistence, vaccines should be tested to reduce the medical consequences of HCV infection among people at highest risk."
In an accompanying commentary, Michael Grant, Ph.D., associate professor of immunology, Memorial University of Newfoundland, said, "While the most positive interpretation of this unique study offers hope that protection against HCV can be acquired, the immunogenicity of human vaccines pales compared with that of genuine infections. The need for creative research in vaccine design is emphatically underlined by the, at best, part protection against persistent secondary infection conferred by clearance of primary infection with HCV itself."
