Immunology

Resist and Persist

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Science  18 Jan 2002:
Vol. 295, Issue 5554, pp. 407
DOI: 10.1126/science.295.5554.407b

Hepatitis C virus (HCV) is a pathogen of worldwide importance and a primary cause of liver disease in many of the 170 million infected individuals. How HCV can persist for years in its host is unclear, although it is likely that chronic infection is achieved through a variety of strategies for evading or resisting the immune system. Among these may be the ability of HCV to directly manipulate antiviral immune responses.

Crotta et al. and Tseng et al. both show that the viral envelope protein HCV-E2 has a direct and potent effect on the activity of natural killer (NK) cells, which are critical for the early innate response to pathogens. Binding of the cell surface protein CD81 by HCV-E2 inhibited activation signals that normally induce killing activity and antiviral cytokine expression by NK cells. Interestingly, these effects were opposite to those seen upon HCV-E2 binding of CD81 on T cells. Both groups suggest that by suppressing the immediate NK response, HCV may overwhelm and possibly modify subsequent immune responses generated by T and B lymphocytes, allowing an acute infection to become chronic. — SJS

J. Exp. Med.195, 35; 43 (2002).

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