Introduction and Goals
Introduction
Hepatitis is a very significant global health concern. Several different viruses have been identified—(hepatitis A, B, C, D, and E viruses)—which, collectively, account for the majority of viral hepatitis in humans. Of these, hepatitis A and E viruses are transmitted through the fecal-oral route and cause only acute infections that are generally resolved without complications and impart long-term immunity. Hepatitis B, C, and D, on the other hand, are transmitted through infected blood, frequently causing chronic infection, and are exceedingly dangerous, and often insidious, pathogens. They afflict more than half a billion people worldwide, and are responsible for over a million deaths a year. Chronic infection with these three viruses leads to cirrhosis of the liver, end stage liver disease, and primary liver cancer.
Effective vaccines are now available against hepatitis A and B viruses, and a vaccine for the hepatitis E virus is in advanced clinical trials. The vaccine against hepatitis B also protects against hepatitis D, because replication of the latter is dependent on hepatitis B virus and hepatitis D can therefore only exist as a co-infection with hepatitis B virus. There is no vaccine against the hepatitis C virus at present. There are only moderately successful treatment options for hepatitis B and C chronic infections. These are poorly tolerated, expensive, and inevitably rendered ineffective in the long run by the development of drug-resistant mutant viruses or nonresponsiveness.
Plans, Priorities and Goals
The NIAID Hepatitis Research Program supports research on all hepatitis viruses. However, commensurate with the magnitude of the medical burdens imposed by these viruses, the greatest emphasis is placed on the study of hepatitis C and hepatitis B viruses. These studies focus on
- Understanding the pathogenesis and immunology of hepatitis viruses
- Developing novel therapeutics and vaccines against diseases caused by hepatitis viruses
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