Currently, there is no hepatitis C vaccine for three basic reasons:
- HCV has different genotypes. These genotypes are basically genetic variations of a theme. They're hepatitis C viruses, but they have enough genetic difference to be classified in distinct genotypes. Since hepatitis C has at least six genotypes, several different vaccines would be needed to protect against each genotype.
Maybe it's helpful to compare genotypes with members of a family. A family is made up of many different people, each with their own personality and looks, but all are still members of a family. It's very similar with the hepatitis virus. There are different genotypes, but they are all hepatitis C viruses.
- HCV mutates very easily. This means that some of its genetic code can change a little bit when it replicates itself. The result is a virus that keeps its genotype, but is different enough to confuse a vaccine.
- There is no effective small animal model or cell culture system. This makes vaccine development very challenging because researchers can't see how the virus really works in a natural environment. Really, scientists don't truly understand the whole life-cycle of the hepatitis C virus because infecting liver cells (called hepatocytes) is very difficult.
This may be changing. Researchers from the University of California, San Diego School of Medicine announced in July 2008 that they have developed a culture system that can model infection with the hepatitis C virus. This is great news for HCV vaccine development.