The success of interferon-based treatment has shown that by boosting the immune system’s ability to fight the virus HCV can be reduced to undetectable levels. Drug companies have also been looking to see if there are other ways of stimulating our immune system which might be effective against the virus.
To date, the most advanced research focuses on the receptors we use to sense the presence of invading microorganisms such as bacteria, viruses and parasites. These are called toll-like receptors (TLRs).
So far, ten different TLRs have been identified in humans. Four of these have been shown to specialize in the recognition of the nucleic acids of viruses.
When TLRs are stimulated they emit signals which are essential to the immune system’s response. They are also partially responsible for triggering the inflammatory response to the presence of a virus by activating proteins called cytokines. Cytokines act as chemical messengers within the immune system, passing on signals which enable other reactions to take place. They also stimulate other parts of the immune system, which are vital in fighting HCV infection.
These are known as immunomodulatory treatments. Interferon-based therapies reveal that HCV infection can be cleared by stimulating the immune system’s response to the virus. Various drugs are currently being tested aimed at boosting this response. There is also research into making a therapeutic vaccine, which, in theory, will also bolster the immune system’s response.
Therapeutic vaccines offer a new approach to the use of vaccines. They are designed to treat people who are already infected with HCV. A preventive or prophylactic vaccine against hepatitis C is also being researched, though a viable preventive vaccine is probably many years away.