Friday, August 5, 2011
A Vaccine For Hepatitis C Has Been Tested Successfully
European scientists say they have successfully tested in animals a vaccine for hepatitis C, a contagious and debilitating virus that can cause liver failure and cancer.
Currently, there is no human vaccine for hepatitis C (HCV), which is spread through contaminated blood and kills some 350,000 people worldwide each year, according to the World Health Organization.
Around 170 million people are estimated to be living with chronic disease caused by the virus. At least 10 million of them are illegal drug users who have contracted HCV by sharing needles or other drug paraphernalia, a recent study has shown. "Without rapid intervention to contain the spread of the disease, the death rate from hepatitis C is estimated to surpass that from AIDS in the next century," the researchers warn.
Unlike hepatitis A or B, most people infected with HCV cannot shake off the virus on their own because, when under attack by the immune system, it morphs into stronger variants.
The body is unable to produce enough "neutralising antibodies," the only kind able to handling a broad array of mutations. But in the case of HCV, using the classic technique of making a vaccine from a weakened or inactive form of the virus which works well in inducing such antibodies is too dangerous due to potential side-effects and the risk of infection.
As an alternative strategy, a team led by French researcher David Klatzmann of the Universite Pierre et Marie Curie in Paris used so-called "virus-like particles" to create the vaccine, which was tested on mice and monkeys.
Virus-like particles provoke an immune reaction, helping the body to develop resistance, but do not contain any genetic material that would allow a "virus" to multiply. "Once injected into the body, the virus-like particles have the capacity to trigger neutralising antibodies that could protect a person if they are exposed to the virus," the researchers said in a statement.
This technique has already been used in other vaccines, notably for the human papillomavirus, also a cancer-causing agent.
The new vaccine, developed in partnership with French start-up Epixis, worked against five different variants of HCV, offering hope that it would also beat back mutations as they occurred.
The results were published Wednesday in the journal Science Translational Medicine.
The next step will be to conduct human trials, which could start as early as next year.
It is still uncertain, however, whether the same vaccine will work as well in people, notes Rajit Ray, a researcher from Saint Louis University in Saint Louis, Missouri, in a commentary in the same journal.
HCV does not replicate in non-human primates other than chimpanzees which are no longer used in experiments so the potency of the vaccine could not be evaluated in a human-like scenario.
The WHO estimates that three to four million people are newly infected with HCV each year. Countries with the highest rates of prevalence include Egypt (22 percent), Pakistan (4.0 percent) and China (3.2 percent), according to WHO.
Contamination can occur through blood transfusions, blood products and organ transplants, and the virus can also be passed on to a child if the mother is infected.