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New Hepatitis C Shot Shows Promise in Human Trials

Hepatitis C Vaccine

photo credit: NIAID, “Syringe and Vaccine” via Flickr. CC BY 2.0

It is estimated that about three percent of the world’s population is chronically infected with hepatitis C virus, also known as HCV. Compared with hepatitis A or B viruses, at present, no approved vaccine has been identified for HCV, which has posed a heavy burden on global health.

However, a group of scientists from Oxford University has been making great efforts in this respect and based on their latest human trial, the research result is so promising that an efficient vaccine would be found in the near future.

According to the description in the journal Science Translational Medicine, the strong and broad immune responses against hepatitis C virus was induced by the vaccine and at the same time, it was tolerated well in the volunteers. In the following move, the scientists is now testing the vaccine to examine its effectiveness in intravenous drug users in the U.S.A, allowing it to be the furthest stage where a hepatitis C vaccine was able to reach in clinical trials so ever.

Hepatitis is generally related to inflammation of the liver, which could be caused by different things, like alcohol and drugs as well as bacterial infections. In addition, a lot of viruses are the causes leading to hepatitis, but in most cases, they are hepatitis A, B, C, D and E viruses. Among all these five viruses, A, B and C are blamed for the most infections all over the world. Although HAV infections could be typically swept from the body with no treatment, HBV and HCV could create chronic infections causing liver problems, liver scarring and even liver cancer in a long run.

It is already known that effective vaccines to deal with hepatitis A and B viruses have been discovered, but researchers are trying very hard to find the same achievement for HCV, because HCV could mutate itself more frequently, thus resulting in difficulty of focusing on individual viral components. However, as one in four people infected for the first time are capable of getting rid of the virus in naturally, it is suggested that effective immune responses could be actually increased against it.

Further examination targeted on these individuals has demonstrated that a certain group of cells in the immune system, known as T cells, could play an important part to controll the virus. Therefore, scientists from OxfordUniversity have tried in development of a vaccine which can induce a similar immune response against the virus in people.

To this end, they have developed two different vaccines which could be generated by the means of adding genes for various HCV components to two different viruses. As the viruses applied are replication defective, they could not be able to cause disease. The concept goes like this; when the genetic material is injected into host cells, these cells would in turn create viral proteins which could stimulate the immune system.

In their designing, the first vaccine was used to prime the immune system, being ready for attack, and the second would serve as a booster for enhancement of the immune response.

In testing their vaccines on 15 healthy volunteers, researchers found that these volunteers had induced strong and broad T cell responses sustaining the period of over six months. The T cells generated after vaccination, compared with those observed in individuals who are capable of getting rid of infection naturally, targeted numerous different parts of the virus, which has shown a very promising image. But scientists are not sure at this stage whether the vaccine would be effective in prevention of infection. To find out more practical solutions, researchers are now engaged in efficacy trials.

Source: STMOxford UniversityHealthday and Reuters

Journal reference: Swadling, Leo, et al. “A human vaccine strategy based on chimpanzee adenoviral and MVA vectors that primes, boosts, and sustains functional HCV-specific T cell memory.” Science translational medicine 6.261 (2014): 261ra153-261ra153.

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