- Hepatitis C has at least six genotypes, several different vaccines would be needed to protect against each genotype.
- The hepatitis C virus mutates very easily and therefore change its antigens. This would mean memory cells would not recognise the virus and cannot divide rapidly to produce plasma and more memory cells.
- No effective small animal model or cell culture system.
However, recently, a clinical trial was carried out by researchers from the Universities of Oxford and Birmingham, and from institutions throughout Italy to test a newly developed hep C vaccine. This phase 1 clinical trial tested the safety and tolerability of the new vaccine. The vaccine was created by inserting small pieces of DNA from the hepatitis C virus into a rare form of the virus that causes the common cold. First, the dosage required to produce an optimal immune response was studied using a 'dose-escalation' test where volunteers were divided into groups of four or five people, with each group being given a different dose of the vaccine. They also tested whether the immune response would hold against different strains of the hepatitis C virus, by taking a blood sample from the participants, challenging the blood cell with proteins found in the different strains of the virus and analysed the immune response.
The results found that there were no serious side effects and any side effects due to high dosage were short lived.
