Innate immunity, adoptive immunity and vaccine development

Abstract number: 1133_150

Abrignani S.

There is no vaccine for HCV and the only treatment which has proven efficacious is IFN- therapy. However, the success rate of this treatment is not satisfactory, thus there is a pressing need to develop prophylactic as well as therapeutic vaccines. HCV copes very well with the host's immune system. Once HCV enters the body, it is cleared naturally in a minority of cases. While most HCV infections do elicit immune responses, evidence of immunity is controversial. Obviously, an ideal vaccine should protect from infection in that it should elicit sterilising immunity. However, in the case of HCV where infection can only be assessed by PCR, a more realistic goal might be to look for vaccines capable of protecting from chronic infection. After all, HCV acute hepatitis is not a serious public health problem and most of us would be satisfied with a vaccine that allowed subclinical acute infection but which after a few months would be cleared by the immune response. Overall, our view is that a candidate HCV vaccine would be one that protects from infection and/or progression to chronic infection by the major genotypes. Our experience in chimpanzees demonstrates that a subunit vaccine composed by a recombinant form of the envelope glycoproteins can prime antibody and CD4+ T-cell responses that protect from chronic infection by heterologous HCV strains. Based on these results, we have now started prophylactic as well as therapeutic clinical trials for such a vaccine.