Z Gastroenterol 2006; 44 - P182
DOI: 10.1055/s-2006-950779

Evaluation of cross-genotype immunity by multigenotype HCV-NS3 recombinant vaccinia virus surrogat infection

C Eisenbach 1, A Freyse 1, C Lupu 1, K Weigand 1, E Ernst 1, B Hoyler 1, W Stremmel 1, J Bugert 2, J Encke 1
  • 1Universität Heidelberg, Gastroenterologie, Heidelberg, Germany
  • 2Cardiff University School of Medicine, Dept. of Medical Microbiology, Cardiff, United Kingdom

Aims: The development of an effective prophylactic vaccine against the hepatitis C virus (HCV) remains a major problem despite considerable efforts. Progress has been hampered by the lack of a convenient animal model and until recently by the limitations in growing the virus in cell culture. Therefore, experimental vaccines are frequently tested in mice, often employing HLA-A2.1 transgenic strains. Surrogate infections with HCV-recombinant vaccinia viruses (rVV) that replicate in the mouse have been used in a number of studies to evaluate vaccine potency in vivo. Although a lot has been learned about various vaccination strategies the genetic variability of HCV has been largely neglected.

Methods: We constructed a set of 16 vaccinia viruses recombinant for the HCV non-structural protein 3 (NS3) derived from patient isolates of HCV genotypes 1a, 1b, 2, 3 and 4, respectively, with an amino acid homology ranging from 0.800 to 0.998 as verified by direct sequencing. BALB/c mice immunized with recombinant NS3 protein derived from a genotype 1b isolate were challenged with the NS3-rVV and compared to mock immunized animals. The amount of viruses recovered from mouse ovaries after surrogate infection were taken as a measure of the specific immunity induced.

Results: Mice challenged with genotype 1 recombinant viruses showed a decrease in rVV titers ranging from factor 3.8–8.5 for subtype 1a and 32–54 for subtype 1b. In animals challenged with genotype 2, 3, 4 or wild type VV no change in titers could be detected.

Conclusions: Our proposed infection model is a convenient and reliable tool to analyse the induction of cross-genotype immunity by experimental vaccination of mice. The protection seen in our study has been limited to the same genotype with striking differences even between closely related subtypes. We conclude that for the development of a potential vaccine great care must be taken to cover the genetic broadness of HCV.