In vivo infectivity of liver extracts after resolution of hepadnaviral infection following therapy associating DNA vaccine and cytokine genes.

Abstract

DNA-based vaccination appears of promise for chronic hepatitis B immunotherapy, although there is an urgent need to increase its efficacy. In this preclinical study, we evaluated the therapeutic benefit of cytokine (IL-2, IFN-γ) genes co-delivery with DNA vaccine targeting hepadnaviral proteins in the chronic duck hepatitis B virus (DHBV) infection model. Then, we investigated the persistence of replication-competent virus in the livers of apparently resolved animals. DHBV carriers received four injections of plasmids encoding DHBV envelope and core alone or co-delivered with duck IL-2 (DuIL-2) or duck IFN-γ (DuIFN-γ) plasmids. After long-term (8 months) follow-up, viral covalently closed circular (ccc) DNA was analysed in duck necropsy liver samples. Liver homogenates were also tested for in vivo infectivity in neonatal ducklings. Co-delivery of DuIFN-γ resulted in significantly lower mean viremia starting from week 21. Viral cccDNA was undetectable by conventional methods in the livers of 25% and 57% of animals co-immunized with DuIL-2 and DuIFN-γ, respectively. Interestingly, inoculation of liver homogenates from 7 such apparently resolved animals, exhibiting cccDNA undetectable in Southern blotting and DHBV expression undetectable or restricted to few hepatocytes, revealed that three liver homogenates transmitted high-titre viremia (3-5×10(10) vge/mL) to naïve animals. In conclusion, our results indicate that IFN-γ gene co-delivery considerably enhances immunotherapeutic efficacy of DNA vaccine targeting hepadnaviral proteins. Importantly, we also showed that livers exhibiting only minute amounts of hepadnaviral cccDNA could induce extremely high-titre infection, highlighting the caution that should be taken in occult hepatitis B patients to prevent HBV transmission in liver transplantation context.

• Authors: F Saade, T Buronfosse, S Guerret, P Pradat, M Chevallier, F Zoulim, C Jamard, L Cova
• Journal: Journal of viral hepatitis (J Viral Hepat) Vol. 20 Issue 4 Pg. e56-65 (Apr 2013) ISSN: 1365-2893 [Electronic] England
• PMID: 23490390 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2012 Blackwell Publishing Ltd.

Chemical References

• DNA, Viral
• Hepatitis B Vaccines
• Interleukin-2
• Vaccines, DNA
• Interferon-gamma

Topics

• Animals
• Carrier State (therapy, virology)
• DNA, Viral (isolation & purification)
• Ducks
• Follow-Up Studies
• Hepadnaviridae Infections (therapy, virology)
• Hepatitis B Vaccines (administration & dosage, genetics, immunology)
• Hepatitis B Virus, Duck (genetics, immunology)
• Hepatitis, Viral, Animal (therapy, virology)
• Interferon-gamma (administration & dosage, genetics, immunology)
• Interleukin-2 (administration & dosage, genetics, immunology)
• Liver (virology)
• Vaccines, DNA (administration & dosage, genetics, immunology)
• Viral Load
• Viremia (therapy, virology)