title: 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.affiliation: Université de Lyon, Lyon, Lyon, France.
authors.forename: F
authors.initials: F
authors.lastname: Saade
authors.forename: T
authors.initials: T
authors.lastname: Buronfosse
authors.forename: S
authors.initials: S
authors.lastname: Guerret
authors.forename: P
authors.initials: P
authors.lastname: Pradat
authors.forename: M
authors.initials: M
authors.lastname: Chevallier
authors.forename: F
authors.initials: F
authors.lastname: Zoulim
authors.forename: C
authors.initials: C
authors.lastname: Jamard
authors.forename: L
authors.initials: L
authors.lastname: Cova
mesh_terms: D000818:Animals; D002353:Carrier State / Q000628:therapy / Q000821:virology; D004279:DNA, Viral / Q000302:isolation & purification; D004372:Ducks; D005500:Follow-Up Studies; D018347:Hepadnaviridae Infections / Q000628:therapy* / Q000821:virology; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D015611:Hepatitis B Virus, Duck / Q000235:genetics / Q000276:immunology*; D006524:Hepatitis, Viral, Animal / Q000628:therapy* / Q000821:virology; D007371:Interferon-gamma / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D007376:Interleukin-2 / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D008099:Liver / Q000821:virology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D019562:Viral Load; D014766:Viremia / Q000628:therapy / Q000821:virology
chemical_list: D004279:DNA, Viral; D017325:Hepatitis B Vaccines; D007376:Interleukin-2; D019444:Vaccines, DNA; D007371:Interferon-gamma