Transgenic mice replicating hepatitis B virus but lacking expression of the major HBsAg

Abstract

Hepatitis B Virus (HBV) transgenic mice replicating the viral genome at high level but lacking expression of the small envelope protein (HBsAg) have been produced using a terminally redundant viral DNA construct (HBV 1.4). The generation of viable infectious progeny was dependent on sex and age of mice. Viral mRNA was abundant in liver and kidneys and at low levels in other organs of the mice. No viral particles or HBV envelope proteins could be detected in sera of mice. Despite expression of non-secreted LHBs and MHBs proteins in the liver, there was no accumulation of viral particles in the endoplasmic reticulum of hepatocytes and no necroinflammatory hepatitis was observed. Therefore, these mice represent an excellent model for studies of the role of HBsAg in viral assembly, antiviral immune responses, the further understanding of HBV immunopathogenesis, and the development of antiviral vaccines.

Elimination of Immunodominant Epitopes from Multispecific DNA-Based Vaccines Allows Induction of CD8 T Cells That Have a Striking Antiviral Potential

“…C57BL/6JBom (B6) H-2 b mice, C57BL/6J-TgN(Alb1HBV)44Bri tg (Alb/ HBs) (27), 1.4HBV-S mut tg (32), and HLA-A*0201 (HHD) mice (38) were bred and kept under standard pathogen-free conditions in the animal colony of Ulm University (Ulm, Germany). Male and female mice were used at 12-16 wk of age.…”

“…Male and female mice were used at 12-16 wk of age. We used 1.4HBV-S mut tg males for immunization studies because HBV replication was reproducible higher and shows less variability than in the liver of tg females (32). All animal experiments were performed according to the guidelines of the local Animal Use and Care Committee and the National Animal Welfare Law.…”

“…This epitope may therefore be useful for therapeutic vaccines. We previously generated the 1.4HBV-S mut tg line that expresses the intracellular large surface but not the secreted small surface HBsAg (due to a mutation introduced at the translation start codon of the S-gene) (32). HBeAg is readily detected in the sera of 1.4HBV-S mut tg mice and HBcAg is efficiently expressed in the liver (32).…”

“…Most striking was the observation that the immune response can noncytolytically clear HBV from hepatocytes (33). We used the 1.4HBV-S mut tg mice (32) to test whether CD8 T cells deliver antiviral (replication-inhibiting) effector functions to the liver. 1.4HBV-S mut tg mice express a mutant, replicating HBV genome in the liver.…”

“…1.4HBV-S mut tg mice express a mutant, replicating HBV genome in the liver. An introduced T1438C mutation blocks expression of the small HBsAg (and hence secretion of HBsAg particles or virions from transgene-expressing hepatocytes) but allows HBV replication in hepatocytes, HBcAg expression by hepatocytes, and HBeAg secretion into the serum (32). This allowed us to investigate which vaccine-induced CD8 T cells can locally suppress HBV replication in hepatocytes.…”