Novel hepatitis B virus infection mouse model using herpes simplex virus type 1 thymidine kinase transgenic mice

Spermidine enhances the efficacy of adjuvant in HBV vaccination in mice

Background: Various vaccine adjuvants have been developed to eliminate HBV from patients with chronic HBV infection. In addition, spermidine (SPD), a type of polyamine, has been reported to enhance the activity of immune cells. In the present study, we investigated whether the combination of SPD and vaccine adjuvant enhances the HBV antigen-specific immune response to HBV vaccination. Methods: Wild-type and HBV-transgenic (HBV-Tg) mice were vaccinated 2 or 3 times. SPD was orally administered in drinking water. Cyclic guanosine monophosphate-AMP (cGAMP) and nanoparticulate CpG-ODN (K3-SPG) were used as the HBV vaccine adjuvants. The HBV antigen-specific immune response was evaluated by measuring the HBsAb titer in blood collected over time and the number of interferon-γ producing cells by enzyme-linked immunospot assay. Results: The administration of HBsAg + cGAMP + SPD or HBsAg + K3-SPG + SPD significantly enhanced HBsAg-specific interferon-γ production by CD8 T cells from wild-type and HBV-Tg mice. The administration of HBsAg, cGAMP, and SPD increased serum HBsAb levels in wild-type and HBV-Tg mice. In HBV-Tg mice, the administration of SPD + cGAMP or SPD + K3-SPG with HBV vaccination significantly reduced HBsAg levels in the liver and serum.

CONCLUSIONS

These results indicate that the combination of HBV vaccine adjuvant and SPD induces a stronger humoral and cellular immune response through T-cell activation. These treatments may support the development of a strategy to completely eliminate HBV.

Modeling Hepatotropic Viral Infections: Cells vs. Animals

The lack of an appropriate platform for a better understanding of the molecular basis of hepatitis viruses and the absence of reliable models to identify novel therapeutic agents for a targeted treatment are the two major obstacles for launching efficient clinical protocols in different types of viral hepatitis. Viruses are obligate intracellular parasites, and the development of model systems for efficient viral replication is necessary for basic and applied studies. Viral hepatitis is a major health issue and a leading cause of morbidity and mortality. Despite the extensive efforts that have been made on fundamental and translational research, traditional models are not effective in representing this viral infection in a laboratory. In this review, we discuss in vitro cell-based models and in vivo animal models, with their strengths and weaknesses. In addition, the most important findings that have been retrieved from each model are described.