Identification of CD4+ and CD8+ T cell epitopes of woodchuck hepatitis virus core and surface antigens in BALB/c mice

The Strategy of Conditionally Replicating Adenovirus-Mediated PreS2 Mini-Antibody Expression Has Dual Effects of Inhibiting HBV Infection and Preventing Hepatocellular Carcinoma

Aim

To investigate the inhibitory effect of hepatitis B virus (HBV) preS2 mini-antibody (mPreS2) against HBV infection, HBV-associated liver injury and HBV-associated hepatic carcinogenesis.

Methods

A recombinant adenovirus vector with the human survivin promoter and mPreS2 gene, Ad5SVP-mPreS2, was constructed. Fluorescence microscopy examination and TCID 50 analysis were utilized to determine the specific proliferation of recombinant adenovirus in liver cancer cells. Western blot analysis was used to determine the mPreS2 expression levels. Enzyme-linked immunosorbent assay (ELISA) was used to examine HBsAg levels to evaluate the inhibitory effect of mPreS2 against HBV infection. The protective effects on hepatic function and preventive effects against hepatic carcinogenesis of Ad5SVP-mPreS2 were studied in diethylnitrosamine (DEN)-treated HBV transgenic Imprinting Control Region mice.

Results

The recombinant adenovirus regulated by the human survivin promoter proliferated exclusively in liver cancer cells rather than normal liver cells. The expression levels of mPreS2 were increased in liver cancer cells compared with normal liver cells, and mPreS2 could be used to recognize liver cells from HBV transgenic mice. ELISA showed that HBsAg levels were decreased in the group treated with Ad5SVP-mPreS2. Ad5SVP-mPreS2 had a protective effect on hepatic function in a DEN-induced liver injury model because of lower serum levels of alanine transaminase and aspartate transaminase. Additionally, HBV transgenic mice treated with Ad5SVP-mPreS2 had fewer and smaller cancerous nodes after induction with DEN than untreated mice.

Conclusion

Conditionally replicating adenovirus-mediated mPreS2 expression inhibited HBV infection and had an inhibitory effect on liver injury and hepatocellular carcinogenesis in HBV transgenic mice.

Identification of HLA-A*0201-restricted CD8+ T-cell epitope C₆₄₋₇₂ from hepatitis B virus core protein

The efficacy of a potential therapeutic vaccine against chronic hepatitis B virus (HBV) infection depends on the development of strong and multi-specific T cell responses. The potency of CD8+ cytotoxic T lymphocyte (CTL) responses toward HBV core antigen (HBcAg) has been shown to be critical for the outcomes of HBV chronic infection. In this study we have identified a previously undescribed HLA-A*0201-restricted HBcAg-specific CTL epitope (HBcAg₆₄₋₇₂, C₆₄₋₇₂, ELMTLATWV). T2 binding assay showed that C₆₄₋₇₂ had high affinity to HLA-A*0201 molecule. Functionally, the peptide C₆₄₋₇₂ could induce peptide-specific CTLs both in vivo (HLA-A2.1/K(b) transgenic mice) and in vitro (PBLs of healthy HLA-A2.1+ donors), as demonstrated by interferon-γ (IFN-γ) secretion upon stimulation with C₆₄₋₇₂-pulsed T2 cells or autologous human dendritic cells (DCs) respectively. HLA-A*0201-C₆₄₋₇₂ tetramer staining revealed the presence of a significant population of C₆₄₋₇₂-specific CTLs in C₆₄₋₇₂-stimulated CD8+ T cells. Furthermore, the peptide-specific cytotoxic reactivity and the production of perforin and granzyme B of CTLs also increased after stimulation with C₆₄₋₇₂-pulsed autologous DCs. These results indicate that the newly identified epitope C₆₄₋₇₂ has potential to be used in the development of immunotherapeutic approaches to HBV infection.

Adenovirus-expressed preS2 antibody inhibits hepatitis B virus infection and hepatic carcinogenesis

AIM: To investigate the inhibitory effect of hepatitis B virus (HBV) preS2 antibody (preS2Ab) against HBV infection and HBV-associated hepatic carcinogenesis.

METHODS: An adenoviral vector carrying the full-length light and heavy chains of the HBV preS2Ab gene, Ad315-preS2Ab, was constructed. Enzyme linked immunosorbent assay (ELISA) and Western blotting analyses were used to determine the preS2Ab expression levels in vitro. Immunofluorescent techniques were used to examine the binding affinity between the expressed HBV preS2Ab and HBV-positive liver cells. ELISAs were also used to determine hepatitis B surface antigen (HBsAg) levels to assess the inhibitory effect of the preS2Ab against HBV infection in L02 cells. The inhibitory effect of preS2Ab against hepatic carcinogenesis was studied with diethylnitrosamine (DEN)-induced hepatocellular carcinomas (HCCs) in HBV transgenic mice.

RESULTS: The expression of HBV preS2Ab increased with increases in the multiplicity of infection (MOI) of Ad315-preS2Ab in L02 cells, with 350.87 ± 17.37 μg/L of preS2Ab when the MOI was 100 plaque forming units (pfu)/cell. The expressed preS2Abs could recognize liver cells from HBV transgenic mice. ELISA results showed that L02 cells expressing preS2Ab produced less HBsAg after treatment with the serum of HBV patients than parental L02 cells expressing no preS2Ab. HBV transgenic mice treated with Ad315-preS2Ab had fewer and smaller cancerous nodes after induction with DEN than mice treated with a blank Ad315 vector or untreated mice. Additionally, the administration of Ad315-preS2Ab could alleviate hepatic cirrhosis and decrease the serum levels of alanine transaminase and aspartate transaminase.

CONCLUSION: Adenovirus-mediated HBV preS2Ab expression could inhibit HBV infection in L02 cells, and then inhibit DEN-induced hepatocellular carcinogenesis and protect hepatic function in HBV transgenic mice.

Identification of H-2d restricted T cell epitope of foot-and-mouth disease virus structural protein VP1

Background

Foot-and-mouth disease (FMD) is a highly contagious and devastating disease affecting livestock that causes significant financial losses. Therefore, safer and more effective vaccines are required against Foot-and-mouth disease virus(FMDV). The purpose of this study is to screen and identify an H-2d restricted T cell epitope from the virus structural protein VP1, which is present with FMD. We therefore provide a method and basis for studying a specific FMDV T cell epitope.

Results

A codon-optimized expression method was adopted for effective expression of VP1 protein in colon bacillus. We used foot-and-mouth disease standard positive serum was used for Western blot detection of its immunogenicity. The VP1 protein was used for immunizing BALB/c mice, and spleen lymphocytes were isolated. Then, a common in vitro training stimulus was conducted for potential H-2Dd, H-2Kd and H-2Ld restricted T cell epitope on VP1 proteins that were predicted and synthesized by using a bioinformatics method. The H-2Kd restricted T cell epitope pK1 (AYHKGPFTRL) and the H-2Dd restricted T cell epitope pD7 (GFIMDRFVKI) were identified using lymphocyte proliferation assays and IFN-γ ELISPOT experiments.

Conclusions

The results of this study lay foundation for studying the FMDV immune process, vaccine development, among other things. These results also showed that, to identify viral T cell epitopes, the combined application of bioinformatics and molecular biology methods is effective.