A novel mouse model for immunogenic evaluation of human HBV vaccines

Microarray gene expression profiling provides insights into functions of TIPE2 in HBV-related apoptosis

Tumor necrosis factor-α-induced protein-8 like-2 (TNFAIP8L2, TIPE2), a member of TNFAIP8 family, functions as a regulator in inflammation. Our previous studies showed that TIPE2 can negatively regulate HBV-specific CD8⁺ T lymphocyte functions. But the effect of TIPE2 on the apoptosis of HBV-infected hepatocytes which is very important for eliminating viruses remains unclear. Using gene expression microarray analysis, we find that TIPE2 deficiency can regulate the expression of apoptotic genes in liver tissues from HBV hydrodynamic injection (HI) mouse model. TIPE2 protein was detected in TUNEL staining positive hepatocytes in HBV-infected C57 mice. Interestingly, the TIPE2 expressed hepatocytes were just the HBV infected cells. Furthermore, TIPE2 upregulates the mRNA levels of FasL, Bim and TNFRsF1b which promote cells death, when TIPE2 was transfected into HepG2 cells in vitro. As a result, TIPE2 overexpression cells showed a higher number of apoptotic cells and increased level of cleavage caspase3 compared to controls. Those results indicate that TIPE2 participates in HBV infection by regulating apoptosis of virus-infected hepatocytes.

Interleukin-22 as a molecular adjuvant facilitates IL-17-producing CD8+ T cell responses against a HBV DNA vaccine in mice

Interleukin-22 (IL-22) is mainly produced by activated Th1 cells, Th17 cells and NK cells and promotes anti-microbial defense, pro-inflammatory and tissue remodeling responses. However, its potential use as a vaccine adjuvant has not been tested. In this study, we tested if a DNA construct expressing IL-22 (pVAX-IL-22) could be used as a molecular adjuvant to enhance host immune responses induced by HBV DNA vaccination (pcD-S2). After immunizing mice with pcD-S2 combined with pVAX-IL-22, we didn't find enhancement of HBsAg-specific antibody responses in comparison to mice immunized with pcD-S2 alone. However, there was an enhancement of the level of IL-17 expression in antigen specific CD8(+) cytotoxic T lymphocytes (Tc17). By using CD8 T-cell knockout (KO) and IL-17 KO mice, Tc17 cells were found to be a dominant population driving cytotoxicity. Importantly, there was a correlation between pVAX-IL-22 enhancement of T lymphocytes and a reduction of HBsAg-positive hepatocytes in HBsAg transgenic mice. These results demonstrate that IL-22 might be used as an effective adjuvant to enhance cellular immune responses during HBsAg DNA vaccination since it can induce Tc17 cells to break tolerance in HBsAg transgenic mice.

Successful establishment and evaluation of a new animal model for studying the hepatitis B virus YVDD mutant

The treatment of infection with lamivudine-resistant mutants of hepatitis B virus (HBV) with mutations in the YMDD motif has become a crucial issue in the clinic. In this work, the plasmids pcDNA3.1 (+)-HBV/C-YVDD and pcDNA3.1 (+)-HBV/C-YMDD were constructed and injected into BALB/c mice using a hydrodynamics-based procedure to investigate viral replication and expression of HBV lamivudine-resistant YVDD mutants in vivo. Compared with the YMDD group, HBsAg levels were higher in sera of mice in the YVDD group, but HBeAg levels were lower on day 1 after injection. Levels of HBcAg in hepatocytes were higher in the YVDD group on day 1, whereas the HBsAg levels were lower. The levels of HBV mRNA in the liver were higher in mice in the YVDD group on day 1 after injection. The results showed that injection with these plasmids resulted in efficient initiation of replication of HBV in mice and also suggested that the combined mutations in YVDD mutants could affect the replication process.

Effect of revaccination using different schemes among adults with low or undetectable anti-HBs titers after hepatitis B virus vaccination

Our objective was to investigate the effect of various reimmunization schemes for hepatitis B in adults with low or undetectable anti-HBs titers. Over 2 years, 10 μg of Saccharomyces cerevisiae-recombinant hepatitis B virus (HBV) vaccine (synthesized in China) was used in at least one standardized scheme to immunize 2,310 healthy male and nonpregnant female adults. Of these, 240 subjects tested negative for hepatitis B markers. These 240 subjects were equally divided into 4 groups. The first group, designated Engerix-40, was revaccinated with 40 μg Engerix-B; the second, Engerix-20, was revaccinated with 20 μg Engerix-B; the third, Chinese-20, was revaccinated with 20 μg Chinese-made yeast-recombinant vaccine; and the last group, Chinese-10, was revaccinated with 10 μg Chinese-made yeast-recombinant vaccine. Blood samples were collected before and 1, 2, 8, and 12 months after the first injection. The anti-HBs-positive conversion rates of the Engerix-40, Engerix-20, and Chinese-20 groups were higher than that of the Chinese-10 group (P < 0.01). Over time, the anti-HBs conversion rate increased in all groups, but values were significantly different from those for the other groups only in the Chinese-10 group (P < 0.001). The anti-HBs geometric mean titers (GMTs) of the Engerix-40, Engerix-20, and Chinese-20 groups were higher than in the Chinese-10 group (P < 0.05). Increased doses raise and maintain anti-HBs titers in subjects with low or undetectable titers after HBV vaccination.