Humoral Immune Response in Mice Elicited by Combined Yeast-Derived Hepatitis B Virus Core, Surface, and Mosaic Surface Antigens

Background: Although successful, the second-generation hepatitis B vaccine programs around the world have a small group of immunized individuals that does not respond efficiently to the vaccination. Other issues of these vaccines are individuals that are low or nonresponders and/or have incomplete protection against heterologous hepatitis B virus (HBV) genotypes/subtypes and against HBV escape mutants. In addition, there are approximately 240 million people chronically infected with HBV worldwide and 620,000 deaths per year caused by the infection. Methods : In this study we developed three Hansenula polymorpha plasmids containing the following sequences: (a) HBsAg subtype ayw, (b) HBcAg sequence subtype adw2, and (c) chimeric HBsAg (adw4/ ayw)-preS1 (adw2)-3 repetitions of preS2 (genotypes A, B, and C). The sequences were successfully expressed and the antigens purified. Using Balb/c mice the antigens were tested in different dosage combinations. Results: Three antigens were obtained at a high purity level and with high re-producibility. We also assessed their immunogenic properties, showing that the antigens, individually or in combination, generated anti-HBs, anti-preS1, anti-preS2, and anti-HBc antibodies efficiently in mice. Conclusions: The formulation tests showed that a combination of 0.02 mu g of HBs, 0.2 mu g of preS1-preS2-HBs, and 0.02 mu g of HBc was effective in eliciting specific antibodies in mice. (C) 2017 S. Karger AG, Basel