Genetic-engineered Schizochytrium sp. expressing a multiepitopic protein based on Vibrio parahaemolyticus toxins triggers immune responses in mice

Abstract

Vibrio parahaemolyticus is a bacterium that naturally occurs in coastal waters and can multiply in warmer temperatures. Infection with these bacteria can inflict acute gastroenteritis by consuming contaminated seafood. Antibiotics must be prescribed. However, some antibiotics are no longer effective and no vaccine is available yet. Herein a microalgae-made immunogenic protein made up of epitopes from V. parahaemolyticus hemolysin toxins named Epi_Vp is reported. Epitopes from the proteins TDH, TRH, and TLH were selected for the Epi_Vp vaccine design by in silico studies, revealing an antigenic but not allergenic multiepitopic protein. The expression of Epi_Vp in Schizochytrium sp. was confirmed by Western blot after induction. Yields measured by ELISA reach 218. 63 μg g−1 dry-weight microalgae 48 h post-induction. Schizochytrium sp.-expressing Epi_Vp was found immunogenic in mice upon oral whole-cell administration in terms of specific serum IgG mucosa IgA. In addition, an increase of IFN-γ, IL-10, and IL-4 cytokine levels in splenocytes was detected. In conclusion, Epi_Vp protein expressed and delivered within the microalgae Schizochytrium sp. is capable of triggering humoral responses in an animal model and represents a potential oral vaccine prototype to combat infectious gastroenteritis caused by Vibrio parahaemolyticus.