© 2014 The American Society of Gene & Cell Therapy. In this study, we have engineered a new mycobacterial vaccine design by using an antibiotic-free plasmid selection system. We assembled a novel Escherichia coli (E. coli)-mycobacterial shuttle plasmid p2auxo.HIVA, expressing the HIV-1 clade A immunogen HIVA. This shuttle vector employs an antibiotic resistance-free mechanism for plasmid selection and maintenance based on glycine complementation in E. coli and lysine complementation in mycobacteria. This plasmid was first transformed into glycine auxotroph of E. coli strain and subsequently transformed into lysine auxotroph of Mycobacterium bovis BCG strain to generate vaccine BCG.HIVA 2auxo. We demonstrated that the episomal plasmid p2auxo.HIVA was stable in vivo over a 7-week period and genetically and phenotypically characterized the BCG.HIVA 2auxo vaccine strain. The BCG.HIVA 2auxo vaccine in combination with modified vaccinia virus Ankara (MVA). HIVA was safe and induced HIV-1 and Mycobacterium tuberculosis-specific interferon-γ-producing T-cell responses in adult BALB/c mice. Polyfunctional HIV-1-specific CD8+ T cells, which produce interferon-γ and tumor necrosis factor-α and express the degranulation marker CD107a, were induced. Thus, we engineered a novel, safer, good laboratory practice-compatible BCG-vectored vaccine using prototype immunogen HIVA. This antibiotic-free plasmid selection system based on double auxotrophic complementation might be a new mycobacterial vaccine platform to develop not only recombinant BCG-based vaccines expressing second generation of HIV-1 immunogens but also other major pediatric pathogens to prime protective response soon after birth.
|Journal||Molecular Therapy - Methods and Clinical Development|
|Publication status||Published - 8 Jan 2014|