Turning self-destructing Salmonella into a universal DNA vaccine delivery platform

Abstract

We previously developed a biological containment system using recombinant Salmonella Typhimurium strains that are attenuated yet capable of synthesizing protective antigens. The regulated delayed attenuation and programmed self-destructing features designed into these S . Typhimurium strains enable them to efficiently colonize host tissues and allow release of the bacterial cell contents after lysis. To turn such a recombinant attenuated Salmonella vaccine (RASV) strain into a universal DNA vaccine-delivery vehicle, our approach was to genetically modify RASV strains to display a hyperinvasive phenotype to maximize Salmonella host entry and host cell internalization, to enable Salmonella endosomal escape to release a DNA vaccine into the cytosol, and to decrease Salmonella -induced pyroptosis/apoptosis that allows the DNA vaccine time to traffic to the nucleus for efficient synthesis of encoded protective antigens. A DNA vaccine vector that encodes a domain that contributes to the arabinose-regulated lysis phenotype but has a eukaryotic promoter was constructed. The vector was then improved by insertion of multiple DNA nuclear-targeting sequences for efficient nuclear trafficking and gene expression, and by increasing nuclease resistance to protect the plasmid from host degradation. A DNA vaccine encoding influenza WSN virus HA antigen delivered by the RASV strain with the best genetic attributes induced complete protection to mice against a lethal influenza virus challenge. Adoption of these technological improvements will revolutionize means for effective delivery of DNA vaccines to stimulate mucosal, systemic, and cellular protective immunities, and lead to a paradigm shift in cost-effective control and prevention of a diversity of diseases.

Oral Delivery of a Novel Attenuated Salmonella Vaccine Expressing Influenza A Virus Proteins Protects Mice against H5N1 and H1N1 Viral Infection

“…For example, the recent seminal studies carried out by Curtiss and colleagues have shown the utility of attenuated Salmonella strains as oral vaccine candidates against influenza viruses [7, 26]. Anti-influenza vaccines were constructed based on an attenuated Salmonella mutant with the deletion of sif A gene [7].…”

Biomaterials at the interface of nano- and micro-scale vector–cellular interactions in genetic vaccine design

“…Various steps have been taken to address these criteria, including optimization of the plasmid backbone (origin of replication, backbone size and content, and antibiotic resistance markers), 18–24 engineering of the promoter and enhancer regions, 25–29 development of improved DNA and mRNA sequences, 13, 30–32 and the incorporation of leader and polyadenylation (poly A) sequences. 33 …”

Fabrication of nanocomposites and hybrid materials using microbial biotemplates

“…Synthetic microbes, as a kind of cell therapy, have broad potential for future applications in human disease treatment. For example, bioengineers have been designing various engineered bacteria to perform different specialized functions, such as detection and diagnosis of diseases [75] and production of therapeutics [76] and their delivering [77], which can self-eliminate after therapy [78]. With the development of synthetic biology, the future directions of bacterial cell therapy systems will set a variety of abilities in one and will be smarter as autonomous microbial Bphysicians^ [79].…”