From Drug Discovery and Development
A new class of therapeutics, known as recombinant attenuated Salmonella vaccines (RASV), holds potential in the fight against fatal diseases including hepatitis B, tuberculosis, cholera, typhoid fever, AIDS, and pneumonia.
Qingke Kong and his colleagues at the Biodesign Institute at Arizona State University, have developed a technique to make such vaccines safer and more effective. Under the direction of Roy Curtiss, MD, chief scientist at Biodesign’s Center for Infectious Diseases and Vaccinology, demonstrated that a modified strain of S showed a five-fold reduction in virulence in mice, while preserving strong, immunogenic properties.
Streptococcus pneumoniae, an aerobic bacterium, is the causative agent of diseases including community-acquired pneumonia, otitis media, meningitis, and bacteremia; it remains a leading killer.
Existing vaccines are inadequate for protecting vulnerable populations for several reasons. Heat stabilization and needle injection are required, which are often impractical for mass inoculation efforts in the developing world. Repeated doses are also needed to induce full immunity.
One of the most promising strategies for new vaccine development is to use a given pathogen as a cargo ship to deliver key antigens from the pathogen researchers wish to vaccinate against. salmonella, the bacterium responsible for food poisoning, has proven particularly attractive for this purpose, as Curtiss explains: “Orally-administered RASVs stimulate all three branches of the immune system stimulating mucosal, humoral, and cellular immunity that will be protective, in this case, against a majority of pneumococcal strains causing disease.”
Recombinant Salmonella is a highly versatile vector–capable of delivering disease-causing antigens originating from viruses, bacteria, and parasites. An attenuated Salmonella vaccine against pneumonia, developed in the Curtiss lab, is in FDA phase 1 clinical trials.