Salmonella Vaccines Fight Disease
(Ivanhoe Newswire) — A new class of therapeutics, known as recombinant attenuated Salmonella vaccines (RASV), may fight against fatal diseases such as hepatitis B, tuberculosis, cholera, typhoid fever, AIDS and pneumonia, according to a new study.
Researchers from Arizona State University have developed a way to make these vaccines safer and more effective. They demonstrated that a modified strain of Salmonella showed a five-fold reduction in virulence in mice, while preserving strong immunogenic properties.
Current vaccines are not adequate for protecting vulnerable populations against Streptococcus pneumoniae — the causative agent of diseases including pneumonia, otitis media, meningitis and bacteremia. With existing vaccines, heat stabilization and needle injection are required, which are often impractical for mass inoculation efforts in the developing world. Also, repeated doses are often needed to ensure full immunity, and costs for these vaccines are often high.
One route researchers have been looking at for vaccine development is to use a given pathogen as a "cargo ship" to deliver key antigens from the pathogen they wish to vaccinate against. Salmonella, the bacterium responsible for food poisoning, has shown promise for this purpose.
almonella is capable of delivering disease-causing antigens originating from viruses, bacteria and parasites. A Salmonella vaccine against pneumonia is currently in FDA phase 1 clinical trials.
"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," Dr. Roy Curtiss, chief scientist at Biodesign’s Center for Infectious Diseases and Vaccinology, was quoted as saying.
In the current research, the team describe a method aimed at retaining the immunogenicity of an anti-pneumonia RASV while reducing or eliminating unwanted side effects sometimes associated with such vaccines, including fever and intestinal distress.
"Many of the symptoms associated with reactogenic Salmonella vaccines are consistent with known reactions to lipid A, the endotoxin component of the Salmonella lipopolysaccharide (LPS)," the major surface membrane component, Qingke Kong, from the Biodesign Institute at Arizona State University, was quoted as saying. "In this paper, we describe a method for detoxifying the lipid A component of LPS in living cells without compromising the ability of the vaccine to stimulate a desirable immune response."
SOURCE: Journal of Immunology, June 29, 2011