New technique could make hepatitis B, TB vaccines safer

A group of researchers directed by Dr. Roy Curtiss has developed a technique to make recombinant attenuated salmonella vaccines safer and more effective against diseases like hepatitis B and tuberculosis.

Using a given pathogen as a sort of cargo ship to deliver key antigens stimulates the immune system, according to the report written by researchers at the Biodesign Institute at Arizona State University in Tempe, Ariz. A modified strain of salmonella was found to yield a five-fold reduction in virulence in mice while preserving strong immunogenic properties, Scicasts.com reports.

"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,” Curtiss said, according to Scicasts.com.

An attenuated salmonella vaccine against pneumonia that was developed in the Curtiss lab is now in FDA phase 1 clinical trials. In the report, published in the current issue of the Journal of Immunology, researcher Qingke Kong describes a method to reduce or eliminate unwanted side effects in Salmonella while retaining immunogenicity.

"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,” Kong said, according to Scicasts.com. "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."

By inducing Salmonella to produce dephosphoylated lipid A, the vaccine may be rendered safer and may hold promise for the construction of such vaccines for humans.