Scientists describe biochemistry of vaccine adjuvants.

2003 DEC 17 - (NewsRx.com & NewsRx.net) -- A team of scientists at the Scripps Research Institute (TSRI) has published a paper that explains how adjuvants work in greater biochemical detail than has been known previously.

Adjuvants are preparations like killed bacteria mixed with mineral oil that are usually administered with a vaccine. Vaccines themselves are also composed of specific proteins or other bacterial or viral markers that prime the immune system to recognize the strain of virus or bacteria from which they are derived. Immunization works by priming the immune system to recognize this material so it can respond quickly and clear the infection from the system.

For reasons that were not entirely understood, adjuvants help this process by co-stimulating the immune system when the vaccine is given. Adjuvants make vaccines more effective - in fact, immune responses to vaccines are usually meager in the absence of co-administered adjuvant.

But while scientists have known for 80 years that certain components of microbes make good adjuvants - like double-stranded RNA, a common form of viral genome, or lipopolysaccharide (LPS), a fatty component of certain bacteria - the biochemical basis for their action has not been understood at all.

The new research, which appears in an upcoming issue of the journal Nature Immunology, has changed this.

"We have now found a highly specific biochemical pathway required for adjuvanticity," said TSRI Professor Bruce Beutler, MD, who led the research with Kasper Hoebe, PhD, a postdoctoral fellow in the Beutler laboratory.

In their paper, Beutler, Hoebe, and their colleagues show that LPS and dsRNA create an adjuvant effect by inducing the synthesis of molecules known as type I interferons.