System admits vaccine adjuvants not safe.

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Posted: September 14, 2009

 

 

 

New nanoparticle-based 'adjuvant' could hold future of vaccine development

 

 

 

Vaccine development has always been difficult and at times

controversial, Cui said, because of concerns about adverse effects when

giving vaccines to healthy people.(Nanowerk News)

Scientists at Oregon State University have developed a new "adjuvant"

that could allow the creation of important new vaccines, possibly

become a universal vaccine carrier and help medical experts tackle many

diseases more effectively.

 

 

 

Adjuvants are substances that are not immunogenic themselves, but

increase the immune response when used in combination with a vaccine.

 

 

 

However, due to concerns about safety and toxicity, there's only a

single vaccine adjuvant – aluminum hydroxide, or alum – that has been

approved for human use in the United States. It's found in such common

vaccines as hepatitis B and tetanus. But even though widely used, alum

is comparatively weak and will only work with certain diseases.

 

 

 

The new adjuvant is based on nanoparticles prepared with lecithin, a

common food product. In animal models, it helped protein antigens to

induce an immune response more than six times stronger than when alum

was used. Researchers also showed that the lecithin nanoparticles were

able to help induce a reasonable antibody response after only one shot,

whereas it took at least two shots for the alum adjuvant to work.

 

 

 

Based on their studies, researchers believe the lecithin nanoparticles

have wide potential applications and possibly a good safety profile.

Their findings were just published in the Journal of Controlled

Release, a professional journal in the field of pharmaceutics, in work

supported by the National Institute of Allergy and Infectious Diseases.

 

 

 

 

"In many cases, to make progress with vaccine development we need new

adjuvants," said Zhengrong Cui, an assistant professor of pharmaceutics

at OSU and corresponding author on the new study. "The material has to

be safe, and lecithin is a common food product that's already widely

used in pharmaceuticals. This new form of using lecithin nanoparticles

as an adjuvant is promising and could become very important."

 

 

 

Vaccine development has always been difficult and at times

controversial, Cui said, because of concerns about adverse effects when

giving vaccines to healthy people.

 

 

 

 

 

 

 

Because of that, the U.S. Food and Drug Administration has been

conservative about approving new vaccine adjuvants, he said. But even

the safety issue is complex – to help avoid risk, new vaccines are

based on purified compounds from microbes, but these provoke a very

weak immune response and often need an adjuvant to boost them. Vaccines

could be made based on dead or live attenuated microbes, but that would

have a higher level of risk. The ultimate solution is new and improved

adjuvants that help address both concerns about safety and efficacy.

 

 

 

Another problem, he said, is that the alum adjuvant that is common in

some U.S. vaccines has very limited value in the development of many

potential vaccines against viruses or tumors.

 

 

 

By contrast, the lecithin-based nanoparticle adjuvant is more

effective. The extraordinarily small particles move easily to the

lymphatic system that plays a key role in development of immune

response, and they physically "look like" a pathogen to the immune

system, which quickly gears up to fight them.

 

 

 

"Our early studies with laboratory animals seem to suggest that a

vaccine based on the lecithin nanoparticle adjuvant would not only be

more effective, but be tolerated by the body more readily than one

using alum," Cui said. "Lecithin is very non-toxic, it's one of many

compounds 'generally recognized as safe' by the FDA, and at the

injection site we saw none of the nodules and tissue hardening you

sometimes see with vaccines that use alum."

 

 

 

If the new adjuvant is ultimately shown to be safe and is approved

following clinical trials, Cui said, it could become the basis for a

revolution in the production of vaccines and serve as a universal

carrier.

 

 

 

 

Source: Oregon State University

 

 

 

 

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