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nanotimes News in Brief

11-02/03 :: February / March 2011

Healthcare // Virus-Mimicking Nanoparticles Can Stimulate Long Lasting Immunity

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cientists at the Emory Vaccine Center, USA, have designed tiny nanoparticles that resemble

viruses in size and immunological composition and that induce lifelong immunity in mice. They designed the particles to mimic the immune-stimu- lating effects of one of the most successful vacci- nes ever developed – the yellow fever vaccine.

The particles, made of biodegradable polymers, have components that activate two different parts of the innate immune system and can be used interchan- geably with material from many different bacteria or viruses.

“These results address a long-standing puzzle in vac- cinology: how do successful vaccines induce long la- sting immunity?” says senior author Bali Pulendran, PhD, Charles Howard Candler professor of pathology and laboratory medicine at Emory University School of Medicine and a researcher at Yerkes National Primate Research Center.

“These particles could provide an instant way to stretch scarce supplies when access to viral mate- rial is limited, such as pandemic flu or during an emerging infection. In addition, there are many diseases, such as HIV, malaria, tuberculosis and dengue, that still lack effective vaccines, where we

anticipate that this type of immunity enhancer could play a role.” One injection of the live viral yellow fe- ver vaccine, developed in the 1930s by Nobel Prize winner Max Theiler, can protect against disease-cau- sing forms of the virus for decades. Pulendran and his colleagues have been investigating how humans respond to the yellow fever vaccine, in the hopes of imitating it.

Several years ago, they established that the yellow fever vaccine stimulated multiple Toll-like receptors (TLRs) in the innate immune system. TLRs are pre- sent in insects as well as mammals, birds and fish. They are molecules expressed by cells that can sense bits of viruses, bacteria and parasites and can activate the immune system. Pulendran’s group demonstra- ted that the immune system sensed the yellow fever vaccine via multiple TLRs, and that this was required for the immunity induced by the vaccine.

“TLRs are like the sixth sense in our bodies, because they have an exquisite capacity to sense viruses and bacteria, and convey this information to stimulate the immune response,” Pulendran says. “We found that to get the best immune response, you need to hit more than one kind of Toll-like receptor. Our aim was to create a synthetic particle that accomplishes this task.”