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Non-Refrigerated Spray Vaccine Could Curb Diseases in Remote Areas

Nanovaccines trigger cell-mediated immune response

A new kind of single-dose vaccine that comes in a nasal spray and doesn’t require refrigeration could dramatically alter the public health landscape and help address the looming threats of emerging and re-emerging diseases. Researchers presented data on the design and testing of these “nanovaccines” at the 247th National Meeting & Exposition of the American Chemical Society (ACS), held March 16–20 in Dallas, Texas.

“Our nanovaccine approach could be instrumental for containing future outbreaks of recently emerged and re-emerging diseases, such as SARS [severe acute respiratory syndrome], new flu strains, and multidrug-resistant tuberculosis,” said lead investigator Balaji Narasimhan, PhD.

He noted that most of today’s vaccines require needles, boosters, and refrigeration, all of which pose challenges for doctors and patients. Other than the pain factor, which can lower the chances that someone will seek a vaccine, follow-up shots and refrigeration further reduce the reach of these important preventive treatments, Narasimhan says. In some places with limited resources, refrigeration simply isn’t available. Thus, many people who need vaccinations the most aren’t getting them. The good news is that the vaccines that Narasimhan’s team is developing don’t need to be kept cold and are easy to administer.

“Our nanovaccines can be stored at room temperature for as long as 6 to 10 months and still work,” said Narasimhan. “Also, we’re designing them so they get delivered in one dose through a nasal spray, which could potentially allow patients to give the vaccine to themselves.”

Another major limitation of traditional vaccines is the way they work, he said. Most current vaccines help a person develop disease immunity by introducing part of a virus or bacterium, which triggers the body’s humoral response — the part of the immune system that produces antibodies to fight off a harmful pathogen. Later, if the person gets infected by that microbe, the body immediately knows how to respond.

But evidence is emerging that the other component of the body’s immune system — the cell-mediated arm — also plays an important part in some emerging and re-emerging diseases, such as whooping cough. This part of the immune system depends on T cells, rather than antibodies, to fight viruses and bacteria.

Part of the elegance of the nanovaccines is their simplicity and versatility, Narasimhan explained. They are made of only two components: bits of proteins from a virus or bacterium packed into nontoxic, biodegradable polymers that can be custom-designed.

When administered through the nose or by an injection, these tiny packages enter the body and “flag” the immune system. Antigen-presenting cells, which keep watch in the body for foreign invaders, gobble up the nanovaccine particles, chop up the polymers and pathogen proteins, and appropriately put pieces of the proteins on their surfaces. Depending on the chemistry of the nanovaccine, this activity triggers the body’s cell-mediated immune response and trains it to recognize the pathogen and to attack it quickly in case of future infections.

Source: ACS; March 19, 2014.

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