April 23, 2012
Army Researcher Develops Way To Extend Vaccine Shelf Life
An Army medical researcher has reportedly developed a potential vaccine carrier he believes will extend the shelf life of essential vaccines, allowing for stockpiles of them to be created and shortages of these critical treatments to be avoided, the American Society for Biochemistry and Molecular Biology (ASBMB) said in a statement Sunday.
The findings, which were presented Sunday afternoon at the Experimental Biology 2012 meeting, were discovered by U.S. Army Major Jean M. Muderhwa. Muderhwa, a researcher at the Brooke Army Medical Center (BAMC) / San Antonio Military Medical Center (SAMMC), said that he has developed a microemulsion -- a clear, thermodynamically stable, isotropic liquid mixtures of oil, water and surfactant -- which he says "has been found to be both stable and a good candidate for delivering a variety of antigens."
He created the microemulsion with what appears to be a simple recipe with five components, which interact in a special way. Muderhwa's solution is created by combining oil, water, glycerol (which is used in skin-care products), a mixture of the surfactants Span 80 and Tween 60, and an aluminum adjuvant-adsorbed protein used in vaccines to amplify the immune system's protective response to antigens -- a combination which he says has a "synergy" and had been sitting in his laboratory for half a year without showing signs of degradation.
"If I were to make an emulsion (of oil and water), which is just a cream and white, that emulsion would separate within weeks," he said in a statement. "If you make a vaccine containing an emulsion, it's only (good for) probably a few months because the emulsion is not thermodynamically stable. The surface tension is too high, and the molecules are repelling one another until the emulsion fails."
"You can make those particles in a cream smaller and smaller and smaller," Muderhwa added. "The way you do that is you have to lower the surface tension to near zero. You know if you take water and put it in the oil, they don't mix. So you have to add a compound that can bring them together. If you take egg yolk — it has phospholipids, and these are emulsifiers — that helps to bring the water and oil to combine."
Muderhwa, a native of the Democratic Republic of the Congo who studied biochemistry at the University of Languedoc Roussillon in Montpellier (France) and biophysics at the University of Minnesota, believes that what he has discovered could be a game-changer when it comes to keeping up with the demand for vaccines.
"There is a need (for new vaccine carriers like this) especially if we want to stockpile a vaccine," he said. "The (U.S. Agency for International Development) and FDA are responsible for stocking, for example, the influenza vaccine in the case of epidemic. They have to deliver them as quickly as possible. So if you have a vaccine just sitting on the shelf for more than 10 or 20 years, you don't have to worry about its stability."
Image 2: This is US Army Major Jean M. Muderhwa's microemulsion vaccine carrier. Credit: Courtesy of US Army Major Jean M. Muderhwa