Inhaled tuberculosis vaccine better than conventional procedures

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Washington, Mar 13 : A novel spray-drying method for preserving and delivering the most common tuberculosis (TB) vaccine is being developed to provide a better approach for vaccination against the disease.

The study, by researchers at the University of North Carolina-Chapel Hill, the Aeras Global TB Vaccine Foundation, MEND South Africa, the Harvard School of Public Health and School of Engineering and Applied Sciences, found that the aerosol version of TB vaccine, administered directly to the lungs as an oral mist, offered significantly better protection against the disease in experimental animals than a comparable dose of the traditional injected vaccine.

The new technique offers several potential advantages over conventional freezing procedures such as it could provide a low-cost, needle-free TB treatment that is highly stable at room temperature.

"While most new TB vaccines continue to call for needle injection, our vaccine could provide safer, more consistent protection by eliminating these injections and the need for refrigerated storage," said David Edwards, the Gordon McKay Professor of the Practice of Biomedical Engineering in Harvard's School of Engineering and Applied Sciences.

Barry R. Bloom, dean of the Harvard School of Public Health: "Tuberculosis is one of the most resistant and challenging diseases to protect against, and the successful results of aerosol delivery using nanoparticle technology offers a potentially new platform for immunization.

"Were the animal results here confirmed in human studies, this technology could be used not only for TB vaccines, but those protecting against other infectious diseases as well," he added.

The findings are based on studies involving guinea pigs, a species of rodent highly sensitive to TB.

The researchers found that among guinea pigs vaccinated with the aerosol treatment and subsequently exposed to TB, less than 1 percent of lung and spleen tissue showed effects of the disease.

On contrary, in animals treated with the same dose of the traditional injected vaccine, some 5 percent of lung tissue and 10 percent of spleen tissue showed symptoms following TB exposure.

In the aerosol vaccine, particles form at micrometer and nanometer scales and in spherical and elongated shapes, a combination that appears to improve dispersal in the mouth.

While commonly used with food, cosmetics, and pharmaceuticals, this spray drying of small and large molecules is seldom used for drying cellular material.

The new technique enables TB vaccines, and potentially other bacterial and viral-based vaccines, to sidestep the traditional problems linked to keeping vaccines chilled.

"Spray drying is lower-cost than BCG, easily scalable for manufacturing, and ideal for needle-free use, such as via inhalation. Its greater stability at room temperature could ultimately provide a better means of creating and delivering vaccine throughout the world," Edwards said.

The study is published in the Proceedings of the National Academy of Sciences.

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