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Archive - Mar 18, 2011

Protein Is Promising Candidate for New TB Vaccine

Scientists have discovered a protein secreted by tuberculosis (TB) bacteria that could be a promising new vaccine candidate, they report online on March 18, 2011, in PNAS. The protein could also be used to improve diagnosis of TB. TB is caused by the bacterium Mycobacterium tuberculosis (MTB), which infects the lungs and spreads through the air as a result of coughing. There are 9 million new cases of TB each year, killing 4,700 people a day worldwide. BCG, an attenuated mycobacterial strain, is the only available vaccine but it is of limited effectiveness in protecting against TB. BCG derives from the Mycobacterium bovis bacterium, which infects cattle and is closely related to MTB. Vaccines work by stimulating the immune system to retain a memory of particular molecules from a microbe that will trigger a rapid immune response if the microbe is encountered later. The best candidates for vaccines are those that trigger the strongest response from the immune system. In the new study, scientists identified a protein, called EspC, that triggers a stronger immune response in people infected with the TB bacterium than any other known molecule. This protein is secreted by the TB bacterium but not by the BCG vaccine. As a result, the BCG vaccine does not induce an immune response to this protein, so deploying it as a new TB vaccine would provide additive immunity over and above that provided by BCG. The protein could also be useful as a diagnostic tool, because an immune response to it is seen in TB-infected people, but not in non-infected people who have had a BCG vaccine. Detecting immune responses to it would distinguish BCG-vaccinated people from TB-infected people, which the currently-used tuberculin skin prick test (the Mantoux test) is unable to do.

Scientists Show Enzyme Family Plays Key Role in Cell Motility

Researchers at Albert Einstein College of Medicine of Yeshiva University and colleagues have discovered that members of an enzyme family found in humans and throughout the plant and animal kingdoms play a crucial role in regulating cell motility. Their findings suggest an entirely new strategy for treating conditions ranging from diabetic ulcers to metastatic cancer. Dr. David Sharp, associate professor of physiology & biophysics, was the senior author of the study, which was published online on March 6, 2011, in Nature Cell Biology. "Cells in our bodies are in constant motion, migrating from their birth sites to distant targets," said Dr. Sharp. "Cellular movement builds our tissues and organs and underlies key functions such as the immune response and wound healing. But uncontrolled cell migration can lead to devastating problems including mental retardation, vascular disease, and metastatic cancer." Dr. Sharp and his colleagues found that certain members of an enzyme family known as katanins concentrate at the outer edge of non-dividing cells where they break up microtubules – dynamic intracellular polymers that regulate cell movement by controlling the formation of protrusions called lamellipodia. When Dr. Sharp's team treated motile cells of the fruit fly Drosophila with a drug that inhibited katanin production, the treated cells moved significantly faster than control cells and with a striking increase in high-velocity movements, indicating that katanin prevents cells from moving too rapidly or in an uncontrolled manner. The researchers observed similar effects with katanin when they examined human cells. "Our study opens up a new avenue for developing therapeutic agents for treating wounds – burns and diabetic ulcers, for example – as well as metastatic disease," added Dr. Sharp.