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A genetic investigation by an international research team including 69热视频 researcher Marcel Behr suggests a bacterium commonly used as a vaccine against tuberculosis may have outlived 鈥� or out-evolved 鈥� its usefulness.

Dr. Behr, along with researchers from France鈥檚 Institut Pasteur and genetics labs in the United Kingdom, mapped and analyzed the genetic code of bacillus Calmette-Gu茅rin (BCG), a derivative of Mycobacterium bovis that is part of the World Health Organization鈥檚 Expanded Program on Immunization.

鈥淲e鈥檝e determined that this bacteria, which is given as a vaccine two million times a week around the world, is highly evolved from when it was first used in 1921,鈥� said Dr. Behr. 鈥淐onsequently, we鈥檙e not really sure if it鈥檚 as effective as it鈥檚 been in the past or as it could be.鈥�

Their findings, published by the Proceedings of the National Academy of Sciences (PNAS) Online, indicate that the vaccine鈥檚 decreased virulence against tuberculosis appears to be attributable to genetic factors such as the loss of the protein secretion system ESX-1.

Though previous trials dating back to the 1960s have called into question the efficacy of BCG, the new study 鈥減uts a punctuation mark鈥� on the need to develop a more effective vaccine, said Dr. Behr. He said the research has been presented to the World Health Organization, which has declared worldwide tuberculosis control among its top priorities for 2007, to draw attention to the issue.

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