Beat the bug

 作者:戴陧     |      日期:2019-03-08 01:06:08
By Nell Boyce in Washington DC ELDERLY and sick people may soon be spared the extra worry of catching a killer bug while in hospital, if an experimental vaccine works as well on humans as it does on mice. Every year, Staphylococcus aureus strikes hundreds of thousands of people, causing illnesses ranging from minor skin abscesses to life-threatening pneumonia. The bacterium has a talent for developing antibiotic resistance, and the appearance of vancomycin-resistant strains two years ago alarmed infectious disease experts who think of this antibiotic as the last resort. Gerald Pier and his colleagues at Harvard Medical School in Boston found a polysaccharide molecule called PNSG in tissue samples taken from humans and mice that had S. aureus. This molecule is seldom produced by strains grown in the lab. After purifying the molecule, they injected it into rabbits. The rabbits produced antibodies to the molecule that lasted for at least eight months. Pier’s group turned the antibodies into a vaccine for mice that were then exposed to eight different strains of S. aureus —including antibiotic-resistant strains. Mice that hadn’t been immunised developed kidney infections and died, while those given PNSG antibodies showed no signs of infection or had significantly less kidney damage (Science, vol 284, p 1523). “I think showing that we can protect against eight different strains is a little bit of a breakthrough,” says Pier. Human trials of the vaccine could start sometime next year. “It’s a good candidate and we’re excited about it,” says Stephen Heyse of the National Institute of Allergy and Infectious Diseases near Washington DC. An effective vaccine could be given to people before surgery, who are particularily vulnerable,