The vaccine protected mice against potentially lethal infections with five virulent S. aureus strains, the researchers report in the Nov. 7, 2006, issue of the Proceedings of the National Academy of Sciences, available early online. These strains include USA100, a common cause of hospital-acquired infections, and USA400, a virulent community-associated strain that carries lung-damaging toxins. All five strains were resistant to most of the drugs used to treat S. aureus infections.
"This microbe's ability to acquire the tools it needs to protect itself from the drugs we use to treat it is legendary," said study director Olaf Schneewind, M.D., Ph.D., professor and chairman of microbiology at the University of Chicago, "which is why a vaccine has become such a high priority. One by one, this organism has learned how to evade nearly all of our current antibiotics. So, generating protective immunity against invasive S. aureus has become an important goal."
Previous vaccine attempts using killed or live attenuated bacteria, or selected bacterial subunits, produced, at best, only partial immunity. "For S. aureus vaccines to succeed," said Schneewind, "we need to stimulate an immune response that can recognize the specific cell-surface proteins responsible for virulence and can recognize them from multiple strains."
The researchers turned to a newer technique, known as "reverse vaccinology," recently used to develop candidate vaccines against group A and group B streptococci and group B meningococci. Access to the S. aureus genome
Source:University of Chicago Medical Center