"The phenomenon of genetic transformation, which led Oswald Avery and his Rockefeller colleagues in 1944 to identify DNA as the genetic material, is the very process that Streptococcus pneumoniae uses during evolution in its real in vivo environment," says Tomasz.
Other phenomena first identified in the laboratory also appear in stages of pneumococcal evolution in vivo. For instance, at least some of the recombination changes observed among the clinical isolates seem to use the "competence" system, a DNA uptake mechanism induced by a specific bacterial quorum sensing agent first detected by Tomasz and colleagues in laboratory experiments. Also, the mechanism of penicillin resistance, first identified by Tomasz and colleagues in the 1980s as changes in the affinity of penicillin target proteins known as penicillin binding proteins, or PBPs, is shown to involve the borrowing of genes from other bacteria, a finding previously documented in studies of individual penicillin resistant isolates.
"Perhaps the most fascinating part of the research is the description of how rapidly this clone has responded to massive in vivo interventions in the clinical environment, such as the introduction of penicillin and other antibiotics and more recently the introduction of conjugate anti-pneumococcal vaccines," says Tomasz. "These vaccines are directed against the most abundant serotypes of this bacterium, which are carried in the nasopharynx of children and which cause invasive disease."
"This research also demonstrates the importance of close collaborations between groups like the Sanger Laboratory, with expertise in high resolution genomic analysis, and laboratories that can provide carefully characterized c
|Contact: Joseph Bonner|