Protection induced by Streptococcus pneumoniae extracellular vesicles against nasal colonization and invasive infection in mice and the role of PspA.

Diseases caused by Streptococcus pneumoniae (pneumococcus) produce a great impact on public health, killing about one million people annually despite available vaccines. Recent research has revealed that the pneumococcus produces extracellular vesicles (pEVs), which display selective cargo and hold potential for vaccine development. Here, we evaluated the immunogenicity and protective potential of pEVs derived from a non-encapsulated pneumococcal strain (R6) using murine models of pneumococcal colonization and invasive pneumonia.

Pneumococcal extracellular vesicles mediate horizontal gene transfer via the transformation machinery.

Bacterial cells secrete extracellular vesicles (EVs), the function of which is a matter of intense investigation. Here, we show that the EVs secreted by the human pathogen (pneumococcus) are associated with bacterial DNA on their surface and can deliver this DNA to the transformation machinery of competent cells. These findings suggest that EVs contribute to gene transfer in Gram-positive bacteria and, in doing so, may promote the spread of drug resistance genes in the population.