The UCSD-SM team investigated the functions of a protein known as NanA in order to discover how an entire bacterium can breech the BBB and gain access to the central nervous system.

NanA is produced by all strains of pneumococcus and displayed prominently on the bacteria's outer surface. Through genetic manipulations, the researchers removed the entire NanA protein, or just specific sections of the molecule, from the pathogen, said an UCSD-SM release.

'Our tissue culture studies showed that the NanA protein was both necessary and sufficient for bacterial penetration of the blood brain barrier...,' said Satoshi Uchiyama, a postdoctoral fellow in the Nizet Lab, who led the study.

These findings were published online in the Journal of Experimental Medicine.