PRNP and prion disease: RPSA expressed on the surface of cerebrovascular endothelial cells may facilitate bacterial invasion via ligand-receptor binding to specific bacterial virulence factors (e.g., PilQ and PorA in N. meningitis, OmpP2 in H. influenzae, CbpA in S. pneumoniae, and CNF1 in E. coli) (12, 13).Many pathogens infect host cells via RPSA, for instance, the prion protein (PrP) that causes spongiform encephalopathy is internalized by binding to RPSA, which has also been reported to interact specifically with dengue virus serotypes (14).