Immunization with polyamine transport protein PotD protects mice against systemic infection with Streptococcus pneumoniae

Infect Immun. 2006 Oct;74(10):5888-92. doi: 10.1128/IAI.00553-06.


The human pathogen Streptococcus pneumoniae contains genes for a putative polyamine ABC transporter which are organized in an operon and designated potABCD. Polyamine transport protein D (PotD) is an extracellular protein which binds polyamines and possibly other structurally related molecules. PotD has been shown to contribute to virulence in both a murine sepsis model and a pneumonia model with capsular type 3 pneumococci. The protective efficacy of recombinant PotD was evaluated by active immunization and intravenous challenge with capsular type 3 pneumococci in CBA/N mice. Immunized mice had 91.7% survival following lethal pneumococcal challenge, compared with 100% mortality in the control group. Immunized animals had high-titer anti-PotD antibodies following three immunizations with alum. Protection in a sepsis model was also seen after passive administration of rabbit antiserum raised against PotD (P < 0.004). These results suggest that antibodies to PotD confer protection against invasive pneumococcal disease and that this protein should be studied further as a potential vaccine candidate for protection against invasive pneumococcal infections.

MeSH terms

  • ATP-Binding Cassette Transporters / administration & dosage*
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / immunology
  • Animals
  • Antibodies, Bacterial / administration & dosage
  • Antibodies, Bacterial / immunology
  • Immunization, Passive
  • Mice
  • Mice, Inbred CBA
  • Pneumococcal Infections / prevention & control*
  • Polyamines / metabolism
  • Rabbits
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Streptococcus pneumoniae / immunology*
  • Vaccination*


  • ATP-Binding Cassette Transporters
  • Antibodies, Bacterial
  • Polyamines
  • Recombinant Proteins