Streptococcus pneumoniae causes considerable morbidity and mortality worldwide. The need for a cheap and effective pneumococcal vaccine has necessitated the evaluation of common virulence-associated proteins as potential vaccine antigens. PiuA and PiaA are the lipoprotein components of two pneumococcal iron ABC transporters. Here, we show that patients with culture confirmed pneumococcal septicaemia have elevated levels of antibody to PiuA and PiaA in convalescent-phase, compared with acute-phase serum. Additionally, sera from septicaemic patients infected with 13 pneumococcal strains covering eight different serotypes, cross-reacted with recombinant PiuA-His 6 and PiaA-His 6 from a single pneumococcal strain, indicating that this immune response is serotype independent. Anti-PiuA and anti-PiaA antibodies were also found in healthy seven-month-old infants, indicating that they are immunogenic at a very early age.
Bibliographical noteFunding Information:
This work was supported through funding from the UK Department of Health by the Health Protection Agency, Porton Down (formerly Centre For Applied Microbiology And Research). The views expressed in this publication are those of the authors and not necessarily those of the Department of Health. We thank Dr. A. Lloyd and Dr. D. Roper (University of Warwick) for expert technical assistance, L. Foster, R. Winn and P. Hawtin (Public Health Laboratory, Southampton General Hospital) for collection and supply of human acute and convalescent phase sera, Dr. Maija Korkeila (KTL, Helsinki, Finland) for the supply of infant sera, and Professor Tim Mitchell (University of Glasgow) for the gift of purified pneumolysin.
- Streptococcus pneumoniae