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Serum antibodies to putative proteinase maturation protein A in children with acute otitis media

Anni Vainio1, Riku Fagerlund, Krister Melén

  • 1Department of Bacterial and Inflammatory Diseases, National Public Health Institute (KTL), Mannerheimintie 166, FIN-00300 Helsinki, Finland.

Vaccine
|November 18, 2005
PubMed

Insights

This study shows that the pneumococcal protein PpmA (proteinase maturation protein A) is immunogenic in humans. Antibody responses to PpmA varied in children with acute otitis media, suggesting its potential for new pneumococcal vaccines.

Area of Science:

  • Microbiology
  • Immunology
  • Vaccinology

Background:

  • Surface-associated proteins of Streptococcus pneumoniae are key targets for vaccine development.
  • The proteinase maturation protein A (PpmA) gene (SP098l/ppmA) is a potential candidate for pneumococcal vaccines.

Purpose of the Study:

  • To clone and express the PpmA gene.
  • To evaluate the immunogenicity of recombinant PpmA in animal models and children with acute otitis media (AOM).
  • To investigate the correlation between antibody responses to PpmA and pneumococcal infection status.

Main Methods:

  • Cloning of the full-length PpmA gene.
  • High-level expression and purification of recombinant PpmA in E. coli.
  • Western blotting to detect serum IgG antibody responses against PpmA.

Main Results:

  • Recombinant PpmA was successfully produced and purified.
  • Serum IgG antibody titers against PpmA increased with age in children.
  • Antibody titers showed significant differences based on pneumococcal presence in middle ear fluid and nasopharyngeal aspirates, being lower in cases with middle ear infection.

Conclusions:

  • PpmA is immunogenic in humans.
  • PpmA represents a promising antigen for further investigation in the development of novel pneumococcal multicomponent protein vaccines.

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