title: Limited diversity of Streptococcus pneumoniae psaA among pneumococcal vaccine serotypes.
abstract: The pneumococcal surface adhesin A (PsaA) is a surface-exposed protein of the gram-positive bacterium Streptococcus pneumoniae. It belongs to a group of proteins designated the lipoprotein receptor I antigen family. The gene encoding PsaA from an encapsulated strain of pneumococcal serotype 6B was cloned and sequenced. The peptide sequence was compared to that of homologs found in S. pneumoniae serotype 2, viridans streptococci, and Enterococcus faecalis. Identity values among the deduced peptides ranged from 57 to 98%. The polymorphism of psaA was examined among the 23 encapsulated vaccine serotypes by using PCR-restriction fragment length polymorphism analysis. Ten different enzymes were used to analyze 80 strains representing the 23 serotypes in a 23-valent polysaccharide vaccine. This analysis showed that restriction sites within the gene were highly conserved, with only a minor variation occurring in 10% of the strains, the result of an additional Tsp509I site. The lack of variation for the other restriction sites within the gene examined here indicates that psaA is genetically conserved, an important characteristic necessary for a candidate common protein vaccine.
authors.affiliation: Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. jas5@ciddbd2.em.cdc.gov
authors.forename: J S
authors.initials: JS
authors.lastname: Sampson
authors.forename: Z
authors.initials: Z
authors.lastname: Furlow
authors.forename: A M
authors.initials: AM
authors.lastname: Whitney
authors.forename: D
authors.initials: D
authors.lastname: Williams
authors.forename: R
authors.initials: R
authors.lastname: Facklam
authors.forename: G M
authors.initials: GM
authors.lastname: Carlone
mesh_terms: D018829:Adhesins, Bacterial; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology; D015153:Blotting, Western; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D013293:Enterococcus faecalis / Q000235:genetics; D015723:Gene Library; D008074:Lipoproteins; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D045331:Photosystem I Protein Complex; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015183:Restriction Mapping; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013291:Streptococcus / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000235:genetics*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; D045331:Photosystem I Protein Complex; C085000:PsaA protein, Streptococcus; C051592:pneumococcal surface protein A