title: Differential transcription of virulence genes in Aggregatibacter actinomycetemcomitans serotypes.
abstract: BACKGROUND
  Aggregatibacter actinomycetemcomitans serotypes are clearly associated with periodontitis or health, which suggests distinct strategies for survival within the host.
  
  
  OBJECTIVE
  We investigated the transcription profile of virulence-associated genes in A. actinomycetemcomitans serotype b (JP2 and SUNY 465) strains associated with disease and serotype a (ATCC 29523) strain associated with health.
  
  
  METHODS
  Bacteria were co-cultured with immortalized gingival epithelial cells (OBA-9). The adhesion efficiency after 2 hours and the relative transcription of 13 genes were evaluated after 2 and 24 hours of interaction.
  
  
  RESULTS
  All strains were able to adhere to OBA-9, and this contact induced transcription of pgA for polysaccharide biosynthesis in all tested strains. Genes encoding virulence factors as Omp29, Omp100, leukotoxin, and CagE (apoptotic protein) were more transcribed by serotype b strains than by serotype a. ltxA and omp29, encoding the leukotoxin and the highly antigenic Omp29, were induced in serotype b by interaction with epithelial cells. Factors related to colonization (aae, flp, apaH, and pgA) and cdtB were upregulated in serotype a strain after prolonged interaction with OBA-9.
  
  
  CONCLUSIONS
  Genes relevant for surface colonization and interaction with the immune system are regulated differently among the strains, which may help explaining their differences in association with disease.
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Josely Emiko
authors.initials: JE
authors.lastname: Umeda
authors.forename: Priscila Larcher
authors.initials: PL
authors.lastname: Longo
authors.forename: Maria Regina Lorenzetti
authors.initials: MR
authors.lastname: Simionato
authors.forename: Marcia Pinto Alves
authors.initials: MP
authors.lastname: Mayer
keywords: Aggregatibacter actinomycetemcomitans; epithelial cell; gene expression; infection