title: Coaggregation between Prevotella oris and Porphyromonas gingivalis.
abstract: OBJECTIVE
  The coaggregation of bacteria has been defined as one of the most important processes in the oral infection such as periodontitis. Prevotella oris and Porphyromonas gingivalis, which are two of the periodontopathogens, are frequently detected in severe forms of periodontal diseases. However, the interaction between P. oris and P. gingivalis is still unknown. In this study, the coaggregation of P. oris with nine oral bacterial species including P. gingivalis was examined.
  
  
  METHODS
  All bacteria used in this study were cultured anaerobically and suspended in coaggregation buffer. Each cell suspension was mixed in a test tube and subjected to shaking at room temperature for 1 hour. Subsequently, the coaggregation values were scored. Furthermore, the effects of various chemical reagents, and heat, proteinase K, and serum treatment were examined.
  
  
  RESULTS
  In this study, P. oris coaggregated only with P. gingivalis. A heat-stable, nonproteinous component of P. oris and a heat-labile, proteinous component of P. gingivalis play important roles in this coaggregation. In addition, this coaggregation was inhibited by l-arginine, l-lysine, and Nα-p-tosyl-l-lysine. Therefore, it was considered that a cell surface protein on P. gingivalis, such as gingipain, may be involved in the coaggregation. Furthermore, the coaggregation was not inhibited by serum treatment.
  
  
  CONCLUSIONS
  This is the first report to describe the coaggregation of P. oris and P. gingivalis. Our study proposes the possibility that P. oris may promote the colonization of P. gingivalis in an early stage of biofilm formation. Furthermore, this coaggregation may contribute to the initiation and progression of periodontitis.
authors.affiliation: Department of Oral Microbiology, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Oral Microbiology, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, Japan. Electronic address: nakazawa@hoku-iryo-u.ac.jp.
authors.forename: Futoshi
authors.initials: F
authors.lastname: Nakazawa
mesh_terms: D000818:Animals; D018441:Biofilms; D018920:Coculture Techniques; D019286:Endopeptidase K / Q000494:pharmacology; D006736:Horses; D006358:Hot Temperature; D006801:Humans; D056265:Microbial Interactions / Q000187:drug effects / Q000502:physiology*; D010518:Periodontitis / Q000382:microbiology; D016966:Porphyromonas gingivalis / Q000187:drug effects / Q000502:physiology*; D018720:Prevotella / Q000187:drug effects / Q000502:physiology*; D044967:Serum
chemical_list: D019286:Endopeptidase K