Detection of Hsa Homologue in Oral Streptococcal Wild Type Strains

Objectives: Objectives:
Streptococcus gordonii and other mitis group oral streptococci colonize primarily on the human tooth as members of oral biofilm, also known as dental plaque. S. gordonii Hsa adhesin has been reported as one of the virulence factors, recognizing terminal sialic acid of the host sialoglycoconjugates, such as mucin in acquired pellicle of the tooth surface. NR2, one of non-repetitive regions of Hsa, is thought to be binding region to sialic acid. The gene encoding Hsa homologues have been found in not only S. gordonii strains, but also other streptococcal species and even other genus such as Staphylococcus. However it is still unclear how widely Hsa homologue is present among streptococcal wild type strains. The aim of the present study is to detect the Hsa expression on streptococcal strains.
Methods: Methods:
The collection and use of oral samples in this study was approved by the Research Ethics Committee of Nippon Dental University. After obtaining written informed consent for using the collected samples in a scientific study, dental plaque, and buccal and lingual swab were collected from healthy volunteers. From these samples bacterial strains were isolated by using mitis-salivarius agar plate. Gram-positive and catalase-negative strains were maintained as streptococcal strains. Bacterilal cell suspension of the strains was spotted on nitrocellulose membrane. Hsa expression on the bacterial cell surface was detected by dot blot analysis with anti-S. gordonii, anti-Hsa, and anti-NR2 antibodies.
Results: Results:
From the 7 volunteers, 46 wild strains were isolated as streptococci. Of these strains, 44 strains were positively detected by anti-S. gordonii. As well, 43 strains and 30 strains reacted with anti-Hsa and anti-NR2, respectively.
Conclusions: Conclusion:
The results indicated almost all of the isolated wild streptococcal strains similar to S. gordonii express Hsa or its homologues. In addition, some homologues may include the region similar to NR2.