Open Peer Review Any reports and responses or comments on the article can be found at the end of the article. RESEARCH ARTICLE Identification and phylogenetic analysis of oral Veillonella species isolated from the saliva of Japanese children [version 4; peer review: 2 approved] Ariadna A. Djais , Citra Fragrantia Theodorea , Izumi Mashima , Maiko Otomo , Masato Saitoh , Futoshi Nakazawa 2 Department of Oral Biology, Faculty of Dentistry, Universitas Indonesia, Jakarta, 10430, Indonesia Department of Oral Microbiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Kusumoto-cho, Nagoya, 470-0915, Japan Department of Pediatric Dentistry, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, 061-0293, Japan Abstract As the most frequent infectious disease among children Background: worldwide, dental caries have a strong relationship with oral hygiene status, specifically in the development of infection. However, the study regarding the identification and distribution of oral are limited. The oral Veillonella community may affected by the differences in geographical Veillonella location, age, diet, lifestyle, socio-economic status and oral hygiene status. Here, we studied the oral hygiene status by examining the composition and proportion of oral species in saliva of Japanese children. Veillonella Microbial samples collected from 15 Japanese children divided Methods: into three oral hygiene groups were cultured under anaerobic conditions after homogenization and dilution, and inoculated onto brain heart infusion and selective medium agar. Genomic DNA was extracted from Veillonella each isolate. species were detected by one-step PCR using Veillonella species-specific primers. To analyse the phylogenetic properties of rpoB the unknown strains, PCR amplification and sequence analysis Veillonella of were conducted for 10 representative strains. rpoB Although was found as the predominant species Results: V. rogosae among all groups, its prevalence was significantly lower in the children with poor oral hygiene than in those with good oral hygiene. was the V. parvula prevalent species in the poor oral hygiene group. Approximately 10% of the isolated strains were not classified to any established species; Veillonella the phylogenetic analysis showed that they were most closely related to V. infantium This study demonstrates that the composition and proportion Conclusions: of oral species in the saliva of Japanese children is correlated Veillonella with different oral hygiene status. Changes in detection ratios of V. parvula and can be useful indicators of oral hygiene status. V. rogosae 1 1,2 3 4 4 2 1 2 3 4 Reviewer Status Invited Reviewers version 4 published 08 Aug 2019 version 3 published 18 Jul 2019 version 2 published 20 Jun 2019 version 1 published 03 May 2019 1 2 report report report report report report , Gadjah Mada University, Juni Handajani Yogyakarta, Indonesia 1 , Niigata University Graduate Takuichi Sato School of Health Sciences, Niigata, Japan 2 03 May 2019, :616 ( First published: 8 ) https://doi.org/10.12688/f1000research.18506.1 20 Jun 2019, :616 ( Second version: 8 ) https://doi.org/10.12688/f1000research.18506.2 18 Jul 2019, :616 ( Third version: 8 ) https://doi.org/10.12688/f1000research.18506.3 08 Aug 2019, :616 ( Latest published: 8 ) https://doi.org/10.12688/f1000research.18506.4 v4 Page 1 of 18 F1000Research 2019, 8:616 Last updated: 08 AUG 2019