The salivary virome during childhood dental caries

While many studies have examined the bacterial taxa associated with dental caries, the most common chronic infectious disease, little is known about the caries-associated virome. In this study, the salivary viromes of 21 children with severe caries (>2 dentin lesions) and 23 children with healthy dentition were examined. A total of 2,485 viral metagenome-assembled genomes (vMAGs) were identified, binned, and quantified from the metagenomic assemblies. These vMAGs were mostly phages and represented 1,865 unique species-level viral operational taxonomic units (vOTUs), of which 478 appear to be novel. The metagenomes were also queried for all 3,858 unique species-level vOTUs of DNA viruses with a human host on NCBI Virus; however, all but Human betaherpesvirus 7 were at very low abundance in the saliva. The oral viromes of the children with caries exhibited significantly different beta diversity compared to the oral virome of the children with healthy dentition; several vOTUs predicted to infect Haemophilus and Neisseria were strongly correlated with health, and five vOTUs predicted to infect Saccharibacteria, Prevotella, and Veillonella were correlated with caries. Co-occurrence analysis indicated that the phage typically co-occurred with both their predicted hosts and with bacteria that were themselves associated with the same disease status. Overall, this study provided the sequences of 35 complete or nearly complete novel oral phages and illustrated the potential significance of the oral virome in the context of dental caries, which has been largely overlooked. This work represents an important step toward the identification and study of phage therapy candidates that treat or prevent caries pathogenesis.IMPORTANCEDental caries is the most common chronic infectious disease worldwide and is caused by dysbiosis of the oral microbiome featuring an increased abundance of acid-tolerant, acid-producing, and biofilm-forming bacteria. The oral microbiome also contains viruses; however, very little is known about the caries-associated virome. In this study, the salivary virome of children with severe caries was compared to the salivary virome of children with healthy dentition. The metagenomes contained a total of 1,865 unique species-level viral operational taxonomic units (vOTUs), of which 478 appeared to be novel. The viromes from the children with caries were significantly different than the viromes from the children with healthy teeth, and several health- and disease-associated vOTUs were identified. This study illustrated the potential importance of the oral virome in the context of dental caries and serves as a step towards a better understanding of oral inter-kingdom interactions and identification of potential phage-based caries therapeutics.