The Subgingival Microbiome Relationship to Periodontal Disease in Older Women.

Understanding of the oral microbiome in relation to periodontal disease in older adults is limited. The composition and diversity of the subgingival microflora and their oligotypes in health and levels of periodontal disease were investigated in this study on older postmenopausal women. The 16S rRNA gene was sequenced using the Illumina MiSeq platform in 1,206 women aged 53 to 81 y. Presence and severity of periodontal disease were defined by Centers for Disease Control and Prevention/American Academy of Periodontology criteria. Composition of the microbiome was determined by 16S rRNA amplicon sequencing and the abundance of taxa described by the centered log2-ratio (CLR) transformed operational taxonomic unit (OTU) values. Differences according to periodontal disease status were determined by analysis of variance with Bonferroni correction. Bacteria oligotypes associated with periodontal disease and health were determined by minimum entropy decomposition and their functions estimated in silico using PICRUSt. Prevalence of none/mild, moderate, and severe periodontal disease was 25.1%, 58.3%, and 16.6%, respectively. Alpha diversity of the microbiome differed significantly across the 3 periodontal disease categories. ß-Diversity differed between no/mild and severe periodontal disease, although considerable overlap was noted. Of the 267 bacterial species identified at ≥0.02% abundance, 56 (20.9%) differed significantly in abundance according to periodontal disease status. Significant linear correlations for pocket depth and clinical attachment level with bacterial amounts were observed for several taxa. Of the taxa differing in abundance according to periodontal disease status, 53% had multiple oligotypes appearing to differ between none/mild and severe periodontal disease. Among older women, taxonomic differences in subgingival microbiome composition and diversity were observed in relation to clinical periodontal disease measures. Potential differences in bacterial subspecies (oligotypes) and their function were also identified in periodontal disease compared with health.

The molecular population genetics of the Tomato spotted wilt virus (TSWV) genome.

RNA viruses are characterized by high genetic variability resulting in rapid adaptation to new or resistant hosts. Research for plant RNA virus genetic structure and its variability has been relatively scarce compared to abundant research done for human and animal RNA viruses. Here, we utilized a molecular population genetic framework to characterize the evolution of a highly pathogenic plant RNA virus [Tomato spotted wilt virus (TSWV), Tospovirus, Bunyaviridae]. Data from genes encoding five viral proteins were used for phylogenetic analysis, and for estimation of population parameters, subpopulation differentiation, recombination, divergence between Tospovirus species, and selective constraints on the TSWV genome. Our analysis has defined the geographical structure of TSWV, attributed possibly to founder effects. Also, we identify positive selection favouring divergence between Tospovirus species. At the species level, purifying selection has acted to preserve protein function, although certain amino acids appear to be under positive selection. This analysis provides demonstration of population structuring and species-wide population expansions in a multisegmented plant RNA virus, using sequence-based molecular population genetic analyses. It also identifies specific amino acid sites subject to selection within Bunyaviridae and estimates the level of genetic heterogeneity of a highly pathogenic plant RNA virus. The study of the variability of TSWV populations lays the foundation in the development of strategies for the control of other viral diseases in floral crops.