Thao T To

University of Washington | UW · Department of Periodontics

The ability of the subgingival microbial community to induce an inappropriate inflammatory response ultimately results in the destruction of bone and gingival tissue. In this study, subgingival plaque samples from both healthy and diseased sites in the same individual were obtained from adults with chronic periodontitis and screened for their abili...

We present the draft genome of Porphyromonas gingivalis MP4-504, a low-passage clinical isolate obtained from a periodontitis patient. The genome is composed of 92 contigs for a length of 2,373,453 bp and a G+C of 48.3%. The traA-Q conjugative transfer locus is genetically distinct from W83 but highly similar to ATCC 33277.

Here, we present the draft genome sequence of Actinomyces odontolyticus subsp. actinosynbacter strain XH001, isolated from the human oral cavity. Uniquely, it was discovered as a host bacterium to the ultrasmall epibiont TM7x, which is the first cultivated member of “ Candidatus Saccharibacteria” (formerly candidate phylum TM7).

Signal transduction following binding of lipopolysaccharide (LPS) to Toll-like receptor 4 (TLR4) is an essential aspect of host innate immune responses to infection by Gram-negative pathogens. Here, we describe a novel molecular mechanism used by a prevalent human bacterial pathogen to evade and subvert the human innate immune system. We show that...

The human symbiont Bacteroides thetaiotaomicron promotes intestinal function and health, whereas the phylogenetically related pathogen Porphyromonas gingivalis is associated with the chronic oral inflammatory disease periodontitis. Although both B. thetaiotaomicron and P. gingivalis synthesize lipopolysaccharides (LPS) consisting of penta-acylated,...

Developing a laboratory model of oral polymicrobial communities is essential for in vitro studies of the transition from healthy to diseased oral plaque. SHI-medium is an enriched growth medium capable of supporting in vitro biofilms with similar diversity to healthy supragingival inocula; however, this medium does not maintain the diversity of gra...

The first cultivated representative of the enigmatic phylum Saccharibacteria (formerly TM7) was isolated from humans and revealed an ultra-small cell size (200–300 nm), a reduced genome with limited biosynthetic ca- pabilities, and a unique parasitic lifestyle. TM7x was the only cultivated member of the candidate phyla radi- ation (CPR), estimated...

Oral microbiome research has moved from asking “Who’s there?” to “What are they doing?” Understanding what microbes “do” involves multiple approaches, including obtaining genomic information and examining the interspecies interactions. Recently we isolated a human oral Saccharibacteria (TM7) bacterium, HMT-952, strain TM7x, which is an ultrasmall p...

Gingival epithelium plays a pivotal role in protecting the underlying periodontium from the microbial colonization found in the gingival sulcus. Having an appropriate phenotype displayed by gingival epithelial cells is a critical host component required for protection against bacterial invasion into gingival tissues. In the present study, gingival...

The P. gingivalis ATCC 33277 (33277) and 381 genomes are nearly identical. However, strain 33277 displays a significantly diminished capacity to stimulate host cell TLR2-dependent signaling and IL-1β production relative to 381, suggesting that there are strain-specific differences in one or more bacterial immune-modulatory factors. Genomic sequenci...

Significance Cultivation-independent sequencing has revealed enormous numbers of bacterial species. Amongst the most enigmatic are members of the Candidate Phyla Radiation, which are estimated to represent over 26% of all bacterial diversity. This group of ultrasmall bacteria are thought to be mostly symbionts; however, understanding these bacteria...

Streptococcus mutans, the organism most frequently associated with the development of dental caries, is able to utilize a diverse array of carbohydrates for energy metabolism. One such molecule is trehalose, a disaccharide common in human foods, which has been recently implicated in enhancing the virulence of epidemic strains of the pathogen Clostr...

Aim: To investigate the influence of auxiliary chemical substances (ACS) and calcium hydroxide [Ca(OH)2] dressings on LPS/lipid A detection and its functional ability in activating Toll-like receptor 4 (TLR4). Methodology: Fusobacterium nucleatum pellets were exposed to antimicrobial agents as following: 1) ACS: 5.25%, 2.5% and 1% sodium hypochl...

Recently, we discovered that a member of the Saccharibacteria/TM7 phylum (strain TM7x) isolated from the human oral cavity, has an ultra-small cell size (200-300nm), a highly reduced genome (705 Kbp) with limited de novo biosynthetic capabilities, and a very novel lifestyle as an obligate epibiont on the surface of another bacterium ¹ . There has b...

Background Recently, we reported that toll-like receptor (TLR)2 and TLR4 localized on the glomerular endothelium in the glomeruli of streptozotocin (STZ)-induced type 1 diabetic mice and high fat diet feed-induced type 2 diabetic mice, and that periodontal pathogen Porphyromonas gingivalis LPS (Pg-LPS) administration lowered the survival rate of di...

We present here the draft genome sequence of Tannerella forsythia 9610, a clinical isolate obtained from a periodontitis patient. The genome is composed of 79 scaffolds with 82 contigs, for a length of 3,201,941 bp and a G+C of 47.3%.

Importance: The guts of animals harbor a variety of Gram-negative bacteria associated with both states of intestinal health or disease. Environmental factors, such as dietary habits, can drive the microbial composition of the host animal's intestinal bacterial community towards a more pathogenic state. Both beneficial and harmful Gram-negative bac...

We announce here a draft genome sequence of Veillonella parvula strain SHI-1, obtained from healthy human saliva, discovered to be active at low pH using metatranscriptomics within an in vitro oral biofilm model. The genome is composed of 7 contigs, for a total of 2,200,064 bp.

Natural heterogeneity in the structure of the lipid A portion of LPS structure results in differential effects on the innate immune response. Gram-negative bacterial species produce LPS structures that vary from the classic endotoxic LPS structures. These variations include hypo-acylation and hypo-phosphorylation of the diglucosamine backbone, both...

To elucidate the genetic basis for the pronounced resistance that the oral pathogen, Porphyromonas gingivalis (P. gingivalis), exhibits towards the cationic antimicrobial peptide, polymyxin B. A genetic screen of P. gingivalis clones generated by a Tn4400'-based random insertion mutagenesis strategy was performed to identify bacteria harboring nove...