Comparative Genomics of Gardnerella vaginalis Strains Reveals Substantial Differences in Metabolic and Virulence Potential

Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA.
PLoS ONE (Impact Factor: 3.23). 08/2010; 5(8):e12411. DOI: 10.1371/journal.pone.0012411
Source: PubMed


Gardnerella vaginalis is described as a common vaginal bacterial species whose presence correlates strongly with bacterial vaginosis (BV). Here we report the genome sequencing and comparative analyses of three strains of G. vaginalis. Strains 317 (ATCC 14019) and 594 (ATCC 14018) were isolated from the vaginal tracts of women with symptomatic BV, while Strain 409-05 was isolated from a healthy, asymptomatic individual with a Nugent score of 9.
Substantial genomic rearrangement and heterogeneity were observed that appeared to have resulted from both mobile elements and substantial lateral gene transfer. These genomic differences translated to differences in metabolic potential. All strains are equipped with significant virulence potential, including genes encoding the previously described vaginolysin, pili for cytoadhesion, EPS biosynthetic genes for biofilm formation, and antimicrobial resistance systems, We also observed systems promoting multi-drug and lantibiotic extrusion. All G. vaginalis strains possess a large number of genes that may enhance their ability to compete with and exclude other vaginal colonists. These include up to six toxin-antitoxin systems and up to nine additional antitoxins lacking cognate toxins, several of which are clustered within each genome. All strains encode bacteriocidal toxins, including two lysozyme-like toxins produced uniquely by strain 409-05. Interestingly, the BV isolates encode numerous proteins not found in strain 409-05 that likely increase their pathogenic potential. These include enzymes enabling mucin degradation, a trait previously described to strongly correlate with BV, although commonly attributed to non-G. vaginalis species.
Collectively, our results indicate that all three strains are able to thrive in vaginal environments, and therein the BV isolates are capable of occupying a niche that is unique from 409-05. Each strain has significant virulence potential, although genomic and metabolic differences, such as the ability to degrade mucin, indicate that the detection of G. vaginalis in the vaginal tract provides only partial information on the physiological potential of the organism.

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Available from: Carl James Yeoman, Sep 30, 2015
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    • "[20] [24] Bacterial density within the biofilm is on the order of 10 10 e10 12 cells per gram compared to 10 6 e10 8 cells per gram of dispersed GV found in vaginal fluid washings. Yeoman et al. suggest that different GV strains have substantially different metabolic and virulence potentials [21]. "
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    ABSTRACT: Vulvovaginitis (VV) is one of the most commonly encountered problems by a gynecologist. Many women frequently self-treat with over-the-counter medications, and may present to their health-care provider after a treatment failure. Vulvovaginal candidiasis, bacterial vaginosis, and trichomoniasis may occur as discreet or recurrent episodes, and have been associated with significant treatment cost and morbidity. We present an update on diagnostic capabilities and treatment modalities that address recurrent and refractory episodes of VV.
    Bailli&egrave re s Best Practice and Research in Clinical Obstetrics and Gynaecology 07/2014; 28(7). DOI:10.1016/j.bpobgyn.2014.07.006 · 1.92 Impact Factor
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    • "Understanding the function of different microbes across species will also be crucial for understanding the dynamics of host-microbe interactions, health and disease , and facilitating the development of new strategies for disease diagnosis and prevention and for personalized treatments to improve the quality of women's lives. Functional differences cannot be assumed simply by species identification due to species-level or strain-level genomic heterogeneity (Yeoman et al., 2010). Metagenomics can help to identify the functional properties of the microbiomes and the extent of fuctional redundancy across hosts. "
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    American Journal of Physical Anthropology 12/2013; 152(Suppl 57). DOI:10.1002/ajpa.22395 · 2.38 Impact Factor
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    • "Several strains possess spacers matching the gene encoding the glycoside hydrolase (GH) family 25 protein and the non-coding regions in its close vicinity. The GH 25 family comprises lysozyme able to hydrolyse peptidoglycan and two Abi proteins conferring resistance to a broad range of related bacteriocins [15,50]. It has been suggested that these findings are in agreement with the data showing that G. vaginalis strains produce substances antagonistic to bacterial isolates common to the vaginal microbiome [15,51]. "
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    ABSTRACT: Background Gardnerella vaginalis is identified as the predominant colonist of the vaginal tracts of women diagnosed with bacterial vaginosis (BV). G. vaginalis can be isolated from healthy women, and an asymptomatic BV state is also recognised. The association of G. vaginalis with different clinical phenotypes could be explained by different cytotoxicity of the strains, presumably based on disparate gene content. The contribution of horizontal gene transfer to shaping the genomes of G. vaginalis is acknowledged. The CRISPR loci of the recently discovered CRISPR/Cas microbial defence system provide a historical view of the exposure of prokaryotes to a variety of foreign genetic elements. Results The CRISPR/Cas loci were analysed using available sequence data from three G. vaginalis complete genomes and 18 G. vaginalis draft genomes in the NCBI database, as well as PCR amplicons of the genomic DNA of 17 clinical isolates. The cas genes in the CRISPR/Cas loci of G. vaginalis belong to the E. coli subtype. Approximately 20% of the spacers had matches in the GenBank database. Sequence analysis of the CRISPR arrays revealed that nearly half of the spacers matched G. vaginalis chromosomal sequences. The spacers that matched G. vaginalis chromosomal sequences were determined to not be self-targeting and were presumably neither constituents of mobile-element-associated genes nor derived from plasmids/viruses. The protospacers targeted by these spacers displayed conserved protospacer-adjacent motifs. Conclusions The CRISPR/Cas system has been identified in about one half of the analysed G. vaginalis strains. Our analysis of CRISPR sequences did not reveal a potential link between their presence and the virulence of the G. vaginalis strains. Based on the origins of the spacers found in the G. vaginalis CRISPR arrays, we hypothesise that the transfer of genetic material among G. vaginalis strains could be regulated by the CRISPR/Cas mechanism. The present study is the first attempt to determine and analyse the CRISPR loci of bacteria isolated from the human vaginal tract.
    BMC Microbiology 12/2012; 12(1):301. DOI:10.1186/1471-2180-12-301 · 2.73 Impact Factor
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