Comparative genomics of Gardnerella vaginalis strains reveals substantial differences in metabolic and virulence potential.
BACKGROUND
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.


RESULTS
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.


CONCLUSIONS
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.
Yeoman
Carl J
CJ
Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA.
Yildirim
Suleyman
S
Thomas
Susan M
SM
Durkin
A Scott
AS
Torralba
Manolito
M
Sutton
Granger
G
Buhay
Christian J
CJ
Ding
Yan
Y
Dugan-Rocha
Shannon P
SP
Muzny
Donna M
DM
Qin
Xiang
X
Gibbs
Richard A
RA
Leigh
Steven R
SR
Stumpf
Rebecca
R
White
Bryan A
BA
Highlander
Sarah K
SK
Nelson
Karen E
KE
Wilson
Brenda A
BA
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D006194:Gardnerella vaginalis / Q000145:classification / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D023281:Genomics; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D014621:Vagina / Q000382:microbiology; D016585:Vaginosis, Bacterial / Q000382:microbiology*; D014774:Virulence
D001426:Bacterial Proteins