Infective endocarditis is a serious illness that requires lengthy medical or surgical treatment, causes severe complications including congestive heart failure and stroke, and is often fatal, even when treated. The viridans streptococci as a group and Streptococcus sanguis in particular are a leading cause of this disease. Identification of streptococcal virulence determinants would lead to a better understanding of the pathogenesis of streptococcal endocarditis and to the identification of targets for prevention and therapy. We have applied signature-tagged mutagenesis (STM) to identify Streptococcus sanguis virulence factors for endocarditis. This approach relies on the infection process in an animal model to identify bacterial genes needed for disease causation. Our initial three-year project resulted in adaptation of an in vitro transposition STM technique for use with S. sanguis and the creation and screening of 800 tagged mutants. The current application proposes to use STM and non-STM approaches to examine the contribution of cell wall-anchored proteins and lipoproteins to endocarditis virulence. The S. sanguis strain being used for these analyses is also being sequenced by us and our collaborators and is near completion. The availability of the sequence will allow for the remainder of the mutagenesis to be performed using a targeted approach involving in vitro transposition into defined amplicons. This approach will be technically simpler than our previous STM analysis and will also be more informative, allowing for categorization of these genes as essential for normal growth in culture, essential for endocarditis virulence, or dispensable for both traits. This approach will provide a comprehensive analysis of the role of two classes of surface proteins in endocarditis virulence. We also expect the study to examine virtually all potential vaccine candidates in S. sanguis and to identify those that are most promising.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Rubin, Fran A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Virginia Commonwealth University
Schools of Dentistry
United States
Zip Code
Eijkelkamp, Bart A; McDevitt, Christopher A; Kitten, Todd (2015) Manganese uptake and streptococcal virulence. Biometals 28:491-508
Crump, Katie E; Bainbridge, Brian; Brusko, Sarah et al. (2014) The relationship of the lipoprotein SsaB, manganese and superoxide dismutase in Streptococcus sanguinis virulence for endocarditis. Mol Microbiol 92:1243-59
Kitten, Todd; Munro, Cindy L; Zollar, Nicai Q et al. (2012) Oral streptococcal bacteremia in hospitalized patients: taxonomic identification and clinical characterization. J Clin Microbiol 50:1039-42
Ge, Xiuchun; Kitten, Todd; Munro, Cindy L et al. (2010) Pooled protein immunization for identification of cell surface antigens in Streptococcus sanguinis. PLoS One 5:e11666
Turner, Lauren Senty; Das, Sankar; Kanamoto, Taisei et al. (2009) Development of genetic tools for in vivo virulence analysis of Streptococcus sanguinis. Microbiology 155:2573-82
Turner, Lauren Senty; Kanamoto, Taisei; Unoki, Takeshi et al. (2009) Comprehensive evaluation of Streptococcus sanguinis cell wall-anchored proteins in early infective endocarditis. Infect Immun 77:4966-75
Das, Sankar; Kanamoto, Taisei; Ge, Xiuchun et al. (2009) Contribution of lipoproteins and lipoprotein processing to endocarditis virulence in Streptococcus sanguinis. J Bacteriol 191:4166-79
Ge, Xiuchun; Kitten, Todd; Chen, Zhenming et al. (2008) Identification of Streptococcus sanguinis genes required for biofilm formation and examination of their role in endocarditis virulence. Infect Immun 76:2551-9
Tang, Gaoyan; Kitten, Todd; Munro, Cindy L et al. (2008) EmaA, a potential virulence determinant of Aggregatibacter actinomycetemcomitans in infective endocarditis. Infect Immun 76:2316-24
Xu, Ping; Alves, Joao M; Kitten, Todd et al. (2007) Genome of the opportunistic pathogen Streptococcus sanguinis. J Bacteriol 189:3166-75

Showing the most recent 10 out of 12 publications