Pooled protein immunization for identification of cell surface antigens in Streptococcus sanguinis.
BACKGROUND
Available bacterial genomes provide opportunities for screening vaccines by reverse vaccinology. Efficient identification of surface antigens is required to reduce time and animal cost in this technology. We developed an approach to identify surface antigens rapidly in Streptococcus sanguinis, a common infective endocarditis causative species.


RESULTS
We applied bioinformatics for antigen prediction and pooled antigens for immunization. Forty-seven surface-exposed proteins including 28 lipoproteins and 19 cell wall-anchored proteins were chosen based on computer algorithms and comparative genomic analyses. Eight proteins among these candidates and 2 other proteins were pooled together to immunize rabbits. The antiserum reacted strongly with each protein and with S. sanguinis whole cells. Affinity chromatography was used to purify the antibodies to 9 of the antigen pool components. Competitive ELISA and FACS results indicated that these 9 proteins were exposed on S. sanguinis cell surfaces. The purified antibodies had demonstrable opsonic activity.


CONCLUSIONS
The results indicate that immunization with pooled proteins, in combination with affinity purification, and comprehensive immunological assays may facilitate cell surface antigen identification to combat infectious diseases.
Ge
Xiuchun
X
Philips Institute of Oral and Craniofacial Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America.
Kitten
Todd
T
Munro
Cindy L
CL
Conrad
Daniel H
DH
Xu
Ping
P
D000465:Algorithms; D000818:Animals; D000954:Antigens, Surface / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D007114:Immunization / Q000379:methods; D011817:Rabbits; D013298:Streptococcus sanguis / Q000276:immunology*
D000954:Antigens, Surface; D001426:Bacterial Proteins