Related Experiment Video
Updated: Apr 16, 2026
A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites
Published on: August 8, 2014
Immunoreactive antigens recognized in serum samples from mice intranasally immunized with Porphyromonas gingivalis
Dongying Bai1, Ryoma Nakao2, Akihiro Ito3
1Department of Bacteriology I, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8640, Japan Department of Gerodontology, Graduate school of Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
Abstract:
Outer membrane vesicles (OMVs) of the periodontopathic bacterium Porphyromonas gingivalis contain a wide range of virulence factors including lipopolysaccharide (LPS), fimbriae and gingipains. We have recently reported strong immunogenicity of OMVs using an intranasal vaccine mouse model. In the present study, we performed sub-immunoproteome analysis of OMV-immunized mouse serum samples from six different mice in order to identify immunodominant antigens. The combination of two-dimensional (2D) gel electrophoresis and mass spectrometry analysis identified OMV proteins of 53 spots on a 2D map, and it was notable that OMV proteins were largely distributed within a low pH range, in marked contrast to the ubiquitous distribution of outer membrane proteins. Western blot using the six serum samples after 2D electrophoresis revealed that all showed immunoreactivity to some diffuse signals at extremely low pH, which was similar to the distribution of immunoreactive signals when the A-LPS antibody was used. Mass spectrometry analysis also demonstrated that the signals corresponded to a wide range of virulence factors including A-LPS-modified proteins such as gingipains. Absorption of serum with LPS resulted in a dramatic reduction of immmunoreactivity. We conclude that LPS and A-LPS-modified proteins in OMVs carry immunodominant determinants and eventually elicit P. gingivalis-specific antibodies in mice.
Insights
Outer membrane vesicles (OMVs) from Porphyromonas gingivalis contain virulence factors that trigger strong immune responses. Lipopolysaccharide (LPS) and LPS-modified proteins within OMVs are key targets, eliciting P. gingivalis-specific antibodies in mice.
Area of Science:
- Microbiology
- Immunology
- Bacteriology
Background:
- Porphyromonas gingivalis outer membrane vesicles (OMVs) harbor critical virulence factors.
- Previous research demonstrated the potent immunogenicity of these OMVs in a mouse model.
Purpose of the Study:
- To identify immunodominant antigens within P. gingivalis OMVs using sub-immunoproteome analysis.
- To characterize the specific components of OMVs that elicit antibody responses in immunized mice.
Main Methods:
- Sub-immunoproteome analysis of serum from OMV-immunized mice.
- Two-dimensional (2D) gel electrophoresis combined with mass spectrometry.
- Western blot analysis and LPS absorption assays.
Main Results:
- Fifty-three OMV protein spots were identified, predominantly at low pH.
- Immunoreactivity was observed at extremely low pH, correlating with A-LPS antibody signals.
- Mass spectrometry identified virulence factors, including gingipains, modified by A-LPS.
- Serum absorption with LPS significantly reduced immunoreactivity.
Conclusions:
- Lipopolysaccharide (LPS) and A-LPS-modified proteins in P. gingivalis OMVs are major carriers of immunodominant determinants.
- These components are responsible for eliciting P. gingivalis-specific antibodies in mice.
