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Immunochemical characteristics and localization on cells of protective antigen (PAg) prepared from Leptospira
T Masuzawa1, R Nakamura, Y Beppu
1Department of Microbiology, University of Shizuoka, Japan.
Abstract:
Immuno-electron microscopic methods revealed that the protective antigen (PAg) of Leptospira interrogans serovar lai exists on the outer envelope sheathing the leptospiral cell body. PAg lost its protective activity after treatment by hydrolysis with 2 M formic acid at 100 C for 2 hr, or oxidation with periodate at 4 C for 40 hr. The antigenic oligosaccharide fraction was further purified from the hydrolyzed PAg by immunoaffinity column coupled with protective monoclonal antibody, LW2, and by gel filtration of HPLC. The antigenic oligosaccharide fraction contained two unknown sugars and 4-O-methylmannose (molar ratio 3:5:1). These findings suggested that these sugars are components of an antigenic determinant contributing to the protective immunity against serovar lai infection.
Insights
The protective antigen (PAg) of Leptospira interrogans serovar lai is located on the outer envelope. Its key antigenic components, identified as specific sugars, are crucial for protective immunity against infection.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Leptospira interrogans serovar lai causes significant disease.
- The protective antigen (PAg) is vital for immunity but its structure is not fully understood.
Purpose of the Study:
- To investigate the localization and structural components of the protective antigen (PAg) from Leptospira interrogans serovar lai.
- To identify specific antigenic determinants responsible for protective immunity.
Main Methods:
- Immuno-electron microscopy was used to determine PAg localization.
- Protective activity was assessed after chemical hydrolysis and oxidation.
- Antigenic oligosaccharides were purified using immunoaffinity chromatography and HPLC gel filtration.
Main Results:
- PAg was found on the outer envelope of Leptospira interrogans serovar lai.
- PAg lost protective activity upon hydrolysis or oxidation, indicating the importance of its structural integrity.
- Purified antigenic oligosaccharides contained two novel sugars and 4-O-methylmannose.
Conclusions:
- The identified sugars are likely key components of the antigenic determinant for protective immunity.
- Understanding these antigenic structures can aid in developing effective vaccines against Leptospira interrogans serovar lai infection.