Antigenic variation of indigenous streptococci.

Area of Science:

• Microbiology
• Immunology
• Oral Biology

Background:

• Group D streptococci are common oral bacteria in mice.
• Antigenic variation can impact bacterial identification and host-pathogen interactions.
• Understanding strain dynamics in the murine oral cavity is crucial.

Purpose of the Study:

• To investigate antigenic variation in indigenous Group D streptococci from the mouse oral cavity.
• To identify specific antigens that undergo variation.
• To quantify the prevalence of antigenic variants over time.

Main Methods:

• Culturing streptococci from mouse molar homogenates.
• Biotyping isolates using the API 20S system.
• Serotyping via Lancefield extraction and rocket immunoelectrophoresis.
• Comparing isolates to a standard strain (W1S-1) using specific antisera.

Main Results:

• Four biotypes of Group D streptococci were identified.
• Antigenic variation was observed in antigens O and K, but not the group antigen D.
• Antigenic variants lacking O or K antigens were repeatedly isolated.
• 16% and 26% of strains in two experimental series were identified as antigenic variants.

Conclusions:

• Group D streptococci in the murine oral cavity demonstrate significant antigenic variation.
• The group antigen D is stable, while surface antigens O and K are subject to change.
• Antigenic variation is a common phenomenon in these indigenous streptococcal populations.