Antibody to streptococcal opacity factor in human sera.

Area of Science:

• Microbiology
• Immunology
• Infectious Diseases

Background:

• Group A streptococci (GAS) cause various infections, including streptococcal sore throat.
• Opacity factor (OF) is a characteristic virulence factor produced by certain GAS strains.
• Detecting specific antibodies can help understand host immune responses to GAS infections.

Purpose of the Study:

• To describe and evaluate two tests for detecting antibodies against the type-specific opacity factor (OF) of group A streptococci.
• To investigate the presence of anti-OF antibodies in patients recovering from streptococcal sore throat during outbreaks.
• To compare the distribution of anti-OF antibodies with bactericidal M-antibody in different GAS M-type outbreaks.

Main Methods:

• Development and description of two distinct assays for anti-OF antibody detection.
• Serological testing of patient samples from convalescent phases of GAS outbreaks.
• Comparison of anti-OF antibody levels with M-antibody levels in relation to specific M-types (M22 and M58).

Main Results:

• Antibodies to the type-specific opacity factor (OF) were detected in patients convalescent from streptococcal sore throat.
• In an outbreak involving M-type 22 GAS, anti-OF antibody distribution closely correlated with bactericidal M-antibody.
• In an M-type 58 GAS outbreak, M-antibody was found more frequently than anti-OF antibody.

Conclusions:

• The developed tests are capable of detecting antibodies to the type-specific opacity factor of group A streptococci.
• The immune response, as indicated by antibody presence, can differ between GAS M-types.
• Opacity factor antibody detection may serve as a useful marker, though its prevalence relative to M-antibody can vary by M-type.