Related Experiment Videos
Anti-Hsp65 antibodies recognize M proteins of group A streptococci
A Quinn1, T M Shinnick, M W Cunningham
1Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, 73190, USA.
Abstract:
Group A streptococcal M protein and the mycobacterial heat shock protein, hsp65, are strong bacterial immunogens that have been linked to arthritis and autoimmunity. Recent evidence has shown that streptococcal arthritis and adjuvant arthritis may be related to epitopes shared between group A streptococci and hsp65. We investigated the possibility that immunological similarities were shared between streptococcal M protein and hsp65. Antibodies against the 65-kDa heat shock protein of Mycobacterium tuberculosis were tested for reactivity with group A streptococci and purified recombinant M proteins (rM5 and rM6). Rabbit polyclonal anti-hsp65 serum was highly reactive with M type 5 Streptococcus pyogenes and rM5 and rM6 proteins in an enzyme-linked immunosorbent assay (ELISA). A mouse anti-hsp65 monoclonal antibody (MAb), IIC8, reacted with streptococcal M types 5, 6, 19, 24, and 49 in an ELISA but showed no reactivity with an isogenic streptococcal mutant which did not express M protein. Anti-hsp65 MAb IIC8 recognized rM5 and rM6 proteins in the ELISA, and MAbs IIC8 and IIH9 reacted strongly with rM6 protein in Western immunoblots. The binding of M protein by anti-hsp65 MAbs was shown to be inhibited by both hsp65 and M protein. These data show that anti-hsp65 antibodies recognize streptococcal M proteins.
Insights
Antibodies targeting the heat shock protein 65 (hsp65) from Mycobacterium tuberculosis also recognize group A streptococcal M proteins. This cross-reactivity suggests a shared epitope, potentially linking bacterial infections to autoimmune conditions like arthritis.
Area of Science:
- Immunology
- Microbiology
- Autoimmunity
Background:
- Group A streptococcal M protein and mycobacterial hsp65 are potent bacterial immunogens.
- Both proteins are implicated in arthritis and autoimmunity.
- Shared epitopes between these bacteria may explain cross-reactive arthritis.
Purpose of the Study:
- To investigate immunological similarities between streptococcal M protein and hsp65.
- To determine if antibodies against hsp65 react with streptococcal M proteins.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) using rabbit polyclonal anti-hsp65 serum and mouse monoclonal antibodies (MAbs) against hsp65.
- Testing reactivity with various strains of Streptococcus pyogenes and purified recombinant M proteins (rM5, rM6).
- Western immunoblots with MAbs IIC8 and IIH9 against rM6 protein.
- Inhibition assays using hsp65 and M protein to block antibody binding.
Main Results:
- Rabbit anti-hsp65 serum showed high reactivity with Streptococcus pyogenes M type 5 and recombinant M proteins (rM5, rM6).
- Mouse anti-hsp65 MAb IIC8 reacted with multiple M types (5, 6, 19, 24, 49) but not with M protein-deficient mutants.
- MAbs IIC8 and IIH9 recognized rM5 and rM6 proteins in ELISA and Western immunoblots.
- Antibody binding to M protein was inhibited by both hsp65 and M protein, confirming epitope sharing.
Conclusions:
- Anti-hsp65 antibodies recognize streptococcal M proteins.
- A shared immunological epitope exists between mycobacterial hsp65 and streptococcal M protein.
- This cross-reactivity may contribute to the pathogenesis of autoimmune diseases like streptococcal and adjuvant arthritis.