T lymphocyte responses in CVB3-induced murine myocarditis

Area of Science:

• Immunology
• Virology
• Cardiology

Background:

• Group A Streptococcus (GAS) and coxsackievirus B-3 (CVB3) can both cause myocarditis.
• Monoclonal antibodies (mABs) to GAS M5 serotype cross-react with cardiac antigens.
• Molecular mimicry is a proposed mechanism for autoimmune heart disease.

Purpose of the Study:

• To investigate the role of molecular mimicry between GAS and CVB3 in autoimmune myocarditis.
• To characterize CVB3 variants selected by GAS mABs and their pathogenicity.
• To determine the effect of peptide immunization on CVB3-induced myocarditis.

Main Methods:

• Isolation of CVB3 variants using GAS mABs.
• Induction of myocarditis in Balb/c and CBA mice with wild-type and variant CVB3.
• Assessment of viral load, cardiac histology, and lymphocyte-mediated cytotoxicity.
• Peptide mapping of CVB3 VP1 protein and immunization studies.

Main Results:

• GAS mABs cross-reacted with cardiac antigens (myosin, tropomyosin, vimentin) and neutralized CVB3.
• CVB3 variants induced myocarditis in a mouse strain-dependent manner, correlating with mAB specificity.
• No significant differences in cardiac viral titers were observed between variants.
• Pre-immunization with specific CVB3 VP1 peptides differentially affected viral load, mortality, and myocarditis severity.

Conclusions:

• Shared epitopes between GAS and CVB3 support a molecular mimicry mechanism in autoimmune myocarditis.
• CVB3 variants selected by GAS mABs exhibit distinct pathogenicities.
• Specific CVB3 VP1 peptides can modulate the host immune response and disease outcome, highlighting their potential as therapeutic targets.