Now, an epitope is basically a special sequence on that antigen that binds onto our antibody. So when an individual is infected by a pathogen that pathogen may contain or produce antigens that resemble the self antigens of the healthy cells of our body. When the pathogenic antigens induced the immune system to produce antibodies the antibodies not only bind on the pathogenic antigen but because of the resemblance they also bind onto our self antigens. In this particular case, the streptococcal infection produces antibodies that not only bind to that pathogen but also to the cells of our heart. So we have gene mutations as well as pathogenic infections that can lead to autoimmunity. Now, what about the third factor?