Background:Acute rheumatic fever (ARF) is a multifocal autoimmune disorder that typically occurs after pharyngeal infection by Streptococcus pyogenes and can affect the skin, brain, joints and heart. Repeated episodes of pharyngitis or skin infection may lead to serious and chronic rheumatic heart disease (RHD) with heart valve lesions resulting in mitral valve stenosis or regurgitation. RHD is believed to result from immune cross-reactivity between S. pyogenes and host extracellular matrix (ECM) molecules in the heart valves. Methods: we aimed to develop a mouse 14 weeks model of RHD with multiple nasal or subcutaneous immunizations with S. pyogenes cell-wall extracts to gain further insight into RHD pathogenesis.Results: Following repeated immunizations of S. pyogenes cell-wall extracts in mice that are transgenic for human MHC-II molecules, we detected antibodies against streptococcal M-protein and the group A carbohydrate as well as valvular ECM molecules and heart proteins. We also detected increased IL-17, IL-9, IL-13, VEGF, G-CSF, IL-12p70, and IFNγ in the blood of subcutaneously immunized mice. Additionally, increased levels of sP-Selectin, sICAM, and thrombomodulin were detected. Using color doppler echocardiography, changes in the mitral blood flow were observed in the immunized groups and heart histopathology demonstrated dysmorphic, enlarged, and thickened lesions in the mitral and aortic valves as well as hypercellularity aggregation in the valves using immunofluorescence. Conclusion: This work suggests this humanized-mouse model may be used to study the pathophysiology of RHD to help develop additional strategies for clinical diagnosis and treatment.