This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
Group A beta haemolytic streptococci (GAbHS) cross reacts with? 
Select and explain. 
A. Valves & myocardium, B. Annular ring, C. Endocardium, D. Pericardium
A: Valves & myocardium
Answer: A: Valves & myocardium 
Explanation: Ans. a (Valves & Myocardium). (Ref. Harrison's principles of internal medicine, 18th Chapter 322.)Rheumatic heart disease# Group A beta haemolytic streptococci (GAbHS) is implicated as the cause of rheumatic valvular heart disease.# Age of occurence: 5-15 years.# Pathogenesis: Hypothesis of 'antigenic mimicry'; carbohydrate of GAbHS and glycoprotein of valves and streptococcal cell membrane, M protein sarcolemma and myocardial cell moieties have interactions i.e they cross react with each other. Antigenic relationships have been shown between capsular hyluronic acid & human synovial fluid, CE11 wall protein & myocardium, group A Carbohydrate & Cardiac valves, Cytoplasmic membrane antigens & vascular intima, & peptidoglycans & skin antigens.Streptococcal antigenCross-reacts withCapsular hyaluronic acidHuman Synovial FluidCytoplasmic membrane antigensVascular intimaPeptidoglycansSkin antigensCell wall proteinMyocardiumGroup A carbohydrateCardiac valves