This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: general microbiology, Subject name: Microbiology
[{'content': 'A child is suffering from recurrent chronic infections with encapsulated bacteria; Which subclass of IgG does the child has deficiency \nSelect and explain. \nA. IgG1, B. IgG2, C. IgG3, D. IgG4', 'role': 'user'}, {'content': 'Answer: B \nExplanation: * IgG has four subclasses: IgG1, IgG2, IgG3 and IgG4 * IgG2 antibody is directed against polysaccharide antigens and hence it is most impoant defence against encapsulated bacteria. Ref:- Review of medical microbiology and immunology 13th ed; pg num:- 1127', 'role': 'assistant'}]