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What is Antigenic variation is seen in all EXCEPT: and explain in detail?
ANSWER: (C) Influenza type CREF: Park 18th ed Page 144INFLUENZA VIRUS:Family orthomyxoviridaeIncubation period: 18-72 hoursTypes: A, B, C (No cross immunity and antigenically distinct)Both A and B have surface antigens, H (hemagglutinin), N (neuraminidase)Major antigenic variations occur in A, some in B while C seems to be antigenically stable.Rimantidine and Amantadine are used as prophylaxis for influenza AAntigenic variations:Antigenic shift: sudden change , due to genetic reassortment, causes major pandemicsAntigenic drift: A gradual change, due to point mutations, causes epidemics.