Microbiology Virology dd7f78b0 Causes of antigenic drift in influenza viral infections - A Small mutation in neuraminidase and hemagglutinin B Large mutations in viral genome C Step mutations in viral genome D None of the above High-Yield Explanation Antigenic drift is due to mutation and selection. REF:ANANTHANARAYAN AND PANIKER'S TEXTBOOK OF MICROBIOLOGY 9TH EDITION PAGE NO-499