Antigenic drift is seen in: (DNB Dec 2010)
Antigenic shift and drift is seen in influenza virus.
Antigenic Drift & Shift In Influenza
a. Gradual sequential change in antigenic structure occurring at frequent intervals.
b. d/to mutation & selection occurs under selection pressure of community.
c. Accounts for small periodical epidemics (which can occur between major pandemics).
d. Drift is accumulation of point mutations.
e. Associated with type A or B
a. Sudden, drastic, discontinuous variation in antigenic structure.
b. d/to antigenic variation (changes involve hemagglutinin, neuraminidase or both antigens)
c. Responsible for major epidemic & pandemic.
d. Result from genetic recombination of human with avian/animal viruses
e. Associated with type A>B
a. In influenza antigen variations Occurs mainly in Type A. (A>B>C)------Influenza type C is antigenically stable / antigen variation does not . occur
b. In polio most outbreaks are d/to type-l [ most common], type-2 is most effective antigen (immunogenic) and type-3 causes most cases of vaccine associated paralytic poliomyelitis.