Antigenic Shift v. Drift in Avian and Mammalian Sino- Influenza Type A Viruses. By Charles Hauser, St. Edward’s University Mark Maloney, Spelman College Young Kim, Northland College Michael P. Saclolo, St. Edward’s University

Issues Role of viral hemagglutinin diversity in pathology Creation of new viral strains Antigenic shift versus drift

Influenza type A Subtypes designated by Hemagglutinin (H) and Neuraminidase (N) expression

Subtypes H and N are on surface H and N are components of flu vaccines Subtypes A (H1N1) and A (H3N2) are common human viruses

Vaccines must match subtype and specific strain New flu viruses evade immunity: –Antigenic Shift vs. –Antigenic Drift

Antigenic Shift New subtypes match different H and N genes Avian and human viruses mix and match in swine

Antigenic Drift Small differences in sequence within a subtype define strains “alleles” or different versions of same H genes

BIRD FLU “Bird flu” is unusual Some strains of avian subtypes (H5N1, H9N2, H7N7) can directly infect humans

Module Components Chinese Avian and Mammalian Influenza Hemagglutinin Sequences ClustalW Alignment Dendogram Analysis

H5N1 H9N2 H3N2 H1N1