A two-amino acid change in the hemagglutinin of the 1918 influenza virus abolishes transmission.
Tumpey TM, Maines TR, Van Hoeven N, Glaser L, Solórzano A, Pappas C, Cox NJ, Swayne DE, Palese P, Katz JM, García-Sastre A. A two-amino acid change in the hemagglutinin of the 1918 influenza virus abolishes transmission. Science. 2007 Feb 02; 315(5812):655-9.