[The mechanism of antigenic shift and drift of human influenza virus].

Influenza virus has a remarkable ability in escaping host defense mechanisms by altering its the antigenic character. The molecular mechanisms by which viruses alter their antigenic character form an important subject of study since they ultimately control epidemics of influenza. 1) We showed how the 1993/1994 antigenic variant viruses appeared from the 1991 virus by analyzing human sera with a chimeric protein method. 2) We introduced random one-point amino acid changes on the A/Aichi/2/68(A/Aichi/68) HA protein by PCR mutation methods and estimated the viability of the H3HA protein resulting from theses amino acid changes and to determine which changes are allowed during evolution of the H3HA protein.