IMMUNOLOGICAL AND PHYSICOCHEMICAL STUDIES OF INFLUENZA MATRIX (M) POLYPEPTIDES

Immunologically active preparations of M polypeptides were recovered from influenza A viruses and had a sedimentation coefficient of 3.3 s. The type-specific antigenic determinants of the M polypeptide were resistant to denaturation by heat at 100.degree. for 2 min in the presence of detergents and to treatment with acidic-chloroform methanol. Mild proteolysis with trypsin or caseinase C produced fragments of 13,000 and 6000 daltons. The 13,000-dalton fragments possessed some identical antigenic determinants to the whole 25,000-dalton M molecule and partially absorbed antibody to the 25,000-dalton polypeptide from a specific [rabbit] antiserum. Immunization of ferrets with M polypeptide or M polypeptide fragments had no preventative or enhancing effect on influenza virus infection; immunization with homologous bromelain-released HA [hemagglutinin] polypeptides conferred absolute protection to virus challenge.