THE IMMUNOLOGICAL ACTIVITY OF A DELETION MUTANT OF INFLUENZA-VIRUS HEMAGGLUTININ LACKING THE GLOBULAR REGION

A deletion mutant of influenza virus haemagglutinin (HA; headless HA) lacking the globular region was expressed in CV-1 cells and detected w ith a monoclonal antibody, C179, which recognizes a conformational epi tope in the middle of the stem region of HA and neutralizes all H1 and H2 subtypes. The cDNA coding for the headless HA was constructed from influenza virus A/Okuda/S7 (H2N2), which was also used to select C179 . The conformational epitope recognized by C179 was highly stable even after removal of the globular region. The survival rate of mice immun ized with the headless HA and challenged with lethal influenza virus A /FM/1/47 (H1N1) was significantly higher than that of the control mice . The headless HA has the potential to induce cross-protection against influenza virus infection.