student Natl. Taiwan Univ. Col. of Med., Taipei, Taiwan (Republic of China)
Disclosure(s):
Yung-Chin Lin, MA: No financial relationships to disclose
Introduction/Rationale: Influenza B viruses continue to cause seasonal outbreaks around the world. The mismatch between vaccine and circulating strains was commonly detected in the outbreaks in Taiwan. Co-circulation of both antigenic lineages (Yamagata and Victoria lineages) was frequently found in the outbreaks in Taiwan as well. While antibody immunity plays a major role in the protection against influenza, the information of human antibody response to influenza B virus mainly comes from serological studies.
Methods: We have detected the induction of antibody-secreting B cell response to influenza B viruses and isolated B cell-derived antibodies from adults status post inactivated influenza vaccination. A panel of human antibodies that react to influenza B hemagglutinin in the binding assays was identified and further characterized in details.
Results: Each of influenza B antibodies has unique sequence and variable region VDJ rearrangements. Among anti-influenza B hemagglutinin antibodies, a substantial portion showed cross-reactivity with both Yamagata and Victoria lineage hemagglutinins. The majority of lineage-specific and cross-lineage anti-influenza B hemagglutinin antibodies neutralized the corresponding virus in the vaccine. Epitope mapping by selection of escape mutants revealed that neutralizing antibodies recognized the epitopes that surrounds the receptor-binding site. Besides, the influenza B hemagglutinin residue change of circulating strains was tightly related to the loss of neutralization by antibodies, which indicates the occurrence of antigenic change.
Conclusion: In summary, we dissected the human antibody repertoire against influenza B hemagglutinin induced by vaccination, performed fine epitope mapping of viral hemagglutinin, and demonstrated the role of critical antigenic determinants in the process of antigenic evolution of virus.
