A collaborative research group between RIKEN and Tokyo University of Science has revealed a new regulatory mechanism for the induction of antibodies (neutralizing antibodies) that diminish or eliminate influenza virus activity in mice.
Vaccination is effective in preventing the virus from entering the body.This is because an antibody that binds to the virus and removes it from the body is induced.Induction of antibodies by vaccination requires both "germinal center" and "lymphoid follicular helper T cells (Tfh cells)", which are the sites of antibody production.This is because antibodies with high binding ability (affinity) to the virus are produced in the germinal center with the help of Tfh cells.Therefore, it has been said that a highly effective vaccine can be developed by efficiently activating Tfh cells.
This time, we found that "immunoglobulin G2 antibody (IgG2 antibody)" is produced by vaccination of mice lacking germinal centers or Tfh cells using seasonal influenza virus and highly pathogenic avian influenza virus. IgG2 antibody does not have a high affinity for influenza virus, but it has a high preventive effect because it has a high effect of blocking virus infection (neutralizing activity).It was also found that "type I helper T cells (Th1 cells)" involved in cell-mediated immunity induce IgG2 antibody.From this, it was found that if Th1 cells are activated, an antibody having a high neutralizing activity can be produced even if the affinity is low.
Germinal center antibody production takes time to improve affinity, and antibody specificity is limited because high affinity antibodies are selected.On the other hand, Th1 cells have a low affinity, but can rapidly produce antibodies that can respond to a wide range of viruses.Therefore, the development of a vaccine that can activate Th1 cells efficiently will be a new vaccine tactic against various influenza viruses.
