Broadly neutralising antibodies could form basis of influenza vaccine

A new study has revealed that B cells can produce antibodies against the H1N1 influenza virus that also neutralise various other influenza strains. The researchers, from various US institutions including the University of Chicago, say that these findings could inform research into potential universal flu vaccines.

According to the researchers, current vaccines for seasonal flu induce antibodies against the “head” region of haemagglutinin, the major surface antigen on influenza viruses. However, this strategy only protects against a few strains of influenza and these antigen sites mutate frequently enough that a new vaccine is needed each year.

Searching for better vaccine targets, the scientists studied the properties of antibodies from memory B cells exposed to the H1N1 influenza virus, the cause of the 2009 swine flu pandemic. They saw that the B cells produced antibodies that targeted the receptor-binding site or lateral patch epitopes, two regions of the haemagglutinin head that are conserved across many strains of influenza. As a result, these antibodies neutralised most H1 influenza viruses the researchers tested and antibodies against the lateral patch also reacted to the H3N2 strain and to influenza B viruses.

Furthermore, transfers of the antibodies protected mice from lethal doses of H1N1 influenza and some of the lateral patch antibodies also neutralised a natural, recent flu strain with mutations in a major antigen site.

The findings showed that the antibodies targeted two conserved regions of the virus and that transfers of the antibodies protected mice from lethal infection. Vaccines that target the two sites might therefore be able to protect against a broader array of flu strains, the team say. 

The findings from the study are published in Science Translational Medicine.