Prospects of HA-based universal influenza vaccine

Abstract

Current influenza vaccines afford substantial protection in humans by inducing strain-specific neutralizing antibodies (Abs). Most of these Abs target highly variable immunodominant epitopes in the globular domain of the viral hemagglutinin (HA). Therefore, current vaccines may not be able to induce heterosubtypic immunity against the divergent influenza subtypes. The identification of broadly neutralizing Abs (BnAbs) against influenza HA using recent technological advancements in antibody libraries, hybridoma, and isolation of single Ab-secreting plasma cells has increased the interest in developing a universal influenza vaccine as it could provide life-long protection. While these BnAbs can serve as a source for passive immunotherapy, their identification represents an important step towards the design of such a universal vaccine. This review describes the recent advances and approaches used in the development of universal influenza vaccine based on highly conserved HA regions identified by BnAbs.

Figure 1

Phylogenetic tree of the 18 influenza A virus subtypes, classified into two groups: Group 1 and Group 2. Representative HA protein sequences were selected for each subtype from viruses belonging to following subtypes (H1N1, H2N2, H3N2, H4N6, H5N1, H6N2, H7N3, H8N4, H9N2, H10N7, H11N6, H12N5, H13N6, H14N5, H15N9, H16N3, H17N10, and H18N11). The phylogenetic tree was made with Geneious version 7.0.