Influenza Virus: A Case Study

Influenza viruses are constantly evolving due to the mechanism of antigenic drift. This results in seasonal vaccination to target only specific strains, which puts us in a race against the clock in the prevention of the next pandemic. One key to solving this is the development of a universal influenza vaccine, which would elicit a broad antibody response. This would target either multiple strains or strains from the past, present, and future in a single vaccination. As vaccine may target sites such as the neuraminidase (NA) or the M2 Ion channel, hemagglutinin (HA) is preferred by most approaches due to the consensus amino acids found throughout the different subtype, specifically the stem region (3). However, there are boundaries to the stem approach, such as, that some antibodies have reduced affinity for the stem region (1).

Summary

Hemagglutinin (HA) is an antigenic receptor-binding glycoprotein found on the surface of the influenza viruses. Its molecular structure has been classified as a homotrimer with each monomer being the precursors to HA1, head region, and HA2, stem region. The stem region, which contains conserved proteins common among other influenza pandemic strains, are currently being explored for vaccination opportunities, along with the variable head region where antibodies target and bind to elicit immune

In focus of specifically the H5N1 subtype, the results confirmed that COBRA-vaccinated animals showed equal or better results - i.e., the HAI titers was higher and drawn out a much extensive level of binding antibodies (4). A stem-based approach seemed more feasible, with it being a more stable, conserved target, however, stem epitopes are less accessible compared to the HA head epitopes