New research provides insights on how exposure to the flu impacts the immune system, which may be helpful for designing more effective and longer-lasting vaccines. According to a Science Daily news report, a person’s first infection with the influenza virus likely stimulates the production of key antibodies that then shape later immune responses to different seasonal influenza strains. A team of researchers led by Stephen Harrison of Harvard Medical School examined how antibodies evolve over the years as a person is exposed to different seasonal influenza strains.

The researchers focused on one individual who reported that he received his first flu vaccine at 18 years old, looking especially close at antibodies that target a site called hemagglutinin on the influenza virus that is necessary for binding to a host cell. Harrison explains, “The virus cannot tolerate changes at the center of this site, which is essential for infection. Because they target a site that can mutate only at its edges, these antibodies can block infection by a large number of different influenza viruses.”

By examining the various seasonal influenza strains that came and went while the person was growing up, the research team determined that viruses circulating around the time of the person’s birth were likely responsible for eliciting the initial immune response involving antibodies that bind viral hemagglutinin. Essentially, the person probably caught the flu as a small child, which led to the production of antibodies against hemagglutinin that were important in later immune responses against other seasonal influenza strains, according to Science Daily.

First author of the study Aaron Schmidt says, “The approach demonstrates how early imprinting of our immune system by exposure to a particular virus can influence our response to later encounters.” The researchers also found that vaccination at the age of 18 stimulated and updated the initial antibodies against hemagglutinin.

The research team hopes to conduct additional experiments in other individuals to assess how annual vaccinations or influenza infections might continue to impact these antibodies overtime. According to Science Daily, the findings suggest that vaccinating infants against the conserved regions of hemagglutinin may be an essential step toward developing a vaccine that elicits long-lasting immunity.

Source: Science Daily