H1N1 Paves the Way for Possible Universal Flu Vaccines
A study published by researchers in the Journal of Experimental Medicine suggests that scientist are nearing an understanding of influenza viruses that could lead to a universal flu vaccine.
Before a vaccine was available in 2009, the team analyzed antibodies found in nine patients whom had been infected during the first pandemic wave of H1N1. They found five antibodies that proved cross-protective against a number of influenza variants including the 1918 pandemic strain and the avian flu, H5N1.
Flu viruses possess a lollipop-shaped protein structure called hemagglutinin. The protein at the “head” of the lollipop allows the virus to latch onto and infect other cells. Since all viruses require this structure to reproduce, flu drugs and vaccines focus on identifying this protein to the immune system so that it can fight infection. The genius of the flu virus is that this protein readily mutates so that the virus appears to the immune system to be completely different from one flu season to the next.
Two years ago, researchers found that the stalk of the protein –the lollipop’s “stick”– does not mutate and is generally the same for all flu viruses. Because the H1N1 strain was so different from other flu viruses, it’s likely that the immune systems of those infected made antibodies for the only part of the virus that it recognized: the hemagglutinin stalk. “Previously, this type of broadly protective, stalk-reactive antibody was thought to be very rare,” said Jens Wrammert, a member of the research team. But in the H1N1 patients, they were “surprisingly abundant.”
According to Patrick Wilson, who also worked on the project from the University of Chicago, these antibodies could demonstrate “how to make a single vaccine that could potentially provide permanent immunity to all influenza.”
The US National Institutes of Health is now running human tests on a two-step vaccine process that uses stalk-reactive antibodies to prime the immune system before a regular flu shot. Reuters