Designing a universal flu vaccine by refocusing the immune system
A universal flu vaccine that can protect people against any influenza strain is considered a holy grail of flu research because it could spare scientists from the often inaccurate process of predicting the circulating strains each year and redesigning the vaccine to match them.
Now, a group of researchers at the Massachusetts Institute of Technology, the Ragon Institute and Bristol Myers Squibb has shed light on a possible strategy for developing a universal flu vaccine by targeting a more stable region of the influenza virus that’s normally not targeted by the immune system.
In mice, a vaccine that uses nanoparticles to carry flu proteins triggered an antibody response to the desired segment of the virus, suggesting the vaccine could be broadly effective against any flu strain. The team reported the findings in the journal Cell Systems.
“The reason we're excited about this work is that it is a small step toward developing a flu shot that you just take once, or a few times, and the resulting antibody response is likely to protect against seasonal flu strains and pandemic strains as well,” Arup Chakraborty, Ph.D., the study’s senior author, said in a statement Influenza virus coats itself with a protein called hemagglutinin (HA), which is crucial for its ability to infect human cells. HA consists of two parts: a globular head region and a stem or stalk region. The head region often mutates and varies across different strains of influenza viruses. In contrast, the stem or stalk region rarely mutates, making it a great target for a universal vaccine.
However, the immune system is almost always drawn to the highly variable head region, producing antibodies that can only recognize a few virus subtypes rather than what are known as broadly neutralizing antibodies.