Flu "Super Antibody" Provides Hope for Universal Vaccine

Researchers have uncovered a flu “super antibody” called FI6 that can fight all types of influenza A viruses, a discovery that they believe may be a turning point in the development of new flu treatments.

In a study published July 28 in the journal Science, Antonio Lanzavecchia, MD, director of the Institute for Research in Biomedicine (Bellinzona, Switzerland), and colleagues used a new method to identify an antibody from a human patient which neutralizes both main groups of influenza A viruses.

Although it is an early step, it is an important one that eventually may pave the way for the development of a universal flu vaccine, they said in a Reuters article.

Vaccine makers currently have to change the formulations of their flu shots every year to make sure they protect against the strains of the virus circulating—a process that is both time-consuming and costly. The goal is come up with a universal flu vaccine that could protect patients from all flu strains for decades, or even for life.

“As we saw with the 2009 pandemic, a comparatively mild strain of influenza can place a significant burden on emergency services. Having a universal treatment which can be given in emergency circumstances would be an invaluable asset,” said John Skehel, PhD, of Britain’s National Institute for Medical Research, who worked on the study.

Lanzavecchia said high rates of seasonal flu and the unpredictability of possible future pandemics underlined the need for better treatments that target all flu viruses.

When an individual is infected with the flu virus, their antibodies target the virus' hemagglutinin protein, the researchers explained in the study. Because this protein evolves so rapidly, there are currently 16 different subtypes of influenza A, which form 2 main groups. Humans usually produce antibodies to a specific subtype, and new vaccines are made each year to match these strains.

To make progress toward a universal shot that could be used every year, scientists need to identify the molecular signatures that prompt the development of broadly neutralizing antibodies.

Previous research work has found antibodies that work in Group 1 influenza A viruses or against most Group 2 viruses, but not against both.

This team developed a method using X-ray crystallography to test very large numbers of human plasma cells, to increase their odds of finding an antibody even if it was extremely rare. When they identified FI6, they injected it into mice and ferrets and found that it protected the animals against infection by either a Group 1 or Group 2 influenza A virus.

“As the first and only antibody which targets all known subtypes of the influenza A virus, FI6 represents an important new treatment option,” Lanzavecchia said.

Researchers in the United States said last year they were having some success with another possible approach to developing a universal flu shot, using a two-step system of a vaccine using DNA to "prime" the immune system and then a traditional seasonal flu shot.