Each year, scientists across the globe make highly educated guesses to determine which influenza viruses might be the most prevalent in a given season and then craft a vaccine to match a handful of the top strains.
Sometimes it works, sometimes it doesn’t. Part of the problem is that influenza viruses are constantly mutating, and there is no vaccine to universally protect against many strains. All that could soon change, though, according to a new study, “Vaccine-Induced Antibodies that Neutralize Group 1 and Group 2 Influenza A Viruses,” published in Cell.
Researchers from the National Institute of Allergy and Infectious Diseases at the National Institutes of Health have found a protein on most strains of influenza viruses that has helped them to identify three types of vaccine-induced antibodies effective in neutralizing influenza A infection.
Influenza A viruses are the source of seasonal influenza infection in about 10% of the population. Other types of influenza—B and C—cause the remainder, but influenza A is responsible for some of the some fatal infections, as well many of the new divergent and zoonotic strains.
Every year, researchers attempt to predict which influenza strains will be more prevalent, eventually developing a vaccine that focuses on just three or four strains. The result is varying levels of efficacy, but this can lead to years—like the 2014-2015 flu season—where dominant circulating strains are not covered by that year’s vaccine.
The discovery of broadly neutralizing antibodies against influenza A has long been a goal in the quest for a universal flu vaccine, according to the report.
While a universal vaccine may still be years away, Peter D. Kwong, PhD, chief of structural biology at the Vaccine Research Center at National Institute of Allergy and Infectious Diseases/National Institutes of Health, said the research confirms that humans are able to make antibodies to neutralize several strains of influenza A and that the most current immunogens elicit too low levels of those antibodies for serological detection.
The study used blood samples from individuals vaccinated against H5N1—also known as the Asian Avian Influenza virus—and were able to identify B cells that not only neutralized the influenza virus, but that were activated in response to the vaccine rather than infection by the actual virus.
Kwong told Medical Economics the research has reached a point that allows the team to develop a universal influenza vaccine yet, but it is a step in the right direction.
“We do not specify a new influenza A vaccine immunogen, but rather identify classes of antibodies and NGS-based quantification that alters the developmental process itself,” Kwong said.
The research team was able to identify reproducible classes of antibodies capable of neutralizing influenza A subtypes from both groups 1 and 2.
There are several steps in developing a universal influenza vaccine, Kwong said, the first being developing a “universal” antigen and then demonstrating that the antigen can elicit a universally protective response. The second and third steps involve optimizing immunogenicity and evaluating the antigen in the clinical setting.
Clinical evaluation can take years, but the identification of the neutralizing antibodies can help speed the early work in vaccine development.
“This provides a shortcut to vaccine development steps 2 and 3—and also allows the latest next-generation sequencing (NGS) technologies to be applied. The NGS technologies are not only high thorough, but much more sensitive than serological means of quantifying neutralization,” Kwong said.
Source: Medical Economics