A Breakthrough in Flu Vaccine: Overcoming Subtype Bias for Broader Protection
Bioengineers at Stanford University have articulated a new strategy to maximise flu vaccine during the dry season and to counter avian flu and other new strains of the virus. Their approach proposed in their Science paper addresses what the authors call “subtype bias”: whenever the immune system develops a response to certain subtypes of influenza, it often neglects others.
The given disease is a severe worldwide problem, still affecting thousands of people a year and putting millions of patients into hospitals. The normal annual flu shot includes four different strains of flu, each strain being a subtype of the virus. However, it has shown low or high effectiveness ranging between 20% and 80%, mainly because the immune reactions differ among these subtypes.
Subtype bias is has been attributed to “original antigenic sin”, the assumption that having been infected by one subtype of the flu virus, the immune system is likely to identify subsequent strains in the same manner. Nevertheless, the lead author, Vamsee Mallajosyula, Ph.D., and senior author, Mark Davis, Ph.D., have shown that genetic factors are the chief underlying cause for this effect. The researchers’ work demonstrated that, indeed, people, including monozygotic multiple twins or newborns who never were infected with flu, have preferences of some subtypes over others.
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To avoid this bias, in the recent study, the researchers synthesized the four antigens, chemically linking them on a single molecule identified as a molecular scaffold. This would make certain that all subtypes are ingested and processed at once by immune cells hence triggering a better immune response. The method was tested using human tonsil organoids – tissue grown in a lab mimicking the structure of lymph nodes. Overall, hemagglutination inhibition antibody responses were demonstrated against all four influenza subtypes and the results were higher than the current standard in vaccine formulations.
Moreover, this technique does not only improve the response to different seasonal flu strains but also account to pandemic possibility. Risk emanating from bird flu is high because the disease can mutate and spread from human to another. By developing a five-antigen platform that includes bird flu hemagglutinin, along with the four regular seasonal subtypes, the researchers were able to obtain an an amazingly stronger response in their tonsil organoid models.
If subtype bias was eliminated by this method, then it can be possible to have a universal flu vaccine with wide protection for the localized and emerging seasonal strains. According to Davis’ information, the given innovation may help minimize the dangers of the next flu pandemic and promote constructing a stronger protection.
This novel in the development of vaccines serves the present needs of fighting flu and demonstrates a significant progress of research in improving global health safety.