Immunity system complexity: response to flu vacines (Introduction)

by David Turell , Friday, December 22, 2023, 16:12 (127 days ago) @ David Turell

Newly found antibodies fight flu viruses:

https://www.livescience.com/health/viruses-infections-disease/never-before-seen-antibod...

"In the new study, published Thursday (Dec. 21) in the journal PLOS Biology, scientists described a newfound class of antibodies in human blood samples that target multiple forms of the influenza A virus.

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"To guard against influenza A, conventional flu vaccines usually prompt the immune system to produce antibodies against the H protein on the surface of the virus. Antibodies have previously been discovered that target two main types of hemagglutinin, called H1 and H3, at the same time. However, they can only do this if there is a specific mutation in H1, namely the insertion of an amino acid in the outer edge of the protein that binds to a receptor on the outside of our cells. This consequently limits the antibodies' efficacy against different flavors of flu virus.

"Through lab experiments, the study authors identified antibodies that are abundant in human blood and can bind to certain H1 and H3 strains of influenza A, whether or not this hemagglutinin mutation is present. This means that they'd theoretically be able to provide broad protection against both subtypes of virus, potentially even as circulating strains mutate over time.

"A newly discovered class of antibodies in human blood can neutralize different types of the flu virus and could be key to the development of broadly protective vaccines against the seasonal viruses, scientists say.

"Circulating flu viruses constantly mutate, so "we need annual influenza virus vaccines to keep pace with continuing viral evolution," the researchers behind the discovery said in a statement. "Our work suggests that the barriers to eliciting more broadly protective immunity may be surprisingly low," they said.

"There are four types of flu virus, known as influenza A, B, C and D, with A and B being responsible for the seasonal flu epidemics in the U.S. every year.

"Influenza A comes in many subtypes whose differences lie in two proteins that the virus uses to infect our cells: hemagglutinin (H) and neuraminidase (N). For example, H1N1 and H3N2 are subtypes of influenza A that routinely infect people.

'Within each subtype are different "strains" that constantly tweak their genetic code. For example, a strain of H1N1 is currently the dominant virus causing flu in the U.S. Influenza B, meanwhile, is divided into two lineages — Yamagata and Victoria — and is typically responsible for a much smaller proportion of flu cases.

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"'Given the right series of influenza virus exposures/vaccinations, it is possible for humans to mount robust antibody responses that neutralize divergent H1N1 and H3N2 viruses, opening new avenues to design improved vaccines," the authors said in the statement.

"'In other words, there may be a way to ensure vaccines trigger the production of these broad-acting antibodies, to ensure the shots guard against both subtypes of the virus equally well."

Comment: our new ingenuity is the knowledge of tailoring vaccines to exact spots on the virus. This matches the body's ability to make specific antibodies.