Another step towards a universal flu vaccine following human trial results

This is not an easy goal, but the scientific community is not giving up on its efforts. Years of research into a universal flu vaccine are making strides. This Wednesday, the magazine Science Translational Medicine publishes the results of a first-phase trial of a new broad-spectrum drug against this virus, which manifests differently every year, forcing epidemiologists to work each season on new formulas to immunize the population.

There are 18 known subtypes of the influenza A virus and two of the B virus that cause the flu. HA and NA proteins are considered for its classification. HA is the one that the virus uses to enter cells and the one that elicits the greatest number of disease-fighting antibodies. The main problem is that these proteins are highly variable and the virus can mutate them. Inside there are two regions: the globule and the stem, which changes little. And it is on this more stable side that most universal vaccine research is focused.

“In this case, the researchers use an artificial protein containing a fragment of the bacterial ferritin protein as a vaccine. Helicobacter pylori Attached to the influenza virus hemagglutinin stem. The ferritin fragment is organized by self-assembly to form nanoparticles that serve as a platform for the stability of the hemagglutinin rod,” explains Estanislao Nistal, virologist and professor of microbiology at CEU San Pablo University. Scientific Media Center Spain.

The result of this study is a continuation of the work that the researchers already published in 2015, which showed that “this artificial protein can induce an effective response against infections in animals”, says Nystal. In this case, the first tests with humans indicate that the drug can produce antibodies against the three most important hemagglutinins: H1, H2 and H5.

this winter In accordance with the recommendations of the World Health Organization For the Northern Hemisphere, a quadrivalent influenza vaccine has been introduced in Spain against types H1/N1 and H3/N2 and one of B. H2 was the cause of the great Asian flu pandemic of 1957 and H5 is in the bird flu that is causing concern. Experts on its ability to spread to humans. The WHO itself has warned that “we must prepare for any change of scenario” after the outbreak, which has already affected mammals such as mink, otter and fox.

Inmaculada Casas, director of the Respiratory Virus and Influenza Research Group at the Carlos III Institute of Health, explained to SMC that “although the H1 antigen from strains before 2009 was used, the authors observed an adequate response to strains that are more divergent. More than 20% in order from H1, including H5 and H2. Application for bird flu prevention can be immediate.

The study showed that “the new H1ssF vaccine is safe in healthy adults, well tolerated, and even without the use of immunogenic adjuvants (substances that make the immune response more effective),” says Casas. In addition, he notes that the drug boosted antibodies in all age groups, when generally authorized vaccines are “less effective in the elderly.”

According to the World Health Organization, between 290,000 and 650,000 people die worldwide each year from influenza epidemics and there are three to five million serious cases. According to these indicators, the most effective way to prevent the disease is vaccination, mainly among vulnerable people: chronically ill, over 65 years and under five years, pregnant women and health professionals.

The work was published in Science Translational Medicine It also contains unknowns. “This study doesn’t show data on cellular immunity,” says Nistal, who notes that “another limitation that researchers will probably look at in the future is whether immunization with this vaccine can protect a patient from infection, how long it lasts. This protection and how many times should be vaccinated to have good protection, as in the case of elderly people or other particularly susceptible groups where the virus poses a greater risk.”

“With this trial,” says Casas, “we cannot talk about the ‘global’ effectiveness of the vaccine, because it will measure the protection of the vaccinated population against seasonal viruses in different seasons of testing.” It is worth noting that the antibodies were developed specifically against the antigen created by them and that they theoretically work on different subtypes of influenza group 1.

other vaccines

This is not the only work in progress. magazine in December 2020 ability published the results of a phase I human trial testing the safety and ability of hemagglutinin-based chimeric vaccines to generate antibodies reactive against the hemagglutinin stem domain in healthy US adults aged 18 to 39 years.

and last november Science published another early-stage animal study in which scientists were developing a “nucleoside-modified LNP-mRNA vaccine encoding the hemagglutinin antigens of all 20 known influenza A and B virus subtypes.” According to the authors, this “provoked high levels of specific antibodies and cross-reactivity in mice and ferrets reacting to all 20 encoded antigens.”

The novelty of this vaccine is that it combines messenger RNA technologies that try to encode antigens of all known influenza subtypes, while other formulations can only provide protection against a limited number of antigens, the researchers noted.

Source: El Diario





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