Successful trials in animal models pave way for universal influenza vaccine strategy

Experimental mRNA-based vaccines against all 20 known subtypes of influenza virus provided broad protection against otherwise deadly influenza strains in the first test, according to a study. may one day serve as a general preventive measure against influenza pandemics in the United States. University of Pennsylvaniasaid the United States.

According to the study, tests in animal models show that the vaccine dramatically reduces disease symptoms and protects against death, even when animals are exposed to strains of influenza different from those used to make the vaccine. was shown.

“Multivalent” Vaccines Described by Researchers in Paper Published in Journal chemistryusing the same messenger ribonucleic acid (mRNA) technology Pfizer When modern SARS-CoV-2 vaccine, according to research.

The mRNA technology that made these COVID-19 vaccines possible was developed at the University of Pennsylvania, the study says. “The idea here is to create a vaccine that gives people a baseline level of immune memory against different flu strains, so that when the next flu pandemic hits, they’ll get much less sick and die. ,” said the study’s senior author. Scott Hensley.

Influenza viruses regularly cause pandemics and cause enormous deaths. The best known of these is his 1918-19 “Spanish flu” pandemic that killed at least tens of millions of people worldwide.

Influenza viruses can circulate among birds, pigs, and other animals, and a pandemic could occur if one of these strains infects humans and acquires mutations that are more suitable for human spread. there is.

Current flu vaccines are only “seasonal” vaccines that protect against strains that have recently circulated, but are not expected to protect against new pandemic strains. To elicit broad protection, the idea is to vaccinate with immunogens (a type of antigen that stimulates an immune response) from all known influenza subtypes, the study said.

Vaccines are not expected to provide “sterile” immunity that completely prevents viral infection. Instead, new research has shown that the vaccine induces a memory immune response that is quickly recalled, adapts to new pandemic virus strains, and significantly reduces severe illness and death from infection.

“It will be comparable to the original targeted first-generation SARS-CoV-2 mRNA vaccine. Wuhan coronavirus strain.

“For later variants such as OmicronAlthough these original vaccines failed to completely block viral transmission, they continue to provide lasting protection against severe illness and death,” Hensley said.

The vaccine, when injected and taken up by recipient cells, is effective against all 20 influenza hemagglutinin subtypes H1 through H18 of influenza A virus and two additional subtypes of influenza B virus. It began to produce copies of the hemagglutinin protein, the major influenza virus protein. virus.

“Immunity against all these subtypes is a big challenge with conventional vaccines, but relatively easy with mRNA technology,” said Hensley.

In mice, the mRNA vaccine induced high levels of antibodies that remained elevated for at least 4 months and responded strongly to all 20 influenza subtypes. Moreover, the vaccine appeared relatively immune to previous exposure to influenza viruses that could skew immune responses to conventional influenza vaccines.

The researchers observed that the antibody responses in the mice were strong and broad, regardless of whether the animals had been previously exposed to the influenza virus.

Hensley and his colleagues are now designing human clinical trials, he said. We hypothesize that it may help elicit long-term immunological memory for subtypes of influenza in humans.

“We believe this vaccine can significantly reduce the chances of getting a severe flu infection,” Hensley said.

In principle, the same multivalent mRNA strategy could be used for other viruses with pandemic potential, including the coronavirus, he added.