A vaccine built from genetically engineered baker’s yeast and decorated with a slow-changing influenza protein has protected mice against three influenza strains, according to researchers at the University of Michigan. The experimental formulation is designed to address one of the central weaknesses of seasonal flu vaccination: conventional vaccines focus largely on hemagglutinin, a highly variable surface protein that can change sufficiently from year to year to reduce the match between a vaccine and circulating viruses. By presenting the more conserved M2 protein in a virus-like structure, the researchers aim to stimulate immunity that could remain effective against a wider range of influenza A viruses, including strains that current vaccines do not anticipate.
The findings are scheduled for presentation on Aug. 24 at the American Chemical Society’s fall 2026 meeting. They remain preclinical, and the results in mice do not establish that the vaccine will protect people or provide long-lasting immunity. Even so, the approach combines two goals that have long challenged influenza researchers: identifying a viral target that changes slowly enough to support broad protection, and developing a manufacturing system that can produce vaccine material rapidly when a new strain begins to spread. The project is led by Fei Wen, a professor of chemical engineering at the University of Michigan, with doctoral student Trang Hoang as first author.
Seasonal influenza vaccines are updated because the virus continually evolves, particularly in hemagglutinin, or HA. This protein forms the majority of the virus’s external surface and is readily recognized by antibodies generated after infection or vaccination. Mutations in HA can alter the sites, known as epitopes, that antibodies bind, allowing new variants to partially escape pre-existing immunity. Global health authorities monitor influenza circulation and recommend vaccine compositions months before each flu season, giving manufacturers time to produce doses. The process can work well when forecasts are accurate, but protection may be reduced when an emerging strain differs substantially from the selected vaccine viruses.
The Michigan team took a different approach by focusing on M2, a small influenza protein involved in the virus’s life cycle. M2 functions as an ion channel in the viral envelope, helping regulate acidity inside virus particles as they enter host cells. Because its structure and activity are constrained by the need to support viral replication, M2 generally tolerates fewer mutations than HA. The researchers specifically use the portion of M2 exposed on the exterior of the virus, often called the M2 ectodomain, as an antigen. This region is relatively conserved across influenza A viruses, although it is present in much smaller quantities than HA and therefore does not normally dominate the immune response to an inactivated flu virus.
That limited natural visibility is one reason M2 has attracted interest as a universal-vaccine target. An immune response directed toward conserved M2 regions may recognize viruses from several influenza A subtypes, rather than responding narrowly to the HA and neuraminidase proteins of one seasonal strain. Such immunity would not necessarily prevent infection in the same way as highly strain-matched HA antibodies. Instead, antibodies and other immune mechanisms targeting M2 could interfere with viral spread or help immune cells identify infected cells more efficiently, potentially reducing disease severity and transmission. The exact balance of these protective mechanisms will need to be established in further animal studies and, eventually, human trials.
To make M2 more immunologically visible, the researchers assembled it on virus-like particles, or VLPs. These particles imitate the approximate size and shape of a virus but contain no influenza genome, so they cannot replicate or cause influenza infection. Their repetitive, ordered surfaces can help cross-link receptors on immune cells and promote antigen uptake, making VLPs useful platforms for vaccine development. In this case, the particles are covered with M2 protein rather than displaying the full collection of proteins found on an infectious influenza virion. The design therefore concentrates the immune system’s attention on a target that is normally overshadowed by the much more abundant HA.
The manufacturing method begins with ordinary baker’s yeast that has been genetically modified to produce large quantities of M2. The yeast is grown in a nutrient-rich liquid, allowing the engineered cells to synthesize the viral protein. Researchers then use mild chemical treatment to remove the rigid cell wall while preserving the cell membrane and the molecular machinery associated with particle formation. According to the team, the wall-less yeast cells bud off M2-bearing particles that can be collected and purified. This strategy uses yeast as a biological production platform rather than relying on influenza virus grown in eggs or cell culture, and it could make it easier to scale production without handling infectious virus.
Speed is a major potential advantage of the platform. Traditional egg-based influenza manufacturing can require roughly six months because candidate viruses must be selected, adapted to grow efficiently in eggs, propagated, harvested, purified and formulated. Production timelines can be shorter with cell-based or recombinant systems, but each has its own technical and regulatory requirements. The Michigan researchers say their yeast-based process can generate a substantial amount of vaccine material in about a month. If validated at industrial scale, that turnaround could be valuable during an outbreak, when health authorities may need to respond to a newly recognized strain rather than wait for the next routine seasonal update.
In mouse experiments, the M2-based VLP vaccine generated strong immune responses and protected animals challenged with three different influenza strains, the researchers report. The breadth of the protection is important because it suggests that the formulation can produce functional immunity beyond a single closely matched virus. However, animal challenge studies are an early stage of vaccine evaluation. The team’s next step is to determine how long protection lasts in vaccinated mice and to characterize the antibodies and cellular responses responsible for it. Researchers will also need to test dosing, safety, repeat vaccination, protection against additional influenza subtypes and performance in animal models that more closely predict human responses.
The technology has been licensed to Esperovax, which is exploring development of an oral vaccine based on the platform. An oral formulation could simplify administration and potentially improve access, although delivering vaccine antigens through the digestive system presents its own challenges. Before the vaccine can be tested in people, the researchers must demonstrate consistent manufacturing, define the composition and purity of the particles, and complete the toxicology and regulatory studies required for clinical development. A broadly protective flu vaccine remains a long-term objective rather than an immediate clinical option, but the yeast-derived M2 particles offer a strategy that links conserved viral biology with rapid, potentially flexible production.
Subject of Research:
An experimental universal influenza vaccine using M2 protein-bearing virus-like particles produced in genetically engineered baker’s yeast.
Article Title:
Yeast-Made Virus-Like Particles Point Toward a Broader Influenza Vaccine
Web References:
https://acs.digitellinc.com/live/37/session/593122
https://che.engin.umich.edu/people/wen-fei/
https://che.engin.umich.edu/people/hoang-trang/
https://www.cdc.gov/flu-vaccines-work/php/effectiveness-studies/index.html
https://www.cdc.gov/flu/vaccine-process/index.html
https://www.who.int/teams/global-influenza-programme/vaccines
References:
“Toward an affordable universal influenza vaccine: M2-based virus-like particles,” American Chemical Society fall 2026 conference presentation.
Keywords
Influenza, flu vaccine, universal vaccine, M2 protein, virus-like particles, genetically engineered yeast, vaccine development, viral immunology, influenza A, biomedical engineering, pandemic preparedness
Tags: Broad-spectrum influenza protectionconserved M2 protein influenza vaccinecross-protection against multiple flu strainsgenetically engineered yeast vaccineinfluenza strain variabilityinfluenza vaccine development challengesinnovative flu immunization strategiespreclinical flu vaccine researchrapid vaccine manufacturing platformseasonal flu vaccine limitationsUniversal flu vaccinevirus-like particle vaccine design
