Andes Virus Outbreak 2026: McLellan Lab Was Already Building the Vaccine That Just Got Its Blueprint
SCIENCEHEALTH
In early 2026, researchers at the University of Texas at Austin, led by Dr. Jason McLellan, made a major breakthrough with the Andes virus. They published the most detailed pictures ever taken of the virus’s outer proteins in the journal Cell. These images act like an atomic-level blueprint, showing exactly how the virus attaches to and enters human cells.
The Key Target on the Virus
The key target is a structure on the virus surface that looks like a mushroom with four stalks. It is made of two proteins called Gn and Gc, arranged in groups of four (a “tetramer”). Gn helps the virus stick to cells, while Gc acts like a spring-loaded machine that fuses the virus to the cell membrane so the virus can get inside. This mushroom shape is in its “pre-fusion” form. This is the shape it has before infection begins. Once the virus is inside a cell, acidity changes cause the structure to rearrange and complete the infection.
How They Captured the Details
The McLellan team used a technique called cryo-electron microscopy (cryo-EM). They flash-freeze samples in ice so delicate structures stay in their natural shape, then use electron beams and computers to build extremely clear 3D models. They created harmless “virus-like particles” (empty shells that look like the real virus but contain no dangerous material). These particles displayed the mushroom structures in the same organized pattern found on actual Andes virus particles.
Thanks to this method, they achieved an impressive 2.35-angstrom resolution. This resolution is fine enough to see individual building blocks of the proteins. They also captured how these mushroom units connect to each other, how they sense acidity to trigger fusion, and exactly where a powerful neutralizing antibody attaches to block the virus.
The Vaccine Candidate
Using this new structural information, the team designed a vaccine candidate. They used special RNA technology (called self-amplifying replicon RNA) that tells the body’s cells to temporarily produce these virus-like particles with the correctly shaped mushroom proteins on their surface.
When they tested this vaccine in mice, it worked well. The mice developed strong antibodies that tightly bind to the virus proteins and neutralize (block) the Andes virus in laboratory tests. The results were as good as or better than earlier, simpler vaccine designs.
The Goal and Strategy
The goal of this approach is simple but powerful: show the immune system the exact shape of the virus before it tries to infect cells. By presenting this stabilized pre-fusion form, the vaccine trains the body to make antibodies that target the virus’s weakest point, stopping infection early. This “structure-based” design strategy has already succeeded with vaccines for other viruses like RSV and COVID-19 in McLellan’s previous work.
Current Status
As of May 2026, this vaccine candidate is still in the very early stages. It has only been tested in mice. No human clinical trials have started, and there is no timeline yet for human use or rollout. The real value of this research right now is the detailed blueprint it provides. Scientists can now engineer better vaccine ingredients, develop antibody treatments, and potentially create protection that works against multiple hantaviruses.
References
Guo L, et al. High-resolution in situ structures of hantavirus glycoprotein tetramers. Cell. 2026.
University of Texas at Austin News, March 11, 2026.
GEN News coverage, March 2026.
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