In most people, the lung-infecting pathogens known as respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) trigger mild cold-like symptoms. But in infants and seniors, these viruses can cause severe pneumonia and even death. Vaccines against both viruses, however, have been difficult to design.

Now, Scripps Research scientists have analyzed the structure and stability of a critical RSV and hMPV protein to better design vaccines that target it. Their research, published in Nature Communications , points toward RSV vaccines that may be more effective than existing ones, as well as a vaccine against hMPV, for which there are no commercially available options. "Creating a combination vaccine for these viruses could significantly reduce viral hospitalizations for both babies and the elderly," says study senior author Jiang Zhu, Ph.

D., an associate professor in the Department of Integrative Structural and Computational Biology at Scripps Research. "This could alleviate the overall health burden during flu season, which is also when most RSV and hMPV cases occur.

" Scientists have long attempted to create vaccines that coax the immune system into recognizing the fusion (F) proteins present on the surfaces of RSV, hMPV and related viruses. These proteins play a key role in letting viruses infect human cells. However, the F protein has a delicate structure that changes rapidly from a "pre-fusion" form to a "post-fusion" form when the viruses fuse with cells.

Ideally, a va.