A K33A substitution in the stable signal peptide (SSP) allowed for stabilization of the pre-fusion GPC, with molecular dynamics suggesting K33A stabilizes GPC by better accommodating membrane lipids in the SSP33 pocket, supported by our cryo-EM density

Further structural and functional analyses also reveal the effect of specific residues in transmembrane and membrane proximal region on pH-mediated fusion, elucidating the attenuation mechanism of the JUNV Candid#1 vaccine

These cryo-EM structures reveal notable differences between JUNV and MACV in GP1 organization at the apex and C terminus. The MACV GPC apex has a more open appearance due to its GP1 subunits slightly rotating outwards and clockwise 🔃compared to JUNV GP1 subunits

Our @natmicrobiol.nature.com paper provides the most complete insight into the molecular organization of the JUNV and MACV GPCs yet 😲revealing new features not seen in previous structures, such as the TM helices and cytosolic portions, including ZBD

Interesting tidbit in the story: a WEEV-related alphavirus that circulates on the east coast (EEEV territory) called highlands J virus (HJV) also uses PCDH10 as a receptor. It diverged from WEEV not that long ago and retained most PCDH10 contact residues.

Some WEEV strains and EEEV both bind VLDLR at the LA1 and LA2 domains, suggesting that VLDLR LA1-LA2 decoy receptor may have broad activity against them. This molecule protected mice against lethal challenge by a WEEV strain that binds VLDLR.

Strains isolated during epidemics of the early 20th century bind VLDLR and ApoER2 as additional receptors. Our structure of a 1941 strain bound by VLDLR revealed a distinct binding mode than other alphaviruses that bind LDLR-related proteins, such as EEEV, SFV or VEEV.

We found a substitution in the E2 glycoprotein, L149Q, that would disrupt hydrophobic contact with PCDH10, and confirmed this mutation alone abolishes human PCDH10 binding. L149Q is found in all strains isolated in California and Texas in 2005, suggesting a wide geographic range.

Protocadherin 10 (PCDH10) is a major receptor for WEEV. Multiple strains isolated in 2005 lost the ability to bind human and horse PCDH10, yet still bind avian PCDH10. Cryo-EM structures show identical binding mode of sparrow and human PCDH10.

We also determined structures of an ancestral WEEV strain bound to VLDLR, revealing a distinct binding mode compared to other alphaviruses that bind LDLR-related receptors such as EEEV, SFV, or VEEV, indicating independent evolution of WEEV to bind VLDLR/ApoER2!

Excited to share our @biorxivpreprint.bsky.social exploring how binding of western equine encephalitis virus (WEEV) to its cellular receptors evolved over the past century 🤩 www.biorxiv.org/content/10.1... @harvardmicro.bsky.social