Synthetic peptides derived from the heptad repeat (HR) of fusion (F) proteins can be used 33 as dominant negative inhibitors to inhibit the fusion mechanism of class I viral F proteins. Here, 34 we have performed a stapled peptide scan across the HR2 domain of the RSV F protein with the 35 aim to identify a minimal domain capable of disrupting the formation of the post fusion six helix 36 bundle required for viral cell entry. Constraining the peptides with a single staple was not 37 sufficient to inhibit RSV infection. However, the insertion of double staples led to the 38 identification of novel short stapled peptides, which display nanomolar potency in HEp-2 cells, 39 and are exceptionally robust to proteolyt... More
Synthetic peptides derived from the heptad repeat (HR) of fusion (F) proteins can be used 33 as dominant negative inhibitors to inhibit the fusion mechanism of class I viral F proteins. Here, 34 we have performed a stapled peptide scan across the HR2 domain of the RSV F protein with the 35 aim to identify a minimal domain capable of disrupting the formation of the post fusion six helix 36 bundle required for viral cell entry. Constraining the peptides with a single staple was not 37 sufficient to inhibit RSV infection. However, the insertion of double staples led to the 38 identification of novel short stapled peptides, which display nanomolar potency in HEp-2 cells, 39 and are exceptionally robust to proteolytic degradation. By replacing each amino-acid of the 40 peptides by an alanine, we found that the substitution of residues 506-509, located in a patch of 41 polar contacts between HR2 and HR1, affected severely inhibition. Finally, we show that 42 intranasal delivery of the most potent peptide to BALB/c mice decreased significantly RSV 43 infection in upper and lower respiratory tract. The discovery of this minimal HR2 sequence as a 44 means for inhibition of RSV infection provides the basis for further medicinal chemistry efforts 45 toward developing RSV fusion antivirals.
