Since the in vitro neutralization assay does not reflect infection of human broncho-epithelial cells, which involves interaction between the RSV G protein and surface CX3CR1 [22–25], an SPR-based assay was performed to measure direct antibody-mediated blocking of recombinant CX3CR1 binding to glycosylated G protein produced in 293T cells (RMG) (Fig 7A).To that end, rabbit pre-vaccination and post 2nd boost sera (at 10-fold dilution) were run on the chip captured with RMG prior to addition of rCXC3R1, and % inhibition was calculated for each serum sample. Here, CX3CR1 is linked to infection.