Mutational analysis of the lassa virus glycoprotein highlights regions required for receptor interaction and fusion protein function

Enveloped viruses utilize surface expressed glycoproteins in order to mediate both virus attachment and entry. The purpose of this work was to characterize the Lassa virus glycoprotein receptor binding (GP1) and fusion active (GP2) subunits, and to identify residues required for receptor interaction(s) and mediating viral-cell fusion. We biochemically evaluated 140 constructs containing mutations in either the GP1 or GP2 subunit. The constructs were assessed for their ability to mediate fusion, become processed and surface expressed, and transduce two well characterized haploid cell lines. Constructs harboring mutations within the GP1 subunit hypothesized to be inhibiting primary receptor alpha-dystroglycan (DG) usage were also tested for protein-protein interaction. Our findings highlighted several amino acid residues required for DG interaction and presumably lysosomal associated membrane protein 1 (LAMP1), a second Lassa virus receptor, interaction. We also identified residues mapping in or near GP2 functional domains that are required for protein function.