At least five arenaviruses cause hemorrhagic fever in humans; Lassa (LASV), Machupo (MACV), Junin (JUNV), Guanarito (GTOV), and Sabiá (SABV). These viruses are classified as NIAID Category A Priority Pathogens. LASV, an Old World arenavirus, uses the cellular receptor α-dystroglycan to infect cells. MACV, JUNV, GTOV, and SABV are New World arenaviruses that do not use α-dystroglycan. Using an immunoprecipitation approach we identified transferrin receptor 1 (TfR1) as an obligate receptor for these viruses. We showed a specific, high-affinity association between human TfR1 (hTfR1) and GP1, the viral surface glycoprotein, of MACV. Furthermore, expression of hTfR1, but not human transferrin receptor 2, markedly enhanced cell entry of retroviruses pseudotyped with the GP of MACV, JUNV, and GTOV into refractory hamster cells. An antibody against hTfR1 efficiently inhibited the replication of infectious MACV, JUNV, GTOV and SABV, but not that of LASV. Soluble recombinant hTfR1, but not transferrin, was able to inhibit GP-mediated entry of MACV and JUNV, indicating that MACV and JUNV glycoproteins bind TfR1 at a site distinct from the transferrin binding site. Iron concentration in culture medium determined the efficiency of transduction of human cells by MACV and JUNV pseutotypes possibly through regulation of hTfR1 expression.
We next compared the ability of TfR1 orthologs from different mammals, including the South American rodent reservoirs of MACV and JUNV ( Calomys callosus and Calomys musculinus, respectively), to support GP-mediated entry of MACV, JUNV, or GTOV. We observed that house-mouse, rat, and dog TfR1 orthologs were inefficient receptors for these viruses, whereas cat and human TfR1 supported efficient entry. JUNV and MACV, but not GTOV, efficiently utilized the C. callosus TfR1, whereas only JUNV used the C. musculinus TfR1 ortholog. Furthermore, mutagenesis studies identified a local region of the hTfR1 apical domain, including tyrosine 211, as a critical determinant for the efficiency with which MACV, JUNV, and GTOV utilized various TfR1 orthologs. Our data highlight the specific adaptation of New World hemorrhagic fever arenaviruses to their respective rodent reservoirs and describe TfR1 determinants necessary for GP-mediated entry of MACV, JUNV, and GTOV, as well as for transmission of these viruses to humans.