Proteolytic activation of LASV GP-C by S1P is not necessary for transport of GP-C to the cell surface, where budding of arenaviruses occurs, but is essential for incorporation of the cleaved subunits into virions, and thus, for the formation of infectious viral particles. In the absence of GP-C cleavage, enveloped non-infectious LASV-like particles are released containing L, NP, Z protein and viral RNA but are devoid of viral glycoproteins [23] . Similar results were described for LCMV and New World hemorrhagic fever viruses [33, 34] .