The most potent a 1 -AT variant RRIL revealed a similar inhibitory potential on virus release of authentic LASV to that observed with the corresponding VSVDG/LASVGP pseudotype. Therefore, this study also demonstrates that the replicationcompetent VSV expressing the LASV glycoprotein is an excellent surrogate model for analyzing potential antivirals that target the biological function of GP and its consequence for virus replication. These studies can be performed under biosafety level 2 laboratory conditions that would otherwise require biosafety level 4 laboratory conditions [71] . Taken together, our data indicate that S1P-adapted a 1 -antitrypsins may represent a promising lead compound for the development of a new class of anti-arenavirus inhibitors.