Sodium hydrogen exchangers contribute to arenavirus cell entry

Several arenaviruses, chiefly Lassa virus (LASV), cause hemorrhagic fever (HF) disease in humans and pose a great public health concern in the regions in which they are endemic. Moreover, evidence indicates that the worldwide-distributed prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) is a neglected human pathogen of clinical significance. The limited existing armamentarium to combat human-pathogenic arenaviruses underscores the importance of developing novel antiarenaviral drugs, a task that would be facilitated by the identification and characterization of virus-host cell factor interactions that contribute to the arenavirus life cycle. A genome-wide small interfering RNA (siRNA) screen identified sodium hydrogen exchanger 3 (NHE3) as required for efficient multiplication of LCMV in HeLa cells, but the mechanisms by which NHE activity contributed to the life cycle of LCMV remain unknown. Here we show that treatment with the NHE inhibitor 5-(N-ethyl-N-isopropyl) amiloride (EIPA) resulted in a robust inhibition of LCMV multiplication in both rodent (BHK-21) and human (A549) cells. EIPA-mediated inhibition was due not to interference with virus RNA replication, gene expression, or budding but rather to a blockade of virus cell entry. EIPA also inhibited cell entry mediated by the glycoproteins of the HF arenaviruses LASV and Junin virus (JUNV). Pharmacological and genetic studies revealed that cell entry of LCMV in A549 cells depended on actin remodeling and Pak1, suggesting a macropinocytosis-like cell entry pathway. Finally, zoniporide, an NHE inhibitor being explored as a therapeutic agent to treat myocardial infarction, inhibited LCMV propagation in culture cells. Our findings indicate that targeting NHEs could be a novel strategy to combat human-pathogenic arenaviruses.