Inhibition of arterivirus RNA synthesis by cyclophilin inhibitors is counteracted by mutations in replicase transmembrane subunits

Adriaan H. de Wilde; A. Linda Boomaars-van der Zanden; Anja W. M. de Jong; Montserrat Barcéna; Eric J. Snijder; Clara C. Posthuma

This suggests that, compared to CsA, ALV has an additional target that is relevant for EAV 518 replication, either directly or indirectly. Residue H114 is positioned in helix α4 in domain I of the 519 PLP2 structure, which is distant from both the protease's active site and the surface involved in 520 ubiquitin binding (van Kasteren et al., 2013), a feature linked to PLP2's secondary function as a 521 deubiquitinase involved in arteriviral innate immune evasion. Unfortunately, only the structure of the 522 PLP2 domain of nsp2 has been resolved, and the overall fold and membrane topology of the subunit of 523 EAV remains unclear. Our study implicates nsp5 in viral RNA synthesis, either directly or indirectly, 524 and provides evidence that mutations in nsp5 are involved in reduced sensitivity to CsA, while the 525 same mutations in combination with the nsp2 H114R substitution contribute to ALV resistance. Future 526 studies should aim to elucidate the difference between the modes of action of ALV and CsA and the 527 exact role of nsp5 and nsp2 in arterivirus sensitivity and resistance to Cyp inhibitors. 528 All rights reserved. No reuse allowed without permission.