Coronaviruses and arteriviruses display striking differences in their cyclophilin A-dependence during replication in cell culture

Abstract

Cyclophilin A (CypA) is an important host factor in the replication of a variety of RNA viruses. Also the replication of several nidoviruses was reported to depend on CypA, although possibly not to the same extent. These prior studies are difficult to compare, since different nidoviruses, cell lines and experimental set-ups were used. Here, we investigated the CypA dependence of three distantly related nidoviruses that can all replicate in Huh7 cells: the arterivirus equine arteritis virus (EAV), the alphacoronavirus human coronavirus 229E (HCoV-229E), and the betacoronavirus Middle East respiratory syndrome coronavirus (MERS-CoV). The replication of these viruses was compared in the same parental Huh7 cells and in CypA-knockout Huh7 cells generated using CRISPR/Cas9-technology. CypA depletion reduced EAV yields by ~ 3-log, whereas MERS-CoV progeny titers were modestly reduced (3-fold) and HCoV-229E replication was unchanged. This study reveals that the replication of nidoviruses can differ strikingly in its dependence on cellular CypA.

Influences of cyclosporin A and non-immunosuppressive derivatives on cellular cyclophilins and viral nucleocapsid protein during human coronavirus 229E replication

“…The role of CypB during CoV replication is not clear as we show that its protein level and subcellular localization completely changes in the presence of CsA and ALV. Divergent results are reported in a recent study which found no difference in HCoV-229E replication in Huh7wt as compared to Huh7-CypA KO (knockout) pool cells and to two Huh7-CypA KO clones (de Wilde et al, 2018). MERS-CoV titers were moderately diminished (3fold), whereas equine arteritis virus was reduced by ∼3 logs.…”

Cyclophilins and cyclophilin inhibitors in nidovirus replication

“…The presence of CypA, but not its PPIase activity (de Wilde et al, manuscript in preparation), was indeed shown to be pivotal for EAV replication (de Wilde et al, 2013a) as knockout of CypA expression resulted in a 3-log reduction of EAV progeny yields. Replication was affected much less strongly in cells expressing reduced levels of CypA (de Wilde et al, 2013a(de Wilde et al, , 2017c, again highlighting that small amounts of CypA may suffice to support efficient nidovirus replication (see above). Collectively, these observations indicate that CypA is an essential host factor that binds to arterivirus replication organelles and supports RNA synthesis (Fig.…”

“…Although CypA normally is an intracellular protein, inflammatory stimuli like infections, hypoxia, or oxidative stress can elicit CypA secretion via a vesicular transport mechanism that depends on Rho kinase activation (reviewed in Bukrinsky, 2015). CypA proved to be non-essential for cell growth as depletion of CypA in cells or in PPIA -/knockout mice did not affect survival and/or growth kinetics (Chatterji et al, 2009;Colgan et al, 2005;de Wilde et al, 2017c).…”

The phosphorylation of the N protein could affect PRRSV virulence in vivo

“…There are many pathogens that have serious effects on society in the Nidovirales order, such as MEAR, SARS, IBV, PEDV and PRRSV (de Wilde et al, 2018). The N proteins of those viruses have a common origin (Yu et al, 2006).…”