Abstract
In the absence of effective vaccines and treatments, annual outbreaks of severe human haemorrhagic fever caused by arenaviruses, such as Lassa virus, continue to pose a significant human health threat. Understanding the balance of cellular factors that inhibit or promote arenavirus infection may have important implications for the development of effective antiviral strategies. Here, we identified the cell-intrinsic zinc transmembrane metalloprotease, ZMPSTE24, as a restriction factor against arenaviruses. Notably, CRISPR-Cas9-mediated knockout of ZMPSTE24 in human alveolar epithelial A549 cells increased arenavirus glycoprotein-mediated viral entry in pseudoparticle assays and live virus infection models. As a barrier to viral entry and replication, ZMPSTE24 may act as a downstream effector of interferon-induced transmembrane protein (IFITM) antiviral function; though through a yet poorly understood mechanism. Overexpression of IFITM1, IFITM2, and IFITM3 proteins did not restrict the entry of pseudoparticles carrying arenavirus envelope glycoproteins and live virus infection. Furthermore, gain-of-function studies revealed that IFITMs augment the antiviral activity of ZMPSTE24 against arenaviruses, suggesting a cooperative effect of viral restriction. We show that ZMPSTE24 and IFITMs affect the kinetics of cellular endocytosis, suggesting that perturbation of membrane structure and stability is likely the mechanism of ZMPSTE24-mediated restriction and cooperative ZMPSTE24-IFITM antiviral activity. Collectively, our findings define the role of ZMPSTE24 host restriction activity in the early stages of arenavirus infection. Moreover, we provide insight into the importance of cellular membrane integrity for productive fusion of arenaviruses and highlight a novel avenue for therapeutic development.
Highlights
Viral haemorrhagic fever (VHF)-causing mammarenaviruses pose significant threats to human health, in endemic regions of Western Africa; most are associated with high case fatality rates due to a lack of approved vaccines and effective countermeasures (Wolff et al, 2016; Whitmer et al, 2018; Kofman et al, 2019; Overbosch et al, 2020)
Murine leukaemia virus (MLV) packaging a green fluorescent protein (GFP) reporter was pseudotyped with different arenavirus GP proteins
Using BlaMVpr-chimaera particles pseudotyped with glycoproteins from lymphocytic choriomeningitis virus (LCMV), LASV, Mopeia virus (MOPV), and murine leukaemia virus (MLV) that would induce the cleavage of CCF2-AM dye upon cytosolic entry, we independently demonstrated that expression of ZMPSTE24 decreased the fusogenicity of arenavirus GP-pseudotyped particles (Figure 1B and Supplementary Figure 1B)
Summary
Viral haemorrhagic fever (VHF)-causing mammarenaviruses pose significant threats to human health, in endemic regions of Western Africa; most are associated with high case fatality rates due to a lack of approved vaccines and effective countermeasures (Wolff et al, 2016; Whitmer et al, 2018; Kofman et al, 2019; Overbosch et al, 2020). These zoonotic enveloped RNA viruses possess single-stranded bi-segmented genomes and are members of the family Arenaviridae (McLay et al, 2014). Unravelling key arenavirus-host interactions is critical toward this effort (Wolff et al, 2016; Whitmer et al, 2018; Kofman et al, 2019; Overbosch et al, 2020)
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