Inhibition of p38 Mitogen-Activated Protein Kinase Impairs Mayaro Virus Replication in Human Dermal Fibroblasts and HeLa Cells

p38-MAPK is prerequisite for the synthesis of SARS-CoV-2 protein

The inhibition of p38 mitogen-activated protein kinase (p38-MAPK) by small molecule chemical inhibitors was previously shown to impair severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication, however, mechanisms underlying antiviral activity remains unexplored. In this study, reduced growth of SARS-CoV-2 in p38-α knockout Vero cells, together with enhanced viral yield in cells transfected with construct expressing p38α, suggested that p38-MAPK is essential for the propagation of SARS-CoV-2. The SARS-CoV-2 was also shown to induce phosphorylation (activation) of p38, at time when transcription/translational activities are considered to be at the peak levels. Further, we demonstrated that p38 supports viral RNA/protein synthesis without affecting viral attachment, entry, and budding in the target cells. In conclusion, we provide mechanistic insights on the regulation of SARS-CoV-2 replication by p38 MAPK.

Current challenges in the discovery of treatments against Mayaro fever

INTRODUCTION

Mayaro fever is an emerging viral disease that manifests as an acute febrile illness. The disease is self-limiting, however joint pain can persist for months leading to chronic arthralgia. There is no specific treatment available, which ultimately leads to socioeconomic losses in populations at risk as well as strains to the public health systems.

AREAS COVERED

We reviewed the candidate treatments proposed for Mayaro virus (MAYV) infection and disease, including antiviral compounds targeting viral or host mechanisms, and pathways involved in disease development and pathogenicity. We assessed compound screening technologies and experimental infection models used in these studies and indicated the advantages and limitations of available technologies and intended therapeutic strategies.

EXPERT OPINION

Although several compounds have been suggested as candidate treatments against MAYV infection, notably those with antiviral activity, most compounds were assessed only in vitro. Compounds rarely progress toin vivo or preclinical studies, and such difficulty may be associated with limited experimental models. MAYV biology is largely inferred from related alphaviruses and reflected by few studies focusing on target proteins or mechanisms of action for MAYV. Therapeutic strategies targeting pathogenic inflammatory responses have shown potential against MAYV-induced disease in vivo, which might reduce long-term sequelae.

Chikungunya patient transcriptional signatures faithfully recapitulated in a C57BL/6J mouse model

Introduction

An adult wild-type C57BL/6J mouse model of chikungunya virus (CHIKV) infection and disease has been extensively used to study the alphaviral arthritic immunopathology and to evaluate new interventions. How well mouse models recapitulate the gene expression profiles seen in humans remains controversial.

Methods

Herein we perform a comparative transcriptomics analysis using RNA-Seq datasets from the C57BL/6J CHIKV mouse model with datasets obtained from adults and children acutely infected with CHIKV.

Results

Despite sampling quite different tissues, peripheral blood from humans and feet from mice, gene expression profiles were quite similar, with an overlap of up to ≈50% for up-regulated single copy orthologue differentially expressed genes. Furthermore, high levels of significant concordance between mouse and human were seen for immune pathways and signatures, which were dominated by interferons, T cells and monocyte/macrophages. Importantly, predicted responses to a series of anti-inflammatory drug and biologic treatments also showed cogent similarities between species.

Discussion

Comparative transcriptomics and subsequent pathway analysis provides a detailed picture of how a given model recapitulates human gene expression. Using this method, we show that the C57BL/6J CHIKV mouse model provides a reliable and representative system in which to study CHIKV immunopathology and evaluate new treatments.

Honokiol and Alpha-Mangostin Inhibit Mayaro Virus Replication through Different Mechanisms

Mayaro virus (MAYV) is an emerging arbovirus with an increasing circulation across the Americas. In the present study, we evaluated the potential antiviral activity of the following natural compounds against MAYV and other arboviruses: Sanguinarine, (R)-Shikonin, Fisetin, Honokiol, Tanshinone IIA, and α-Mangostin. Sanguinarine and Shikonin showed significant cytotoxicity, whereas Fisetin, Honokiol, Tanshinone IIA, and α-Mangostin were well tolerated in all the cell lines tested. Honokiol and α-Mangostin treatment protected Vero-E6 cells against MAYV-induced damage and resulted in a dose-dependent reduction in viral progeny yields for each of the MAYV strains and human cell lines assessed. These compounds also reduced MAYV viral RNA replication in HeLa cells. In addition, Honokiol and α-Mangostin disrupted MAYV infection at different stages of the virus life cycle. Moreover, Honokiol and α-Mangostin decreased Una, Chikungunya, and Zika viral titers and downmodulated the expression of E1 and nsP1 viral proteins from MAYV, Una, and Chikungunya. Finally, in Honokiol- and α-Mangostin-treated HeLa cells, we observed an upregulation in the expression of type I interferon and specific interferon-stimulated genes, including IFNα, IFNβ, MxA, ISG15, OAS2, MDA-5, TNFα, and IL-1β, which may promote an antiviral cellular state. Our results indicate that Honokiol and α-Mangostin present potential broad-spectrum activity against different arboviruses through different mechanisms.

Characterization of Mayaro virus (strain BeAn343102) biology in vertebrate and invertebrate cellular backgrounds

Mayaro virus (MAYV) is an emerging New World alphavirus (genus Alphavirus, family Togaviridae) that causes acute multiphasic febrile illness, skin rash, polyarthritis and occasional severe clinical phenotypes. The virus lifecycle alternates between invertebrate and vertebrate hosts. Here we characterize the replication features, cell entry, lifecycle and virus-related cell pathology of MAYV using vertebrate and invertebrate in vitro models. Electron-dense clathrin-coated pits in infected cells and reduced viral production in the presence of dynasore, ammonium chloride and bafilomycin indicate that viral entry occurs through pH-dependent endocytosis. Increase in FITC-dextran uptake (an indicator of macropinocytosis) in MAYV-infected cells, and dose-dependent infection inhibition by 5-(N-ethyl-N-isopropyl) amiloride (a macropinocytosis inhibitor), indicated that macropinocytosis is an additional entry mechanism of MAYV in vertebrate cells. Acutely infected vertebrate and invertebrate cells formed cytoplasmic or membrane-associated extracytoplasmic replication complexes. Mosquito cells showed modified hybrid cytoplasmic vesicles that supported virus replication, nucleocapsid production and maturation. Mature virus particles were released from cells by both exocytosis and budding from the cell membrane. MAYV replication was cytopathic and associated with induction of apoptosis by the intrinsic pathway, and later by the extrinsic pathway in infected vertebrate cells. Given that MAYV is expanding its geographical existence as a potential public health problem, this study lays the foundation for biological understanding that will be valuable for therapeutic and preventive interventions.

Resistance evolution against host-directed antiviral agents: Buffalopox virus switches to use p38-ϒ under long-term selective pressure of an inhibitor targeting p38-α

Host-dependency factors have increasingly been targeted to minimize antiviral drug resistance. In this study, we have demonstrated that inhibition of p38 mitogen-activated protein kinase (a cellular protein) suppresses buffalopox virus (BPXV) protein synthesis by targeting p38-MNK1-eIF4E signaling pathway. In order to provide insights into the evolution of drug resistance, we selected resistant mutants by long-term sequential passages (P; n = 60) in the presence of p38 inhibitor (SB239063). The P60-SB239063 virus exhibited significant resistance to SB239063 as compared to the P60-Control virus. To provide mechanistic insights on the acquisition of resistance by BPXV-P60-SB239063, we generated p38-α and p38-ϒ (isoforms of p38) knockout Vero cells by CRISPR/Cas9-mediated genome editing. It was demonstrated that unlike the wild type (WT) virus which is dependent on p38-α isoform, the resistant virus (BPXV-P60-SB239063) switches over to use p38-ϒ so as to efficiently replicate in the target cells. This is a rare evidence wherein a virus was shown to bypass the dependency on a critical cellular factor under selective pressure of a drug.

Mayaro Virus: The State-of-the-Art for Antiviral Drug Development

Mayaro virus is an emerging arbovirus that causes nonspecific febrile illness or arthralgia syndromes similar to the Chikungunya virus, a virus closely related from the Togaviridae family. MAYV outbreaks occur more frequently in the northern and central-western states of Brazil; however, in recent years, virus circulation has been spreading to other regions. Due to the undifferentiated initial clinical symptoms between MAYV and other endemic pathogenic arboviruses with geographic overlapping, identification of patients infected by MAYV might be underreported. Additionally, the lack of specific prophylactic approaches or antiviral drugs limits the pharmacological management of patients to treat symptoms like pain and inflammation, as is the case with most pathogenic alphaviruses. In this context, this review aims to present the state-of-the-art regarding the screening and development of compounds/molecules which may present anti-MAYV activity and infection inhibition.

Targeting Host PIM Protein Kinases Reduces Mayaro Virus Replication

Mayaro virus (MAYV) manipulates cell machinery to successfully replicate. Thus, identifying host proteins implicated in MAYV replication represents an opportunity to discover potential antiviral targets. PIM kinases are enzymes that regulate essential cell functions and also appear to be critical factors in the replication of certain viruses. In this study we explored the consequences of PIM kinase inhibition in the replication of MAYV and other arboviruses. Cytopathic effects or viral titers in samples from MAYV-, Chikungunya-, Una- or Zika-infected cells treated with PIM kinase inhibitors were evaluated using an inverted microscope or plaque-forming assays. The expression of viral proteins E1 and nsP1 in MAYV-infected cells was assessed using an immunofluorescence confocal microscope or Western blot. Our results revealed that PIM kinase inhibition partially prevented MAYV-induced cell damage and also promoted a decrease in viral titers for MAYV, UNAV and ZIKV. The inhibitory effect of PIM kinase blocking was observed for each of the MAYV strains tested and also occurred as late as 8 h post infection (hpi). Finally, PIM kinase inhibition suppressed the expression of MAYV E1 and nsP1 proteins. Taken together, these findings suggest that PIM kinases could represent an antiviral target for MAYV and other arboviruses.

Inhibitors of the p38 cell signaling pathway as antiviral compounds against Junín virus

In the present study, we analyzed the modulation of p38 cell signaling by Junín virus (JUNV) and evaluated the antiviral activity of p38 inhibitors against JUNV. While JUNV induced a progressive activation of p38 throughout the infection in Vero cells, a partial downregulation of p38 phosphorylation was observed in HEK293 and HeLa cells. The compounds SB203580 and SB202190, which are selective inhibitors of p38, significantly reduced viral protein expression and viral yield in the cell lines examined, indicating that the p38 signaling pathway might be a promising antiviral target against JUNV infection.