Fatty acid 2-hydroxylase facilitates rotavirus uncoating and endosomal escape.

Despite the clinical significance of many nonenveloped viruses, the molecular mechanisms of their internalization and membrane penetration are not well understood. Rotaviruses (RVs) are nonenveloped double-stranded RNA viruses and the leading cause of severe dehydrating diarrhea in infants and young children. We identified fatty acid 2-hydroxylase (encoded by ) in the fatty acid 2-hydroxylation pathway as a proviral gene that supports RV infection.

SAMD9 senses cytosolic double-stranded nucleic acids in epithelial and mesenchymal cells to induce antiviral immunity.

Sensing of cytosolic, double-stranded (ds) DNA or dsRNA molecules derived from microbial or endogenous sources triggers cell-intrinsic innate immunity, but sensors recognizing both cytosolic dsDNA and dsRNA are sparsely reported. Here we find that full-length human SAMD9 protein directly binds to synthetic or viral dsDNA or dsRNA. Overexpression of SAMD9 from various vertebrate species leads to robust production of interferons and pro-inflammatory cytokines.

Innate immune sensing of rotavirus by intestinal epithelial cells leads to diarrhea.

Diarrhea is the predominant symptom of acute gastroenteritis resulting from enteric infections and a leading cause of death in infants and young children. However, the role of the host response in diarrhea pathogenesis is unclear. Using rotavirus and neonatal mice as a model, we found that oral inoculation of UV-inactivated replication-defective rotavirus consistently induced watery diarrhea by robust activation of cytosolic double-stranded RNA sensing pathways and type III interferon (IFN-λ) secretion.

CRISPR/Cas9 screens identify key host factors that enhance rotavirus reverse genetics efficacy and vaccine production.

Rotaviruses pose a significant threat to young children. To identify novel pro- and anti-rotavirus host factors, we performed genome-wide CRISPR/Cas9 screens using rhesus rotavirus and African green monkey cells. Genetic deletion of either SERPINB1 or TMEM236, the top two antiviral factors, in MA104 cells increased virus titers in a rotavirus strain independent manner.

Rhesus rotavirus NSP1 mediates extra-intestinal infection and is a contributing factor for biliary obstruction.

We previously demonstrated that in Ifnar1-/-Ifngr1-/- or Stat1-/- suckling mice lacking intact type I and type II interferon (IFN) signaling, rhesus rotavirus (RRV) infection causes a lethal disease with clinical manifestations similar to biliary atresia, including acholic stools, oily fur, growth retardation, and excess mortality. Elevated levels of viral RNA are detected in the bile ducts and liver of diseased pups together with severe inflammatory responses in these tissues. However, the viral determinants and the molecular mechanisms driving this process remain incompletely understood.

A basally active cGAS-STING pathway limits SARS-CoV-2 replication in a subset of ACE2 positive airway cell models.

Host factors that define the cellular tropism of SARS-CoV-2 beyond the cognate ACE2 receptor are poorly defined. Here we report that SARS-CoV-2 replication is restricted at a post-entry step in a number of ACE2-positive airway-derived cell lines due to tonic activation of the cGAS-STING pathway mediated by mitochondrial DNA leakage and naturally occurring cGAS and STING variants. Genetic and pharmacological inhibition of the cGAS-STING and type I/III IFN pathways as well as ACE2 overexpression overcome these blocks.

A basally active cGAS-STING pathway limits SARS-CoV-2 replication in a subset of ACE2 positive airway cell models.

Host factors that define the cellular tropism of SARS-CoV-2 beyond the cognate ACE2 receptor are poorly defined. Here we report that SARS-CoV-2 replication is restricted at a post-entry step in a number of ACE2-positive airway-derived cell lines due to tonic activation of the cGAS-STING pathway mediated by mitochondrial DNA leakage and naturally occurring cGAS and STING variants. Genetic and pharmacological inhibition of the cGAS-STING and type I/III IFN pathways as well as ACE2 overexpression overcome these blocks.

A recombinant murine-like rotavirus with Nano-Luciferase expression reveals tissue tropism, replication dynamics, and virus transmission.

Rotaviruses (RVs) are one of the main causes of severe gastroenteritis, diarrhea, and death in children and young animals. While suckling mice prove to be highly useful small animal models of RV infection and pathogenesis, direct visualization tools are lacking to track the temporal dynamics of RV replication and transmissibility . Here, we report the generation of the first recombinant murine-like RV that encodes a Nano-Luciferase reporter (NLuc) using a newly optimized RV reverse genetics system.

m6A modifications regulate intestinal immunity and rotavirus infection.

N6-methyladenosine (m6A) is an abundant mRNA modification and affects many biological processes. However, how m6A levels are regulated during physiological or pathological processes such as virus infections, and the in vivo function of m6A in the intestinal immune defense against virus infections are largely unknown. Here, we uncover a novel antiviral function of m6A modification during rotavirus (RV) infection in small bowel intestinal epithelial cells (IECs).

JIB-04 Has Broad-Spectrum Antiviral Activity and Inhibits SARS-CoV-2 Replication and Coronavirus Pathogenesis.

Pathogenic coronaviruses are a major threat to global public health. Here, using a recombinant reporter virus-based compound screening approach, we identified small-molecule inhibitors that potently block the replication of severe acute respiratory syndrome virus 2 (SARS-CoV-2). Among them, JIB-04 inhibited SARS-CoV-2 replication in Vero E6 cells with a 50% effective concentration of 695 nM, with a specificity index of greater than 1,000.

Rotavirus NSP1 Contributes to Intestinal Viral Replication, Pathogenesis, and Transmission.

Rotavirus (RV)-encoded nonstructural protein 1 (NSP1), the product of gene segment 5, effectively antagonizes host interferon (IFN) signaling via multiple mechanisms. Recent studies with the newly established RV reverse genetics system indicate that NSP1 is not essential for the replication of the simian RV SA11 strain in cell culture. However, the role of NSP1 in RV infection remains poorly characterized due to the limited replication of heterologous simian RVs in the suckling mouse model.

Inhibitor of growth protein 3 epigenetically silences endogenous retroviral elements and prevents innate immune activation.

Endogenous retroviruses (ERVs) are subject to transcriptional repression in adult tissues, in part to prevent autoimmune responses. However, little is known about the epigenetic silencing of ERV expression. Here, we describe a new role for inhibitor of growth family member 3 (ING3), to add to an emerging group of ERV transcriptional regulators.

Cholesterol 25-hydroxylase suppresses SARS-CoV-2 replication by blocking membrane fusion.

Cholesterol 25-hydroxylase () is an interferon (IFN)-stimulated gene that shows broad antiviral activities against a wide range of enveloped viruses. Here, using an IFN-stimulated gene screen against vesicular stomatitis virus (VSV)-SARS-CoV and VSV-SARS-CoV-2 chimeric viruses, we identified CH25H and its enzymatic product 25-hydroxycholesterol (25HC) as potent inhibitors of SARS-CoV-2 replication. Internalized 25HC accumulates in the late endosomes and potentially restricts SARS-CoV-2 spike protein catalyzed membrane fusion via blockade of cholesterol export.

JIB-04 has broad-spectrum antiviral activity and inhibits SARS-CoV-2 replication and coronavirus pathogenesis.

Pathogenic coronaviruses represent a major threat to global public health. Here, using a recombinant reporter virus-based compound screening approach, we identified several small-molecule inhibitors that potently block the replication of the newly emerged severe acute respiratory syndrome virus 2 (SARS-CoV-2). Among them, JIB-04 inhibited SARS-CoV-2 replication in Vero E6 cells with an EC of 695 nM, with a specificity index of greater than 1,000.

MYH9 Key Amino Acid Residues Identified by the Anti-Idiotypic Antibody to Porcine Reproductive and Respiratory Syndrome Virus Glycoprotein 5 Involve in the Virus Internalization by Porcine Alveolar Macrophages.

MYH9 has been identified as an indispensable cellular protein for porcine reproductive and respiratory syndrome virus (PRRSV) entry into permissive cells using the monoclonal anti-idiotypic antibody (Mab2-5G2) recognizing an antibody that specifically interacts with PRRSV glycoprotein 5 (GP5). More recently, we found that Mab2-5G2 interacted with the MYH9 C-terminal domain, designated PRA, which is required for PRRSV internalization. In this study, we demonstrate that blocking of MYH9 with Mab2-5G2 significantly diminished PRRSV internalization by porcine alveolar macrophage (PAM) via interruption of direct interaction between GP5 and MYH9, and thus remarkably inhibited subsequent infection of PAMs by PRRSV-2 isolates.

MYH9 Aggregation Induced by Direct Interaction With PRRSV GP5 Ectodomain Facilitates Viral Internalization by Permissive Cells.

Prevention and control of infection by porcine reproductive and respiratory syndrome virus (PRRSV) remains a challenge, due to our limited understanding of the PRRSV invasion mechanism. Our previous study has shown that PRRSV glycoprotein GP5 interacts with MYH9 C-terminal domain protein (PRA). Here we defined that the first ectodomain of GP5 (GP5-ecto-1) directly interacted with PRA and this interaction triggered PRA and endogenous MYH9 to form filament assembly.

Direct Interaction Between CD163 N-Terminal Domain and MYH9 C-Terminal Domain Contributes to Porcine Reproductive and Respiratory Syndrome Virus Internalization by Permissive Cells.

Porcine reproductive and respiratory syndrome virus (PRRSV) has a highly restricted tropism for cells of the monocyte-macrophage lineage, including porcine alveolar macrophages (PAMs). PRRSV entry into permissive cells involves several mediators in addition to two required host cell receptors, CD163 and MYH9. It is unknown whether CD163 directly interacts and/or cooperates with MYH9 to facilitate PRRSV infection.

A Nanobody Targeting Viral Nonstructural Protein 9 Inhibits Porcine Reproductive and Respiratory Syndrome Virus Replication.

Porcine reproductive and respiratory syndrome (PRRS) is of great concern to the swine industry due to pandemic outbreaks of the disease, current ineffective vaccinations, and a lack of efficient antiviral strategies. In our previous study, a PRRSV Nsp9-specific nanobody, Nb6, was successfully isolated, and the intracellularly expressed Nb6 could dramatically inhibit PRRSV replication in MARC-145 cells. However, despite its small size, the application of Nb6 protein in infected cells is greatly limited, as the protein itself cannot enter the cells physically.

Recombinant MYH9 protein C-terminal domain blocks porcine reproductive and respiratory syndrome virus internalization by direct interaction with viral glycoprotein 5.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important infectious diseases impacting the swine industry worldwide. Prevention and control of PRRS have been problematic, as vaccination has achieved little success. MYH9 (encoded by the gene MYH9) is an essential cellular factor for PRRS virus (PRRSV) infection.

Generation of murine macrophage-derived cell lines expressing porcine CD163 that support porcine reproductive and respiratory syndrome virus infection.

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) exhibits a highly restricted tropism for cells of the monocyte-macrophage lineage, utilizing porcine CD163 (pCD163) as an indispensable cellular receptor for infection. Transfection the gene of pCD163 into several non-permissive cell lines followed by protein expression confers susceptibility to PRRSV. A lack of specialized porcine antibody tools for use with existing porcine-derived primary cells and cell lines has hampered studies of both PRRSV pathogenesis and virus triggering of immune response cascades.

MicroRNA-like viral small RNA from porcine reproductive and respiratory syndrome virus negatively regulates viral replication by targeting the viral nonstructural protein 2.

Many viruses encode microRNAs (miRNAs) that are small non-coding single-stranded RNAs which play critical roles in virus-host interactions. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically impactful viruses in the swine industry. The present study sought to determine whether PRRSV encodes miRNAs that could regulate PRRSV replication.

MicroRNA let-7f-5p Inhibits Porcine Reproductive and Respiratory Syndrome Virus by Targeting MYH9.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important viral pathogens in the swine industry. Current antiviral strategies do not effectively prevent and control PRRSV. Recent reports show that microRNAs (miRNAs) play vital roles in viral infections by post transcriptionally regulating the expression of viral or host genes.