HijAkt: The PI3K/Akt pathway in virus replication and pathogenesis

Schisandra chinensis inhibits the entry of BoHV-1 by blocking PI3K-Akt pathway and enhances the m6A methylation of gD to inhibit the entry of progeny virus

Schisandra chinensis, a traditional Chinese medicine known for its antitussive and sedative effects, has shown promise in preventing various viral infections. Bovine herpesvirus-1 (BoHV-1) is an enveloped DNA virus that causes respiratory disease in cattle, leading to significant economic losses in the industry. Because the lack of previous reports on Schisandra chinensis resisting BoHV-1 infection, this study aimed to investigate the specific mechanisms involved. Results from TCID50, qPCR, IFA, and western blot analyses demonstrated that Schisandra chinensis could inhibit BoHV-1 entry into MDBK cells, primarily through its extract Methylgomisin O (Meth O). The specific mechanism involved Meth O blocking BoHV-1 entry into cells via clathrin- and caveolin-mediated endocytosis by suppressing the activation of PI3K-Akt signaling pathway. Additionally, findings from TCID50, qPCR, co-immunoprecipitation and western blot assays revealed that Schisandra chinensis blocked BoHV-1 gD transcription through enhancing m6A methylation of gD after virus entry, thereby hindering gD protein expression and preventing progeny virus entry into cells and ultimately inhibiting BoHV-1 replication. Overall, these results suggest that Schisandra chinensis can resist BoHV-1 infection by targeting the PI3K-Akt signaling pathway and inhibiting gD transcription.

Drosophila melanogaster Toll-9 elicits antiviral immunity against Drosophila C virus

The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionary conserved pathogen recognition receptors (PRRs), including Toll like receptors (TLRs), play a crucial role in recognition of pathogen associated molecular patterns (PAMPs). The Drosophila genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most Drosophila Tolls recognize the proteolytically cleaved ligand Spätzle to activate downstream signaling cascades. In this study, we demonstrated that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of Drosophila . A transposable element insertion in the Toll-9 gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in S2 cells confers resistance against DCV infection by upregulation of the RNAi pathway. Toll-9 promotes the dephosphorylation of AKT, resulting in the induction of antiviral RNAi genes to inhibit DCV replication. Toll-9 localizes to the endosome where it binds dsRNA, suggesting its role to detect viral dsRNA. Toll-9 also induces apoptosis during DCV infection, contributing to its antiviral role. Together, this work identifies the role of Toll-9 in antiviral immunity against DCV infection through its ability to bind dsRNA and induce AKT-mediated RNAi antiviral immunity.

IMPORTANCE

Insects rely on innate immunity and RNA interference (RNAi) to combat viral infections. Our study underscores the pivotal role of Drosophila Toll-9 in antiviral immunity, aligning with findings in Bombyx mori , where Toll-9 activation upregulates the RNAi component Dicer2 . We demonstrate that Drosophila Toll-9 functions as a pattern recognition receptor (PRR) for double-stranded RNA (dsRNA) during Drosophila C virus (DCV) infection, akin to mammalian TLRs. Toll-9 activation leads to the upregulation of key RNAi components, Dicer2 and Argonaute2 , and dephosphorylation of AKT triggers apoptosis via induction of proapoptotic genes Hid and Reaper . This study also reveals that Toll-9 localizes in endosomal compartments where it interacts with dsRNA. These insights enhance our understanding of Drosophila innate immune mechanisms, reflecting the evolutionary conservation of immune responses across diverse species and providing impetus for further research into the conserved roles of TLRs across the animal kingdom.

Multi-omics analysis reveals the dynamic interplay between Vero host chromatin structure and function during vaccinia virus infection

The genome folds into complex configurations and structures thought to profoundly impact its function. The intricacies of this dynamic structure-function relationship are not well understood particularly in the context of viral infection. To unravel this interplay, here we provide a comprehensive investigation of simultaneous host chromatin structural (via Hi-C and ATAC-seq) and functional changes (via RNA-seq) in response to vaccinia virus infection. Over time, infection significantly impacts global and local chromatin structure by increasing long-range intra-chromosomal interactions and B compartmentalization and by decreasing chromatin accessibility and inter-chromosomal interactions. Local accessibility changes are independent of broad-scale chromatin compartment exchange (~12% of the genome), underscoring potential independent mechanisms for global and local chromatin reorganization. While infection structurally condenses the host genome, there is nearly equal bidirectional differential gene expression. Despite global weakening of intra-TAD interactions, functional changes including downregulated immunity genes are associated with alterations in local accessibility and loop domain restructuring. Therefore, chromatin accessibility and local structure profiling provide impactful predictions for host responses and may improve development of efficacious anti-viral counter measures including the optimization of vaccine design.

Metabolomics combined with network pharmacology reveals a role for astragaloside IV in inhibiting enterovirus 71 replication via PI3K-AKT signaling

BACKGROUND

Astragaloside IV (AST-IV), as an effective active ingredient of Astragalus membranaceus (Fisch.) Bunge. It has been found that AST-IV inhibits the replication of dengue virus, hepatitis B virus, adenovirus, and coxsackievirus B3. Enterovirus 71 (EV71) serves as the main pathogen in severe hand-foot-mouth disease (HFMD), but there are no specific drugs available. In this study, we focus on investigating whether AST-IV can inhibit EV71 replication and explore the potential underlying mechanisms.

METHODS

The GES-1 or RD cells were infected with EV71, treated with AST-IV, or co-treated with both EV71 and AST-IV. The EV71 structural protein VP1 levels, the viral titers in the supernatant were measured using western blot and 50% tissue culture infective dose (TCID50), respectively. Network pharmacology was used to predict possible pathways and targets for AST-IV to inhibit EV71 replication. Additionally, ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) was used to investigate the potential targeted metabolites of AST-IV. Associations between metabolites and apparent indicators were performed via Spearman's algorithm.

RESULTS

This study illustrated that AST-IV effectively inhibited EV71 replication. Network pharmacology suggested that AST-IV inhibits EV71 replication by targeting PI3K-AKT. Metabolomics results showed that AST-IV achieved these effects by elevating the levels of hypoxanthine, 2-ketobutyric acid, adenine, nicotinic acid mononucleotide, prostaglandin H2, 6-hydroxy-1 H-indole-3- acetamide, oxypurinol, while reducing the levels of PC (14:0/15:0). Furthermore, AST-IV also mitigated EV71-induced oxidative stress by reducing the levels of MDA, ROS, while increasing the activity of T-AOC, CAT, GSH-Px. The inhibition of EV71 replication was also observed when using the ROS inhibitor N-Acetylcysteine (NAC). Additionally, AST-IV exhibited the ability to activate the PI3K-AKT signaling pathway and suppress EV71-induced apoptosis.

CONCLUSION

This study suggests that AST-IV may activate the cAMP and the antioxidant stress response by targeting eight key metabolites, including hypoxanthine, 2-ketobutyric acid, adenine, nicotinic acid mononucleotide, prostaglandin H2, 6-Hydroxy-1 H-indole-3-acetamide, oxypurinol and PC (14:0/15:0). This activation can further stimulate the PI3K-AKT signaling to inhibit EV71-induced apoptosis and EV71 replication.

Porcine TLR8 signaling and its anti-infection function are disturbed by immune checkpoint receptor TIM-3 via inhibition of P13K-AKT pathway

Toll-like receptor 8 (TLR8), an important innate immune receptor recognizing single stranded RNA and the antiviral imidazoquinoline compounds, can activate intracellular signaling pathway and produce an inflammatory response to kill and eliminate pathogens. However, the molecular regulation mechanisms of TLR8 signaling and its anti-infection activity are not fully elucidated. Our previous transcriptome analysis of porcine TLR8 (pTLR8) signaling suggested the immune checkpoint receptor TIM-3 as the potential regulator for pTLR8. Here we investigated TIM-3 in the regulation of pTLR8 signaling and its anti-infection activity. Our results showed that porcine TIM-3 is upregulated by pTLR8 signaling and TIM-3 inhibits pTLR8 signaling activity in a negative feedback way. Accordingly, TIM-3 disturbs pTLR8 mediated anti-bacterial and anti-viral activity. Mechanistically, TIM-3 suppresses PI3K-AKT pathway by inhibiting the TLR8-PI3K p85 interaction and subsequent AKT phosphorylation which is essential for TLR8 signaling and anti-infection activity. Therefore, our study reveals new insights into innate immune TLR8 signaling and its anti-infection function.

A viral insulin-like peptide inhibits IGF-1 receptor phosphorylation and regulates IGF1R gene expression

OBJECTIVE

The insulin/IGF superfamily is conserved across vertebrates and invertebrates. Our team has identified five viruses containing genes encoding viral insulin/IGF-1 like peptides (VILPs) closely resembling human insulin and IGF-1. This study aims to characterize the impact of Mandarin fish ranavirus (MFRV) and Lymphocystis disease virus-Sa (LCDV-Sa) VILPs on the insulin/IGF system for the first time.

METHODS

We chemically synthesized single chain (sc, IGF-1 like) and double chain (dc, insulin like) forms of MFRV and LCDV-Sa VILPs. Using cell lines overexpressing either human insulin receptor isoform A (IR-A), isoform B (IR-B) or IGF-1 receptor (IGF1R), and AML12 murine hepatocytes, we characterized receptor binding, insulin/IGF signaling. We further characterized the VILPs' effects of proliferation and IGF1R and IR gene expression, and compared them to native ligands. Additionally, we performed insulin tolerance test in CB57BL/6 J mice to examine in vivo effects of VILPs on blood glucose levels. Finally, we employed cryo-electron microscopy (cryoEM) to analyze the structure of scMFRV-VILP in complex with the IGF1R ectodomain.

RESULTS

VILPs can bind to human IR and IGF1R, stimulate receptor autophosphorylation and downstream signaling pathways. Notably, scMFRV-VILP exhibited a particularly strong affinity for IGF1R, with a mere 10-fold decrease compared to human IGF-1. At high concentrations, scMFRV-VILP selectively reduced IGF-1 stimulated IGF1R autophosphorylation and Erk phosphorylation (Ras/MAPK pathway), while leaving Akt phosphorylation (PI3K/Akt pathway) unaffected, indicating a potential biased inhibitory function. Prolonged exposure to MFRV-VILP led to a significant decrease in IGF1R gene expression in IGF1R overexpressing cells and AML12 hepatocytes. Furthermore, insulin tolerance test revealed scMFRV-VILP's sustained glucose-lowering effect compared to insulin and IGF-1. Finally, cryo-EM analysis revealed that scMFRV-VILP engages with IGF1R in a manner closely resembling IGF-1 binding, resulting in a highly analogous structure.

CONCLUSIONS

This study introduces MFRV and LCDV-Sa VILPs as novel members of the insulin/IGF superfamily. Particularly, scMFRV-VILP exhibits a biased inhibitory effect on IGF1R signaling at high concentrations, selectively inhibiting IGF-1 stimulated IGF1R autophosphorylation and Erk phosphorylation, without affecting Akt phosphorylation. In addition, MFRV-VILP specifically regulates IGF-1R gene expression and IGF1R protein levels without affecting IR. CryoEM analysis confirms that scMFRV-VILP' binding to IGF1R is mirroring the interaction pattern observed with IGF-1. These findings offer valuable insights into IGF1R action and inhibition, suggesting potential applications in development of IGF1R specific inhibitors and advancing long-lasting insulins.

AKT signaling modulates latent viral reservoir viability in HIV-1-infected blood-brain barrier pericytes

Despite antiretroviral therapy (ART), chronic forms of HIV-associated neurocognitive disorders (HAND) affect an estimated 50% of individuals living with HIV, greatly impacting their quality of life. The prevailing theory of HAND progression posits that chronic inflammation arising from the activation of latent viral reservoirs leads to progressive damage in the central nervous system (CNS). Recent evidence indicates that blood-brain barrier (BBB) pericytes are capable of active HIV-1 infection; however, their latent infection has not been defined. Given their location and function, BBB pericytes are poised to be a key viral reservoir in the development of HAND. We present the first transcriptional analysis of uninfected, active, and latent human BBB pericytes, revealing distinct transcriptional phenotypes. In addition, we demonstrate that latent infection of BBB pericytes relies on AKT signaling for reservoir survival. These findings provide insight into the state of reservoir maintenance in the CNS during HIV-1 infection and provide novel targets for reservoir clearance.

Forsythoside A inhibits apoptosis and autophagy induced by infectious bronchitis virus through regulation of the PI3K/Akt/NF-κB pathway

IMPORTANCE

Infectious bronchitis virus (IBV) is an acute and highly infectious viral disease that seriously endangered the development of the chicken industry. However, due to the limited effectiveness of commercial vaccines, there is an urgent need to develop safe and effective anti-IBV drugs. Forsythoside A (FTA) is a natural ingredient with wide pharmacological and biological activities, and it has been shown to have antiviral effects against IBV. However, the antiviral mechanism of FTA is still unclear. In this study, we demonstrated that FTA can inhibit cell apoptosis and autophagy induced by IBV infection by regulating the PI3K/AKT/NF-κB signaling pathway. This finding is important for exploring the role and mechanism of FTA in anti-IBV infection, indicating that FTA can be further studied as an anti-IBV drug.

Targeting Cyclophilin A and CD147 to Inhibit Replication of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and SARS-CoV-2-Induced Inflammation

Identification and development of effective therapeutics for coronavirus disease 2019 (COVID-19) are still urgently needed. The CD147-spike interaction is involved in the severe acute respiratory syndrome coronavirus (SARS-CoV)-2 invasion process in addition to angiotensin-converting enzyme 2 (ACE2). Cyclophilin A (CyPA), the extracellular ligand of CD147, has been found to play a role in the infection and replication of coronaviruses. In this study, our results show that CyPA inhibitors such as cyclosporine A (CsA) and STG-175 can suppress the intracellular replication of SARS-CoV-2 by inhibiting the binding of CyPA to the SARS-CoV-2 nucleocapsid C-terminal domain (N-CTD), and the IC50 is 0.23 μM and 0.17 μM, respectively. Due to high homology, CsA also had inhibitory effects on SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), and the IC50 is 3.2 μM and 2.8 μM, respectively. Finally, we generated a formulation of phosphatidylserine (PS)-liposome-CsA for pulmonary drug delivery. These findings provide a scientific basis for identifying CyPA as a potential drug target for the treatment of COVID-19 as well as for the development of broad-spectrum inhibitors for coronavirus via targeting CyPA. Highlights: 1) SARS-CoV-2 infects cells via the binding of its S protein and CD147; 2) binding of SARS-CoV-2 N protein and CyPA is essential for viral replication; 3) CD147 and CyPA are potential therapeutic targets for SARS-CoV-2; and 4) CsA is a potential therapeutic strategy by interrupting CD147/CyPA interactions. SIGNIFICANCE STATEMENT: New severe acute respiratory syndrome coronavirus (SARS-CoV)-2 variants and other pathogenic coronaviruses (CoVs) are continually emerging, and new broad-spectrum anti-CoV therapy is urgently needed. We found that binding sites of cyclophilin A/cyclosporin A (CyPA/CsA) overlap with CyPA/N-CTD (nucleocapsid C-terminal domain), which shows the potential to target CyPA during SARS-CoV-2 infection. Here, we provide new evidence for targeting CyPA in the treatment of coronavirus disease 2019 (COVID-19) as well as the potential of developing CyPA inhibitors for broad-spectrum inhibition of CoVs.

IRF9 inhibits CyHV-3 replication by regulating the PI3K-AKT signalling pathway in common carp (Cyprinus carpio) epithelial cells

Interferon regulatory factor 9 (IRF9) is an important transcriptional regulator involved in innate and adaptive immunity. Cyprinid herpesvirus-3 (CyHV-3) is a virus causing widespread death and great economic loss in farmed common carp (Cyprinus carpio). However, the effect of IRF9 on CyHV-3 infection in common carp has not been reported. In this study, during CyHV-3 infection, IRF9 overexpression in common carp fin epithelial (CCF) cells significantly reduced the expression of viral factor thymidine kinase (TK) and open reading frame 72 (ORF72), and knockdown of IRF9 produced the opposite results (p < 0.05). In CCF cells. The IRF9 protein was expression in the nucleus and was rapidly induced in CCF cells by CyHV-3 infection. In addition, several genes associated with virus infection, including type I interferon (IFNI), IFN-stimulated gene 15 (ISG15), myxovirus resistance 1 (Mx1) and Viperin were induced in CCF cells overexpressing IRF9 upon CyHV-3 infection. IRF9 overexpression induced by CyHV-3 infection significantly increased the gene expression of Mx1 and phosphoinositide 3-kinase (PI3K) and the protein expression of protein kinase B (AKT) (p < 0.01). Interestingly, IRF9 did not significantly affect Mx1 gene expression when AKT protein levels remained unchanged during CyHV-3 infection of CCF cells. Furthermore, a significant resistance-related locus was found in the IRF9 sequence in "Longke-11" mirror carp (M11) and Yellow River carp (p < 0.05). These results indicated that IRF9 inhibited viral replication by upregulating the expression of Mx1 via the PI3K-AKT signalling pathway during CyHV-3 infection in CCF cells and provide some basis for the study of the antiviral molecular mechanisms of common carp.

Duvelisib for Critically Ill Patients With Coronavirus Disease 2019: An Investigator-Initiated, Randomized, Placebo-Controlled, Double-Blind Pilot Trial

Background

Despite improvements in prevention and treatment, severe coronavirus disease 2019 (COVID-19) is associated with high mortality. Phosphoinositide 3-kinase (PI3K) pathways contribute to cytokine and cell-mediated lung inflammation. We conducted a randomized, placebo-controlled, double-blind pilot trial to determine the feasibility, safety, and preliminary activity of duvelisib, a PI3Kδγ inhibitor, for the treatment of COVID-19 critical illness.

Methods

We enrolled adults aged ≥18 years with a primary diagnosis of COVID-19 with hypoxic respiratory failure, shock, and/or new cardiac disease, without improvement after at least 48 hours of corticosteroid. Participants received duvelisib (25 mg) or placebo for up to 10 days. Participants had daily semi-quantitative viral load measurements performed. Dose modifications were protocol driven due to adverse events (AEs) or logarithmic change in viral load. The primary endpoint was 28-day overall survival (OS). Secondary endpoints included hospital and intensive care unit length of stay, 60-day OS, and duration of critical care interventions. Safety endpoints included viral kinetics and AEs. Exploratory endpoints included serial cytokine measurements and cytometric analysis.

Results

Fifteen patients were treated in the duvelisib cohort, and 13 in the placebo cohort. OS at 28 days was 67% (95% confidence interval [CI], 38%-88%) compared to 62% (95% CI, 32%-86%) for placebo (P = .544). Sixty-day OS was 60% versus 46%, respectively (hazard ratio, 0.66 [95% CI, .22-1.96]; P = .454). Other secondary outcomes were comparable. Duvelisib was associated with lower inflammatory cytokines.

Conclusions

In this pilot study, duvelisib did not significantly improve 28-day OS compared to placebo for severe COVID-19. Duvelisib appeared safe in this critically ill population and was associated with reduction in cytokines implicated in COVID-19 and acute respiratory distress syndrome, supporting further investigation.

Clinical Trials Registration

NCT04372602.

Pharmacological effects and mechanism of Kaihoujian Throat Spray (children's type) in the treatment of pediatric acute pharyngitis and tonsillitis

Context

Kaihoujian Throat Spray children's type (KHJSC) is a Chinese medicine prescription for treating pediatric acute pharyngitis and tonsillitis (APT). However, its relevant mechanisms remain unclear.

Objective

To investigate the pharmacological effects of KHJSC on APT in vitro and in vivo, and explore the possible mechanism and target proteins.

Materials and methods

The antiviral and antibacterial effects in vitro were evaluated by IC50 and MICs. Thirty-six Japanese white rabbits were averagely divided into control group, model group, amoxicillin group and 3 dose groups of KHJSC (720, 540 and 360 μL/kg/d). The model rabbits were injected with β-hemolytic Streptococcus solution into the tonsils for 2 consecutive days. KHJSC treatment started on the third day. The whole blood, serum, tonsil tissues and pharyngeal mucosa tissues were collected for routine blood tests, proteomic, ELISA and other tests on the sixth day.

Results

The IC50 of KHJSC on HCoV-229E, influenza PR8 and Ad3 were 1.99, 1.99 and 4.49 mg/mL, respectively; MICs of MDR-PA, MRSA and β-hemolytic Streptococcus were 350, 350, and 175 mg/mL. KHJSC markedly decreased the number of white blood cells, lymphocytes, neutrophils, and the level of IL-1β, IL-5, IL-6, IL-18, TNF-α and MCP-1; increased the content of IL-2 and IFN-γ. Proteomic analysis and ELISA revealed that PI3K-Akt signaling pathway, NF-κB signaling pathway and Toll-like receptor signaling pathway were the potential mechanisms of KHJSC against APT.

Discussion and conclusion

These results provided the reference and scientific basis for the application of KHJSC in clinic and further mechanisms study.

The Small GTPase Rab14 Regulates the Trafficking of Ceramide from Endoplasmic Reticulum to Golgi Apparatus and Facilitates Classical Swine Fever Virus Assembly

Classical swine fever virus (CSFV) is a highly pathogenic RNA virus belonging to the Flaviviridae family that can cause deadly classical swine fever (CSF) in pigs. However, the molecular details of virus replication in the host are still unclear. Our previous studies have reported that several Rab proteins mediate CSFV entry into host cells, but it is unknown whether CSFV hijacks other Rab proteins for effective viral infection. Here, we systematically studied the role of Rab14 protein in regulating lipid metabolism for promoting viral assembly. First, Rab14 knockdown and overexpression significantly affected CSFV replication, indicating the essential role of Rab14 in CSFV infection. Interestingly, Rab14 could significantly affect virus replication in the late stage of infection. Mechanistically, CSFV NS5A recruited Rab14 to the ER, followed by ceramide transportation to the Golgi apparatus, where sphingomyelin was synthesized. The experimental data of small molecule inhibitors, RNA interference, and replenishment assay showed that the phosphatidylinositol-3-kinase (PI3K)/AKT/AS160 signaling pathway regulated the function of Rab14 to affect the transport of ceramide. More importantly, sphingomyelin on the Golgi apparatus contributed to the assembly of viral particles. Blockage of the Rab14 regulatory pathway induced the reduction of the content of sphingomyelin on the Golgi apparatus, impairing the assembly of virus particles. Our study clarifies that Rab14 regulates lipid metabolism and promotes CSFV replication, which provides insight into a novel function of Rab14 in regulating vesicles to transport lipids to the viral assembly factory. IMPORTANCE The Rab protein family members participate in the viral replication of multiple viruses and play important roles in the virus infection cycle. Our previous research focused on Rab5/7/11, which regulated the trafficking of vesicles in the early stage of CSFV infection, especially in viral endocytosis. However, the role of other Rab proteins in CSFV replication is unclear and needs further clarification. Strikingly, we screened some Rabs and found the important role of Rab14 in CSFV infection. Virus infection mobilized Rab14 to regulate the vesicle to transport ceramide from the ER to the Golgi apparatus, further promoting the synthesis of sphingomyelin and facilitating virus assembly. The treatment of inhibitors showed that the lipid transport mediated by Rab14 was regulated by the PI3K/AKT/AS160 signaling pathway. Knockdown of Rab14 or the treatment with PI3K/AKT/AS160 inhibitors reduced the ceramide content in infected cells and hindered virus assembly. Our study is the first to explain that vesicular lipid transport regulated by Rab promotes CSFV assembly, which is conducive to the development of antiviral drugs.

Antiviral activity of the HSP90 inhibitor VER-50589 against enterovirus 71

Enterovirus 71 (EV71) is the major pathogen responsible for hand, foot, and mouth disease (HFMD) outbreaks; to date, there is no specific anti-EV71 agent. HSP90 is a crucial host factor for the viral life cycle and an ideal therapeutic target for limiting viral proliferation. However, the specific role of HSP90 in EV71-related signaling pathways and anti-EV71 agents targeting HSP90 remains unclear. This study aimed to verify the role of HSP90 in signaling pathways involved in EV71 replication and investigate the antiviral effects of a small molecule of VER-50589, a potent HSP90 inhibitor, against EV71 both in vitro and in vivo. Viral plaque assay, western blotting, and qPCR results showed that VER-50589 diminished the plaque formation induced by EV71 and inhibited EV71 mRNA and protein synthesis. A single daily dose of VER-50589 treatment significantly improved the survival rate of EV71-infected mice (p < 0.005). Interestingly, VER-50589 also exhibits activities against a series of human enteroviruses, including Coxsackievirus B3 (CVB3), Coxsackievirus B4-5 (CVB4-5), Coxsackievirus B4-7 (CVB4-7), and Echovirus 11 (Echo11). EV71 infection activated the AKT and ERK signaling pathways, and phosphorylation of AKT and RAF/MEK/ERK was weakened by VER-50589 administration. Thus, VER-50589 exhibits robust antiviral activity by inhibiting HSP90 and mediating the AKT and RAF/MEK/ERK signaling pathways. Considering that there are no effective antivirals or vaccines for the prevention and cure of HFMD in a clinical setting, the development of an anti-EV71 agent would be a straightforward and feasible therapeutic approach.

Effects of Oncolytic Vaccinia Viruses Harboring Different Marine Lectins on Hepatocellular Carcinoma Cells

Oncolytic viruses are being developed as novel strategies for cancer therapy. Our previous studies have shown that vaccinia viruses armed with marine lectins improved the antitumor efficacy in diverse cancer types. The objective of this study was to assess the cytotoxic effects of oncoVV harboring Tachypleus tridentatus lectin (oncoVV-TTL), Aphrocallistes vastus lectin (oncoVV-AVL), white-spotted charr lectin (oncoVV-WCL), and Asterina pectinifera lectin (oncoVV-APL) on HCC. Our data revealed that the effects of recombinant viruses on Hep-3B cells were oncoVV-AVL > oncoVV-APL > oncoVV-TTL > oncoVV-WCL; oncoVV-AVL showed stronger cytotoxicity than oncoVV-APL, while oncoVV-TTL/WCL had no effect on cell killing in Huh7 cells, and PLC/PRF/5 cells exhibited sensitivity to oncoVV-AVL/TTL but not to oncoVV-APL/WCL. The cytotoxicity of oncoVV-lectins could be enhanced by apoptosis and replication in a cell-type-dependent manner. Further research revealed that AVL may mediate various pathways, including MAPK, Hippo, PI3K, lipid metabolism, and androgen pathways through AMPK crosstalk, to promote oncoVV replication in HCC in a cell-dependent manner. OncoVV-APL replication could be affected by AMPK/Hippo/lipid metabolism pathways in Hep-3B cells, AMPK/Hippo/PI3K/androgen pathways in Huh7 cells, and AMPK/Hippo pathways in PLC/PRF/5 cells. OncoVV-WCL replication was also multi-mechanistic, which could be affected by AMPK/JNK/lipid metabolism pathways in Hep-3B cells, AMPK/Hippo/androgen pathways in Huh7 cells, and AMPK/JNK/Hippo pathways in PLC/PRF/5 cells. In addition, AMPK and lipid metabolism pathways may play critical roles in oncoVV-TTL replication in Hep-3B cells, and oncoVV-TTL replication in Huh7 cells may depend on AMPK/PI3K/androgen pathways. This study provides evidence for the application of oncolytic vaccinia viruses in hepatocellular carcinoma.

Polymorphisms in PI3K/AKT genes and gene‑smoking interaction are associated with susceptibility to tuberculosis

BACKGROUND

Phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) are involved in the clearance of Mycobacterium tuberculosis (MTB) by macrophages.

AIM

This study aimed to investigate the effects of polymorphisms in the PI3K/AKT genes and the gene-smoking interaction on susceptibility to TB.

METHODS

This case-control study used stratified sampling to randomly select 503 TB patients and 494 control subjects. Logistic regression analysis was used to determine the association between the polymorphisms and TB. Simultaneously, the marginal structure linear dominance model was used to estimate the gene-smoking interaction.

RESULTS

Genotypes GA (OR 1.562), AA (OR 2.282), and GA + AA (OR 1.650) at rs3730089 of the PI3KR1 gene were significantly associated with the risk to develop TB. Genotypes AG (OR 1.460), GG (OR 2.785), and AG + GG (OR 1.622) at rs1130233 of the AKT1 gene were significantly associated with the risk to develop TB. In addition, the relative excess risk of interaction (RERI) between rs3730089 and smoking was 0.9608 (95% CI: 0.5959, 1.3256, p < 0.05), which suggests a positive interaction.

CONCLUSION

We conclude that rs3730089 and rs1130233 are associated with susceptibility to TB, and there was positive interaction between rs3730089 and smoking on susceptibility to TB.

Modifications of the PI3K/Akt/mTOR axis during FeHV-1 infection in permissive cells

FeHV-1 is the causative agent of infectious rhinotracheitis in cats. The relationship between viral infection and the PI3K/Akt/mTOR pathway, as well as its function in crucial physiological processes like as autophagy, apoptosis or the IFN induction cascade is known for other varicelloviruses. However, there is no information on whether autophagy is activated during FeHV-1 infection nor on how this infection modifies PI3K/Akt/mTOR pathway. In this work, we aim to elucidate the involvement of this pathway during cytolytic infection by FeHV-1 in permissive cell lines. Using a phenotypic approach, the expression of proteins involved in the PI3K/Akt/mTOR pathway was examined by Western blot analysis. The findings demonstrated the lack of modifications in relation to viral dose (except for phospho-mTOR), whereas there were changes in the expression of several markers in relation to time as well as a mismatch in the time of activation of this axis. These results suggest that FeHV-1 may interact independently with different autophagic signaling pathways. In addition, we found an early phosphorylation of Akt, approximately 3 h after infection, without a concomitant decrease in constitutive Akt. This result suggests a possible role for this axis in viral entry. In a second phase, the use of early autophagy inhibitors was examined for viral yield, cytotoxic effects, viral glycoprotein expression, and autophagy markers and resulted in inefficient inhibition of viral replication (12 h post-infection for LY294002 and 48 h post-infection for 3-methyladenine). The same markers were examined during Akt knockdown, and we observed no differences in viral replication. This result could be explained by the presence of a protein kinase in the FeHV-1 genome (encoded by the Us3 gene) that can phosphorylate various Akt substrates as an Akt surrogate, as has already been demonstrated in genetically related viruses (HSV-1, PRV, etc.). For the same reasons, the use of LY294002 at the beginning of infection did not affect FeHV-1-mediated Akt phosphorylation. Our findings highlight changes in the PI3K/Akt/mTOR pathway during FeHV-1 infection, although further research is needed to understand the importance of these changes and how they affect cellular processes and viral propagation.

Synthetic Fibroblasts: Terra Incognita in Cardiac Regeneration

Ischemic heart disease, a major risk factor for myocardial infarction (MI), occurs when the blood vessels supplying oxygen-rich blood to the heart become partially or fully occluded by lipid-rich plaques, resulting in myocardial cell death, remodeling, and scarring. In addition, MI occurs as result of lipid-rich plaque rupture, resulting in thrombosis and vessel occlusion. Cardiac fibroblasts (CFs) and CF-derived growth factors are crucial post-MI in myocardial remodeling. Information regarding the regenerative phenotypes of CFs is scarce; however, regenerative CFs are translationally relevant in myocardial regeneration following MI. The emerging technologies in regenerative cardiology offer cutting-edge translational opportunities, including synthetic cells. In this review, we critically reviewed the current knowledge and the ongoing research efforts on application of synthetic cells for improving cardiac regeneration post-MI. Impact statement Synthetic cells offer tremendous regenerative potential in otherwise deleterious cardiac remodeling postmyocardial infarction. Understanding the role of fibroblasts in cardiac healing and the therapeutic applications of synthetic cells would open a multitude of novel cardiac regenerative approaches. The novel concept of synthetic fibroblasts that emulate native cardiac fibroblasts can provide an effective solution in cardiac healing.

Live and let die: signaling AKTivation and UPRegulation dynamics in SARS-CoVs infection and cancer

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the coronavirus disease 2019 (COVID-19) pandemic. Of particular interest for this topic are the signaling cascades that regulate cell survival and death, two opposite cell programs whose control is hijacked by viral infections. The AKT and the Unfolded Protein Response (UPR) pathways, which maintain cell homeostasis by regulating these two programs, have been shown to be deregulated during SARS-CoVs infection as well as in the development of cancer, one of the most important comorbidities in relation to COVID-19. Recent evidence revealed two way crosstalk mechanisms between the AKT and the UPR pathways, suggesting that they might constitute a unified homeostatic control system. Here, we review the role of the AKT and UPR pathways and their interaction in relation to SARS-CoV-2 infection as well as in tumor onset and progression. Feedback regulation between AKT and UPR pathways emerges as a master control mechanism of cell decision making in terms of survival or death and therefore represents a key potential target for developing treatments for both viral infection and cancer. In particular, drug repositioning, the investigation of existing drugs for new therapeutic purposes, could significantly reduce time and costs compared to de novo drug discovery.

IHNV Infection Induces Strong Mucosal Immunity and Changes of Microbiota in Trout Intestine

The fish intestinal mucosa is among the main sites through which environmental microorganisms interact with the host. Therefore, this tissue not only constitutes the first line of defense against pathogenic microorganisms but also plays a crucial role in commensal colonization. The interaction between the mucosal immune system, commensal microbiota, and viral pathogens has been extensively described in the mammalian intestine. However, very few studies have characterized these interactions in early vertebrates such as teleosts. In this study, rainbow trout (Oncorhynchus mykiss) was infected with infectious hematopoietic necrosis virus (IHNV) via a recently developed immersion method to explore the effects of viral infection on gut immunity and microbial community structure. IHNV successfully invaded the gut mucosa of trout, resulting in severe tissue damage, inflammation, and an increase in gut mucus. Moreover, viral infection triggered a strong innate and adaptive immune response in the gut, and RNA−seq analysis indicated that both antiviral and antibacterial immune pathways were induced, suggesting that the viral infection was accompanied by secondary bacterial infection. Furthermore, 16S rRNA sequencing also revealed that IHNV infection induced severe dysbiosis, which was characterized by large increases in the abundance of Bacteroidetes and pathobiont proliferation. Moreover, the fish that survived viral infection exhibited a reversal of tissue damage and inflammation, and their microbiome was restored to its pre−infection state. Our findings thus demonstrated that the relationships between the microbiota and gut immune system are highly sensitive to the physiological changes triggered by viral infection. Therefore, opportunistic bacterial infection must also be considered when developing strategies to control viral infection.

RIOK3-mediated Akt phosphorylation facilitates synergistic replication of Marek's disease and reticuloendotheliosis viruses

Co-infection of Marek’s disease virus (MDV) and reticuloendotheliosis virus (REV) synergistically drives disease progression, yet little is known about the mechanism of the synergism. Here, we found that co-infection of REV and MDV increased their replication via the RIOK3-Akt pathway. Initially, we noticed that the viral titres of MDV and REV significantly increased in REV and MDV co-infected cells compared with single-infected cells. Furthermore, tandem mass tag peptide labelling coupled with LC/MS analysis showed that Akt was upregulated in REV and MDV co-infected cells. Overexpression of Akt promoted synergistic replication of MDV and REV. Conversely, inhibition of Akt suppressed synergistic replication of MDV and REV. However, PI3K inhibition did not affect synergistic replication of MDV and REV, suggesting that the PI3K/Akt pathway is not involved in the synergism of MDV and REV. In addition, we revealed that RIOK3 was recruited to regulate Akt in REV and MDV co-infected cells. Moreover, wild-type RIOK3, but not kinase-dead RIOK3, mediated Akt phosphorylation and promoted synergistic replication of MDV and REV. Our results illustrate that MDV and REV activated a novel RIOK3-Akt signalling pathway to facilitate their synergistic replication.

Novel genes and sex differences in COVID-19 severity

Here we describe the results of a genome-wide study conducted in 11 939 COVID-19 positive cases with an extensive clinical information that were recruited from 34 hospitals across Spain (SCOURGE consortium). In sex-disaggregated genome-wide association studies for COVID-19 hospitalization, genome-wide significance (p < 5x10-8) was crossed for variants in 3p21.31 and 21q22.11 loci only among males (p = 1.3x10-22 and p = 8.1x10-12, respectively), and for variants in 9q21.32 near TLE1 only among females (p = 4.4x10-8). In a second phase, results were combined with an independent Spanish cohort (1598 COVID-19 cases and 1068 population controls), revealing in the overall analysis two novel risk loci in 9p13.3 and 19q13.12, with fine-mapping prioritized variants functionally associated with AQP3 (p = 2.7x10-8) and ARHGAP33 (p = 1.3x10-8), respectively. The meta-analysis of both phases with four European studies stratified by sex from the Host Genetics Initiative confirmed the association of the 3p21.31 and 21q22.11 loci predominantly in males and replicated a recently reported variant in 11p13 (ELF5, p = 4.1x10-8). Six of the COVID-19 HGI discovered loci were replicated and an HGI-based genetic risk score predicted the severity strata in SCOURGE. We also found more SNP-heritability and larger heritability differences by age (<60 or ≥ 60 years) among males than among females. Parallel genome-wide screening of inbreeding depression in SCOURGE also showed an effect of homozygosity in COVID-19 hospitalization and severity and this effect was stronger among older males. In summary, new candidate genes for COVID-19 severity and evidence supporting genetic disparities among sexes are provided.

Investigation on anti-Corona viral potential of Yarrow tea

Achillea millefolium (Yarrow) is a herbaceous plant of Greek origin noted to treat pneumonia, common cold, cough, and other respiratory disorders. The flowers and leaves are the core part used to prepare herbal tea that gains the world's recognition as medicinal tea. Coronavirus disease is spreading across the globe, and numerous approaches are lodged to treat virus-induced lung inflammation. Here, we used the network pharmacology, metabolite analysis, docking and molecular simulation and MM-PBSA analysis to comprehend the biochemical basis of the health-boosting impact of Yarrow tea. Next, we performed the microscopic and dynamic light scattering (DLS) analysis of yarrow-treated ChAdOx1 nCoV-19 to evaluate the virucidal activity of the Yarrow. The present study investigates the druggability, metabolites and potential interaction of the title tea with genes associated with Covid-19-induced pathogenesis. Towards this, 1022 gene hits were obtained, 30 are mutually shared. Network Pharmacology and microarray gene expression analysis find the connection of PTGS2 in relieving the virus-induced inflammation. Yarrow constituents Luteolin may inhibit or down-regulate the Cyclooxygenase II (PTGS2), a plausible mechanism underlying the Yarrow's anti-inflammatory actions. Further, the Yarrow's virucidal activity was assessed towards Transmission Electron Microscopic (TEM). The Yarrow treated SARS-nCoV-2 cell exhibits the disintegration of the virus membrane. This work provides a scientific basis for further elucidating the mechanism underlying Achillea millefolium's antiviral and anti-inflammatory properties.

Screening of candidate genes associated with high titer production of oncolytic measles virus based on systems biology approach

The number of viral particles required for oncolytic activity of measles virus (MV) can be more than a million times greater than the reported amount for vaccination. The aim of the current study is to find potential genes and signaling pathways that may be involved in the high-titer production of MV. In this study, a systems biology approach was considered including collection of gene expression profiles from the Gene Expression Omnibus (GEO) database, obtaining differentially expressed genes (DEGs), performing gene ontology, functional enrichment analyses, and topological analyses on the protein-protein interaction (PPI) network. Then, to validate the in-silico data, total RNA was isolated from five cell lines, and full-length cDNA from template RNA was synthesized. Subsequently, quantitative reverse transcription-PCR (RT-qPCR) was employed. We identified five hub genes, including RAC1, HSP90AA1, DNM1, LTBP1, and FSTL1 associated with the enhancement in MV titer. Pathway analysis indicated enrichment in PI3K-Akt signaling pathway, axon guidance, proteoglycans in cancer, regulation of actin cytoskeleton, focal adhesion, and calcium signaling pathways. Upon verification by RT-qPCR, the relative expression of candidate genes was generally consistent with our bioinformatics analysis. Hub genes and signaling pathways may be involved in understanding the pathological mechanisms by which measles virus manipulates host factors in order to facilitate its replication. RAC1, HSP90AA1, DNM1, LTBP1, and FSTL1 genes, in combination with genetic engineering techniques, will allow the direct design of high-throughput cell lines to answer the required amounts for the oncolytic activity of MV.

Marek's Disease Virus and Reticuloendotheliosis Virus Coinfection Enhances Viral Replication and Alters Cellular Protein Profiles

Coinfection with Marek's disease virus (MDV) and reticuloendotheliosis virus (REV) causes synergistic pathogenic effects and serious losses to the poultry industry. However, whether there is a synergism between the two viruses in viral replication and the roles of host factors in regulating MDV and REV coinfection remains elusive. In this study, we found that MDV and REV coinfection increased viral replication in coinfected cells as compared to a single infection in a limited period. Further, we explore the host cell responses to MDV and REV coinfection using tandem mass tag (TMT) peptide labeling coupled with liquid chromatography–tandem mass spectrometry (LC-MS/MS). Compared with MDV/REV-infected cells, 38 proteins increased (fold change > 1.2) and 60 decreased (fold change < 0.83) their abundance in MDV and REV coinfected cells. Differentially accumulated proteins (DAPs) were involved in important biological processes involved in the immune system process, cell adhesion and migration, cellular processes, and multicellular organismal systems. STRING analysis found that IRF7, MX1, TIMP3, and AKT1 may be associated with MDV and REV synergistic replication in chicken embryo fibroblasts (CEFs). Western blotting analysis showed that the selected DAPs were identical to the quantitative proteomics data. Taken together, we verified that MDV and REV can synergistically replicate in coinfected cells and revealed the host molecules involved in it. However, the synergistic pathogenesis of MDV and REV needs to be further studied.

PI3K/AKT/p53 pathway inhibits infectious spleen and kidney necrosis virus infection by regulating autophagy and immune responses

The PI3K/AKT/p53 signaling pathway is activated by various types of cellular stimuli or pathogenic infection, and then regulates fundamental cellular functions to combat these stimulations. Here, we studied the meaningful roles of PI3K/AKT/p53 in regulating cellular machine such as autophagy, immune responses, as well as antiviral activity in Chinese perch brain (CPB) cells infected by infectious spleen and kidney necrosis virus (ISKNV), which is an agent caused devastating losses in mandarin fish (Siniperca chuatsi) industry. We found that ISKNV infection induced up-regulation of host PI3K/AKT/p53 axis, but inhibited autophagy in CPB cells. Interestingly, activation of PI3K/AKT/p53 axis factors trough agonists or overexpression dramatically decreased host autophagy level, inhibited ISKNV replication, and elevated the expression of immune-related genes in CPB cells. In contrast, suppression of PI3K/AKT/p53 pathway by inhibitors or small interfering RNA (siRNA)-mediated gene silence increased the autophagy and ISKNV replication, but down-regulated immune responses in CPB cells. All these results indicate that PI3K/AKT/p53 pathway plays an important role in anti-ISKNV infection and can be used as a new target for controlling ISKNV disease.

The Expression of ephrinA1/ephA2 Receptor Increases in Chronic Rhinosinusitis and ephrinA1/ephA2 Signaling Affects Rhinovirus-Induced Innate Immunity in Human Sinonasal Epithelial Cells

EphA2 receptor and its ephrin ligands are involved in virus infection, epithelial permeability, and chemokine secretion. We hypothesized that ephrinA1/ephA2 signaling participates in rhinovirus (RV)-induced antiviral immune response in sinonasal mucosa of patients with chronic rhinosinusitis (CRS). Therefore, we investigated the expression of ephrinA1/ephA2 in normal and inflamed sinonasal mucosa and evaluated whether they regulate chemokine secretion and the production of antiviral immune mediators including interferons (IFNs) in RV-infected human primary sinonasal epithelial cells. For this purpose, the expression and distribution of ephrinA1/ephA2 in sinonasal mucosa were evaluated with RT-qPCR, immunofluorescence, and western blot. Their roles in chemokine secretion and the production of antiviral immune mediators such as type I and III IFNs, and interferon stimulated genes were evaluated by stimulating ephA2 with ephrinA1 and inactivating ephA2 with ephA2 siRNA or inhibitor in cells exposed to RV and poly(I:C). We found that ephrinA1/ephA2 were expressed in normal mucosa and their levels increased in inflamed sinonasal mucosa of CRS patients. RV infection or poly(I:C) treatment induced chemokine secretion which were attenuated by blocking the action of ephA2 with ephA2 siRNA or inhibitor. The production of antiviral immune mediators enhanced by rhinovirus or poly (I:C) is increased by blocking ephA2 compared with that of cells stimulated by either rhinovirus or poly(I:C) alone. In addition, blocking ephA2 attenuated RV replication in cultured cells. Taken together, these results describe a novel role of ephrinA1/ephA2 signaling in antiviral innate immune response in sinonasal epithelium, suggesting their participation in RV-induced development and exacerbations of CRS.

Akt plays differential roles during the life cycles of acute and persistent murine norovirus strains in macrophages

Akt (Protein kinase B) is a key signaling protein in eukaryotic cells that controls many cellular processes such as glucose metabolism and cell proliferation for survival. As obligate intracellular pathogens, viruses modulate host cellular processes, including Akt signaling, for optimal replication. The mechanisms by which viruses modulate Akt and the resulting effects on the infectious cycle differ widely depending on the virus. In this study, we explored the effect of Akt serine 473 phosphorylation (p-Akt) during murine norovirus (MNV) infection. p-Akt increased during infection of murine macrophages with acute MNV-1 and persistent CR3 and CR6 strains. Inhibition of Akt with MK2206, an inhibitor of all three isoforms of Akt (Akt1/2/3), reduced infectious virus progeny of all three virus strains. This reduction was due to decreased viral genome replication (CR3), defective virus assembly (MNV-1), or diminished cellular egress (CR3 and CR6) in a virus strain-dependent manner. Collectively, our data demonstrate that Akt activation increases in macrophages during the later stages of the MNV infectious cycle, which may enhance viral infection in unique ways for different virus strains. The data, for the first time, indicate a role for Akt signaling in viral assembly and highlight additional phenotypic differences between closely related MNV strains. Importance Human noroviruses (HNoV) are a leading cause of viral gastroenteritis, resulting in high annual economic burden and morbidity; yet there are no small animal models supporting productive HNoV infection, or robust culture systems producing cell culture-derived virus stocks. As a result, research on drug discovery and vaccine development against norovirus infection has been challenging, and no targeted antivirals or vaccines against HNoV are approved. On the other hand, murine norovirus (MNV) replicates to high titers in cell culture and is a convenient and widespread model in norovirus research. Our data demonstrate the importance of Akt signaling during the late stage of the MNV life cycle. Notably, the effect of Akt signaling on genome replication, virus assembly and cellular egress is virus strain specific, highlighting the diversity of biological phenotypes despite small genetic variability among norovirus strains. This study is the first to demonstrate a role for Akt in viral assembly.

Alteration in Cellular Signaling and Metabolic Reprogramming during Viral Infection

Cellular activities are finely regulated by numerous signaling pathways to support specific functions of complex life processes. Viruses are obligate intracellular parasites. Each step of viral replication is ultimately governed by the interaction of a virus with its host cells. Because of the demands of viral replication, the nutritional needs of virus-infected cells differ from those of uninfected cells. To improve their chances of survival and replication, viruses have evolved to commandeer cellular processes, including cell metabolism, augmenting these processes to support their needs. This article summarizes recent findings regarding virus-induced alterations to major cellular metabolic pathways focusing on how viruses modulate various signaling cascades to induce these changes. We begin with a general introduction describing the role played by signaling pathways in cellular metabolism. We then discuss how different viruses target these signaling pathways to reprogram host metabolism to favor the viral needs. We highlight the gaps in understanding metabolism-related virus-host interactions and discuss how studying these changes will enhance our understanding of fundamental processes involved in metabolic regulation. Finally, we discuss the potential to harness these processes to combat viral diseases, as well as other diseases, including metabolic disorders and cancers.

Antiviral Effectivity of Favipiravir Against Peste Des Petits Ruminants Virus Is Mediated by the JAK/STAT and PI3K/AKT Pathways

Peste des petits ruminants virus (PPRV), belonging to the genus Morbillivirus in the family Paramyxoviridae, causes severe infectious disease in small ruminants and has been rapidly spreading in many parts of Africa, the Middle East, and Asia. Although vaccination is considered to be an effective means of controlling PPR, the heat-sensitive nature of the vaccines against PPRV greatly limits their application in areas with a hot climate. In the present study, we investigated the anti-PPRV effects of favipiravir and sought to identify the underlying mechanisms in vitro using the Vero cell line. MTT assays, Western blotting, indirect immunofluorescence assays, virus plaque formation assays, and qRT-PCR were used to assess the effects of favipiravir on the life cycle of PPRV and the expression of RNA-dependent RNA polymerase (RdRp). Additionally, the expression levels of JAK1, STAT1, phosphorylated (p)-STAT1, PI3K, AKT, and p-AKT, as well as those of signaling molecules acting downstream of the JAK/STAT and PI3K/AKT signaling pathways, were determined by Western blotting and qRT-PCR. The results indicated that, in PPRV-infected, favipiravir-treated Vero cells, the attachment, invasion, replication, and release of PPRV were significantly inhibited, as was the expression of RdRp, when compared with that in untreated PPRV-infected cells. Furthermore, in favipiravir-treated cells, the expression of JAK1 and STAT1 was downregulated, whereas that of p-STAT1 was significantly upregulated. Similarly, the expression levels of PKR, IRF9, ISG54, and MxA proteins that are associated with innate antiviral activity in host cells were also markedly increased. Moreover, with favipiravir treatment, the expression of PI3K and p-AKT and the p-AKT/AKT ratio were significantly decreased, whereas the expression of AKT was noticeably upregulated. The expression of GSK3, NF-κB p65, p-NF-κB p65, and BAD was also increased with favipiravir treatment, while the expression of CREB, p-CREB, p-GSK3, and Bcl-2 was slightly decreased. In addition, all the p-GSK3/GSK3, p-CREB/CREB, p-NF-κB/NF-κB, and p-BAD/BAD ratios were significantly reduced in favipiravir-treated cells. These results implied that the antiviral effectivity of favipiravir against PPRV is mediated by the JAK/STAT and PI3K/AKT pathways and that favipiravir has potential for use as an effective antiviral agent against PPRV.

Clinical Manifestations and Outcomes of Activated Phosphoinositide 3-Kinase δ Syndrome from the USIDNET Cohort

BACKGROUND

Activated phosphoinosidtide 3-kinase δ syndrome (APDS) is a combined primary immunodeficiency characterized by gain-of-function mutations in PIK3CD and PIK3R1. APDS demonstrates a large range of phenotypes including respiratory and herpesvirus infections, lymphadenopathy, autoimmunity, and developmental delay.

OBJECTIVE

This study describes clinical phenotypes and disease outcomes of a large APDS cohort from the USIDNET Registry.

METHODS

38 patients were enrolled in USIDNET and 2 additional patients were obtained from the Clinical Immunology division at Mount Sinai Hospital. Each patient's demographics, disease complications, genetic studies, laboratory data, therapeutic interventions, and clinical outcomes were reviewed.

RESULTS

There was a high frequency of respiratory infections (70.0% pneumonia) and herpesvirus infections (37.5%). Bronchiectasis was observed in 45.0% of patients. Lymphadenopathy was common (52.5%) and 12.5% of patients developed lymphoma. Neurological and developmental findings were common: 20.0% had developmental delay, 15.0% had seizures, and 10.0% had dysmorphic features. Asthma was more common in PIK3CD compared to PIK3R1 patients (63.6% vs 14.3%). More subjects with PIK3CD had CD3 lymphopenia compared to the PIK3R1 cohort. Seven patients underwent hematopietic stem cell transplantation. One patient died from infectious complications.

CONCLUSION

This is the first cohort comparing clinical manifestations in PIK3CD and PIK3R1 patients from the USIDNET Registry. Similar frequencies of respiratory and herpesvirus infections, lymphadenopathy, and developmental delay were observed compared to prior cohort studies. However, a higher frequency of asthma and CD3 lymphopenia in the PIK3CD cohort compared to the PIK3R1 cohort was observed.

Autophagy impairment by African swine fever virus

African swine fever is a devastating disease of domestic swine and wild boar caused by a large double-stranded DNA virus that encodes for more than 150 open reading frames. There is no licensed vaccine for the disease and the most promising current candidates are modified live viruses that have been attenuated by deletion of virulence factors. Like many viruses African swine fever virus significantly alters the host cell machinery to benefit its replication and viral genes that modify host pathways represent promising targets for development of gene deleted vaccines. Autophagy is an important cellular pathway that is involved in cellular homeostasis, innate and adaptive immunity and therefore is manipulated by a number of different viruses. Autophagy is regulated by a complex protein cascade and here we show that African swine fever virus can block formation of autophagosomes, a critical functional step of the autophagy pathway through at least two different mechanisms. Interestingly this does not require the A179L gene that has been shown to interact with Beclin-1, an important autophagy regulator.

Immunoprotective potential of Ayurvedic herb Kalmegh (Andrographis paniculata) against respiratory viral infections - LC-MS/MS and network pharmacology analysis

INTRODUCTION

Immunity boosting has emerged as a global strategy to fight the SARS-CoV-2 pandemic situation. In India, AYUSH systems of medicine have been promoted as an immune-protection strategy. Andrographis paniculata (Burm. F) Nees (AP) mentioned in Ayurveda has been widely used for treating sore throat, flu, and upper respiratory tract infections which may provide possible novel therapeutic approaches, exclusively targeting SARS-CoV-2 and its pathways.

OBJECTIVES

The present work uses liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics and combination synergy analysis based on network pharmacology to mine multimode evidence to understand the possible mechanism of action, diseases association, protein-protein interaction and major pathways involved therein.

MATERIAL AND METHODS

Metabolite profiling was performed by Agilent QTOF LC-MS/MS system. Network pharmacology analysis was performed by using functional annotation analysis based on databases like Binding DB, STRING, DAVID and KEGG for further data mining. Further combination synergy was evaluated using "neighbourhood approach" and networks were constructed through Cytoscape 3.2.1.

RESULTS

The molecules from kalmegh provides immune-protection and anti-viral response via involving different pathways, like toll-like receptor pathway, PI3/AKT pathway and MAP kinase pathways against COVID-19 infection. The KEGG analysis showed that in a vast majority of the most enriched pathways, AP were associated with viral infections and upper respiratory tract infections.

CONCLUSIONS

The results suggest a synergy between andrographolide and other molecules identified as safe and efficacious anti-inflammatory agent having effects on upper respiratory tract infections and can significantly decrease the production of cytokines and pro-inflammatory factors in viral infections.

Akt Kinase Intervenes in Flavivirus Replication by Interacting with Viral Protein NS5

Arthropod-borne flaviviruses, such as Zika virus (ZIKV), Usutu virus (USUV), and West Nile virus (WNV), are a growing cause of human illness and death around the world. Presently, no licensed antivirals to control them are available and, therefore, search for broad-spectrum antivirals, including host-directed compounds, is essential. The PI3K/Akt pathway controls essential cellular functions involved in cell metabolism and proliferation. Moreover, Akt has been found to participate in modulating replication in different viruses including the flaviviruses. In this work we studied the interaction of flavivirus NS5 polymerases with the cellular kinase Akt. In vitro NS5 phosphorylation experiments with Akt showed that flavivirus NS5 polymerases are phosphorylated and co-immunoprecipitate by Akt. Polymerase activity assays of Ala- and Glu-generated mutants for the Akt-phosphorylated residues also indicate that Glu mutants of ZIKV and USUV NS5s present a reduced primer-extension activity that was not observed in WNV mutants. Furthermore, treatment with Akt inhibitors (MK-2206, honokiol and ipatasertib) reduced USUV and ZIKV titers in cell culture but, except for honokiol, not WNV. All these findings suggest an important role for Akt in flavivirus replication although with specific differences among viruses and encourage further investigations to examine the PI3K/Akt/mTOR pathway as an antiviral potential target.

A Phenome-Wide Association Study of the Effects of Fusarium graminearum Transcription Factors on Fusarium Graminearum Virus 1 Infection

The Fusarium graminearum virus 1 (FgV1) causes noticeable phenotypic changes such as reduced mycelial growth, increase pigmentation, and reduced pathogenicity in its host fungi, Fusarium graminearum. Previous study showed that the numerous F. graminearum genes including regulatory factors were differentially expressed upon FgV1 infection, however, we have limited knowledge on the effect(s) of specific transcription factor (TF) during FgV1 infection in host fungus. Using gene-deletion mutant library of 657 putative TFs in F. graminearum, we transferred FgV1 by hyphal anastomosis to screen transcription factors that might be associated with viral replication or symptom induction. FgV1-infected TF deletion mutants were divided into three groups according to the mycelial growth phenotype compare to the FgV1-infected wild-type strain (WT-VI). The FgV1-infected TF deletion mutants in Group 1 exhibited slow or weak mycelial growth compare to that of WT-VI on complete medium at 5 dpi. In contrast, Group 3 consists of virus-infected TF deletion mutants showing faster mycelial growth and mild symptom compared to that of WT-VI. The hyphal growth of FgV1-infected TF deletion mutants in Group 2 was not significantly different from that of WT-VI. We speculated that differences of mycelial growth among the FgV1-infected TF deletion mutant groups might be related with the level of FgV1 RNA accumulations in infected host fungi. By conducting real-time quantitative reverse transcription polymerase chain reaction, we observed close association between FgV1 RNA accumulation and phenotypic differences of FgV1-infected TF deletion mutants in each group, i.e., increased and decreased dsRNA accumulation in Group 1 and Group 3, respectively. Taken together, our analysis provides an opportunity to identify host's regulator(s) of FgV1-triggered signaling and antiviral responses and helps to understand complex regulatory networks between FgV1 and F. graminearum interaction.

Heparanase, cell signaling, and viral infections

Heparanase (HPSE) is a multifunctional protein endowed with many non-enzymatic functions and a unique enzymatic activity as an endo-β-D-glucuronidase. The latter allows it to serve as a key modulator of extracellular matrix (ECM) via a well-regulated cleavage of heparan sulfate side chains of proteoglycans at cell surfaces. The cleavage and associated changes at the ECM cause release of multiple signaling molecules with important cellular and pathological functions. New and emerging data suggest that both enzymatic as well as non-enzymatic functions of HPSE are important for health and illnesses including viral infections and virally induced cancers. This review summarizes recent findings on the roles of HPSE in activation, inhibition, or bioavailability of key signaling molecules such as AKT, VEGF, MAPK-ERK, and EGFR, which are known regulators of common viral infections in immune and non-immune cell types. Altogether, our review provides a unique overview of HPSE in cell-survival signaling pathways and how they relate to viral infections.

Examining the effector mechanisms of Xuebijing injection on COVID-19 based on network pharmacology

Background

Chinese medicine Xuebijing (XBJ) has proven to be effective in the treatment of mild coronavirus disease 2019 (COVID-19) cases. But the bioactive compounds and potential mechanisms of XBJ for COVID-19 prevention and treatment are unclear. This study aimed to examine the potential effector mechanisms of XBJ on COVID-19 based on network pharmacology.

Methods

We searched Chinese and international papers to obtain the active ingredients of XBJ. Then, we compiled COVID-19 disease targets from the GeneCards gene database and via literature searches. Next, we used the SwissTargetPrediction database to predict XBJ’s effector targets and map them to the abovementioned COVID-19 disease targets in order to obtain potential therapeutic targets of XBJ. Cytoscape software version 3.7.0 was used to construct a “XBJ active-compound-potential-effector target” network and protein-protein interaction (PPI) network, and then to carry out network topology analysis of potential targets. We used the ClueGO and CluePedia plugins in Cytoscape to conduct gene ontology (GO) biological process (BP) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis of XBJ’s effector targets. We used AutoDock vina and PyMOL software for molecular docking.

Results

We obtained 144 potential COVID-19 effector targets of XBJ. Fourteen of these targets-glyceraldehyde 3-phosphate dehydrogenase (GAPDH), albumin (ALB), tumor necrosis factor (TNF), epidermal growth factor receptor (EGFR), mitogen-activated protein kinase 1 (MAPK1), Caspase-3 (CASP3), signal transducer and activator of transcription 3 (STAT3), MAPK8, prostaglandin-endoperoxide synthase 2 (PTGS2), JUN, interleukin-2 (IL-2), estrogen receptor 1 (ESR1), and MAPK14 had degree values > 40 and therefore could be considered key targets. They participated in extracellular signal–regulated kinase 1 and 2 (ERK1, ERK2) cascade, the T-cell receptor signaling pathway, activation of MAPK activity, cellular response to lipopolysaccharide, and other inflammation- and immune-related BPs. XBJ exerted its therapeutic effects through the renin-angiotensin system (RAS), nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), MAPK, phosphatidylinositol-4, 5-bisphosphate 3-kinase (PI3K)-protein kinase B (Akt)-vascular endothelial growth factor (VEGF), toll-like receptor (TLR), TNF, and inflammatory-mediator regulation of transient receptor potential (TRP) signaling pathways to ultimately construct a “drug-ingredient-target-pathway” effector network. The molecular docking results showed that the core 18 effective ingredients had a docking score of less than − 4.0 with those top 10 targets.

Conclusion

The active ingredients of XBJ regulated different genes, acted on different pathways, and synergistically produced anti-inflammatory and immune-regulatory effects, which fully demonstrated the synergistic effects of different components on multiple targets and pathways. Our study demonstrated that key ingredients and their targets have potential binding activity, the existing studies on the pharmacological mechanisms of XBJ in the treatment of sepsis and severe pneumonia, could explain the effector mechanism of XBJ in COVID-19 treatment, and those provided a preliminary examination of the potential effector mechanism in this disease.

Phosphatidylinositol-3-kinase-Akt pathway in negative-stranded RNA virus infection: a minireview

The PI3K/Akt signalling pathway is a crucial signalling cascade that regulates transcription, protein translation, cell growth, proliferation, cell survival, and metabolism. During viral infection, viruses exploit a variety of cellular pathways, including the well-known PI3K/Akt signalling pathway. Conversely, cells rely on this pathway to stimulate an antiviral response. The PI3K/Akt pathway is manipulated by a number of viruses, including DNA and RNA viruses and retroviruses. The aim of this review is to provide up-to-date information about the role of the PI3K-Akt pathway in infection with members of five different families of negative-sense ssRNA viruses. This pathway is hijacked for viral entry, regulation of endocytosis, suppression of premature apoptosis, viral protein expression, and replication. Although less common, the PI3K/Akt pathway can be downregulated as an immunomodulatory strategy or as a mechanism for inducing autophagy. Moreover, the cell activates this pathway as an antiviral strategy for interferon and cytokine production, among other strategies. Here, we present new data concerning the role of this pathway in infection with the paramyxovirus Newcastle disease virus (NDV). Our data seem to indicate that NDV uses the PI3K/Akt pathway to delay cell death and increase cell survival as a means of improving its replication. The interference of negative-sense ssRNA viruses with this essential pathway might have implications for the development of antiviral therapies.

Activation of the PI3K-AKT Pathway by Old World Alphaviruses

Alphaviruses can infect a broad range of vertebrate hosts, including birds, horses, primates, and humans, in which infection can lead to rash, fever, encephalitis, and arthralgia or arthritis. They are most often transmitted by mosquitoes in which they establish persistent, asymptomatic infections. Currently, there are no vaccines or antiviral therapies for any alphavirus. Several Old World alphaviruses, including Semliki Forest virus, Ross River virus and chikungunya virus, activate or hyperactivate the phosphatidylinositol-3-kinase (PI3K)-AKT pathway in vertebrate cells, potentially influencing many cellular processes, including survival, proliferation, metabolism and autophagy. Inhibition of PI3K or AKT inhibits replication of several alphaviruses either in vitro or in vivo, indicating the importance for viral replication. In this review, we discuss what is known about the mechanism(s) of activation of the pathway during infection and describe those effects of PI3K-AKT activation which could be of advantage to the alphaviruses. Such knowledge may be useful for the identification and development of therapies.

An off-target effect of BX795 blocks herpes simplex virus type 1 infection of the eye

Herpes simplex virus type 1 (HSV-1) causes recurrent mucocutaneous lesions in the eye that may advance to corneal blindness. Nucleoside analogs exemplified by acyclovir (ACV) form the primary class of antiherpetic drugs, but this class suffers limitations due to the emergence of viral resistance and other side effects. While studying the molecular basis of ocular HSV-1 infection, we observed that BX795, a commonly used inhibitor of TANK-binding kinase 1 (TBK1), strongly suppressed infection by multiple strains of HSV-1 in transformed and primary human cells, cultured human and animal corneas, and a murine model of ocular infection. Our investigations revealed that the antiviral activity of BX795 relies on targeting Akt phosphorylation in infected cells, leading to the blockage of viral protein synthesis. This small-molecule inhibitor, which was also effective against an ACV-resistant HSV-1 strain, shows promise as an alternative to existing drugs and as an effective topical therapy for ocular herpes infection. Collectively, our results obtained using multiple infection models and virus strains establish BX795 as a promising lead compound for broad-spectrum antiviral applications in humans.

Viral Hormones: Expanding Dimensions in Endocrinology

Viruses have developed different mechanisms to manipulate their hosts, including the process of viral mimicry in which viruses express important host proteins. Until recently, examples of viral mimicry were limited to mimics of growth factors and immunomodulatory proteins. Using a comprehensive bioinformatics approach, we have shown that viruses possess the DNA/RNA with potential to encode 16 different peptides with high sequence similarity to human peptide hormones and metabolically important regulatory proteins. We have characterized one of these families, the viral insulin/IGF-1-like peptides (VILPs), which we identified in four members of the Iridoviridae family. VILPs can bind to human insulin and IGF-1 receptors and stimulate classic postreceptor signaling pathways. Moreover, VILPs can stimulate glucose uptake in vitro and in vivo and stimulate DNA synthesis. DNA sequences of some VILP-carrying viruses have been identified in the human enteric virome. In addition to VILPs, sequences with homology to 15 other peptide hormones or cytokines can be identified in viral DNA/RNA sequences, some with a very high identity to hormones. Recent data by others has identified a peptide that resembles and mimics α-melanocyte-stimulating hormone's anti-inflammatory effects in in vitro and in vivo models. Taken together, these studies reveal novel mechanisms of viral and bacterial pathogenesis in which the microbe can directly target or mimic the host endocrine system. These findings also introduce the concept of a system of microbial hormones that provides new insights into the evolution of peptide hormones, as well as potential new roles of microbial hormones in health and disease.

Differentially Expressed MiRNAs and tRNA Genes Affect Host Homeostasis During Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Infections in Young Pigs

Background: Porcine respiratory and reproductive syndrome virus (PRRSV) is a single-stranded RNA virus member that infects pigs and causes losses to the commercial industry reaching upward of a billion dollars annually in combined direct and indirect costs. The virus can be separated into etiologies that contain multiple heterologous low and highly pathogenic strains. Recently, the United States has begun to see an increase in heterologous type 2 PRRSV strains of higher virulence (HP-PRRSV). The high pathogenicity of these strains can drastically alter host immune responses and the ability of the animal to maintain homeostasis. Because the loss of host homeostasis can denote underlying changes in gene and regulatory element expression profiles, the study aimed to examine the effect PRRSV infections has on miRNA and tRNA expression and the roles they play in host tolerance or susceptibility.

Results: Using transcriptomic analysis of whole blood taken from control and infected pigs at several time points (1, 3, 8 dpi), the analysis returned a total of 149 statistically significant (FDR ⫹ 0.15) miRNAs (n = 89) and tRNAs (n = 60) that were evaluated for possible pro- and anti-viral effects. The tRNA differential expression increased in both magnitude and count as dpi increased, with no statistically significant expression at 1 dpi, but increases at 3 and 8 dpi. The most abundant tRNA amino acid at 3 dpi was alanine, while glycine was the most abundant at 8 dpi. For the miRNAs, focus was put on upregulation that can inhibit gene expression. These results yielded candidates with potential anti- and pro-viral actions such as Ssc-miR-125b, which is predicted to limit PRRSV viral levels, and Ssc-miR-145-5p shown to cause alternative macrophage priming. The results also showed that both the tRNAs and miRNAs displayed expression patterns.

Conclusions: The results indicated that the HP-PRRSV infection affects host homeostasis through changes in miRNA and tRNA expression and their subsequent gene interactions that target and influence the function of host immune, metabolic, and structural pathways.

Glycolysis Is an Intrinsic Factor for Optimal Replication of a Norovirus

Viruses depend on the host cells they infect to provide the machinery and substrates for replication. Host cells are highly dynamic systems that can alter their intracellular environment and metabolic behavior, which may be helpful or inhibitory for an infecting virus. In this study, we show that macrophages, a target cell of murine norovirus (MNV), increase glycolysis upon viral infection, which is important for early steps in MNV infection. Human noroviruses (hNoV) are a major cause of gastroenteritis globally, causing enormous morbidity and economic burden. Currently, no effective antivirals or vaccines exist for hNoV, mainly due to the lack of high-efficiency in vitro culture models for their study. Thus, insights gained from the MNV model may reveal aspects of host cell metabolism that can be targeted for improving hNoV cell culture systems and for developing effective antiviral therapies.

The metabolic pathways of central carbon metabolism, glycolysis and oxidative phosphorylation (OXPHOS), are important host factors that determine the outcome of viral infections and can be manipulated by some viruses to favor infection. However, mechanisms of metabolic modulation and their effects on viral replication vary widely. Herein, we present the first metabolomics and energetic profiling of norovirus-infected cells, which revealed increases in glycolysis, OXPHOS, and the pentose phosphate pathway (PPP) during murine norovirus (MNV) infection. Inhibiting glycolysis with 2-deoxyglucose (2DG) in macrophages revealed that glycolysis is an important factor for optimal MNV infection, while inhibiting the PPP and OXPHOS showed a relatively minor impact of these pathways on MNV infection. 2DG affected an early stage in the viral life cycle after viral uptake and capsid uncoating, leading to decreased viral protein production and viral RNA. The requirement of glycolysis was specific for MNV (but not astrovirus) infection, independent of the type I interferon antiviral response, and unlikely to be due to a lack of host cell nucleotide synthesis. MNV infection increased activation of the protein kinase Akt, but not AMP-activated protein kinase (AMPK), two master regulators of cellular metabolism, implicating Akt signaling in upregulating host metabolism during norovirus infection. In conclusion, our findings suggest that the metabolic state of target cells is an intrinsic host factor that determines the extent of norovirus replication and implicates glycolysis as a virulence determinant. They further point to cellular metabolism as a novel therapeutic target for norovirus infections and improvements in current human norovirus culture systems.

How Viral and Intracellular Bacterial Pathogens Reprogram the Metabolism of Host Cells to Allow Their Intracellular Replication

Viruses and intracellular bacterial pathogens (IBPs) have in common the need of suitable host cells for efficient replication and proliferation during infection. In human infections, the cell types which both groups of pathogens are using as hosts are indeed quite similar and include phagocytic immune cells, especially monocytes/macrophages (MOs/MPs) and dendritic cells (DCs), as well as nonprofessional phagocytes, like epithelial cells, fibroblasts and endothelial cells. These terminally differentiated cells are normally in a metabolically quiescent state when they are encountered by these pathogens during infection. This metabolic state of the host cells does not meet the extensive need for nutrients required for efficient intracellular replication of viruses and especially IBPs which, in contrast to the viral pathogens, have to perform their own specific intracellular metabolism to survive and efficiently replicate in their host cell niches. For this goal, viruses and IBPs have to reprogram the host cell metabolism in a pathogen-specific manner to increase the supply of nutrients, energy, and metabolites which have to be provided to the pathogen to allow its replication. In viral infections, this appears to be often achieved by the interaction of specific viral factors with central metabolic regulators, including oncogenes and tumor suppressors, or by the introduction of virus-specific oncogenes. Less is so far known on the mechanisms leading to metabolic reprogramming of the host cell by IBPs. However, the still scant data suggest that similar mechanisms may also determine the reprogramming of the host cell metabolism in IBP infections. In this review, we summarize and compare the present knowledge on this important, yet still poorly understood aspect of pathogenesis of human viral and especially IBP infections.

Recruitment of Vps34 PI3K and enrichment of PI3P phosphoinositide in the viral replication compartment is crucial for replication of a positive-strand RNA virus

Tombusviruses depend on subversions of multiple host factors and retarget cellular pathways to support viral replication. In this work, we demonstrate that tomato bushy stunt virus (TBSV) and the closely-related carnation Italian ringspot virus (CIRV) recruit the cellular Vps34 phosphatidylinositol 3-kinase (PI3K) into the large viral replication compartment. The kinase function of Vps34 is critical for TBSV replication, suggesting that PI(3)P phosphoinositide is utilized by TBSV for building of the replication compartment. We also observed increased expression of Vps34 and the higher abundance of PI(3)P in the presence of the tombusviral replication proteins, which likely leads to more efficient tombusvirus replication. Accordingly, overexpression of PI(3)P phosphatase in yeast or plants inhibited TBSV replication on the peroxisomal membranes and CIRV replication on the mitochondrial membranes. Moreover, the purified PI(3)P phosphatase reduced TBSV replicase assembly in a cell-free system. Detection of PI(3)P with antibody or a bioprobe revealed the enrichment of PI(3)P in the replication compartment. Vps34 is directly recruited into the replication compartment through interaction with p33 replication protein. Gene deletion analysis in surrogate yeast host unraveled that TBSV replication requires the vesicle transport function of Vps34. In the absence of Vps34, TBSV cannot efficiently recruit the Rab5-positive early endosomes, which provide PE-rich membranes for membrane biogenesis of the TBSV replication compartment. We found that Vps34 and PI(3)P needed for the stability of the p33 replication protein, which is degraded by the 26S proteasome when PI(3)P abundance was decreased by an inhibitor of Vps34. In summary, Vps34 and PI(3)P are needed for providing the optimal microenvironment for the replication of the peroxisomal TBSV and the mitochondrial CIRV.

Replication of RNA viruses infecting various eukaryotic organisms is the central step in the infection process that leads to generation of progeny viruses. The replication process requires the assembly of numerous viral replicase complexes within the large replication compartment, whose formation is not well understood. Using tombusviruses and the model host yeast, the authors discovered that a highly conserved cellular lipid kinase, Vps34 phosphatidylinositol 3-kinase (PI3K), is critical for the formation of the viral replication compartment. Expression of PI3K mutants and the PI(3)P phosphatase revealed that the PI(3)P phosphoinositide produced by Vps34 is crucial for tombusvirus replication. Tombusviruses co-opt Vps34 through interaction with the viral replication protein into the replication compartment. In vitro reconstitution of the tombusvirus replicase revealed the need for Vps34 and PI(3)P for the full-activity of the viral replicase. Chemical inhibition of Vps34 in yeast or plants showed that PI(3)P is important for the replication of several plant viruses within the Tombusviridae family and the insect-infecting Nodamuravirus. These results open up the possibility that the cellular Vps34 PI3K could be a target for new antiviral strategies.

Marek's Disease Virus Activates the PI3K/Akt Pathway Through Interaction of Its Protein Meq With the P85 Subunit of PI3K to Promote Viral Replication

It is known that viruses can active the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in host cells to support cell survival and viral replication; however, the role of PI3K/Akt signaling in the pathogenic mechanisms induced by Marek’s disease virus (MDV) which causes a neoplastic Marek’s disease in poultry, remains unknown. In this study, we showed that MDV activated the PI3K/Akt pathway in chicken embryo fibroblasts (CEFs) at the early phase of infection, whereas treatment with a PI3K inhibitor LY294002 prior to MDV infection decreased viral replication and DNA synthesis. Flow cytometry analysis showed that inhibition of the PI3K/Akt pathway could significantly increase apoptosis in MDV-infected host cells, indicating that activation of PI3K/Akt signaling could facilitate viral replication through support of cell survival during infection. Evaluation of the underlying molecular mechanism by co-immunoprecipitation and laser confocal microscopy revealed that a viral protein Meq interacted with both p85α and p85β regulatory subunits of PI3K and could induce PI3K/Akt signaling in Meq-overexpressing chicken fibroblasts. Our results showed, for the first time, that MDV activated PI3K/Akt signaling in host cells through interaction of its Meq protein with the regulatory p85 subunit of PI3K to delay cell apoptosis and promote viral replication. This study provides clues for further studies of the molecular mechanisms underlying MDV infection and pathogenicity for the host.

Herpesviruses in the Activated Phosphatidylinositol-3-Kinase-δ Syndrome

The phosphatidylinositol-3-kinase (PI3K)/Akt pathway is important for multiple stages of herpesvirus replication including virus entry, replication, latency, and reactivation. Recently, patients with gain-of-function mutations in the p110δ-catalytic subunit of PI3K or in the p85-regulatory subunit of PI3K have been reported. These patients have constitutively active PI3K with hyperactivation of Akt. They present with lymphoproliferation and often have infections, particularly recurrent respiratory infections and/or severe virus infections. The most frequent virus infections are due to Epstein-Barr virus (EBV) and cytomegalovirus (CMV); patients often present with persistent EBV and/or CMV viremia, EBV lymphoproliferative disease, or CMV lymphadenitis. No patients have been reported with CMV pneumonia, colitis, or retinitis. Other herpesvirus infections have included herpes simplex pneumonia, recurrent zoster, and varicella after vaccination with the varicella vaccine. Additional viral infections have included adenovirus viremia, severe warts, and extensive Molluscum contagiosum virus infection. The increased susceptibility to virus infections in these patients is likely due to a reduced number of long-lived memory CD8 T cells and an increased number of terminally differentiated effector CD8 T cells.