Classical swine fever virus non-structural protein 5B hijacks host METTL14-mediated m6A modification to counteract host antiviral immune response.

Classical Swine Fever (CSF), caused by the Classical Swine Fever Virus (CSFV), inflicts significant economic losses on the global pig industry. A key factor in the challenge of eradicating this virus is its ability to evade the host's innate immune response, leading to persistent infections. In our study, we elucidate the molecular mechanism through which CSFV exploits m6A modifications to circumvent host immune surveillance, thus facilitating its proliferation. We initially discovered that m6A modifications were elevated both in vivo and in vitro upon CSFV infection, particularly noting an increase in the expression of the methyltransferase METTL14. CSFV non-structural protein 5B was found to hijack HRD1, the E3 ubiquitin ligase for METTL14, preventing METTL14 degradation. MeRIP-seq analysis further revealed that METTL14 specifically targeted and methylated TLRs, notably TLR4. METTL14-mediated regulation of TLR4 degradation, facilitated by YTHDF2, led to the accelerated mRNA decay of TLR4. Consequently, TLR4-mediated NF-κB signaling, a crucial component of the innate immune response, is suppressed by CSFV. Collectively, these data effectively highlight the viral evasion tactics, shedding light on potential antiviral strategies targeting METTL14 to curb CSFV infection.

Two novel compounds inhibit Flavivirus infection in vitro and in vivo by targeting lipid metabolism.

Flavivirus infection capitalizes on cellular lipid metabolism to remodel the cellular intima, creating a specialized lipid environment conducive to viral replication, assembly, and release. The Japanese encephalitis virus (JEV), a member of the Flavivirus genus, is responsible for significant morbidity and mortality in both humans and animals. Currently, there are no effective antiviral drugs available to combat JEV infection. In this study, we embarked on a quest to identify anti-JEV compounds within a lipid compound library. Our research led to the discovery of two novel compounds, isobavachalcone (IBC) and corosolic acid (CA), which exhibit dose-dependent inhibition of JEV proliferation. Time-of-addition assays indicated that IBC and CA predominantly target the late stage of the viral replication cycle. Mechanistically, JEV nonstructural proteins 1 and 2A (NS1 and NS2A) impede 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) activation by obstructing the liver kinase B1 (LKB1)-AMPK interaction, resulting in decreased p-AMPK expression and a consequent upsurge in lipid synthesis. In contrast, IBC and CA may stimulate AMPK by binding to its active allosteric site, thereby inhibiting lipid synthesis essential for JEV replication and ultimately curtailing viral infection. Most importantly, in vivo experiments demonstrated that IBC and CA protected mice from JEV-induced mortality, significantly reducing viral loads in the brain and mitigating histopathological alterations. Overall, IBC and CA demonstrate significant potential as effective anti-JEV agents by precisely targeting AMPK-associated signaling pathways. These findings open new therapeutic avenues for addressing infections caused by Flaviviruses. IMPORTANCE: This study is the inaugural utilization of a lipid compound library in antiviral drug screening. Two lipid compounds, isobavachalcone (IBC) and corosolic acid (CA), emerged from the screening, exhibiting substantial inhibitory effects on the Japanese encephalitis virus (JEV) proliferation in vitro. In vivo experiments underscored their efficacy, with IBC and CA reducing viral loads in the brain and mitigating JEV-induced histopathological changes, effectively shielding mice from fatal JEV infection. Intriguingly, IBC and CA may activate 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) by binding to its active site, curtailing the synthesis of lipid substances, and thus suppressing JEV proliferation. This indicates AMPK as a potential antiviral target. Remarkably, IBC and CA demonstrated suppression of multiple viruses, including Flaviviruses (JEV and Zika virus), porcine herpesvirus (pseudorabies virus), and coronaviruses (porcine deltacoronavirus and porcine epidemic diarrhea virus), suggesting their potential as broad-spectrum antiviral agents. These findings shed new light on the potential applications of these compounds in antiviral research.

Chemerin and apelin are positively correlated with inflammation in obese type 2 diabetic patients.

BACKGROUND: As two novel adipocytokines, chemerin and apelin play a key role in the pathological process of insulin resistance (IR), glucose metabolism and obesity, researchers have found that the levels of chemerin and apelin changed significantly in type 2 diabetic patients with obesity, however, the underlying mechanism involved remains unclear. The aim of this study was to investigate whether chemerin and apelin play an important role in the pathophysiologic proceeding of diabetes. METHODS: This study enrolled 81 newly diagnosed obese type 2 diabetes mellitus (T2DM) patients (T2DM group, n = 81). All the patients were randomly assigned to DM1 group treated with metformin (n = 41) and DM2 group treated with pioglitazone (n = 40). After hypoglycemic agents treatment, patients under better blood glucose control were chosen to be given antioxidant treatment. Another 79 subjects without T2DM were recruited as normal control group (NC group), including 40 subjects (NC1 group) with normal body mass index (BMI) and 39 obese subjects (NC2 group). Levels of chemerin, apelin, BMI, tumor necrosis factor-α (TNF-α), homeostasis model assessment of IR (HOMA-IR) and 8-isoprotaglandim F2α (8-iso-PGF2α) were examined at baseline and post-treatment. The relationship between chemerin, apelin and BMI, TNF-α, HOMA-IR, 8-iso-PGF2α was analyzed. RESULTS: The baseline levels of chemerin, apelin, TNF-α, HOMA-IR and 8-iso-PGF2α in T2DM group were significantly higher than normal control group (P < 0.001). All indices mentioned above were significantly decreased after treatment (P < 0.05). In T2DM patients treated with pioglitazone, indices mentioned above except for HOMA-IR, were decreased significantly compared with patients treated with metformin (P < 0.05). After antioxidant treatment using lipoic acid, levels of chemerin, apelin, TNF-α and 8-iso-PGF2α were further significantly decreased (P < 0.05). Correlation analysis showed that the levels of chemerin and apelin correlated positively with BMI, TNF-α, HOMA-IR and 8-iso-PGF2α before and after treatment with hypoglycemic agents (P < 0.01). The levels of chemerin and apelin also had positive correlation with TNF-α and 8-iso-PGF2α after antioxidant treatment (P < 0.05). CONCLUSIONS: The levels of chemerin and apelin in obese T2DM patients are closely related to IR. The increased levels may be a result of compensatory response to IR, and also may be the causative factor of IR. The levels of chemerin and apelin correlate closely with oxidative stress and inflammation. The two adipokines may be inflammatory factors playing important roles in the initiation and development of obese T2DM. Chemerin and apelin are related to the pathophysiology of IR, oxidative stress and inflammation.