DEF Cell-Derived Exosomal miR-148a-5p Promotes DTMUV Replication by Negative Regulating TLR3 Expression

Development of a Rapid Visual Detection Assay for Duck Tembusu Virus Using RT-LAMP-CRISPR/Cas12a

Duck Tembusu virus (DTMUV) is an emerging flavivirus that has inflicted significant economic losses on China's poultry industry. Rapid and accurate detection of DTMUV is crucial for effective prevention and control measures. In this study, we developed a novel, rapid visual detection assay that combines reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) with the CRISPR/Cas12a system for on-site detection of DTMUV. Our results demonstrate that this assay can sensitively and specifically detect the specific DNA plasmids containing the DTMUV NS3 gene within 100 min, with a limit of detection as low as 19.3 copies/μL. We successfully applied the RT-LAMP-CRISPR/Cas12a assay to diagnose DTMUV in eight duck embryos and 11 chicken embryonic fibroblast samples, and the results obtained with direct visualization by the naked eye were consistent with those obtained using real-time RT-PCR. Overall, our RT-LAMP-CRISPR/Cas12a assay is a reliable, sensitive, specific, and user-friendly method that holds great promise for early on-site detection of DTMUV in clinical samples, facilitating timely interventions and improved disease management in the poultry industry.

Advancements in Research on Duck Tembusu Virus Infections

Duck Tembusu Virus (DTMUV) is a pathogen of the Flaviviridae family that causes infections in poultry, leading to significant economic losses in the duck farming industry in recent years. Ducks infected with this virus exhibit clinical symptoms such as decreased egg production and neurological disorders, along with serious consequences such as ovarian hemorrhage, organ enlargement, and necrosis. Variations in morbidity and mortality rates exist across different age groups of ducks. It is worth noting that DTMUV is not limited to ducks alone; it can also spread to other poultry such as chickens and geese, and antibodies related to DTMUV have even been found in duck farm workers, suggesting a potential risk of zoonotic transmission. This article provides a detailed overview of DTMUV research, delving into its genomic characteristics, vaccines, and the interplay with host immune responses. These in-depth research findings contribute to a more comprehensive understanding of the virus's transmission mechanism and pathogenic process, offering crucial scientific support for epidemic prevention and control.

Multiplex digital PCR: a superior technique to qPCR for the simultaneous detection of duck Tembusu virus, duck circovirus, and new duck reovirus

Duck Tembusu virus (DTMUV), duck circovirus (DuCV), and new duck reovirus (NDRV) have seriously hindered the development of the poultry industry in China. To detect the three pathogens simultaneously, a multiplex digital PCR (dPCR) was developed and compared with multiplex qPCR in this study. The multiplex dPCR was able to specifically detect DTMUV, DuCV, and NDRV but not amplify Muscovy duck reovirus (MDRV), Muscovy duck parvovirus (MDPV), goose parvovirus (GPV), H4 avian influenza virus (H4 AIV), H6 avian influenza virus (H6 AIV), and Newcastle disease virus (NDV). The standard curves showed excellent linearity in multiplex dPCR and qPCR and were positively correlated. The sensitivity results showed that the lowest detection limit of multiplex dPCR was 1.3 copies/μL, which was 10 times higher than that of multiplex qPCR. The reproducibility results showed that the intra- and interassay coefficients of variation were 0.06-1.94%. A total of 173 clinical samples were tested to assess the usefulness of the method; the positive detection rates for DTMUV, DuCV, and NDRV were 18.5, 29.5, and 14.5%, respectively, which were approximately 4% higher than those of multiplex qPCR, and the kappa values for the clinical detection results of multiplex dPCR and qPCR were 0.85, 0.89, and 0.86, indicating that the two methods were in excellent agreement.

RNF123 Mediates Ubiquitination and Degradation of SOCS1 To Regulate Type I Interferon Production during Duck Tembusu Virus Infection

Many RING domain E3 ubiquitin ligases play critical roles in fine-tuning the innate immune response, yet little is known about their regulatory role in flavivirus-induced innate immunity. In previous studies, we found that the suppressor of cytokine signaling 1 (SOCS1) protein mainly undergoes lysine 48 (K48)-linked ubiquitination. However, the E3 ubiquitin ligase that promotes the K48-linked ubiquitination of SOCS1 is unknown. In the present study, we found that RING finger protein 123 (RNF123) binds to the SH2 domain of SOCS1 through its RING domain and facilitates the K48-linked ubiquitination of the K114 and K137 residues of SOCS1. Further studies found that RNF123 promoted the proteasomal degradation of SOCS1 and promoted Toll-like receptor 3 (TLR3)- and interferon (IFN) regulatory factor 7 (IRF7)-mediated type I IFN production during duck Tembusu virus (DTMUV) infection through SOCS1, ultimately inhibiting DTMUV replication. Overall, these findings demonstrate a novel mechanism by which RNF123 regulates type I IFN signaling during DTMUV infection by targeting SOCS1 degradation. IMPORTANCE In recent years, posttranslational modification (PTM) has gradually become a research hot spot in the field of innate immunity regulation, and ubiquitination is one of the critical PTMs. DTMUV has seriously endangered the development of the waterfowl industry in Southeast Asian countries since its outbreak in 2009. Previous studies have shown that SOCS1 is modified by K48-linked ubiquitination during DTMUV infection, but E3 ubiquitin ligase catalyzing the ubiquitination of SOCS1 has not been reported. Here, we identify for the first time that RNF123 acts as an E3 ubiquitin ligase that regulates TLR3- and IRF7-induced type I IFN signaling during DTMUV infection by targeting the K48-linked ubiquitination of the K114 and K137 residues of SOCS1 and the proteasomal degradation of SOCS1.

Duck hepatitis A virus type 1 transmission by exosomes establishes a productive infection in vivo and in vitro

Duck hepatitis A virus type 1 (DHAV-1) infection causes an acute and highly fatal disease in young ducklings. Exosomes are nano-sized small extracellular vesicles secreted by various cells, which participate in intercellular communication and play a key role in the physiological and pathological processes. However, the role of exosomes in DHAV-1 transmission remains unknown. In this study, through RT-PCR, WB analysis and TEM observation, the complete DHAV-1 genomic RNA, partial viral proteins, and virions were respectively identified in the exosomes derived from DHAV-1-infected duck embryo fibroblasts (DEFs). The productive DHAV-1 infection was transmitted by exosomes in DEFs, duck embryos, and ducklings, and high titers of neutralizing antibodies completely blocked DHAV-1 infection but did not significantly neutralize exosome-mediated DHAV-1 infection. To the best of our knowledge, this is the first report that exosome-mediated DHAV-1 infection was resistant to antibody neutralization in vivo and in vitro, which might be an immune evasion mechanism of DHAV-1.

Photobiomodulation promotes spinal cord injury repair by inhibiting macrophage polarization through lncRNA TUG1-miR-1192/TLR3 axis

BACKGROUND

Secondary spinal cord injury (SCI) often causes the aggravation of inflammatory reaction and nerve injury, which affects the recovery of motor function. Bone-marrow-derived macrophages (BMDMs) were recruited to the injured area after SCI, and the M1 polarization is the key process for inducing inflammatory response and neuronal apoptosis. We previously showed that photobiomodulation (PBM) can inhibit the polarization of M1 phenotype of BMDMs and reduce inflammation, but the underlying mechanisms are unclear. The purpose of this study is to explore the potential target and mechanism of PBM in treating SCI.

METHODS

Transcriptome sequencing and bioinformatics analysis showed that long noncoding RNA taurine upregulated gene 1 (lncRNA TUG1) was a potential target of PBM. The expression and specific mechanism of lncRNA TUG1 were detected by qPCR, immunofluorescence, flow cytometry, western blotting, fluorescence in situ hybridization, and luciferase assay. The Basso mouse scale (BMS) and gait analysis were used to evaluate the recovery of motor function in mice.

RESULTS

Results showed that lncRNA TUG1 may be a potential target of PBM, regulating the polarization of BMDMs, inflammatory response, and the axial growth of DRG. Mechanistically, TUG1 competed with TLR3 for binding to miR-1192 and attenuated the inhibitory effect of miR-1192 on TLR3. This effect protected TLR3 from degradation, enabling the high expression of TLR3, which promoted the activation of downstream NF-κB signal and the release of inflammatory cytokines. In vivo, PBM treatment could reduce the expression of TUG1, TLR3, and inflammatory cytokines and promoted nerve survival and motor function recovery in SCI mice.

CONCLUSIONS

Our study clarified that the lncRNA TUG1/miR-1192/TLR3 axis is an important pathway for PBM to inhibit M1 macrophage polarization and inflammation, which provides theoretical support for its clinical application in patients with SCI.

miR-155-1 as a positive factor for novel duck reovirus replication by regulating SOCS5-mediated interferons

Diseases caused by novel duck reovirus (NDRV) have brought considerable economic losses to the poultry industry. MicroRNAs (miRNAs) have an impact on virus replication and antiviral immunity. However, the miRNA profile upon NDRV infection in duck embryo fibroblasts (DEFs) remains to be discovered. In this study, small RNA (sRNA) sequencing was performed to decipher the cellular miRNA response to NDRV infection. Based on 26 differentially expressed miRNAs (19 upregulated and 7 downregulated miRNAs) obtained from sequencing data and their target genes predicted by software, GO and KEGG analyses were performed to elucidate the functions of miRNAs in NDRV invasion, replication, and virus spread. "FoxO signaling pathway", "autophagy", and "Toll-like receptor signaling pathway" might participate in NDRV replication as revealed by KEGG enrichment analysis. The miR-155-1 sequence was found to be identical to rno-miR-155-5p and was sharply increased with the progression of NDRV infection. Moreover, NDRV-induced miR-155-1 could act as a positive factor for virus replication in DEFs, which inhibited type I interferon (IFN-I) production. Luciferase assay confirmed that miR-155-1 disturbed the abundance of suppressor of cytokine signaling (SOCS) 5 by targeting 3'-UTR. SOCS5, which is linked to increased IRF7 expression, restricts IFN expression and promotes NDRV replication in DEFs. Therefore, this study proposed that miR-155-1 was used by NDRV to restrict SOCS5 expression, attenuating the production of IFN-I and creating a favorable environment for virus replication.

Duck Tembusu Virus Inhibits Type I Interferon Production through the JOSD1-SOCS1-IRF7 Negative-Feedback Regulation Pathway

Duck Tembusu virus (DTMUV) is an emerging pathogenic flavivirus that mainly causes a decrease in egg production in infected waterfowl. Similar to other members of the Flaviviridae family, it can proliferate in most mammalian cells and may also pose a potential threat to nonavian animals. In previous studies, we found that DTMUV infection can upregulate suppressor of cytokine signaling 1 (SOCS1) to inhibit type I interferon (IFN) production and promote virus replication, but the specific mechanism is unclear. Furthermore, little is known about the regulatory role of ubiquitination during flavivirus infection. In this study, we found that activation of Toll-like receptor 3 (TLR3) signaling rather than type I IFN stimulation led to the upregulation of SOCS1 during DTMUV infection. Further studies revealed that JOSD1 stabilized SOCS1 expression by binding to the SH2 domain of SOCS1 and mediating its deubiquitination. In addition, JOSD1 also inhibited type I IFN production through SOCS1. Finally, SOCS1 acts as an E3 ubiquitin ligase that binds to IFN regulatory factor 7 (IRF7) through its SH2 domain and mediates K48-linked ubiquitination and proteasomal degradation of IRF7, ultimately inhibiting type I IFN production mediated by IRF7 and promoting viral proliferation. These results will enrich and deepen our understanding of the mechanism by which DTMUV antagonizes the host interferon system. IMPORTANCE DTMUV is a newly discovered flavivirus that seriously harms the poultry industry. In recent years, there have been numerous studies on the involvement of ubiquitination in the regulation of innate immunity. However, little is known about the involvement of ubiquitination in the regulation of flavivirus-induced type I IFN signaling. In this study, we found that SOCS1 was induced by TLR3 signaling during DTMUV infection. Furthermore, we found for the first time that duck SOCS1 protein was also modified by K48-linked polyubiquitination, whereas our previous study found that SOCS1 was upregulated during DTMUV infection. Further studies showed that JOSD1 stabilized SOCS1 expression by mediating the deubiquitination of SOCS1. While SOCS1 acts as a negative regulator of cytokines, we found that DTMUV utilized SOCS1 to mediate the ubiquitination and proteasomal degradation of IRF7 and ultimately inhibit type I IFN production, thereby promoting its proliferation.

Virofree, an Herbal Medicine-Based Formula, Interrupts the Viral Infection of Delta and Omicron Variants of SARS-CoV-2

Coronavirus disease 2019 (COVID-19) remains a threat with the emergence of new variants, especially Delta and Omicron, without specific effective therapeutic drugs. The infection causes dysregulation of the immune system with a cytokine storm that eventually leads to fatal acute respiratory distress syndrome (ARDS) and further irreversible pulmonary fibrosis. Therefore, the promising way to inhibit infection is to disrupt the binding and fusion between the viral spike and the host ACE2 receptor. A transcriptome-based drug screening platform has been developed for COVID-19 to explore the possibility and potential of the long-established drugs or herbal medicines to reverse the unique genetic signature of COVID-19. In silico analysis showed that Virofree, an herbal medicine, reversed the genetic signature of COVID-19 and ARDS. Biochemical validations showed that Virofree could disrupt the binding of wild-type and Delta-variant spike proteins to ACE2 and its syncytial formation via cell-based pseudo-typed viral assays, as well as suppress binding between several variant recombinant spikes to ACE2, especially Delta and Omicron. Additionally, Virofree elevated miR-148b-5p levels, inhibited the main protease of SARS-CoV-2 (Mpro), and reduced LPS-induced TNF-α release. Virofree also prevented cellular iron accumulation leading to ferroptosis which occurs in SARS-CoV-2 patients. Furthermore, Virofree was able to reduce pulmonary fibrosis-related protein expression levels in vitro. In conclusion, Virofree was repurposed as a potential herbal medicine to combat COVID-19. This study highlights the inhibitory effect of Virofree on the entry of Delta and Omicron variants of SARS-CoV-2, which have not had any effective treatments during the emergence of the new variants spreading.

Characteristics of the MicroRNA Expression Profile of Exosomes Released by Vero Cells Infected with Porcine Epidemic Diarrhea Virus

Exosomes are nanoscale vesicles actively secreted by a variety of cells. They contain regulated microRNA (miRNA), allowing them to function in intercellular communication. In the present study, the role of exosomal miRNAs in porcine epidemic diarrhea virus (PEDV) infection was investigated using exosomes isolated from Vero cells infected with PEDV. The results of transmission electron microscopy observation showed that the exosomes are spherical in shape, uniform in size, and negatively stained in the membrane. Nanoparticle tracking analysis showed that the average exosome particle size is 130.5 nm. The results of miRNA sequencing showed that, compared with the control group, a total of 115 miRNAs are abnormally expressed in the exosomes of infected cells. Of these, 80 miRNAs are significantly upregulated and 35 miRNAs are significantly downregulated. Functional annotation analysis showed that the differentially expressed miRNAs are associated with PEDV infection through interaction with the cAMP, Hippo, TGF-beta, HIF-1, FoxO, MAPK, and Ras signaling pathways. Thus, our findings provide important information about the effects of PEDV infection on exosomal miRNA expression and will aid the search for potential anti-PEDV drug candidates.

SARS-CoV-2 Spike Targets USP33-IRF9 Axis via Exosomal miR-148a to Activate Human Microglia

SARS-CoV-2, the novel coronavirus infection has consistently shown an association with neurological anomalies in patients, in addition to its usual respiratory distress syndrome. Multi-organ dysfunctions including neurological sequelae during COVID-19 persist even after declining viral load. We propose that SARS-CoV-2 gene product, Spike, is able to modify the host exosomal cargo, which gets transported to distant uninfected tissues and organs and can initiate a catastrophic immune cascade within Central Nervous System (CNS). SARS-CoV-2 Spike transfected cells release a significant amount of exosomes loaded with microRNAs such as miR-148a and miR-590. microRNAs gets internalized by human microglia and suppress target gene expression of USP33 (Ubiquitin Specific peptidase 33) and downstream IRF9 levels. Cellular levels of USP33 regulate the turnover time of IRF9 via deubiquitylation. Our results also demonstrate that absorption of modified exosomes effectively regulate the major pro-inflammatory gene expression profile of TNFα, NF-κB and IFN-β. These results uncover a bystander pathway of SARS-CoV-2 mediated CNS damage through hyperactivation of human microglia. Our results also attempt to explain the extra-pulmonary dysfunctions observed in COVID-19 cases when active replication of virus is not supported. Since Spike gene and mRNAs have been extensively picked up for vaccine development; the knowledge of host immune response against spike gene and protein holds a great significance. Our study therefore provides novel and relevant insights regarding the impact of Spike gene on shuttling of host microRNAs via exosomes to trigger the neuroinflammation.

Innate immune responses to duck Tembusu virus infection

The disease caused by duck Tembusu virus (DTMUV) is characterized by severe egg-drop in laying ducks. Currently, the disease has spread to most duck-raising areas in China, leading to great economic losses in the duck industry. In the recent years, DTMUV has raised some concerns, because of its expanding host range and increasing pathogenicity, as well as the potential threat to public health. Innate immunity is crucial for defending against invading pathogens in the early stages of infection. Recently, studies on the interaction between DTMUV and host innate immune response have made great progress. In the review, we provide an overview of DTMUV and summarize current advances in our understanding of the interaction between DTMUV and innate immunity, including the host innate immune responses to DTMUV infection through pattern recognition receptors (PRRs), signaling transducer molecules, interferon-stimulated genes (ISGs), and the immune evasion strategies employed by DTMUV. The aim of the review is to gain an in-depth understanding of DTMUV pathogenesis to facilitate future studies.

Duck Tembusu virus promotes the expression of suppressor of cytokine signaling 1 by downregulating miR-148a-5p to facilitate virus replication

Duck Tembusu virus (DTMUV), an emerging infectious pathogen, has caused severe disease in ducks and huge economic losses to the poultry industry in China since 2009. Despite considerable advances in understanding the effects of microRNAs on host antiviral immune responses, it remains unclear how miRNAs regulate DTMUV replication in duck embryo fibroblast (DEF) cells. This study aims to clarify the role of host microRNA-148a-5p (miR-148a-5p) in regulating DTMUV replication by targeting SOCS1. First, we found that during DTMUV infection, the expression of miR-148a-5p in DEFs was downregulated in a time-dependent and dose-dependent manner, while the expression of SOCS1 was significantly upregulated. In addition, we found that when miR-148a-5p mimics were transfected into DEFs, viral RNA copies, viral E protein expression levels and viral titres, which represent viral replication and proliferation, were significantly downregulated, while the opposite result was observed when miR-148a-5p inhibitor was transfected into DEFs. Next, we found that SOCS1 was the target gene of miR-148a-5p through software analysis. Therefore, we further confirmed that SOCS1 was the target of miR-148a-5p and that miR-148a-5p could negatively regulate the expression of SOCS1 at the mRNA and protein levels. Furthermore, our results indicated that overexpression of SOCS1 promoted DTMUV replication, while knockdown of SOCS1 inhibited DTMUV replication. Finally, we found that in DTMUV-infected DEFs, the overexpression of SOCS1 inhibited the production of IFN-α and IFN-β, while knocking down SOCS1 produced the opposite result. This indicates that during DTMUV infection, the virus promotes the expression of SOCS1 by downregulating the expression of miR-148a-5p, while the upregulation of SOCS1 suppresses the production of type I interferon and promotes virus replication. Taken together, these findings provide new insights into virus-host interactions during DTMUV infection and provide potential new antiviral treatment strategies for DTMUV infection.

Exosomes: Potential Therapies for Disease via Regulating TLRs

Exosomes are small membrane vesicles that retain various substances such as proteins, nucleic acids, and small RNAs. Exosomes play crucial roles in many physiological and pathological processes, including innate immunity. Innate immunity is an important process that protects the organism through activating pattern recognition receptors (PRRs), which then can induce inflammatory factors to resist pathogen invasion. Toll-like receptor (TLR) is one member of PRRs and is important in pathogen clearance and nervous disease development. Although exosomes and TLRs are two independent materials, abundant evidences imply exosomes can regulate innate immunity through integrating with TLRs. Herein, we review the most recent data regarding exosome regulation of TLR pathways. Specifically, exosome-containing materials can regulate TLR pathways through the interaction with TLRs. This is a new strategy regulating immunity to resist pathogens and therapy diseases, which provide a potential method to cure diseases.