NRF1-mediated mitochondrial biogenesis antagonizes innate antiviral immunity.

Mitochondrial biogenesis is the process of generating new mitochondria to maintain cellular homeostasis. Here, we report that viruses exploit mitochondrial biogenesis to antagonize innate antiviral immunity. We found that nuclear respiratory factor-1 (NRF1), a vital transcriptional factor involved in nuclear-mitochondrial interactions, is essential for RNA (VSV) or DNA (HSV-1) virus-induced mitochondrial biogenesis. NRF1 deficiency resulted in enhanced innate immunity, a diminished viral load, and morbidity in mice. Mechanistically, the inhibition of NRF1-mediated mitochondrial biogenesis aggravated virus-induced mitochondrial damage, promoted the release of mitochondrial DNA (mtDNA), increased the production of mitochondrial reactive oxygen species (mtROS), and activated the innate immune response. Notably, virus-activated kinase TBK1 phosphorylated NRF1 at Ser318 and thereby triggered the inactivation of the NRF1-TFAM axis during HSV-1 infection. A knock-in (KI) strategy that mimicked TBK1-NRF1 signaling revealed that interrupting the TBK1-NRF1 connection ablated mtDNA release and thereby attenuated the HSV-1-induced innate antiviral response. Our study reveals a previously unidentified antiviral mechanism that utilizes a NRF1-mediated negative feedback loop to modulate mitochondrial biogenesis and antagonize innate immune response.

Prevalence and genetic variation of the M, N, and S2 genes of feline coronavirus in Shandong Province, China.

Feline coronavirus (FCoV) is the causative agent of feline infectious peritonitis and diarrhoea in kittens worldwide. In this study, a total of 73 feline diarrhoeal faecal samples were collected from animal hospitals and pet markets in ShanDong province from 2017 to 2019. FCoV was detected in 58.23% (46/73) of the samples, using the RT-PCR method. The results showed that the detection rate of FCoV in healthy cats and sick cats was 41.7% (10/24) and 81.6% (40/49), respectively. Full gene amplification and sequencing of the N, M, and S2 genes of FCoV isolates were performed. An amino acid mutation (M1058L) in the S2 gene was found that can be used as a marker for distinguishing feline enteric coronavirus (FECV) from feline infectious peritonitis virus (FIPV). This study provides new epidemiological information about FCoV that will aid in the prevention of FCoV in China.

Decontamination of face masks with steam for mask reuse in fighting the pandemic COVID-19: Experimental supports.

The coronavirus disease 2019 pandemic caused by the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has claimed many lives worldwide. Wearing medical masks (MMs) or N95 masks ([N95Ms] namely N95 respirators) can slow the virus spread and reduce the infection risk. Reuse of these masks can minimize waste, protect the environment, and help solve the current imminent shortage of masks. Disinfection of used masks is needed for their reuse with safety, but improper decontamination can damage the blocking structure of masks. In this study, we demonstrated using the avian coronavirus of infectious bronchitis virus to mimic SARS-CoV-2 that MMs and N95Ms retained their blocking efficacy even after being steamed on boiling water for 2 hours. We also demonstrated that three brands of MMs blocked over 99% viruses in aerosols. The avian coronavirus was completely inactivated after being steamed for 5 minutes. Altogether, this study suggested that MMs are adequate for use on most social occasions and both MMs and N95Ms can be reused for a few days with steam decontamination between use.

Modulation of integrin activation and signaling by α1/α1'-helix unbending at the junction.

How conformational signals initiated from one end of the integrin are transmitted to the other end remains elusive. At the ligand-binding ßI domain, the α1/α1'-helix changes from a bent to a straightened α-helical conformation upon integrin headpiece opening. We demonstrated that a conserved glycine at the α1/α1' junction is crucial for maintaining the bent conformation of the α1/α1'-helix in the resting state. Mutations that facilitate α1/α1'-helix unbending rendered integrin constitutively active; however, mutations that block the α1/α1'-helix unbending abolished soluble ligand binding upon either outside or inside stimuli. Such mutations also blocked ligand-induced integrin extension from outside the cell, but had no effect on talin-induced integrin extension from inside the cell. In addition, integrin-mediated cell spreading, F-actin stress fiber and focal adhesion formation, and focal adhesion kinase activation were also defective in these mutant integrins, although the cells still adhered to immobilized ligands at a reduced level. Our data establish the structural role of the α1/α1' junction that allows relaxation of the α1/α1'-helix in the resting state and transmission of bidirectional conformational signals by helix unbending upon integrin activation.

Avian influenza virus H9N2 infections in farmed minks.

BACKGROUND: The prevalence of avian H9N2 viruses throughout Asia, along with their demonstrated ability to infect mammals, puts them high on the list of influenza viruses with pandemic potential for humans. In this study, we investigated whether H9N2 viruses could infect farmed minks. METHODS: First, we conducted a serological survey for avian influenza virus antibodies on a random sample of the field-trial population of farmed minks. Then we inoculated farmed minks with A/Chicken/Hebei/4/2008 H9N2 viruses and observed the potential pathogenicity of H9N2 virus and virus shedding in infected minks. RESULTS: H9 influenza antibodies could be detected in most farmed minks with a higher seropositivity, which indicated that farmed minks had the high prevalence of exposure to H9 viruses. After infection, the minks displayed the slight clinical signs including lethargy and initial weight loss. The infected lungs showed the mild diffuse pneumonia with thickened alveolar walls and inflammatory cellular infiltration. Influenza virus detection showed that viruses were detected in the allantoic fluids inoculated supernatant of lung tissues at 3 and 7 days post-infection (dpi), and found in the nasal swabs of H9N2-infected minks at 3-11 dpi, suggesting that H9N2 viruses replicated in the respiratory organ, were then shed outwards. HI antibody test showed that antibody levels began to rise at 7 dpi. CONCLUSIONS: Our data provided the serological and experimental evidences that strongly suggested farmed minks under the natural state were susceptible to H9N2 viral infection and might be the H9N2 virus carriers. It is imperative to strengthen the H9N2 viral monitoring in farmed minks and pay urgent attention to prevent and control new influenza viruses pandemic prevalence.

Genetic and pathogenicity analysis for the two FCV strains isolated from Eastern China.

In this study, the diversity and regularity of two new feline calicivirus (FCV) isolates, QD-7 and QD-164, were investigated. The genomes of these new strains were compared with 39 strains from the NCBI database including isolates from China, United States, Germany, South Korea, the United Kingdom and Japan. The nucleotide sequence identities ranged from 75-88%, indicating a high degree of variability. These variations were not related to distributions of the virus by time of isolation and geographical location. Cats that were experimentally infected with the new isolate QD-164 showed typical clinical symptoms of sneezing, fever and conjunctivitis and all recovered within 30 days. In contrast, QD-7 infections were asymptomatic and the virus was cleared within 16 days. These results indicate that QD-7 and QD-164 were naturally attenuated strains. NNS mutations characteristic of highly virulent strains at positions 441-443 were absent in QD-7 while QD-164 possessed an N at position 442. This indicated that mutations in regions 441-443 may be linked to disease severity.

Social Capital, Political Efficacy and Chinese Residents' Willingness to Participate in Food Safety Governance.

Residents play an important role as one of the main actors in food safety governance. To build a pattern of food safety risk co-governance, the positive and effective participation of residents is vital. This study first establishes a comprehensive analysis framework combining social capital theory and political efficacy theory. Data from a survey of 714 residents in Shandong Province, China, were analysed through structural equation modelling and fuzzy-set qualitative comparative analysis (fsQCA) to examine the causal relationship between residents' willingness to participate and its driving factors. The results indicated that: (1) reciprocity norm, institutional trust and social engagement have significant positive effects on willingness to participate; (2) political efficacy has a partial mediating effect in the relationship between social capital and willingness to participate; (3) fsQCA findings have four solutions to achieving residents' strong willingness to participate; reciprocity norm, institutional trust and political efficacy are the core elements that affected residents' high willingness to participate, whereas social engagement and sociodemographic variables are the non-core variables. Therefore, we put forward suggestions for improving residents' willingness to participate in food safety governance, including improving the appeal expression and feedback mechanism, cultivating residents' social capital and paying attention to the superposition effect of social capital and political efficacy.

Receptor-mediated mitophagy regulates EPO production and protects against renal anemia.

Erythropoietin (EPO) drives erythropoiesis and is secreted mainly by the kidney upon hypoxic or anemic stress. The paucity of EPO production in renal EPO-producing cells (REPs) causes renal anemia, one of the most common complications of chronic nephropathies. Although mitochondrial dysfunction is commonly observed in several renal and hematopoietic disorders, the mechanism by which mitochondrial quality control impacts renal anemia remains elusive. In this study, we showed that FUNDC1, a mitophagy receptor, plays a critical role in EPO-driven erythropoiesis induced by stresses. Mechanistically, EPO production is impaired in REPs in Fundc1-/- mice upon stresses, and the impairment is caused by the accumulation of damaged mitochondria, which consequently leads to the elevation of the reactive oxygen species (ROS) level and triggers inflammatory responses by up-regulating proinflammatory cytokines. These inflammatory factors promote the myofibroblastic transformation of REPs, resulting in the reduction of EPO production. We therefore provide a link between aberrant mitophagy and deficient EPO generation in renal anemia. Our results also suggest that the mitochondrial quality control safeguards REPs under stresses, which may serve as a potential therapeutic strategy for the treatment of renal anemia.

Emergence of an Eurasian avian-like swine influenza A (H1N1) virus from mink in China.

We evaluated the phenotype and genotype of a fatal influenza/canine distemper virus coinfection found in farmed mink in China. We identified a novel subtype H1N1 influenza virus strain from the lungs of infected mink designated A/Mink/Shandong/1121/2017 (H1N1). The results of phylogenetic analysis of 8 gene fragments of the H1N1 strain showed the virus was a swine origin triple-reassortant H1N1 influenza virus: with the 2009 pandemic H1N1 segments (PB2, PB1, PA, NP and M), Eurasian avian-like H1N1 swine segments (HA and NA) and classical swine (NS) lineages. The EID50/0.2 mL of this strain was 10-6.2 and pathogenicity tests were 100 % lethal in a mouse model of infection. We found that while not lethal and lacking any overt signs of infection in mink, the virus could proliferate in the upper respiratory tracts and the animals were converted to seropositive for the HA protein.

Construction and Immunogenicity of Virus-Like Particles of Feline Parvovirus from the Tiger.

Feline panleukopenia, caused by feline parvovirus (FPV), is a highly infectious disease characterized by leucopenia and hemorrhagic gastroenteritis that severely affects the health of large wild Felidae. In this study, tiger FPV virus-like particles (VLPs) were developed using the baculovirus expression system. The VP2 gene from an infected Siberian tiger (Panthera tigris altaica) was used as the target gene. The key amino acids of this gene were the same as those of FPV, whereas the 101st amino acid was the same as that of canine parvovirus. Indirect immunofluorescence assay (IFA) results demonstrated that the VP2 protein was successfully expressed. SDS-PAGE and Western blotting (WB) results showed that the target protein band was present at approximately 65 kDa. Electron micrograph analyses indicated that the tiger FPV VLPs were successfully assembled and were morphologically similar to natural parvovirus particles. The hemagglutination (HA) titer of the tiger FPV VLPs was as high as 1:218. The necropsy and tissue sections at the cat injection site suggested that the tiger FPV VLPs vaccine was safe. Antibody production was induced in cats after subcutaneous immunization, with a >1:210 hemagglutination inhibition (HI) titer that persisted for at least 12 months. These results demonstrate that tiger FPV VLPs might provide a vaccine to prevent FPV-associated disease in the tiger.

Dynamic PGAM5 multimers dephosphorylate BCL-xL or FUNDC1 to regulate mitochondrial and cellular fate.

Mitochondria are highly dynamic organelles and respond to stress by changing their fission-fusion cycle, undergoing mitophagy, or releasing apoptotic proteins to initiate cell death. The molecular mechanisms that sense different stresses and coordinate distinct effectors still await full characterization. Here, we show that PGAM5, which exists in an equilibrium between dimeric and multimeric states, dephosphorylates BCL-xL to inhibit apoptosis or FUNDC1 to activate mitofission and mitophagy in response to distinct stresses. In vinblastine-treated cells, PGAM5 dephosphorylates BCL-xL at Ser62 to restore BCL-xL sequestration of BAX and BAK and thereby resistance to apoptosis. Selenite-induced oxidative stress increases the multimerization of PGAM5, resulting in its dissociation from BCL-xL, which causes increased BCL-xL phosphorylation and apoptosis. Once freed, the more multimeric and active PGAM5 dephosphorylates FUNDC1 to initiate mitofission and mitophagy. The reciprocal interaction of PGAM5 with FUNDC1 and BCL-xL, controlled by PGAM5 multimerization, serves as a molecular switch between mitofission/mitophagy and apoptosis.

Characterization of H5N1 highly pathogenic mink influenza viruses in eastern China.

Members of the H5 subtype of highly pathogenic avian influenza viruses pose a great threat to both poultry and humans with severe consequences for both industry and public health sectors. Here, we isolated and characterized two H5N1 highly pathogenic influenza viruses in deceased mink from eastern China. Phylogenetic analyses showed that the G15 and XB15 viruses belonged to clade 2.3.2.1b and 2.3.2.1e, respectively. Both of these viruses were highly pathogenic in chickens. They were also shown to exhibit moderate to high pathogenicity in mice without pre-adaptation. Further, the mink influenza viruses had severe antigenic drift with corresponding Re-6 vaccine and current vaccines may fail to confer protection against these H5N1 viruses in poultry.

Development of a PCR-RFLP assay for the detection and differentiation of canine parvovirus and mink enteritis virus.

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay has been developed to detect and differentiate between canine parvovirus (CPV) and mink enteritis virus (MEV). Eight CPV and three MEV epidemic strains isolated from 28 pathological samples from dogs and minks suspected of being infected with parvovirus were amplified by PCR using a pair of specific primers designed based on the CPV-N strain (M19296). PCR amplified a fragment of 1016bp from the genomic DNA of both MEV and CPV. The MEV-derived fragment could be digested with the restriction enzyme BSP1407I into three fragments of 102bp, 312bp and 602bp, while the fragment amplified from the CPV genomic DNA was digested into only two fragments of 414bp and 602bp. The lowest DNA concentration of CPV and MEV that could be detected using this assay was 0.004µg/ml and 0.03µg/ml, respectively. The PCR-RFLP assay developed in the present study can, therefore, be used to detect and differentiate MEV from CPV with high specificity and sensitivity.

WITHDRAWN: Development of an RT-PCR-RFLP assay for the detection and differentiation of wild-type and vaccine strains of classical swine fever virus.

This article has been withdrawn at the request of the author(s). The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.