Rapid conversion of porcine pluripotent stem cells into macrophages with chemically defined conditions.

A renewable source of porcine macrophages derived from pluripotent stem cells (PSCs) would be a valuable alternative to primary porcine alveolar macrophages (PAMs) in the research of host-pathogen interaction mechanisms. We developed an efficient and rapid protocol, within 11 days, to derive macrophages from porcine PSCs (pPSCs). The pPSC-derived macrophages (pPSCdMs) exhibited molecular and functional characteristics of primary macrophages. The pPSCdMs showed macrophage-specific surface protein expression and macrophage-specific transcription factors, similar to PAMs. The pPSCdMs also exhibited the functional characteristics of macrophages, such as endocytosis, phagocytosis, porcine respiratory and reproductive syndrome virus infection and the response to lipopolysaccharide stimulation. Furthermore, we performed transcriptome sequencing of the whole differentiation process to track the fate transitions of porcine PSCs involved in the signaling pathway. The activation of transforming growth factor beta signaling was required for the formation of mesoderm and the inhibition of the transforming growth factor beta signaling pathway at the hematopoietic endothelium stage could enhance the fate transformation of hematopoiesis. In summary, we developed an efficient and rapid protocol to generate pPSCdMs that showed aspects of functional maturity comparable with PAMs. pPSCdMs could provide a broad prospect for the platforms of host-pathogen interaction mechanisms.

The emerging roles of MARCH8 in viral infections: A double-edged Sword.

The host cell membrane-associated RING-CH 8 protein (MARCH8), a member of the E3 ubiquitin ligase family, regulates intracellular turnover of many transmembrane proteins and shows potent antiviral activities. Generally, 2 antiviral modes are performed by MARCH8. On the one hand, MARCH8 catalyzes viral envelope glycoproteins (VEGs) ubiquitination and thus leads to their intracellular degradation, which is the cytoplasmic tail (CT)-dependent (CTD) mode. On the other hand, MARCH8 traps VEGs at some intracellular compartments (such as the trans-Golgi network, TGN) but without inducing their degradation, which is the cytoplasmic tail-independent (CTI) mode, by which MARCH8 hijacks furin, a cellular proprotein convertase, to block VEGs cleavage. In addition, the MARCH8 C-terminal tyrosine-based motif (TBM) 222YxxL225 also plays a key role in its CTI antiviral effects. In contrast to its antiviral potency, MARCH8 is occasionally hijacked by some viruses and bacteria to enhance their invasion, indicating a duplex role of MARCH8 in host pathogenic infections. This review summarizes MARCH8's antiviral roles and how viruses evade its restriction, shedding light on novel antiviral therapeutic avenues.

[Development of porcine induced pluripotent stem cells with a CD163 reporter system].

As main recipient cells for porcine reproductive and respiratory syndrome virus (PRRSV), porcine alveolar macrophage (PAM) are involved in the progress of several highly pathogenic virus infections. However, due to the fact that the PAM cells can only be obtained from primary tissues, research on PAM-based virus-host interactions remains challenging. The improvement of induced pluripotent stem cells (iPSCs) technology provides a new strategy to develop IPSCs-derived PAM cells. Since the CD163 is a macrophage-specific marker and a validated receptor essential for PRRSV infection, generation of stable porcine induced pluripotent stem cells lines containing CD163 reporter system play important roles in the investigation of IPSCs-PAM transition and PAM-based virus-host interaction. Based on the CRISPR/Cas9- mediated gene editing system, we designed a sgRNA targeting CD163 locus and constructed the corresponding donor vectors. To test whether this reporter system has the expected function, the reporter system was introduced into primary PAM cells to detect the expression of RFP. To validate the low effect on stem cell pluripotency, we generated porcine iPSC lines containing CD163 reporter and assessed the pluripotency through multiple assays such as alkaline phosphatase staining, immunofluorescent staining, and EdU staining. The red-fluorescent protein (RFP) expression was detected in CD163-edited PAM cells, suggesting that our reporter system indeed has the ability to reflect the expression of gene CD163. Compared with wild-type (WT) iPSCs, the CD163 reporter-iPSCs display similar pluripotency-associated transcription factors expression. Besides, cells with the reporter system showed consistent cell morphology and proliferation ability as compared to WT iPSCs, indicating that the edited-cells have no effect on stem cell pluripotency. In conclusion, we generated porcine iPSCs that contain a CD163 reporter system. Our results demonstrated that this reporter system was functional and safe. This study provides a platform to investigate the iPS-PAM development and virus-host interaction in PAM cells.

Efficacy and Safety of Yanggan Jian in Hepatitis B Virus-related Decompensated Cirrhosis: A Randomized, Double-blind, Controlled Trial.

Background and Aims: The aim was to evaluate the efficacy and safety of Yanggan Jian (YGJ) in HBV-infected patients with decompensated cirrhosis. Methods: This randomized, double-blind controlled trial enrolled 160 patients with HBV-related decompensated cirrhosis who were already receiving or about to start antiviral therapy. Patients were randomly assigned to receive YGJ or placebo for 24 weeks, and were followed-up to 36 weeks. The primary outcome was the proportion of patients with a ≥2 point reduction in Child-Turcotte-Pugh (CTP) score from baseline at week 24. Secondary outcomes were CTP class and score, serum liver function indices, mortality, incidence of hepatocellular carcinoma and variceal bleeding. Results: The proportion of patients with a CTP score reduction ≥2 was significantly greater in the YGJ than in the placebo group (p=0.009); the percentage of patients with CTP class C was significantly less than that in the placebo group (p<0.05), and the YGJ group had a significantly greater mean change from baseline in CTP score at week 24 (p=0.034). The improvement in measured values and change from baseline of prothrombin time, serum albumin, platelets, cholinesterase, international normalized ratio, and activated partial thromboplastin time were significantly better with YGJ than with placebo. Between-group differences in cumulative rates of variceal bleeding, hepatocellular carcinoma, death, or the frequency of any adverse event (AE), AEs related to treatment, or discontinuation because of AEs were not significant. Conclusions: YGJ significantly improved CTP scores and hepatic synthetic and reserve function in patients with HBV-related decompensated cirrhosis, and was safe and well tolerated.

Molecular characterization and phylogenetic analysis of porcine epidemic diarrhea virus strains circulating in China from 2020 to 2021.

BACKGROUND: Porcine epidemic diarrhea virus (PEDV), an enteric coronavirus, has become the major causative agent of acute gastroenteritis in piglets since 2010 in China. RESULTS: In the current study, 91 complete spike (S) gene sequences were obtained from PEDV positive samples collected from 17 provinces in China from March 2020 to March 2021. A phylogenetic analysis showed that 92.3% (84 out of 91) of the identified strains belonged to GII subtype, while 7.7% (7 out of 91) were categorized as S-INDEL like strains and grouped within GI-c clade. Based on a recombination analysis, six of S-INDEL like strains were recombinant strains originated from S-INDEL strain FR/001/2014 and virulent strain AJ1102. In addition, PEDV variant strains (CH/GDMM/202012, CH/GXDX/202010 et al) carrying novel insertions (360QGRKS364 and 1278VDVF1281) in the S protein were observed. Furthermore, the deduced amino acid sequences for the S protein showed that multiple amino acid substitutions in the antigenic epitopes in comparison with the vaccine strains. CONCLUSIONS: In conclusion, these data provide novel molecular evidence on the epidemiology and molecular diversity of PEDV in 2020-2021. This information may help design a strategy for controlling and preventing the prevalence of PEDV variant strains in China.

Review detection of Newcastle disease virus.

Newcastle disease (ND) is an acute and highly contagious disease caused by the Newcastle disease virus (NDV) infecting poultry, which has caused great harm to the poultry industry around the world. Rapid diagnosis of NDV is important to early treatment and early institution of control measures. In this review, we comprehensively summarize the most recent research into NDV, including historical overview, molecular structure, and infection mechanism. We then focus on detection strategies for NDV, including virus isolation, serological assays (such as hemagglutination and hemagglutination-inhibition tests, enzyme linked immunosorbent assay, reporter virus neutralization test, Immunofluorescence assay, and Immune colloidal gold technique), molecular assays (such as reverse transcription polymerase chain reaction, real-time quantitative PCR, and loop-mediated isothermal amplification) and other assays. The performance of the different serological and molecular biology assays currently available was also analyzed. To conclude, we examine the limitations of currently available strategies for the detection of NDV to lay the groundwork for new detection assays.

Bushen Jianpi Formula Combined with Entecavir for the Treatment of HBeAg-Negative Chronic Hepatitis B: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial.

Background: Bushen Jianpi formula (BSJPF, also known as Lingmao formula) is a traditional Chinese medicine for chronic hepatitis B (CHB). The previous study has suggested that the treatment combination of BSJPF and entecavir (ETV) can achieve a significant loss of hepatitis B e antigen (HBeAg) and a significant decrease in serum level of hepatitis B virus (HBV) DNA in HBeAg-positive CHB patients with mildly elevated alanine aminotransferase. Objective: This study aimed to evaluate the efficacy and safety of BSJPF combined with ETV for treating HBeAg-negative CHB patients. Methods: A total of 640 patients were assigned randomly to the treatment group (receiving BSJPF combined with ETV for 96 weeks) or the control group (receiving a placebo combined with ETV for 96 weeks) in a 1 : 1 ratio. The primary endpoints are the rate of loss of hepatitis B surface antigen (HBsAg). The secondary outcomes included the rate of decrease in the HBsAg concentration to ≥1 lg·IU/mL, the HBV DNA suppression, the decline of the level of covalently closed circular DNA (cccDNA) in the liver, histological improvements, and the rate of ALT normalization. Results: The rate of HBsAg loss in the treatment group was significantly higher than that of the control group (5.5% versus 1.8%, P=0.031). There were 11.1% of patients in the treatment group who recorded a reduction in HBsAg ≥1 lg·IU/mL, which is better than 5.9% of patients in the control group (P=0.043). There was no significant difference between the two groups with regard to the rate of HBV DNA clearance, the reduction in intrahepatic cccDNA, and the rate of ALT normalization (P > 0.05). The rate of liver fibrosis improvement in the treatment group was better than that of the control group (35.5% versus 11.8%, P=0.031), but there was no difference in necroinflammatory improvement (P > 0.05). The adverse events (AEs) were similar between the two groups, except for the abnormal kidney function, with 2.2% in the control group and 0.0% in the treatment group (P=0.028). Conclusion: The combination of BSJPF and ETV can increase the rate of HBsAg loss and the rate of histological fibrosis improvement without serious adverse events in CHB patients. Trial Registration. This trial is registered with ChiCTR-IOR-16009880 on November 16, 2016-retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=16836.

Molecular detection and phylogenetic analysis of pigeon circovirus from racing pigeons in Northern China.

BACKGROUND: Pigeon circovirus (PiCV) infections in pigeons (Columba livia) have been reported worldwide. Currently, pigeon racing is becoming increasingly popular and considered to be a national sport in China, and even, the greatest competitions of racing pigeons are taking place in China. However, there are still no epidemiologic data regarding PiCV infections among racing pigeons in China. The purpose of our study was to provide information of prevalence, genetic variation and evolution of PiCV from racing pigeons in China. RESULTS: To trace the prevalence, genetic variation and evolution of PiCV in sick and healthy racing pigeons, 622 samples were collected from 11 provinces or municipalities in China from 2016 to 2019. The results showed that the positive rate of PiCV was 19.3% (120/622) at the sample level and 59.0% (23/39) at the club level, thus suggesting that the virus was prevalent in Chinese racing pigeons. A sequence analysis revealed that the cap genes of the PiCV strains identified in our study displayed a high genetic diversity and shared nucleotide homologies of 71.9%-100% and amino acid homologies of 71.7%-100%. 28 and 36 unique amino acid substitutions were observed in the Cap and Rep proteins derived from our PiCV strains, respectively. A cladogram representation of PiCV strains phylogeny based on 90 cap gene sequences showed that the strains in this study could be further divided into seven clades (A, B, C, E, G, H, and I) and some of them were closely related to worldwide strains from different types of pigeons. A large number of recombination events (31 events) were also detected in the PiCV genomes from Chinese racing pigeons. CONCLUSIONS: These findings indicate that PiCV strains circulating in China exhibit a high genetic diversity and also contribute to information of prevalence, genetic variation and evolution of PiCV from racing pigeons in China.

Breathable Strain/Temperature Sensor Based on Fibrous Networks of Ionogels Capable of Monitoring Human Motion, Respiration, and Proximity.

Wearable strain and temperature sensors are desired for human-machine interfaces, health monitoring, and human motion monitoring. Herein, the fibrous mat with aligned nanofibers of ionic liquid (IL)/thermoplastic polyurethane (TPU) ionogels is fabricated via an electrospinning technique. The resultant fibrous mat is cut into a rectangle specimen and electrodes are loaded along the direction perpendicular to the nanofiber orientation to design a high-performance multimodal sensor based on an ionic conducting mechanism. As a strain sensor, the obtained sensor exhibits a wide strain working range (0-200%), a fast response and recovery (119 ms), a low detection limit (0.1%), and good reproducibility because of the reversible and deformable ionic conductive pathways of the sensor. Moreover, the sensor also exhibits excellent temperature-sensing behaviors, including a monotonic thermal response, high sensitivity (2.75% °C-1), high accuracy (0.1 °C), a fast response time (2.46 s), and remarkable repeatability, attributable to the negative temperature coefficient behavior of the IL/TPU fibrous mat. More interestingly, the IL/TPU fibrous sensor possesses good breathability, which is desired for wearable electronics. Because of these excellent sensing capabilities in strain and temperature, the sensor can not only monitor tiny and large human motions but also detect respiration and proximity, exhibiting enormous potential in wearable electronics.

Origin and transmission of bovine viral diarrhea virus type 1 in China revealed by phylodynamic analysis.

Bovine viral diarrhea virus type 1 (BVDV-1) is prevalent worldwide and causes significant economic loss in animal husbandry. Since its first report in the 1980s in China, several genotypes of BVDV-1 had been reported, but an in-depth phylogenetic analysis on the BVDV isolates from China is lacking. To investigate the molecular evolution and phylodynamics of BVDV-1 genotypes circulating in China, comprehensive phylogenetic and phylodynamic analyses were performed to reconstruct the origin and spatial-temporal distribution, and to trace main viral flows among different areas. BVDV-1 5'-UTR sequences from China and Mongolia were collected from Genbank, and the phylogeny was built using the maximum likelihood method. The Bayesian Skygrid was used to estimate the evolution and population dynamics of BVDV-1. Eight BVDV-1 genotypes were identified, of which 1b and 1 m are the main genotypes. The results indicated that BVDV-1 might be introduced in China in the 1960s, and after a long period of population growth, it gradually leveled off after 2010. The phylodynamic inference clearly shows a more steady BVDV-1 population growth, and the transmission of BVDV-1 may be confined to specific regions. This study will help to understand the molecular epidemiology and long-term evolutionary dynamics of BVDV-1 in China, therefore providing a scientific basis for the prevention and controlof the virus.

Comparison of the blood parameters and histopathology between grass carp infected with a virulent and avirulent isolates of genotype II grass carp reovirus.

Grass carp hemorrhagic disease caused by grass carp reovirus (GCRV) is the most important disease for grass carp aquaculture. Its typical clinical symptom is haemorrhaging, although the mechanism was remained unclear. In this study, we investigated the differences in blood parameters and histopathological features between grass carp infected with a virulent and avirulent isolates of genotype II GCRV. Infection with the virulent isolate resulted in increases in 8 routine blood and 2 serum biochemical parameters (P < 0.05); while 9 routine blood and 5 biochemical parameters were significantly decreased (P < 0.05) compared with fish infected with the avirulent isolate. The majority of these alterations were related to hemorrhage, inflammatory reactions and organic damage. The histopathologic changes were primarily vasodilation and hyperaemia in multiple organs, lymphocyte and macrophage infiltration as well as severe vacuolar degeneration in spleen, kidney and liver. The histopathology changes in fish infected with the avirulent isolate were minimal. These results indicated that the pathogenicity of GCRV was primarily reflected in destruction of the blood circulatory system and parenchymatous organs. This study lays the foundation for further research on the pathogenesis of bleeding caused by GCRV infection and the use of blood parameters and histopathology as tools for disease diagnosis.

[Effects of tillage types on soil aggregate distribution and stability in irrigated sierozem of Gansu Yellow River irrigation area, China]. / 耕作方式对甘肃引黄灌区灌耕灰钙土团聚体分布及稳定性的影响.

A total of six treatments, including continuous conventional tillage (CT), rotary tillage (RT), subsoiling (ST), no-tillage (NT), conventional-no tillage (CT-NT) and subsoiling-no tillage (ST-NT), were conducted to examine the effects of different tillage types on soil aggregates distribution and stability of irrigated sierozem on continuous 8-year-tillage maize fields in the Gansu Yellow River irrigated area in 2014-2017. The results showed that the aggregation and stability of large aggregates in 0-40 cm soil layer were increased by NT and ST-NT treatments, while the size distribution and stability in plough layer were significantly decreased by CT and RT treatments due to strong soil disturbance. Compared with RT, the mechanical stability of aggregates under dry sieving NT was the best. The contents of >0.25 mm aggregate (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 5.8%, 8.0%, and 13.0%, respectively, and fractal dimension (D) decreased by 3.6%. The water-stable aggregates in ST-NT was the best, with R0.25, MWD and GMD increased by 55.3%, 15.1% and 8.7%, respectively, and D value decreased by 0.8%. The percentage of aggregate destruction (PAD) and unstable aggregate index (ELT) of NT and ST-NT treatments were the lowest. PAD was reduced by 5.9% and 7.7% compared with RT, ELT was reduced by 5.8% and 7.2%, respectively. All the results indicated that the subsoiling-notillage (ST-NT) rotation mode was more conducive to the enhancement of soil aggregate content and stability and consistent with the local farmers operating habits, which would be an ideal tillage method and had certain application value for the sustainable agricultural development in this area.

MAVS induces a host cell defense to inhibit CSFV infection.

Classical swine fever virus (CSFV) infection results in highly significant economic losses. Previous studies have suggested that CSFV can be recognized by RIG-I-like receptors (RLRs) to trigger innate defenses. However, the role of mitochondrial antiviral signaling protein (MAVS), the adaptor of RLRs, is still unknown during CSFV infection. Here, we showed that CSFV infection increased MAVS expression in porcine alveolar macrophages (PAMs). Additionally, intracellular reactive oxygen species (ROS) were involved in MAVS expression in CSFV-infected PAMs. Moreover, MAVS enhanced the induction of antiviral and pro-inflammatory cytokines and apoptosis, and inhibited CSFV replication. However, CSFV still establishes a persistent infection in the host. Thus, how CSFV antagonises MAVS-mediated host cell defense was investigated. Importantly, CSFV Npro inhibited MAVS-induced interferons and pro-inflammatory cytokines and apoptosis. Furthermore, IRF3-knockdown also suppressed MAVS-induced host cell defense. Taken together, these results demonstrate that intracellular ROS is involved in CSFV-induced MAVS expression and MAVS induces antiviral cytokines and apoptosis to inhibit CSFV replication while CSFV Npro inhibits MAVS-mediated host cell defenses possibly through degradation of IRF3. These data offer novel insights into the immunomodulatory effects of CSFV infection on the host innate response.

Rab1A is required for assembly of classical swine fever virus particle.

Rab1A belongs to the small Rab GTPase family and is involved in the lifecycle of numerous viruses. Here, knockdown of Rab1A inhibited CSFV growth. Further study revealed that Rab1A depletion decreased intracellular and extracellular CSFV titers, but did not affect intracellular virus genome copies and E2 protein expression within a virus lifecycle, which suggested that Rab1A is required for CSFV particle assembly rather than for genome replication or virion release. This was proofed by blocking the spread of virus using neutralizing antibodies, through which the negative effects of Rab1A knockdown on multi-cycle replication of CSFV were eliminated. Moreover, co-immunoprecipitation and confocal microscopy assays showed that Rab1A bound to CSFV NS5A protein, indicating that Rab1A and viral NS5A proteins may work cooperatively during CSFV particle assembly. In conclusion, this study demonstrated for the first time that Rab1A is required for CSFV particle assembly and binds to viral particle assembly-related NS5A protein.

Erratum to: Role of transcription regulatory sequence in regulation of gene expression and replication of porcine reproductive and respiratory syndrome virus.

After publication of the article [1], it has been brought to our attention that an acknowledgement has been omitted from the original article. The authors would like to include the following, The authors also thank Prof. En-Min Zhou (Northwest A&F University) and his laboratory for technical support."

Role of transcription regulatory sequence in regulation of gene expression and replication of porcine reproductive and respiratory syndrome virus.

In order to gain insight into the role of the transcription regulatory sequences (TRSs) in the regulation of gene expression and replication of porcine reproductive and respiratory syndrome virus (PRRSV), the enhanced green fluorescent protein (EGFP) gene, under the control of the different structural gene TRSs, was inserted between the N gene and 3'-UTR of the PRRSV genome and EGFP expression was analyzed for each TRS. TRSs of all the studied structural genes of PRRSV positively modulated EGFP expression at different levels. Among the TRSs analyzed, those of GP2, GP5, M, and N genes highly enhanced EGFP expression without altering replication of PRRSV. These data indicated that structural gene TRSs could be an extremely useful tool for foreign gene expression using PRRSV as a vector.

Rab5 Enhances Classical Swine Fever Virus Proliferation and Interacts with Viral NS4B Protein to Facilitate Formation of NS4B Related Complex.

Classical swine fever virus (CSFV) is a fatal pig pestivirus and causes serious financial losses to the pig industry. CSFV NS4B protein is one of the most important viral replicase proteins. Rab5, a member of the small Rab GTPase family, is involved in infection and replication of numerous viruses including hepatitis C virus and dengue virus. Until now, the effects of Rab5 on the proliferation of CSFV are poorly defined. In the present study, we showed that Rab5 could enhance CSFV proliferation by utilizing lentivirus-mediated constitutive overexpression and eukaryotic plasmid transient overexpression approaches. On the other hand, lentivirus-mediated short hairpin RNA knockdown of Rab5 dramatically inhibited virus production. Co-immunoprecipitation, glutathione S-transferase pulldown and laser confocal microscopy assays further confirmed the interaction between Rab5 and CSFV NS4B protein. In addition, intracellular distribution of NS4B-Red presented many granular fluorescent signals (GFS) in CSFV infected PK-15 cells. Inhibition of basal Rab5 function with Rab5 dominant negative mutant Rab5S34N resulted in disruption of the GFS. These results indicate that Rab5 plays a critical role in facilitating the formation of the NS4B related complexes. Furthermore, it was observed that NS4B co-localized with viral NS3 and NS5A proteins in the cytoplasm, suggesting that NS3 and NS5A might be components of the NS4B related complex. Taken together, these results demonstrate that Rab5 positively modulates CSFV propagation and interacts with NS4B protein to facilitate the NS4B related complexes formation.

TRAF6 is a novel NS3-interacting protein that inhibits classical swine fever virus replication.

Classical swine fever virus (CSFV) non-structural protein 3 (NS3) is a multifunctional non-structural protein that plays a major role in viral replication. However, how exactly NS3 exerts these functions remains unknown. Here, we identified tumour necrosis factor receptor-associated factor 6 (TRAF6) as a novel NS3-interacting protein via yeast two-hybrid analysis, co-immunoprecipitation, and glutathione S-transferase pull-down assays. Furthermore, we observed that TRAF6 overexpression significantly inhibited CSFV replication, and TRAF6 knockdown promoted CSFV replication in porcine alveolar macrophages. Additionally, TRAF6 was degraded during CSFV infection or NS3 expression exclusively, indicating that CSFV and TRAF6 were mutually antagonistic and that TRAF6 degradation might contribute to persistent CSFV replication. Moreover, nuclear factor-kappa B (NF-κB) activity and interferon (IFN)-ß and interleukin (IL)-6 expression were increased in TRAF6-overexpressing cells, whereas TRAF6-knockdown cells exhibited decreased NF-κB activity and IFN-ß and IL-6 levels. Notably, TRAF6 overexpression did not reduce CSFV replication following inhibition of NF-κB activation by p65 knockdown. Our findings revealed that TRAF6 inhibits CSFV replication via activation of NF-κB-signalling pathways along with increases in the expression of its targets IFN-ß and IL-6. This work addresses a novel aspect concerning the regulation of innate antiviral immune response during CSFV infection.

uS10, a novel Npro-interacting protein, inhibits classical swine fever virus replication.

Classical swine fever (CSF) is a severe, febrile and highly contagious disease caused by classical swine fever virus (CSFV) that has resulted in huge economic losses in the pig industry worldwide. CSFV Npro has been actively studied but remains incompletely understood. Few studies have investigated the cellular proteins that interact with Npro and their participation in viral replication. Here, the yeast two-hybrid (Y2H) system was employed to screen Npro-interacting proteins from a porcine alveolar macrophage (PAM) cDNA library, and a blast search of the NCBI database revealed that 15 cellular proteins interact with Npro. The interaction of Npro with ribosomal protein S20, also known as universal S10 (uS10), was further confirmed by co-immunoprecipitation and glutathione S-transferase pull-down assays. Furthermore, uS10 overexpression inhibited CSFV replication, whereas the knockdown of uS10 promoted CSFV replication in PAMs. In addition, Npro or CSFV reduced uS10 expression in PAMs in a proteasome-dependent manner, indicating that Npro-uS10 interaction might contribute to persistent CSFV replication. Our previous research showed that CSFV decreases Toll-like receptor 3 (TLR3) expression. The results showed that uS10 knockdown reduced TLR3 expression, and that uS10 overexpression increased TLR3 expression. Notably, uS10 knockdown did not promote CSFV replication following TLR3 overexpression. Conversely, uS10 overexpression did not inhibit CSFV replication following TLR3 knockdown. These results revealed that uS10 inhibits CSFV replication by modulating TLR3 expression. This work addresses a novel aspect of the regulation of the innate antiviral immune response during CSFV infection.

The effect of classical swine fever virus NS5A and NS5A mutants on oxidative stress and inflammatory response in swine testicular cells.

Infection with classical swine fever virus (CSFV) results in highly significant economic losses; this infection is characterized by being highly contagious and accompanied by hyperthermia and systemic bleeding. Oxidative stress (OS) plays a critical role in the pathological process of viral infection. The function of the nonstructural protein 5A (NS5A) in the pathogenesis of CSFV has not been completely understood. Here, OS and the inflammatory response were studied with NS5A and substitution mutants in swine testicular (ST) cells. ST cell lines stably expressing CSFV NS5A or substitution mutants were established. Reactive oxygen species (ROS) production, antioxidant protein expression and inflammatory response were analyzed by quantitative real-time PCR (qRT-PCR), ELISA and flow cytometry analysis. The results showed that CSFV NS5A did not increase ROS production or the antioxidant protein (Trx, HO-1 and PRDX-6) expression in ST cells. However, NS5A inhibited cyclooxygenase-2 (COX-2) expression, a pro-inflammatory protein related to OS. Further studies have shown that NS5A mutants S15A and S92A increased ROS production and inhibited antioxidant protein expression. S15A, S81A and T274A affected the inflammatory response. This study suggested that CSFV NS5A did not induce OS, and amino acids Ser15 and Ser92 of CSFV NS5A were essential for inhibiting OS. Additionally, Ser15, Ser81 and Thr274 played important roles in the inflammatory response in ST cells. These observations provided insight into the function of CSFV NS5A and the mechanism of CSFV persistent infection in ST cells.