Bovine viral diarrhea virus (BVDV) is a significant economic pathogen capable of establishing persistent infections in cattle, posing a major challenge to global cattle industries. This review systematically elucidates the multifaceted pathogenic mechanisms of BVDV, spanning from viral entry and intracellular replication to sophisticated strategies for immune evasion. The virus exploits receptor-mediated endocytosis for cellular invasion, with its structural (Erns, E1, E2) and non-structural proteins playing pivotal roles in replication and host cell manipulation. Crucially, BVDV intricately modulates host cellular processes, including autophagy, apoptosis, and ferroptosis, to create a favourable environment for its replication and to evade immune clearance. Furthermore, the virus hijacks host lipid and cholesterol metabolism, notably through lipid droplet accumulation and cholesterol synthesis pathways, to fuel its proliferation. A cornerstone of BVDV pathogenesis is its multi-layered immune evasion strategy, which involves impairing antigen presentation, suppressing T-cell activation, and antagonizing interferon signaling. Emerging research hotspots, such as the virus-induced dysregulation of immune memory and the role of T-cell exhaustion mediated by checkpoint molecules like PD-1 in maintaining persistent infection, are highlighted as critical frontiers for understanding viral persistence. By synthesizing the molecular basis of BVDV's multifaceted virulence and immune evasion, this study provides a theoretical foundation for developing novel antiviral therapeutics and effective vaccines, particularly those aimed at reversing immune dysfunction.

Bovine viral diarrhea virus (BVDV) causes persistent infection and immunosuppression, yet whether it hijacks host immunometabolism to facilitate replication remains unclear. Using untargeted metabolomics in bovine turbinate (BT) cells, we found that BVDV infection significantly elevated xanthurenic acid within the tryptophan-kynurenine (Trp-Kyn) pathway. BVDV persistently upregulated indoleamine 2,3-dioxygenase 1 (IDO1), resulting in decreased extracellular tryptophan and increased kynurenine levels. Supplementation with L-tryptophan or IDO1 inhibition suppressed viral replication, whereas L-kynurenine promoted it. Rescue of viral replication by L-kynurenine in IDO1-silenced cells confirmed that IDO1 promotes BVDV proliferation through downstream kynurenine generation. Mechanistically, IDO1 inhibition enhanced STAT1 phosphorylation and upregulated ISG15, MX1, and OAS1 expression. A negative feedback loop was identified between IFN-γ/STAT1 signaling and the IDO1-kynurenine axis. Furthermore, L-kynurenine activated the aryl hydrocarbon receptor (AhR) target gene CYP1A1, and the AhR antagonist CH-223191 partially reversed its pro-viral effects. In conclusion, BVDV hijacks the IDO1-dependent Trp-Kyn metabolic axis to limit interferon-STAT1 antiviral signaling, while AhR-related signaling may act as a possible partial downstream branch contributing to a pro-viral intracellular environment.

The bovine herpesvirus type I (BHV-1) is a significant pathogen that poses a threat to the healthy development of the cattle industry and has a global prevalence. Paeonol is a phenolic constituent extracted from the dried root bark of peony in the buttercup family. Although paeonol has anti-inflammatory and antioxidant effects, its antiviral capacity remains unclear. Here, we conducted a cytotoxicity assay to screen the safe concentration of the paeonol using bovine turbinate (BT) cells as a model. Antiviral studies showed that paeonol inhibited BHV-1 gB gene and VP8 protein expression, and reduced cytopathic effect and viral titer. Furthermore, paeonol also demonstrated a potent effect on BHV-1 replication with an EC50 of 18.54 μg/mL and a Selectivity Index (SI) of 28.64. Mechanistic analysis revealed that the PI3K/AKT pathway might be involved in the antiviral mechanism of paeonol. Molecular docking combined with western blot assay further confirmed that paeonol was able to bind stably to the active sites of PI3K and AKT proteins, and significantly inhibited the activation of PI3K/AKT pathway. Interestingly, 740Y-P (a PI3K/AKT pathway agonist) significantly attenuated the anti-BHV-1 effect of paeonol. The above experiments are the first to confirm the inhibitory effect of paeonol on BHV-1 replication, which not only adds evidence to the biological function of paeonol as an antiviral agent, but also lays the foundation for the prevention and control of this disease and the development of feed additives.

This study isolated Bacillus from the cecal contents of healthy geese and evaluated their probiotic and enzyme-producing characteristics. The isolated strain was identified through morphological observation, biochemical tests, PCR amplification, and 16S rDNA sequence analysis. Its growth curve, acid and bile salt tolerance, thermotolerance, salt tolerance, auto-aggregation, hydrophobicity, enzyme production profile, drug susceptibility, and safety were assessed. The results showed that a Gram positive bacterium, named DQC81, was isolated from the contents of the cecum of healthy geese. The results of the indole hydrolysis test and starch hydrolysis test of the fungus were both positive. 16S rDNA sequence analysis identified it as Bacillus safensis. The strain entered the logarithmic phase after three hours of cultivation. After three hours of cultivation, this bacterium entered the logarithmic growth phase. The survival rate was relatively high at a pH of 3.0 (60%) and 0.3% bile salt (71%). At 50 ℃ and 8% sodium chloride (NaCl), the survival rate could reach over 80%. Its auto-aggregation rate and hydrophobicity were 32% and 37% for three hours, respectively. The activities of total cellulase, exoglucanase, endoglucanase, and β-glucosidase were 0.67, 0.05, 1.23, and 0.45 U/mL for 48 hours, respectively. Drug susceptibility tests indicated high sensitivity to cefazolin, minocycline, ampicillin, among others, but resistance to cefotaxime. Safety trials showed no mortality or pathological lesions in goslings inoculated with the strain. The study shows that the goose-derived Bacillus safensis DQC81, isolated from the cecum of healthy geese, has the ability to produce cellulase and protease and exhibits beneficial probiotic properties. This strain can therefore serve as a reference for the development of probiotic preparations and bio-fermented feed for geese.

Bovine viral diarrhea virus-1 (BVDV-1), recently reclassified as Pestivirus bovis, exists in cytopathic (CP) and non-cytopathic (NCP) biotypes and causes significant economic losses due to immunosuppression. However, the roles of specific immune checkpoints in BVDV pathogenesis remain unclear. This study investigated the immunomodulatory functions of programmed death-1 (PD-1) and P-selectin glycoprotein ligand-1 (PSGL-1) in murine models of CP and NCP BVDV infection. Both biotypes upregulated PD-1 and PSGL-1 expression on peripheral blood lymphocytes and CD8⁺ T cells, leading to leukopenia, lymphopenia, impaired proliferation, reduced IFN-γ secretion, increased apoptosis, and pathological damage. In CP BVDV infection, blockade of PD-1 or PSGL-1, alone or in combination, elevated leukocyte counts, enhanced CD8+ T-cell activation and proliferation, reduced pathology, inhibited viral replication, and activated the PI3K/Akt/mTOR pathway. In NCP BVDV infection, PSGL-1 blockade alone was ineffective, and significant immune improvement was achieved only through combined PD-1/PSGL-1 blockade, indicating a PD-1-dependent role for PSGL-1 in NCP BVDV infection. Mechanistically, PSGL-1 exhibits immune checkpoint-like activity in CP BVDV infection but acted as a co-regulator dependent on PD-1 signaling in NCP infection. These findings reveal a novel, biotype-specific mechanism of immune checkpoint regulation and provide a theoretical basis for biotype-tailored immunomodulatory strategies against BVDV infection in cattle.

Bovine Viral Diarrhea Virus (BVDV) causes severe economic losses in the cattle industry, threatening both animal health and food security. Its nonstructural protein Npro suppresses type I interferon (IFN-I) responses, yet the underlying mechanism remains incompletely defined. Here, we reveal that BVDV Npro hijacks host heat shock protein 70 (Hsp70) to serve as a degradation adaptor for the transcription factor ELF4, promoting its K48-linked polyubiquitination and proteasomal degradation. ELF4 loss blunts IFN-I signaling, impairing antiviral cytokine production. Notably, the plant flavonoid quercetin, a known Hsp70 inhibitor, blocks this interaction, rescues ELF4 expression, and restores IFN-I responses in vitro and in vivo, leading to significant suppression of viral replication. Our findings uncover a new immune evasion axis and highlight the potential of natural compounds like quercetin in developing sustainable antiviral strategies for livestock health.

Cytopathic (CP) bovine viral diarrhea virus (BVDV) infection is a major cause of lymphocyte dysfunction and immunosuppression in cattle; however, the involvement of the immune checkpoint P-selectin glycoprotein ligand-1 (PSGL-1) in this process remains poorly defined. In this study, bovine peripheral blood lymphocytes (PBL) — rather than total peripheral blood mononuclear cells (PBMCs) — were infected with CP BVDV in vitro. PBL were used because they consist primarily of T cells, B cells, and NK cells without the interference of monocytes/macrophages, allowing a more specific assessment of lymphocyte-intrinsic responses to BVDV infection and antibody blockade. The dynamic expression of PSGL-1, programmed death-1 (PD-1), and their ligands was analyzed by quantitative real-time PCR and Western blotting. Functional antibody blockade was employed to evaluate the effects of individual and combined PSGL-1 and PD-1 inhibition on lymphocyte proliferation, apoptosis, cytokine secretion, and viral replication.We found that CP BVDV infection significantly upregulated PSGL-1 and PD-1 expression in PBL. While blockade of either PSGL-1 or PD-1 partially restored lymphocyte function, combined blockade produced a pronounced synergistic effect, characterized by enhanced proliferation, reduced apoptosis, increased interferon-γ (IFN-γ) and interleukin-2 (IL-2) secretion, and suppression of viral replication. Mechanistically, this synergistic restoration was associated with reactivation of the PI3K/AKT/mTOR and ERK signaling pathways.Collectively, these findings identify PSGL-1 as a critical immune checkpoint involved in BVDV-induced lymphocyte exhaustion and demonstrate that combined PSGL-1/PD-1 blockade effectively restores antiviral lymphocyte function. This study provides new insight into host immune regulation during BVDV infection and highlights a potential combinatorial immunotherapeutic strategy for viral immunosuppression.

Bovine viral diarrhea virus (BVDV) infection induces severe immunosuppression and peripheral blood lymphopenia, driven by PD-1/PD-L1-mediated T cell exhaustion. Emerging evidence highlights 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃, VD), the active metabolite of vitamin D, as a critical modulator of antiviral immunity. However, its interplay with PD-1 signaling in BVDV pathogenesis remains unexplored. This study investigated the therapeutic potential of VD alone or combined with PD-1 blockade in a murine BVDV infection model. We found that BVDV infection significantly reduced serum and intracellular concentrations of VD. Supplementation with VD effectively improved these levels, downregulated PD-1/PD-L1 expression, reduced lymphopenia, and reduced CD8+ T cell apoptosis. While both monotherapies showed benefits, their combination yielded superior outcomes. The combined therapy significantly enhanced viral clearance, improved pathological changes in spleen and duodenum, and enhanced CD8⁺ T cell proliferation and IFN-γ production. Mechanistically, the combination uniquely upregulated key anti-apoptotic signaling molecules (p-Akt, p-mTOR, p-ERK) in CD8⁺ T cells. Notably, therapeutic efficacy differed between cytopathic (CP) and non-cytopathic (NCP) biotypes, with PD-1 blockade showing greater dependency in CP infection. These findings highlight the therapeutic potential of targeting both metabolic dysregulation (via VD) and immune checkpoint inhibition (via PD-1 blockade) to combat BVDV-induced immunosuppression. This dual strategy may offer a novel approach for treating viral infections characterized by metabolic-viral-immune interplay.

Introduction:Escherichia coli infection causes severe diarrhea, decreases growth performance, and increases mortality of poultry, which imposes a significant economic burden on the poultry industry and severely limits its growth. Methods:Here, to investigate the effects of Lactobacillus on the intestinal health, immune response, and growth performance of E. coli-infected goslings, we established a geese model infected with an Stx2f gene-carrying E. coli strain and analyzed the probiotic characteristics of three Lactobacillus isolates obtained from the cecum of healthy geese. In an in vivo study, Zi geese were administered daily gavage of L. johnsonii MC006, L. salivarius MC013, or L. fermentum MC018 (109 CFU/mL) from 1 d of age for 21 d, followed by treatment with E. coli XH197291 gavage (109 CFU/mL) on day 8. Results:The results showed that E. coli XH197291-infected geese exhibited depression, intestinal damage, reduced average daily gain, increased feed conversion ratio, and 100% diarrhea incidence within 48 h post-infection. Remarkably, among the three Lactobacillus isolates, L. fermentum MC018 showed the potential to function as a probiotic because of its ability to resist acid and bile degradation, antibacterial effect, and adhesion property. Notably, oral supplementation containing L. fermentum MC018 alleviated diarrhea and intestinal histological lesions, reduced E. coli counts in both ileum and rectum, increased the population of lactic acid bacteria, and improved the growth performance of E. coli-infected geese. Geese treated with L. fermentum MC018 gavage had higher serum diamine oxidase (p < 0.01) and IgM (p < 0.05) levels than those in the model group. L. fermentum MC018 reduced the levels of IL-1β, IL-6, and TNF-α in intestinal tissues following E. coli infection. Compared to L. salivarius MC013, L. fermentum MC018 increased the levels of ZO-1 in the duodenum and Claudin-1 in the ileum. Discussion:These findings suggest that L. fermentum MC018 is a promising probiotic strain for use as a potential alternative to antibiotics for controlling avian colibacillosis.

Bovine herpesvirus type 1 (BHV-1) seriously affects the production safety of the cattle industry and leads to epidemics worldwide. Luteolin (Lut), a flavonoid substance, can be found in vegetables, fruits, and herbs and possesses various biological properties. Here, we found that Lut can dose-dependently and significantly inhibit the cytopathic effects of BHV-1, decrease the viral titer, and suppress the BHV-1 gB gene and VP8 protein levels on bovine nasal turbinate osteoblasts (BT) and bovine kidney epithelial cells (MDBK). Mechanistic studies revealed that Lut can stably bind to the active sites of PI3K and AKT, and inhibit the PI3K/AKT pathway. Interestingly, 740Y-P (an agonist of the PI3K/AKT pathway) significantly attenuated the anti-BHV-1 effects of Lut. Further studies on the anti-inflammatory effects of Lut revealed that it attenuated BHV-1-induced activation of the NFκB pathway, which significantly suppressed the expression of TNF-α, IL-1β, IL-6, and IL-8 and increased the expression levels of IL-4 and IL-10. The PI3K/AKT pathway was also found to be involved in the anti-inflammatory effects of Lut. These results confirm the inhibitory effect of Lut on BHV-1 replication, which lays the foundation for further studies on the prevention and control of BHV-1.

Bovine viral diarrhea virus (BVDV) can cause typical peripheral lymphopenia and inhibit CD8+ T-cell activation and proliferation. Programmed death-1 (PD-1) blockade has been shown to increase CD8+ T-cell activation during cytopathic (CP) BVDV infection but not non-cytopathic (NCP) BVDV. Notably, ascorbic acid (AA) restores lymphocyte count and activation during SARS-CoV-2 and influenza virus infections and has a synergistic effect with PD-1 blockade to improve antitumor CD8+ T-cell activity. Nevertheless, it remains unclear whether AA exerts an immunomodulatory effect on the activation and proliferation of CD8+ T cells during BVDV infection, especially NCP BVDV infection, or whether PD-1 blockade and AA exert a synergistic effect in regulating CD8+ T cell antiviral activities. In this study, we found that BVDV infection significantly decreased AA levels in serum and CD8+ T cells in a BALB/c mouse model. Interestingly, AA supplementation dramatically downregulated PD-1 expression, restored the activation and proliferation of CD8+ T cells, inhibited viral replication, ameliorated BVDV-induced histological lesions, and upregulated the expression of CD25 and p-ERK. More importantly, we also found a synergistic effect of PD-1 blockade with AA in restoring the activation and proliferation of CD8+ T cells during CP BVDV infection. However, during NCP BVDV infection, a synergistic effect of PD-1 blockade and AA led to the inhibition of viral replication and the promotion of IFN-γ production. Our findings provided new insights into the immunopathological mechanisms of BVDV and the potential value of anti-viral strategies based on AA treatment alone or in combination with PD-1 blockade.

Bovine viral diarrhea virus (BVDV)-induced lymphopenia is associated with immune dysfunction. Vitamin C (VC) improves immune response by increasing peripheral blood lymphocyte (PBL) count, thereby promoting T-cell activation and release of IL-2 and IFN-γ. However, it remains unclear whether VC plays a critical positive regulatory role in the antiviral activities of CD4+ T cells during BVDV infection, or whether the combined treatment with VC and programmed death-1 (PD-1) blockade demonstrates a stronger effect in alleviating BVDV-induced lymphopenia. In this study, we found that both cytopathic (CP) and non-cytopathic (NCP) BVDV infection caused significant reductions in VC in plasma and PBLs of mice. VC supplementation alone or combined with PD-1 blockade significantly increased lymphocyte count and proliferation and upregulated the expression of CD25 and p-ERK in PBLs during CP and NCP BVDV infection. Furthermore, VC supplementation dramatically downregulated PD-1 expression, ameliorated CD4+ T-cell activation and proliferation, and inhibited apoptosis. We further investigated the effect of combined treatment with VC and PD-1 blockade on promoting CD4+ T-cell activation, increasing IFN-γ production, upregulating p-JAK2/p-STAT1 expression, and inhibiting viral replication during NCP BVDV infection. Remarkably, VC supplementation significantly increased IFN-γ production, upregulated p-JAK2/p-STAT1 expression, and reduced viral load in CD4+ T cells after NCP BVDV infection but not after CP BVDV infection. Our findings confirmed an essential regulatory role for VC in alleviating BVDV-induced lymphopenia and enhancing CD4+ T-cell antiviral immunity, as well as the combination's effect on VC and anti-PD-1 antibody during BVDV infection, thereby providing new insights to explore potential therapeutic strategies to control BVDV infection.

Bovine viral diarrhea virus (BVDV) has caused massive economic losses in the cattle business worldwide. Fatty acid synthase (FASN), a key enzyme of the fatty acid synthesis (FAS) pathway, has been shown to support virus replication. To investigate the role of fatty acids (FAs) in BVDV infection, we infected CD8+T lymphocytes obtained from healthy cattle with BVDV in vitro. During early cytopathic (CP) and noncytopathic (NCP) BVDV infection in CD8+ T cells, there is an increase in de novo lipid biosynthesis, resulting in elevated levels of free fatty acids (FFAs) and triglycerides (TG). BVDV infection promotes de novo lipid biosynthesis in a dose-dependent manner. Treatment with the FASN inhibitor C75 significantly reduces the phosphorylation of PI3K and AKT in BVDV-infected CD8+ T cells, while inhibition of PI3K with LY294002 decreases FASN expression. Both CP and NCP BVDV strains promote de novo fatty acid synthesis by activating the PI3K/AKT pathway. Further investigation shows that pharmacological inhibitors targeting FASN and PI3K concurrently reduce FFAs, TG levels, and ATP production, effectively inhibiting BVDV replication. Conversely, the in vitro supplementation of oleic acid (OA) to replace fatty acids successfully restored BVDV replication, underscoring the impact of abnormal de novo fatty acid metabolism on BVDV replication. Intriguingly, during BVDV infection of CD8+T cells, the use of FASN inhibitors prompted the production of IFN-α and IFN-β, as well as the expression of interferon-stimulated genes (ISGs). Moreover, FASN inhibitors induce TBK-1 phosphorylation through the activation of RIG-1 and MDA-5, subsequently activating IRF-3 and ultimately enhancing the IFN-1 response. In conclusion, our study demonstrates that BVDV infection activates the PI3K/AKT pathway to boost de novo fatty acid synthesis, and inhibition of FASN suppresses BVDV replication by activating the RIG-1/MDA-5-dependent IFN response.

Whether the high infection rate of BVDV is related to gut microbiota has not been reported. In addition, most studies on BVDV focus on in vitro experiments, which limits the study of its prevention and control strategy and its pathogenic mechanism. In this study, we successfully confirmed the causal relationship between gut microbiota and BVDV infection as well as the potential molecular mechanism based on a mouse model of BVDV infection and a mouse model of gut microbiota dysbiosis. Meanwhile, a mouse model which is more susceptible to BVDV provided in this study lays an important foundation for further research on prevention and control strategy of BVDV and its pathogenesis. In addition, the antiviral effect of butyrate, the metabolites of butyrate-producing bacteria, has been further revealed. Overall, our findings provide a promising prevention and control strategy to treat this infectious disease which is distributed worldwide.

Bovine viral diarrhea virus (BVDV) infection can result in typical peripheral blood lymphopenia and immune dysfunction. However, the molecular mechanism underlying the onset of lymphopenia remains unclear. B and T lymphocyte attenuator (BTLA) is a novel immune checkpoint molecule that primarily inhibits activation and proliferation of T cells. Blockade of BTLA with antibodies can boost the proliferation and anti-viral immune functions of T cells. Nonetheless, the immunomodulatory effects of BTLA in CD8+ T cells during BVDV infection remain unknown. Therefore, BTLA expression was measured in bovine peripheral blood CD8+ T cells infected with BVDV in vitro. Furthermore, the effects of BTLA or PD-1 blockade on CD8+ T cell activation, proliferation, and anti-viral immunological activities were investigated, as well as expression of signaling molecules downstream of BTLA, both alone and in combination. The results demonstrated that BTLA and PD-1 mRNA and protein levels were considerably increased in CD8+ T cells infected with cytopathic and non-cytopathic (NCP) BVDV. Surprisingly, as compared to blockade of either BTLA or PD-1, blockade of both dramatically increased proliferation and expression of CD25 and p-EKR of CD8+ T cells infected with NCP BVDV. Furthermore, blockade of BTLA, but not PD-1, had no effect on BVDV replication or IFN-γ expression. These findings confirmed the immunomodulatory roles of BTLA during BVDV infection, as well as the synergistic role of BTLA and PD-1 in NCP BVDV infection, thereby providing new insights to promote activation and the anti-viral immunological activities of CD8+ T cells.

For many viruses, controlling the process of infection is largely dependent on the enzymes of the fatty acid synthesis (FAS) pathway. An appealing therapeutic target in antiviral research is fatty acid synthetase (FASN), a crucial enzyme in the FAS pathway. Bovine viral diarrhea, caused by the Bovine viral diarrhea virus (BVDV), is a significant viral infectious disease posing a substantial threat to global animal husbandry. Our study revealed that BVDV infection not only upregulates the expression of FAS-related enzymes in BT cells and the blood, liver, and spleen of mice but also markedly enhances the accumulation of lipid droplets, free fatty acids, and triglycerides. The FAS pathway plays a pivotal role throughout the entire BVDV replication cycle. Additionally, administration of the FASN inhibitor C75 and Acetyl CoA carboxylase-1 (ACC-1) inhibitor TOFA significantly reduced the viral content in both serum and organs of BVDV-infected mice, exhibiting inhibitory effects across diverse viral strains. Intriguingly, We found that RIG-1/TBK1-mediated IFN-I signaling inhibits SREBP-1/FAS and reduces BVDV replication. Conversely, targeting a few essential enzymes of SREBP-1/FAS also activates IFN-I signaling. More importantly, FASN inhibitor led to heightened expression of ISGs in mouse spleens by activating the RIG-1/TBK-1 pathway. These findings highlight that FASN inhibitors inhibit BVDV replication through the activation of the RIG-1/TBK-1 pathway to induce ISGs, and offering a novel therapeutic approach for combating BVDV. Thus, it is crucial to negatively regulate SREBP-1/FAS signaling molecules in order to create novel antiviral drugs that are safe, effective, and broad-spectrum.

Endometritis is a common disease that endangers human and animal health. Cyanidin-3-O-glucoside (C3G), a kind of anthocyanin, exists in a variety of plants and shows many biological activities. Here, we investigated the effect and mechanism of C3G on LPS-induced endometritis in mice. The results showed that C3G significantly decreased wet to dry weight (W/D) ratio of uterine, improved uterine pathological injury, and inhibited MPO activity. Further mechanism investigation showed that the activation of NFκB pathway and the levels of TNF-a, IL-1β, and IL-6 were significantly suppressed after C3G treatment. Conversely, C3G promoted LPS-induced the activation of the PPARγ/ABCA1 pathway. Interestingly, the anti-inflammatory effect of C3G was significantly weakened by GW9662, a PPARγ inhibitor. In addition, the anti-oxidative stress effect of C3G was also found. For the first time, our results showed that treatment with C3G might be a new strategy for treating endometritis.

Although bitter receptors, known as Tas2Rs, have been identified in the testes and mature sperm, their expression in testicular Sertoli cells (SCs) and their role in recognizing harmful substances to maintain the immune microenvironment remain unknown. To explore their potential function in spermatogenesis, this study utilized TM4 cells and discovered the high expression of the bitter receptor Tas2R143 in the cells. Interestingly, when the Tas2R143 gene was knocked down for 24 and 48 h, there was a significant downregulation (P < 0.05) in the expression of tight junction proteins (occludin and ZO-1) and NF-kappa B. Additionally, Western blot results demonstrated that the siRNA-133+NF-kappa B co-treatment group displayed a significant downregulation (P < 0.05) in the expression of occludin and ZO-1 compared to both the siRNA-133 transfection group and the NF-kappa B inhibitors treatment group. These findings suggest that Tas2R143 likely regulates the expression of occludin and ZO-1 through the NF-kappa B signaling pathway and provides a theoretical basis for studying the regulatory mechanism of bitter receptors in the reproductive system, aiming to attract attention to the chemical perception mechanism of spermatogenesis.

Bovine viral diarrhea virus (BVDV) is prevalent worldwide and is an important pathogen that represents a serious threat to the development of the cattle industry by causing significant economic losses. Liver X receptors (LXRs) are members of the nuclear receptor superfamily and have become attractive therapeutic targets for cardiovascular disease. In the present study, we found that LXRs in both Madin-Darby bovine kidney (MDBK) cells and mice were associated with BVDV infection. GW3965, an agonist for LXRs, significantly inhibited BVDV RNA and protein levels in MDBK cells. In vivo studies in a mouse model also confirmed the inhibitory role of GW3965 in BVDV replication and the ameliorating effect of GW3965 on pathological injury to the duodenum. In vitro investigations of the potential mechanisms involved showed that GW3965 significantly inhibited BVDV-induced increases in cholesterol levels and viral internalization. Furthermore, the antiviral activity of GW3965 was significantly reduced following cholesterol replenishment, thus demonstrating that cholesterol was involved in the resistance of GW3965 to BVDV replication. Further studies indicated the role of ATP-binding cassette transporter A1 (ABCA1) and cholesterol-25-hydroxylase (CH25H) in the antiviral activity of GW3965. We also demonstrated the significant antiviral effect of 25hydroxycholesterol (25HC), a product of the catalysis of cholesterol by CH25H. In addition, the anti-BVDV effects of demethoxycurcumin (DMC), cyanidin-3-O-glucoside (C3G), and saikosaponin-A (SSA), three natural agonizts of LXRs, were also confirmed in both MDBK cells and mice. However, the antiviral activities of these agents were weakened by SR9243, a synthetic inhibitor of LXRs. For the first time, our research demonstrated that the activation of LXRs can exert significant anti-BVDV effects in MDBK cells and mice.