Search Results (1,745)

The Influenza A Virus (IAV) is known to hijack cellular proteins during its replication. IAV infection increases the expression of Heat-shock-protein family A (Hsp70) member 5 (HSPA5) in human cells, but its specific function in the viral life cycle remains unclear. This study aims to elucidate the function of HSPA5 in IAV replication, by implementing HSPA5 knockdown (KD) in A549 cells and assessing its impact on IAV’s viral protein translation, genomic RNA transcription, and the host cellular proteome. HSPA5 KD significantly reduced progeny virus release, although viral RNA levels were unaffected. Interestingly, levels of viral structural proteins increased in HSPA5 KD cells after infection. Treatment with HSPA5 inhibitor also suppressed IAV replication, confirming its role as a host dependency factor. Proteomic profiling revealed 116 proteins altered in wild-type cells and 223 in HSPA5 KD cells, with 32 uniquely dysregulated in wild-type and 139 unique to HSPA5 KD cells. In HSPA5 knockdown cells, the altered proteins were linked to pathways such as EIF2, EGF, PEDF, CNTF, IL-13, and G-protein receptor signaling, as well as to cellular processes like lymphocyte activation and regulation of immune and blood cell death, which were not affected in wild-type cells after IAV infection. Overall, this study suggests that HSPA5 contributes to late stages of IAV replication, likely assembly or maturation, and represents a promising target for antiviral drug development. Full article

Streptococcus suis serotype 2 (SS2) is a major zoonotic pathogen causing infectious disease in various species, whose pathogenesis is still not well understood. The sodA gene is an important virulence gene of SS2 involved in the host’s immune response against pathogens. This study aimed to explore the impact of superoxide dismutase A (sodA) gene deletion on the pathogenicity of SS2 to mice. In this study, mice were grouped as control, WT, and ΔsodA, which were intraperitoneally injected with PBS, wild-type strain HA9801, and ΔsodA strain, respectively. WT proved to be a more virulent strain to mice with higher bacterial loads and survival rates in mice than those for ΔsodA. Moreover, more-severe tissue damage was observed in the lungs, liver, spleen, and kidneys of mice injected with WT than with ΔsodA. Additionally, macrophages accumulate to defend against SS2, and the results indicated that sodA gene deficiency decreased macrophage recruitment. In in vitro studies, caspase-1 and gasdermin D (GSDMD) were activated in macrophages induced by SS2; however, the absence of the sodA gene significantly inhibited the expression of pro-caspase-1, caspase-1, and GSDMD-N. Moreover, deletion of the sodA gene also decreased Interleukin-1 beta (IL-1β) and Interleukin-18 (IL-18) release in macrophages induced by SS2. Taken together, the absence of the sodA gene alleviated the pathogenicity of SS2 as a result of decreased macrophage accumulation and breakage of the caspase-1/GSDMD pathway in macrophages. Full article

Host innate immunity is crucial for orchestrating a protective response against dangerous pathogens. Herein, we demonstrate that interferon-inducible protein (IFI204), a DNA sensor, is implicated in protection against pulmonary pathogenic Mannheimia haemolytica (M. haemolytica) infection by driving inflammasome signaling activation. Ifi204^−/− mice are more susceptible to pathogenic M. haemolytica infection compared with their wild-type (WT) counterparts, with decreased survival rates, extensive lung architecture destruction, exacerbated inflammatory cells infiltration, and more bacterial colonization. In vivo and in vitro findings elucidate that Ifi204 deficiency leads to a defect in inflammasome signaling activation, and exogenous recombinant IL-18 is sufficient to rescue the susceptibility of Ifi204^−/− mice. Inflammasome signaling downstream of IFI204 facilitates early bacterial killing and clearance. Mechanistically, IFI204 promotes gasdermin D (GSDMD)-dependent inflammasome activation, and GSDMD is required for IFI204-mediated host defense. Notably, IFI204 detects pathogenic M. haemolytica-derived genomic DNA for the inflammasome signaling response. Thus, these data highlight the requirement of IFI204 in host defense response to M. haemolytica infection, and reveal that IFI204 may be a potential therapeutic target for pathogen control. Full article

The Nearctic leafhopper Scaphoideus titanus is the primary vector of Flavescence Dorée, a severe grapevine disease in Europe. This insect can complete its life cycle on both cultivated Vitis vinifera and American Vitis species, including rootstock-derived plants that have gone wild. While the movement of S. titanus between wild and cultivated vines is well documented, its biological implications remain unclear, particularly regarding the role of the insect-associated microbiome. In this study, we investigated how rearing S. titanus nymphs on different host plants, including American Vitis and several V. vinifera cultivars, affects its bacterial community. 16S rRNA metabarcoding revealed that the bacterial microbiome was dominated by two obligate symbionts, namely ‘Candidatus Karelsulcia’ and ‘Candidatus Cardinium’, with moderate but significant differences in microbial diversity among host plants and developmental stages. When these dominant symbionts were excluded, variability in the remaining bacterial community increased, indicating a modulation of minor taxa according to the plant offered. These findings suggest that host plant species influence the microbiome structure, potentially affecting the insect performance and the microbial exchange between wild and cultivated vines in the field, contributing to disease dynamics. Full article

This research characterized a novel Komagataella phaffii strain generated through intraspecific crossing between a wild isolate and a laboratory strain. This segregant, called S467, expressed 2.2-fold more secreted recombinant β-glucosidase than its parental strains in microtiter scale, which suggested that S467 could be an attractive host for bioprocess optimization. S467 was grown alongside the laboratory strain CBS7435 expressing β-glucosidase (CBS_BGL9), as a control, in a 1.5 L bioreactor to determine kinetics parameters, and similar cell growth rate (0.12 h⁻¹) but higher recombinant protein activity, measured as enzymatic activity, was observed in S467. The effect of specific cell growth rate was studied using continuous cultures (chemostat) at different dilution rates, identifying conditions that provided up to a twofold increase in enzymatic activity in S467. RT-qPCR was conducted on key genes associated with the genetic background of S467, in order to clarify differences at the transcriptomic level that render S467 as a potential superior host for recombinant protein production. Overall, this study provides quantitative evidence of the positive effect of the natural isolate IRA1 allele for the generation of recombinant β-glucosidase and highlights the usability of natural genetic diversity in K. phaffii. Full article

BK polyomavirus (BKPyV) causes severe urinary tract diseases, including BKPyV-associated nephropathy (BKPyVN) and ureteric stenosis, in immunocompromised individuals such as renal transplant recipients. Effective antiviral therapies for BKPyV infection remain an unmet clinical need. While the interferon-stimulated gene 20 (ISG20) exhibits broad-spectrum antiviral activity against RNA viruses, its role and mechanisms against DNA viruses are poorly defined. This study demonstrates, for the first time, potent antiviral activity of ISG20 against BKPyV. This restriction was observed with both endogenous levels of ISG20 and upon overexpression, and this effect was confirmed by ISG20 knockout and immunofluorescence imaging. We observed that ISG20 expression is dynamically regulated during BKPyV infection: it is upregulated both during early infection and by expression of the viral large T antigen (LT) alone. However, endogenous ISG20 expression becomes significantly suppressed during later stages of infection, coinciding with declining LT levels. The physical interaction between LT and both wild-type and mutant ISG20 suggests a potential viral strategy to sequester this restriction factor. These findings establish ISG20 as a novel host restriction factor against BKPyV and suggest that BKPyV employs LT-mediated mechanisms to evade or counteract ISG20’s antiviral effects. Our results elucidate a complex biphasic interplay between BKPyV and host innate immunity, identifying ISG20 as a potential therapeutic target for BKPyV-associated diseases. Full article

To characterize freshwater bivalve communities and their environmental drivers in the Caizi Lake water system following the 10-year fishing ban in Yangtze River, this study three rounds of standardized surveys across hydrological periods in 2024—May (normal-water), September (high-water), and November (low-water). The results recorded 22 freshwater bivalve species belonging to 15 genera and 4 families. Notably, Ptychorhynchus pfisteri and the second-class national key protected wild animals in China, Lamprotula leaii and Uninovaculina chinensis, were first recorded in the Caizi Lake water system. Community composition was partitioned into three subgroups: Group I—Dasha River, Guache River, Longmian River, and Kongcheng River; Group II—the lake area; and Group III—Chang River. Biomass, density, and dominant species exhibited pronounced spatial heterogeneity, and the assemblage reflected a state of moderate disturbance. Redundancy analysis indicated that the variables that contribute significantly to species richness in sequence are the bitterling and suitable host fish, phytoplankton, and zooplankton. The research results reveal for the first time the population status and distribution patterns of bivalve resources in the Caizi Lake water system following the fishing ban. They not only provide a decision-making basis for the conservation and protection management of bivalve resources in the Caizi Lake water system but also offer data support for the assessment of the fishing ban effect and the evaluation of biological integrity in key waters of Anhui Province. Full article

There is increasing research interest in the ORF3 accessory protein of PEDV as a critical element for viral virulence. Here, wild type ORF3 (ORF3_wt) gene was constructed in pEGFP-C1 vector. Additionally, two truncation mutants, ORF3-N (1-98 amino acids [aa]) and ORF3-C (99-224 aa) were inserted in the same vector. Results of ORF3 expression revealed early cytoplasmic localization but 12 h after transfection, ORF3 accumulated around the nucleus, especially ORF3-N. This caused chromosome condensation and morphological distortion that culminated in cell death. In comparison with the native cells expressing GFP alone, ORF3wt-induced lethality was 6.61% above baseline while ORF3- C expression resulted in moderate increase in cell death (0.64%). ORF3-N was affected the most with 220.32% increased lethality. It was, therefore, inferred that the ORF3 gene encodes a protein that causes nuclear damage, distorts cell morphology and leads to cell death. Furthermore, the role of the protein could be inherent in the N-terminal domain, which consists of the transmembrane domains. These findings underpin the importance of ORF3 gene expression in the host and are rudimental insights for further exploration into the mechanistic interactions of ORF3 and the host, as well as a possible role in pathogenesis in PEDV and other coronaviruses. Full article

The structure and assembly mechanism of wild animal gut microbiota represent persistent research hotspots. Among, the impact of geographic factors on the bacterial co-occurrence network characteristics and assembly mechanism of the gut microbiome remains unclear. Therefore, this study analyzed the gut microbiome of Niviventer confucianus and Apodemus agrarius from Anhui and Hubei provinces. The same alpha diversity pattern was found in the gut microbiome of species from the same region. The gut microbiome of the two rodent species in Anhui region exhibited “small world” characteristics, such as nodes with more local connections to allow interaction information (such as metabolites) to rapidly spread throughout the entire microbial community. In addition, dispersal limitations and heterogeneous selection accounted for higher proportions of the gut microbiome in the rodents from the Anhui and Hubei regions, respectively. The higher proportion of heterogeneous selection may exacerbate selection pressure in the Hubei region. Multiple regression on distance matrices analysis revealed that geographic region exerted a limited but significant influence (0 < R² < 0.2, * p < 0.05) on the gut microbiome, surpassing the effects of host phylogeny, gender, and weight. Nevertheless, the roles of regional factors—such as environmental microbes, pollutants, and diet—remain unexamined, and their potential as key drivers of microbiota variation in these rodents warrants further investigation. Full article

Przewalski’s gazelle (Procapra przewalskii) is an endangered ungulate endemic to the Qinghai–Tibet Plateau, with a small population size and exposure to multiple ecological pressures. Its gut microbiota may play a crucial role in host environmental adaptation. To investigate the functional divergence of gut microbial communities, we performed high-throughput metagenomic sequencing on 105 wild fecal samples collected from 10 geographic regions around Qinghai Lake. The results revealed significant regional differentiation in key functional modules related to metabolism, antibiotic resistance mechanisms, and virulence-associated pathways. All populations showed enrichment in core metabolic pathways such as carbohydrate and amino acid metabolism, with carbohydrate-active enzymes dominated by glycoside hydrolases (GHs) and glycosyltransferases (GTs), exhibiting overall functional conservation. Although populations shared many antibiotic- and virulence-related reference genetic markers, the marker composition associated with distinct resistance mechanisms and pathogenic processes exhibited clear population-specific patterns, suggesting differential microbial responses to local environmental pressures. Correlation network analysis further identified core taxa (e.g., Arthrobacter and Oscillospiraceae/Bacteroidales lineages) as key genera linking community structure with core metabolic, resistance-related, and virulence-associated marker functions. Overall, the gut microbiota of Przewalski’s gazelle exhibits a complex spatially structured functional differentiation, reflecting host–microbiome co-adaptation under region-specific ecological pressures. These findings provide critical methodological and theoretical support for microecological health assessment and regionally informed conservation management of this endangered species. Full article

The use of fungal entomopathogens, such as Metarhizium anisopliae, is a promising alternative for pest biocontrol but suffers the disadvantage of a relatively slower killing speed when compared with chemical pesticides. Nilaparvata lugens (brown planthopper, BPH) is a destructive sap-sucking pest that seriously threatens rice production worldwide. In the present study, we characterized a key immune-regulating protein, Spätzle (SPZ), encoding gene NlSPZ5 in BPH, and constructed a transgenic strain of M. anisopliae that expressed a specific dsRNA targeting the NlSPZ5 gene for enhancing the fungal virulence. Expression pattern analysis revealed that NlSPZ5 was expressed with the highest levels in the second-instar nymphs and hemolymph and could be largely activated by M. anisopliae infection. Microinjection of dsNlSPZ5 resulted in a markedly decreased survival rate and increased susceptibility to fungal infection in BPH. Notably, a transgenic strain of M. anisopliae expressing dsNlSPZ5 could effectively suppress the target gene expression and promote fungal proliferation in BPH upon fungal challenge. Compared to the wild-type strain, the transgenic fungal strain exhibited significantly enhanced insecticidal efficacy against BPH without compromising mycelial growth and sporulation. Our results demonstrate that fungal entomopathogens used as a delivery vector to express dsRNAs targeting insect immune defense-associated genes can effectively augment their virulence to the host insect, providing clues to develop novel pest management strategies through the combination of RNAi-based biotechnology and entomopathogen-based biocontrol. Full article

Glycogen metabolism plays a key role in bacterial adaptation. In Streptococcus pneumoniae, the glycogen-degrading enzyme SpuA is widely conserved, but its physiological significance remains unclear. In this study, we investigated how SpuA affects bacterial growth and response to acid stress. We found that the spuA deletion strain (ΔspuA) produced more acidic metabolites under anaerobic conditions than the wild-type strain. In a mouse infection model, bronchoalveolar lavage fluid (BALF) from ΔspuA-infected mice was more acidic on day 1 post-infection, showing a lower bacterial load than wild-type infection—a finding consistent with the early growth delay observed in vitro—but the mutant later exhibited enhanced persistence at 72 h. ΔspuA strains also showed greater tolerance to formic acid and higher intake of serum amyloid A1 (SAA1), which may further contribute to their survival in acidic environments. Transcriptomic analysis revealed reduced utilization of certain amino acids, particularly cysteine, in ΔspuA strains. However, the addition of 0.05% (v/v) formic acid restored amino acid utilization in ΔspuA strains, and co-supplementation with formic acid and cysteine significantly enhanced ΔspuA growth in vitro. These findings suggest that in the absence of SpuA, S. pneumoniae shifts its metabolism toward formic acid production, which may act both as a metabolic signal and a stressor that influences bacterial gene expression. This shift is accompanied by increased expression of tRNAs and growth rescue, suggesting enhanced amino acid utilization capacity. Although our findings reveal a potential link between formic acid metabolism and amino acid utilization through tRNA regulation, further validation using metabolic flux analyses or targeted metabolomics will be required to confirm this relationship. These observations imply a metabolic adaptation that facilitates bacterial growth under low-oxygen, acidic conditions during infection. Our results also raise the possibility that SpuA plays a role in restraining bacterial overgrowth in the host, thereby promoting a more balanced coexistence between pathogen and host. Full article

The SARS-CoV-2 spike protein, through its receptor binding domain (S1-RBD), binds to the angiotensin-converting enzyme 2 (ACE2) receptor on the host cell membrane, leading to viral infection. Several mutations in S1-RBD in SARS-CoV-2 variants are known to enhance infection through an increased affinity for ACE2. While many reports are available describing the SARS-CoV-2 infection mechanism, there is a dearth of studies towards understanding the initial interaction of the S1-RBD with ACE2 on living host cells and the role of endocytosis and cytoskeleton in the process. Here, we reconstituted the interaction between S1-RBD- and ACE2-expressing host cells in a hybrid live cell-supported lipid bilayer (SLB) platform enabling live monitoring of the interaction between S1-RBD on SLBs and the ACE2 receptor on living cells and showed that cells depleted Omicron S1-RBD from SLB corrals, likely through endocytosis. Specifically, interaction of living host cells with S1-RBD-functionalized SLB substrates resulted in the enrichment of S1-RBD and ACE2 at the cell–SLB interface. Interaction of host cells with wild type (WT), Omicron, and Omicron Revertant S1-RBD functionalized on micron-scale SLB corrals, which mimic viral membranes but are flat, also resulted in their enrichment. However, cells interacting with Omicron S1-RBD revealed a depletion of the protein from many corrals, which was generally not observed with the WT S1-RBD and was reduced with the Omicron Revertant, which contains the Q493R mutation reversion, S1-RBD. Further, S1-RBD depletion coincided with the localization of the early endosomal marker EEA1. Importantly, treatment of cells with the clathrin inhibitor, pitstop 2, but not the myosin II inhibitor, blebbistatin, significantly reduced Omicron S1-RBD depletion. Collectively, these observations suggest that the SARS-CoV-2 Omicron variant has evolved, through mutations in its S1-RBD, to take advantage of the cellular endocytic pathway for enhanced infection, which is not observed with the parental SARS-CoV-2 and appears to be lost in the Omicron Revertant variant. Additionally, these results underscore the significance of the hybrid live cell–SLB platform in studying SARS-CoV-2 S1-RBD-ACE2 interaction and the potential impact of mutations in the S1-RBD on adapting to a specific cellular entry mechanism. Full article

Yersinia pestis, the causative agent of plague, is arguably the most devastating pathogen in human history. Paleogenomic studies indicate its presence as early as the Neolithic era. It evolved from Yersinia pseudotuberculosis, with divergence estimates ranging from 1500 to 20,000 years ago, most often placed around 5000 years ago. Its natural reservoirs are wild mammals, particularly rodents, with fleas serving as vectors, while humans are incidental hosts. Over time, Y. pestis has acquired multiple virulence factors that disrupt immune responses and can lead to rapid, often fatal disease. Because the bacterium is maintained in wildlife cycles and can spill over to domestic animals, eradication is difficult, if not impossible. Nevertheless, mitigation is achievable using a One Health approach integrating human health, animal health, and the health of the environment. Neither vaccines nor monoclonal antibodies are currently licensed in most Western countries, thus, antibiotics remain the mainstay of therapy. Timely administration, ideally within 24 h of symptom onset, is critical, particularly in pneumonic forms. Phage therapy is under investigation as a potential treatment. Though often neglected in high-income settings, plague remains endemic in several regions, with the highest burden reported in Madagascar and the Democratic Republic of the Congo. Full article

African swine fever (ASF) is a highly contagious and virulent infectious disease caused by the African swine fever virus (ASFV), with mortality rates approaching 100% in domestic pigs. The global spread of ASF has caused enormous losses to the swine industry and species diversity, seriously affecting food safety in China. ASFV mainly infects the mononuclear system, inducing significant alterations in host-cell gene expression. Multigene family 360 (MGF360) genes play crucial roles in ASFV infection. To investigate the function of MGF360–4L, this study employed high-throughput RNA sequencing to analyze dynamic transcriptomic changes in porcine alveolar macrophages (PAMs) infected with wild-type ASFV (ASFV-WT) or MGF360–4L deletion mutant (ASFVΔMGF360–4L). Results demonstrated that both viruses activated host innate immune responses during early infection, significantly upregulating immune-related genes. At 16 h post-infection, differentially expressed genes in ASFV-WT- and ASFVΔMGF360–4L-infected cells were enriched in aminoacyl-tRNA biosynthesis pathways, suggesting a potential involvement of MGF360–4L in this process. This study elucidates novel ASFV–host interactions using transcriptomics, providing data to support ASF control strategies. Full article