Search Results (342)

Curli fimbriae are a major component of biofilm formation in Escherichia coli, and their expression is regulated by numerous transcription factors and small regulatory RNAs (sRNAs). The RcsD-RcsC-RcsB phosphorelay system, which is involved in the envelope stress response, plays a role in this regulation. In this study, we report that DNase-I footprinting analysis revealed that the response regulator RcsB interacts with the −31 to +53 region of the promoter region of csgD, which encodes a major regulator of biofilm formation, and thus contributes to its transcriptional repression. Additionally, overexpression of RcsB or RcsB D56A that could not be phosphorylated by the histidine kinases RcsC and D both significantly reduced csgD expression and suppressed Curli formation. This indicates that the phosphorylation of RcsB has an insignificant impact on its affinity for its operator sites. Furthermore, we confirm that RcsB binds cooperatively to the csgD promoter region in the presence of the nucleoid-associated protein H-NS. Our study also confirms that RcsB positively regulates the expression of an sRNA, RprA, which is known to reduce mRNA csgD mRNA translation RprA via its binding to the 5′-untranslated region (UTR) of csgD. These findings indicate that, in E. coli, the RcsBCD system suppresses csgD expression through both direct transcriptional repression by the regulator RcsB and translational repression by the sRNA RprA. Full article

In December 2023, infections of western equine encephalitis virus (WEEV) within Argentina were reported to the World Health Organization (WHO). By April 2024, more than 250 human infections, 12 of which were fatal, and 2500 equine infections were identified in South America. Laboratory diagnosis and surveillance in affected countries were hindered by a lack of facilities equipped with BSL-3 laboratories, as confirmatory serodiagnosis for WEEV requires live virus in the plaque reduction neutralization test (PRNT). To expand serodiagnosis for WEEV in the Americas, we developed a virus chimera composed of vesicular stomatitis virus (VSV) engineered to display the E2-E1 glycoproteins of WEEV (VSV/WEEV) in place of the VSV glycoprotein (G). PRNT₉₀ and IC₉₀ values of parental WEEV and VSV/WEEV were analogous using sera collected from mice, horses, and chickens. VSV/WEEV rapidly formed plaques with clear borders and reduced the assay readout time by approximately 8 h compared to the parental virus. Overall, we demonstrate that chimeric VSV/WEEV is a suitable surrogate for WEEV in a diagnostic PRNT. Use of chimeric VSV/WEEV in place of authentic WEEV will dramatically expand testing capacity by enabling PRNTs to be performed at BSL-2 containment, while simultaneously decreasing the health risk to testing personnel. Full article

The Akabane virus (AKAV) is a significant member of the Orthobunyavirus genus, with its envelope glycoprotein Gc, focusing on its molecular structural features, immunoregulatory mechanisms, and application value in pathogen diagnosis and vaccine design. As a key structural protein of AKAV, Gc mediates virus adsorption and neutralizing antibody recognition through the N-terminal highly variable region (HVR), while the C-terminal conserved region (CR) dominates the membrane fusion process, and its glycosylation modification has a significant regulatory effect on protein function. In clinical diagnostics, serological assays based on Gc proteins (e.g., ELISA, immunochromatographic test strips) have been standardized; in vaccine development, the neutralizing epitope of Gc proteins has become a core target for subunit vaccine design. Follow-up studies were deeply needed to analyze the structure-function interaction mechanism of Gc proteins to provide theoretical support for the construction of a new type of AKAV prevention and control system. Full article

The 2016 Zika virus (ZIKV) epidemic has largely subsided, but a key question remains. How did ZIKV evolve to become a virulent human pathogen compared to the virus of its original discovery? What specific virologic and pathologic changes contributed to increased pathogenicity in humans? Phylogenetic studies have identified two genetically distinct ZIKV, the African and Asian lineages, which differ in their pathogenicity. Previous studies including ours suggest that the envelope (E) protein plays a key role in viral entry, immune activation, and neuropathogenesis. This study aimed to further elucidate virologic and pathogenic differences between these lineages by assessing their ability to bind and replicate in host cells, induce apoptotic cell death, trigger inflammatory responses, and influence human neural progenitor cell (hNPC)-derived neurosphere formation. We compared a historic African ZIKV strain (MR766) with an epidemic Brazilian strain (BR15) and evaluated the effects of the E protein inhibitor quercetin-3-β-O-D-glucoside (Q3G) and an E protein-neutralizing antibody (AbII). Our results revealed distinct virologic properties and that MR766 exhibited stronger inhibition of neurosphere formation due to enhanced viral binding to neuronal SH-SY5Y cells, while BR15 infection triggered a heightened pro-inflammatory cytokine response with reduced viral binding. Chimeric virus studies suggested that the E protein likely influences viral binding, replication efficiency, immune activation, and neuropathogenesis. Notably, Q3G exhibited antiviral activities against both MR766 and BR15, whereas AbII preferentially inhibited MR766. These findings highlight the virological differences between ancestral and epidemic viral strains, as well as the critical role of E protein in viral permissiveness, immune response, and neuropathogenesis, providing insights for developing targeted antiviral strategies. Full article

Background/Objectives: Cutaneous melanoma is one of the aggressive forms of skin cancer originating from melanocytes. The high incidence of melanoma metastasis continues to rise, partly due to the complex nature of the molecular mechanisms driving its progression. While melanomas generally arise from melanocytes, we investigated whether aberrant keratinocyte differentiation pathways—like cornified envelope formation—discriminate primary melanoma from metastatic melanoma, revealing novel biomarkers in progression. Methods: In the present study, we retrieved four datasets (GSE15605, GSE46517, GSE8401, and GSE7553) associated with primary and metastatic melanoma tissues and identified differentially expressed genes (DEGs). Thereafter, an integrated meta-analysis and functional enrichment analysis of the DEGs were performed to evaluate the molecular mechanisms involved in melanoma metastasis, such as immune cell deconvolution and protein-protein interaction (PPI) network construction. Hub genes were identified based on four topological methods, including ‘Betweenness’, ‘MCC’, ‘Degree’, and ‘Bottleneck’. We validated the findings using the TCGA-SKCM cohort. Drug-gene interactions were evaluated using the DGIdb, whereas structural druggability was assessed using the ProteinPlus and AlphaFold databases. Results: We identified a total of eleven hub genes associated with melanoma progression. These included members of the keratin gene family (e.g., KRT5, KRT6A, KRT6B, etc.). Except for the gene CDH1, all the hub genes were downregulated in metastatic melanoma tissues. From a prognostic perspective, these hub genes were associated with poor prognosis (i.e., unfavorable). Using the Human Protein Atlas (HPA), immunohistochemistry evaluation revealed mostly undetected levels in metastatic melanoma. Additionally, the cornified envelope formation was the most enriched pathway, with a gene ratio of 17/33. The tumor microenvironment (TME) of metastatic melanomas was predominantly enriched in NK cell–associated signatures. Finally, several hub genes demonstrated favorable druggable potential for immunotherapy. Conclusions: Through integrated meta-analysis, this study identifies transcriptional, immunological, and structural pathways to melanoma metastasis and highlights keratin family genes as promising biomarkers for therapeutic targeting. Full article

Introduction: Genetic plasticity and adaptive camouflage in critical pathogens have contributed to the global surge in multidrug-resistant (MDR) infections, posing a serious threat to public health and therapeutic efficacy. Antimicrobial resistance, now a leading cause of global mortality, demands urgent action through diagnostics, vaccines, and therapeutics. In India, the Indian Council of Medical Research’s surveillance network identifies Escherichia coli as a major cause of urinary tract infections, with increasing prevalence in human gut microbiomes, highlighting its significance across One Health domains. Methods: Whole-genome sequencing of E. coli strain ECG015, isolated from a human gut sample, was performed using the Illumina NextSeq platform. Results: Genomic analysis revealed multiple antibiotic resistance genes, virulence factors, and efflux pump components. Phylogenomic comparisons showed close relatedness to pathovars from both human and animal origins. Notably the genome encoded protein tyrosine kinases (Etk/Ptk and Wzc) and displayed variations in the envelope stress-responsive CpxAR two-component system. Promoter analysis identified putative CpxR-binding sites upstream of genes involved in resistance, efflux, protein kinases, and the MazEF toxin–antitoxin module, suggesting a potential regulatory role of CpxAR in stress response and persistence. Conclusions: This study presents a comprehensive genomic profile of E. coli ECG015, a gut-derived isolate exhibiting clinically significant resistance traits. For the first time, it implicates the CpxAR two-component system as a potential central regulator coordinating antimicrobial resistance, stress kinase signaling, and programmed cell death. These findings lay the groundwork for future functional studies aimed at targeting stress-response pathways as novel intervention strategies against antimicrobial resistance. Full article

Anti-infectives include molecules that target microbes in the context of infection but lack antimicrobial activity under conventional growth conditions. We previously described D66, a small molecule that kills the Gram-negative pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) within cultured macrophages and murine tissues, with low host toxicity. While D66 fails to inhibit bacterial growth in standard media, the compound is bacteriostatic and disrupts the cell membrane voltage gradient without lysis under growth conditions that permeabilize the outer membrane or reduce efflux pump activity. To gain insights into specific bacterial targets of D66, we pursued two genetic approaches. Selection for resistance to D66 revealed spontaneous point mutations that mapped within the gmhB gene, which encodes a protein involved in the biosynthesis of the lipopolysaccharide core molecule. E. coli and S. Typhimurium gmhB mutants exhibited increased resistance to antibiotics, indicating a more robust barrier to entry. Conversely, S. Typhimurium transposon insertions in genes involved in outer membrane permeability or efflux pump activity reduced fitness in the presence of D66. Together, these observations underscore the significance of the bacterial cell envelope in safeguarding Gram-negative bacteria from small molecules. Full article

This study aimed to develop monoclonal antibodies (mAbs) against the gD protein of FHV-1 for rapid and specific virus detection. The gD protein, a highly conserved part of the FHV-1 envelope, is crucial for viral entry into host cells, making it an ideal detection target. We immunized BALB/c mice with an mRNA vaccine encoding the gD gene, achieving a serum antibody titer of 1:140,000 after three immunizations. The mice were then boosted with recombinant gD protein. Through cell fusion and multiple subcloning rounds, we obtained five hybridoma cell lines (D7, E4, E9, E10, and E19) that stably secrete anti-gD protein mAbs. Characterization by indirect immunofluorescence and Western blot showed that mAbs D7 and E4 have high specificity and strong binding activity against FHV-1, detectable at 2 μg/mL. These mAbs provide specific tools for FHV-1 detection and a basis for developing rapid diagnostic methods using ELISA, colloidal gold, and other technologies. Full article

West Nile virus (WNV) causes thousands of arboviral infections in the United States each year. Patients with immune-compromising conditions and elderly people are at higher risk of severe WNV neuroinvasive disease (WNND). Despite its broad endemicity nationwide, no U.S. Food and Drug Administration-approved vaccine or therapeutic treatments exist. We summarized existing peer-reviewed literature on the preclinical development of monoclonal antibody (MAb) prophylaxis and therapeutics for the prevention and treatment of WNND. Five bibliographical databases (CINAHL, Cochrane Library, Embase, MEDLINE, and Scopus) were searched for applicable research studies performed from 1 January 1998 to 1 May 2025. In total, 2347 titles and abstracts were screened, 263 full-text publications reviewed, and 25 studies included. Studies included detailed preclinical development and evaluations of MAbs targeting the envelope (E) protein (n = 13), other viral proteins (n = 3), flaviviral cross-protective monoclonal antibodies (n = 4), and novel antibody configurations or delivery methods (n = 5). The most well-studied MAb, E16, targeting E- Domain III (E-DIII), was effective at inhibiting and treating WNND in experimental animal models. No work investigated ways to traffic therapeutic antibodies across the blood–brain barrier. This review summarizes the current research in the development of monoclonal antibody therapeutics for WNV and addresses gaps in the knowledge for future consideration. Full article

Zika virus (ZIKV) was first discovered in Uganda’s Zika Forest in 1947. The early African viruses posed little or no health risk to humans. Since then, ZIKV has undergone extensive genetic evolution and adapted to humans, and it now causes a range of human diseases, including neurologically related diseases in adults and congenital malformations such as microcephaly in newborns. This raises a critical question as to why ZIKV has become pathogenic to humans, and what virological changes have taken place and enabled it to cause these diseases? This review aims to address these questions. Specifically, we focus on the ZIKV envelope (E) protein, which is essential for initiating infection and plays a crucial role in viral entry. We compare various virologic attributes of E protein between the ancestral African strains, which presumably did not cause human diseases, with epidemic strains responsible for current human pathogenesis. First, we review the role of the ZIKV E protein in viral entry and endocytosis during the viral life cycle. We will then examine how the E protein interacts with host immune responses and evades host antiviral responses. Additionally, we will analyze key differences in the sequence, structure, and post-translational modifications between African and Asian lineages, and discuss their potential impacts on viral infection and pathogenesis. Finally, we will evaluate neutralizing antibodies, small molecule inhibitors, and natural compounds that target the E protein. This will provide insights into the development of potential vaccines and antiviral therapies to prevent or treat ZIKV infections and associated diseases. Full article

Background: The re-emerging mpox virus (MPXV) has spread to numerous countries and raised global concern. There is an urgent need for a safe and effective mRNA vaccine candidate against MPXV infection. Previously, we developed a penta-component mRNA vaccine that contained five distinct antigen-encoded mRNAs encapsulated within lipid nanoparticles (LNPs). Here, we sought to develop a single-chain mRNA vaccine that encodes antigens derived from both intracellular mature virion (IMV) and extracellular enveloped virion (EEV). Methods: A single-chain mRNA vaccine encoding a fusion protein comprising the ectodomains of M1R (eM1R) and A35R (eA35R) (MPXV^eM1-eA35) was developed and characterized, while an admixed formulation of two individual mRNA-LNPs encoding separate antigens was developed as the control (MPXV^eM1+eA35). Meanwhile, based on the same strategy, we designed a single-chain mRNA vaccine encoding dimeric antigens (MPXV^eM1-eA35-Fc). Mice were immunized with two doses of the candidate vaccines, and both humoral and cellular immune responses were evaluated. The protective efficacy of the candidate vaccines was evaluated based on body weight monitoring and tissue viral load measurement after challenge with vaccinia virus (VACV). Results: Immunization with two doses of MPXV^eM1-eA35 elicited robust levels of neutralizing antibodies and antigen-specific cellular immune response. Importantly, MPXV^eM1-eA35 demonstrated protective efficacy in a VACV challenge mouse model and showed superior capacity in preventing weight loss post-challenge compared to MPXV^eM1+eA35. Similarly, MPXV^eM1-eA35-Fc exhibited comparable or superior immunogenicity and protective efficacy compared to the admixed formulations. Conclusions: The single-chain mRNA vaccine elicited a protective immune response in mice, offering significant advantages in terms of manufacturing processes and quality control. Our single-chain mRNA vaccine platform presents a promising strategy for the next generation design of mpox vaccines and contributes to the mitigation of MPXV endemic worldwide. Full article

Background: In Staphylococcus aureus, antimicrobial resistance (AMR) imposes significant fitness costs (FCs), including reduced growth rate, interbacterial competitiveness, and virulence. However, the FC molecular basis remains poorly understood. This study investigated the FC omic basis and compensatory adaptations in high-risk HA-, LA-, and CA-MRSA, acquiring mono- or cross-resistance to second-line daptomycin (DAP) and dalbavancin (DAL), as well as reduced susceptibility (RS) to first-line glycopeptides, i.e., vancomycin and teicoplanin (GLYs, i.e., VAN, TEC), related to the specific mechanism of action (MOA)-related AMR-mechanisms and genomic backgrounds, paying increasing FCs. Methods: The FC omic basis associated with mono- or cross- DAP-/DAL-R and GLY-RS were investigated by integrated omics. This study focused on core-genome essential (EG) and accessory virulence gene (VG) SNPomics and transcriptomics by Illumina MiSeq whole-genome sequencing, RNA-seq, and bioinformatic analysis. Results: Moderate impact nsSNPs were identified in EGs related to vital cellular functions and VGs. Comparative EG transcriptomics revealed differential expressions and key dysregulations—via asRNAs—prevalently affecting the protein synthesis and cell-envelope EG clusters, as well as the VG cluster. Conclusions: Our data, firstly, underlined the EG and VG mutation- and transcription-driven omic-based FC burden and the compensatory adaptations associated with the emergence of mono-DAP-R, cross-DAP-R/hGISA, and DAP-R/DAL-R/GISA, linked to specific MOA-related AMR-mechanisms and genomic backgrounds in high-risk HA-, LA-, and CA-MRSA. Full article

African swine fever (ASF) is caused by the African swine fever virus (ASFV); infection in domestic pigs and wild boars leads to a highly contagious, hemorrhagic disease. The p54 protein is encoded by the ASFV E183L gene and is an important structural protein located on the inner envelope of the virus. It is involved in processes of virus assembly, apoptosis induction, and neutralizing antibody production. In this study, three specific monoclonal antibodies (mAbs) against ASFV p54 protein were generated, namely 6B11, 3E3, and 3C10, from mice who were immunized with recombinant prokaryotic p54-truncated protein. Three novel linear B cell epitopes, recognized by the mAbs, were revealed: ⁶⁰AAIEEEDIQFINP⁷², ¹²⁸MATGGPAAAPAAASAPAHPAE¹⁴⁸, and ¹⁶³MSAIENLRQRNTY¹⁷⁵. The epitopes ⁶⁰AAIEEEDIQFINP⁷² and ¹⁶³MSAIENLRQRNTY¹⁷⁵ were highly conserved in genotype I and II ASFV strains. In addition, the epitope peptide ELISA can be used for the detection of ASFV antibodies. Our work provides new insights for p54 antigenicity and an alternative tool for serological diagnosis of ASF. Full article

Flaviviruses are arthropod-borne RNA viruses that can cause a wide range of human diseases, from mild symptoms to severe illness with multiorgan failure and death. Effective prevention of these diseases relies on identifying reliable vaccine targets, typically measured by correlates of protection (CoPs), which help indicate host immunity after vaccination. Current vaccines primarily focus on neutralizing antibodies (nAbs) against the viral envelope E protein, though emerging evidence suggests other potential targets may also be effective in disease prevention. Additionally, there is growing evidence of cross-protection between different flaviviruses when immunity to one virus is achieved, although this can be limited by antibody-dependent enhancement. This review examines the current understanding of flavivirus immunity, CoPs, and the potential for cross-protection in the context of existing vaccine strategies. Full article

Feline infectious peritonitis (FIP) is a complex immune-mediated disease caused by feline coronavirus (FCoV). Despite advancements in understanding its pathogenesis, challenges persist in elucidating viral factors related to virion composition and replication. This study examined FCoV-infected cats with and without FIP for potential associations with or variation in expression ratios for different viral genes. We analyzed tissue samples with FIP lesions from 46 cats with FIP and mesenteric lymph nodes from 10 FCoV-infected cats (7b RT-qPCR positive) without FIP with three RT-qPCR assays, targeting (sub)-genomic RNAs of the RNA-dependent RNA polymerase (RdRp) and envelope (E) genes. In cats with FIP, the RdRp mRNA assay yielded the highest copy numbers, followed by the combined RdRp gRNA and mRNA assay; the E mRNA assay yielded the lowest copy numbers. In cats without FIP, significantly fewer viral RNA copies were detected regardless of the assay. Viral gene expression was not detected in six and was observed only at low levels in one or more assays in four samples. The observed correlation between assays and the intragroup correlation assay indicate consistent transcription of both the structural E protein and RdRp genes within FIP lesions in cats with FIP but not in cats with systemic FCoV infection alone. Full article