Covert mpox virus (MPXV) infection among people living with HIV (PLWH) remains poorly understood. This study aimed to investigate undetected MPXV infections through seroepidemiological analysis. We recruited 148 PLWH during July 2-9, 2023 (baseline), with 60 and 148 participants returning for 4- and 14-month follow-ups, respectively. PCR testing showed that all saliva and blood samples were negative for MPXV-DNA. The titers of IgG, IgA, and IgM were evaluated using ELISA with virions. MPXV-IgA and IgM were undetectable, 15 participants born before 1980 had low MPXV-IgG at baseline. At 14 months, 10 participants (6.8%) showed increased MPXV-IgG titers. All seroconverters had detectable neutralizing antibodies, and nine were MPXV-IgA positive. Further results showed that IgG seropositivity against MPXV proteins (A29L, A35R, B6R, E8L, H3L, and M1R) ranged from 0% to 80%, while IgA seropositivity ranged from 0% to 60% among the 10 participants at the 14-month. The B6R and E8L combination showed IgG detection comparable to whole virions, while E8L and H3L combination increased IgA seropositivity to 70%. The occurrence of MPXV covert infection among PLWH underscores the need to improve surveillance strategies in the community. The presence of MPXV-IgA in blood may offer a preliminary temporal signal of MPXV infection.

Background: Rapid molecular testing enhances pathogen detection in community-acquired pneumonia (CAP), yet its impact on clinical outcomes remains uncertain. We evaluated whether early precision treatment (PT) guided by evolving molecular diagnostics improves in-hospital mortality, and sought to identify specific patient subgroups that derive the greatest survival benefit. Methods: The multicentre retrospective CCAPP cohort study (June 2005–July 2024) included 2430 adults hospitalised with CAP across four general hospitals in Fujian Province, China, yielding 1904 patients with complete data for final analysis. Patients were categorized by diagnostic strategy: limited-target (LND; n=794; 11 bacterial and atypical pathogens) or diverse-target (DND; n=678; 33 bacterial, atypical, fungal, and viral pathogens) nucleic acid detection, or metagenomic next-generation sequencing (mNGS; n=432). On the basis of whether empirical anti-infective regimens administered within 3 days of admission covered clinically relevant pathogens, patients were classified as PT, non-precision treatment (NP), or no pathogen detected (NPD), and were further stratified into respiratory failure (RF) and non-respiratory failure (nRF) subgroups. Primary outcome was in-hospital mortality; secondary outcomes included length of stay and hospital costs. Confounding was addressed via 1:1:1 triad matching (PT:NP:NPD) in the DND (n=318) and mNGS (n=111) cohorts, analysed using conditional logistic regression and Kaplan-Meier methods. Findings: Pathogen positivity was 23·8% (LND), 60·0% (DND), and 32·6% (mNGS). PT was associated with significantly lower mortality compared with NP exclusively in the mNGS cohort, observed in both the overall population (3·4% vs 18·1%, p<0·001) and the RF subgroup (6·5% vs 34·1%, p=0·002). After matching, logistic regression in the DND cohort revealed that PT mortality benefit was strictly confined to the RF subgroup (OR 0·17, 95% CI 0·01–0·98; p=0·049; overall OR 0·43, p=0·220). Distinctly, PT in the mNGS cohort was associated with markedly lower mortality across both the overall population (OR 0·20, 95% CI 0·05–0·88; p=0·034) and the RF subgroup. Survival analyses corroborated this divergence: survival benefits for PT were consistent across the entire mNGS cohort (overall p=0·027; RF p=0·022), whereas DND-era benefits remained restricted to RF patients (p=0·040). PT did not significantly reduce length of stay or costs compared with non-PT. Interpretation: For hospitalised CAP, standard empirical therapy suffices for nRF patients, as PT yields no additional survival benefit, nor does it decrease length of stay or total costs. Conversely, RF patients derive substantial mortality reduction from PT guided by broad-spectrum diagnostics. While mNGS maximizes this protective effect, DND serves as a pragmatic alternative in resource-constrained settings.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has profoundly impacted global public health and the economy. Systematic screening of host factors influencing viral infection is critical for understanding virus-host interactions and for developing host-targeted antiviral strategies. Here, we conducted a host cDNA overexpression screen to identify host factors involved in regulating SARS-CoV-2 replication. This approach identified prosaposin (PSAP), a precursor of lysosomal saposin activators (saposin A, B, C, and D), as an efficient host restriction factor that blocks SARS-CoV-2 entry. We demonstrate that PSAP binds with high affinity to the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) protein. Secreted PSAP efficiently inhibits infection by both SARS-CoV-2 pseudovirus and authentic virus. Mechanistically, PSAP binding facilitates the release of the S1 subunit from the S protein. Molecular docking analysis further revealed that PSAP interacts with the non-receptor-binding motif (non-RBM) region of the domain (RBD). These results suggest that PSAP inhibits SARS-CoV-2 entry through a mechanism analogous to that of neutralizing antibodies. Our findings highlight PSAP as a novel host restriction factor against SARS-CoV-2 infection, offering new insights into potential therapeutic strategies for combating SARS-CoV-2.IMPORTANCEThe systematic identification of host factors that modulate SARS-CoV-2 infection is critical for elucidating the mechanisms of virus-host interaction and for advancing the development of novel host-directed therapeutic interventions. In this study, we identify the human protein prosaposin (PSAP) as a novel and potent innate restriction factor that effectively blocks SARS-CoV-2 infection. By binding with high affinity to the spike protein's receptor-binding domain (RBD) at a unique site, PSAP neutralizes the virus, thereby preventing cellular entry. Consequently, this discovery establishes a foundation for a novel host-directed therapeutic strategy. The development of pharmacologic agents that recapitulate PSAP's action could yield a new class of antivirals that neutralize SARS-CoV-2 by mechanistically disrupting spike protein integrity, offering a complementary approach to conventional antibody therapies.

Nipah virus (NiV) is a highly lethal single-stranded negative-sense RNA virus designated by the World Health Organization (WHO) as a priority pathogen for pandemic preparedness. NiV has fruit bats as its natural reservoir and can infect humans through direct contact, consumption of contaminated food, and person-to-person transmission, causing severe diseases such as acute encephalitis and acute respiratory distress syndrome, with case fatality rates ranging from 40% to 75%. Based on whole-genome sequence homology and geographical distribution patterns, NiV has differentiated into two major genetic lineages, NiV-Malaysia (NiV-M) and NiV-Bangladesh (NiV-B). NiV-M is primarily transmitted via intermediate hosts (pigs and horses) and outbreaks can be controlled through culling of infected intermediate hosts, whereas NiV-B can directly spill over from fruit bat reservoirs to humans, exhibits greater person-to-person transmissibility, and shows endemic transmission characteristics. Current NiV outbreak prevention and control efforts face multiple challenges, including persistent viral genome evolution, lack of lineage-discriminating capability of diagnostic assays, and the absence of licensed human vaccines. This review systematically summarizes the evolutionary characteristics of NiV, its cross-species transmission patterns, recent advances in vaccine and antiviral drug development, analyzes the impact of viral evolution on surveillance strategies, and provides recommendations for optimizing prevention and control strategies from a pandemic preparedness perspective.

The World Health Organization declared mpox a Public Health Emergency of International Concern in both 2022 and 2024, highlighting the critical need for rapid and reliable diagnostic solutions. To address this challenge, we developed monoclonal antibodies against four mpox virus (MPXV) antigens (A29L, A35R, H3L, and E8L) using hybridoma technology. Epitope binning analyses, performed using competitive enzyme-linked immunosorbent assay (ELISA) and biolayer interferometry, identified non-overlapping antibody pairs (e.g., 18F7–27C3 for A29L and 4E7–6C11 for A35R), which served as the foundation for sandwich ELISA assays exhibiting nanogram-level sensitivity. These antibody pairs demonstrated high specificity, effectively distinguishing MPXV antigens from homologous proteins of cowpox virus, vaccinia virus, and variola virus, while maintaining reactivity toward cultured MPXV. Collectively, this work establishes a robust immunodiagnostic platform with strong translational potential for point-of-care applications during mpox outbreaks.

Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a formidable nosocomial pathogen, with healthcare environments acting as critical reservoirs for its dissemination. In this study, we investigated the prevalence, antimicrobial resistance profiles and genomic characteristics of CRAB isolates collected from hospitals in Shanghai, China, between June and December 2024, identifying ST2Pas (84.13%) and ST164Pas (15.08%) as the predominant lineages among the 126 CRAB isolates recovered from clinical (n=94), environmental (n=29) and healthcare worker (n=3) sources. Environmental CRAB accounted for the highest proportions on patient-contact surfaces (34.48%), medical devices (31.03%) and shared items (24.14%). Within the dominant ST2Pas lineage, clinical isolates exhibited higher resistance rates to ampicillin/sulbactam, cefoperazone/sulbactam and levofloxacin, with significantly higher carriage rates of bla TEM-1D compared to environmental isolates. Compared to ST164Pas, ST2Pas CRAB isolates exhibited greater resistance to amikacin, gentamicin, trimethoprim/sulfamethoxazole and minocycline and a higher prevalence of aph(3')-Ia, aph(3″)-Ib, aph(3')-VI, aph(6)-Id, armA, bla OXA-66 , bla TEM-1D, mph(E) and tet(B), but lower rates of bla CARB-16, bla NDM-1 and bla OXA-91 (P<0.05). Notably, comparative genomic analysis suggested putative adaptive differences between the two lineages. ST2Pas retained the T6SS and biofilm-associated genes (bap), descriptive genomic features that suggest a potential capacity for active colonization. Conversely, the ST164Pas clone lacked the T6SS gene cluster but was enriched with the surface adhesin ata and immune evasion-related genes. Concordantly, ST164Pas CRAB isolates exhibited significantly stronger biofilm-forming capacities than ST2Pas in vitro. We hypothesize that these genomic alterations and phenotypic traits may represent a fitness trade-off, potentially conferring a survival advantage under antibiotic pressure. Furthermore, bla OXA-23 in ST2Pas was predominantly carried on conjugative plasmids restricted to Acinetobacter species, whereas bla NDM-1 in ST164Pas was localized on a broad-host-range non-mobile plasmid, potentially facilitating cross-genus transmission. Although our ST164Pas isolates shared high homology with clinical strains from Zhejiang, China, the genomic localization of bla NDM-1 differed between the plasmid and chromosome, respectively. These descriptive genomic findings highlight the putative adaptive trajectories of the predominant ST2Pas and emerging ST164Pas clones, underscoring the critical need for comprehensive genomic surveillance, complemented by future phenotypic validation, to monitor their rapid evolution and dissemination.

Background/Objectives: To investigate the antagonistic effect of probiotic Lactiplantibacillus plantarum GUANKE against respiratory syncytial virus (RSV) and its underlying molecular mechanisms. Methods: in vitro cell models (A549 and HEp2 cells) and an in vivo mouse model (BALB/c mice) were employed. RT-qPCR, TCID50 assay, immunofluorescence, ELISA, Western blot, and histopathological analysis were used to investigate the effects of GUANKE on RSV replication, inflammatory responses, and the type I interferon pathway. Results: Oral administration of GUANKE effectively cleared RSV and alleviated RSV-induced pulmonary inflammatory responses. GUANKE inhibited viral replication. The GUANKE intervention group exhibited significantly reduced pathological damage to lung tissue and decreased the expression of inflammatory cytokines (IL-1β, IL-6, MCP-1, TNF-α). GUANKE augmented the early type I interferon response and activated the STING-TBK1-IRF3-IFN signaling pathway. Conclusions: GUANKE exerts anti-RSV effects by enhancing the early type I interferon response and activating the STING-TBK1-IRF3-IFN signaling pathway, thereby inhibiting RSV replication and alleviating pulmonary inflammatory responses. This suggests its potential value as an anti-RSV agent.

Post-COVID-19 pulmonary fibrosis represents a significant long-term complication affecting 10–30

Since the 2022 global mpox outbreak, the lack of specific antibodies for mpox virus (MPXV) detection has hindered precise immunoassays due to cross-reactivity among Orthopoxviruses (OPXVs). This study developed and characterized two monoclonal antibodies (mAbs), CML01 and CML02, targeting the MPXV A35 protein, a conserved surface antigen of extracellular virions. Cross-reactivity assessments via enzyme-linked immunosorbent assay (ELISA), western blot, and indirect immunofluorescence assays (IFA) confirmed that both mAbs bound exclusively to MPXV A35, showing no reactivity with homologous proteins from cowpox (A34), vaccinia (A33), or variola viruses (A36) despite 92.3 %–96.1 % sequence homology. IFA showed recognition of MPXV-infected cells with half-maximal effective concentrations (EC50) of 0.15 and 0.17 μg/mL, respectively. Notably, an IFA-based microneutralization assay using the mAb CML02 exhibited strong correlation (r = 0.93, P < 0.0001) with the traditional plaque reduction neutralization test (PRNT) while enabling higher throughput. Plasma from convalescent mpox patients validated the assay’s utility in testing neutralizing antibody titers. These mAbs address critical gaps in MPXV-specific immunological testing by virtue of their high specificity, which prevents cross-reactivity with other OPXVs and eliminates interference from immunity induced by smallpox vaccination. This work underscores A35 as a key epitope for MPXV-specific immunity and provides essential tools for combating the ongoing mpox threat.

Background: In China, Carbapenem-resistant Klebsiella pneumoniae (CRKP) is dominated by sequence type 11 (ST11) harbouring KPC-2, with KL64 displacing KL47 and KL25 emerging. ST859 (ST11 variant) has caused outbreaks, but its epidemiology is unclear. Materials and Methods: A total of 99 non-duplicate CRKP isolates were collected from June to December 2024. Antimicrobial susceptibility was determined by broth microdilution. The genomic sequences of the strains were obtained using next-generation sequencing technology. Resistance genes, virulence loci, and plasmid replicons were identified with Kleborate, Abricate, and MOB-suite, respectively. Results: ST11 accounted for 63.64% and ST859 for 15.15%. All ST859 were KL19, while ST11 were mainly KL25 (60.32%) and KL64 (26.98%). 76.8% co-harbored carbapenemase and extended-spectrum beta-lactamase (ESBL) genes, with KPC-2 and CTX-M-65 being the predominant types. Susceptibility rates were 100% to tigecycline, and 78.79% to ceftazidime/avibactam. ST859 CRKP isolates exhibited higher phenotypic resistance to tetracycline and colistin than ST11 CRKP isolates (p < 0.05), and carrying LAP-2, QnrS1, QnrS10, and tet(A) more frequently. ST11-KL25 showed higher resistance to amikacin, gentamicin, and chloramphenicol, with increased prevalence of CTX-M-65, TEM-1, rmtB, catA2, and dfrA14 compared to ST11-KL64 (p < 0.05). IncF was the most prevalent replicon and both ST859 and ST11 CRKP carry conjugative resistance plasmids, and the host range is predominantly Enterobacterales. Conclusions: ST859-KL19 ranks second to ST11 with higher resistance to tetracyclines and colistin. ST11-KL25 may have already displaced ST11-KL64 as the predominant capsular type in Shanghai, with distinct resistance profiles between KL variants. Long-term, multicenter surveillance is urgently needed to delineate the evolutionary trajectory and clinical impact of these emerging clones.

Enterovirus 71 (EV-A71) is a major causative agent of severe hand, foot, and mouth disease (HFMD) in young children. However, the molecular interplay between EV-A71 and host factors, particularly how these interactions govern viral replication, remains incompletely understood. To systematically identify host factors involved in EV-A71 infection, we performed comprehensive identification of RNA-binding proteins (RBPs) by mass spectrometry (ChIRP-MS) during viral infection and identified 374 host proteins associated with the EV-A71 genomic RNA. Integrative analysis of existing datasets further revealed a broader association between Matrin 3 (MATR3) and enteroviruses, which we functionally validated through gain- and loss-of-function assays, demonstrating that MATR3 acts as a proviral factor essential for efficient EV-A71 replication. Mechanistically, we show that MATR3 specifically binds to the 3' untranslated region (3'UTR) of EV-A71 RNA via its second RNA recognition motif (RRM2). This interaction promotes RNA-dependent condensate formation of MATR3, thereby enhancing viral RNA stability. Furthermore, MATR3 recruits the host palmitoyltransferase ZDHHC20 to the viral ribonucleoprotein complex, facilitating MATR3 palmitoylation. This posttranslational modification promotes the assembly of a stable ribonucleoprotein complex that cooperatively stabilizes the viral genome and supports efficient replication. Together, this study delineates a mechanistic pathway by which EV-A71 co-opts MATR3 through condensate formation and palmitoylation to stabilize its genomic RNA and promote viral replication, and provides a comprehensive profiling dataset of host proteins associated with EV-A71 RNA.

Pulmonary inflammatory response represents a predominant complication arising from influenza virus infections. This investigation elucidates the protective efficacy of Lactiplantibacillus plantarum GUANKE (GUANKE) supplementation against influenza A virus (IAV)-induced pulmonary damage in C57BL/6 murine models, with particular emphasis on its mechanistic underpinnings. The results showed that the use of GUANKE (5 × 109 CFU/day) or exogenous linoleic acid (a metabolite of GUANKE) supplementation (40 mg/kg) significantly attenuated inflammatory cytokine secretion while counteracting virus-mediated downregulation of pulmonary barrier proteins. Mechanistic profiling revealed that GUANKE and GUANKE-derived linoleic acid modulates mitochondrial quality control through enhanced Parkin-dependent mitophagy coupled with restored mitochondrial oxidative phosphorylation (OXPHOS) capacity, thereby providing protection in IAV-infected mice.

Let-7a is a critical miRNA biomarker for early cancer diagnosis; however, its clinical application is hindered by low abundance and poor stability. In this study, a protease-free and amplification-free electrochemical biosensor based on a locked-structure DNAzyme system (DNAzyme-Lock) was developed for the sensitive detection of let-7a. Nitric acid–activated Co-embedded N-doped carbon (Co@NC-acid) was first modified on the electrode surface to facilitate efficient probe immobilization and enhance electron transfer. In the presence of let-7a, the DNAzyme is released and catalyzes the cleavage of single-stranded DNA (S1) conjugated with gold nanoflowers (Au NFs), resulting in a reduced amount of Au NFs on the electrode surface. Consequently, the electrocatalytic oxidation of acetaminophen (AP) is suppressed, leading to a decrease in the electrochemical signal. The signal intensity is negatively correlated with the concentration of let-7a. Under optimal conditions, the biosensor exhibits a low detection limit of 2.036 fM and a wide linear range from 10 fM to 1 nM. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) confirm the successful fabrication of the biosensor, as well as its excellent specificity and stability. Owing to its simple preparation, low cost, and high performance, this biosensor shows great potential for early cancer diagnostics.

Type I interferons (IFNs) play a central role in antiviral immunity by activating the JAK-STAT signaling pathway to induce interferon-stimulated genes (ISGs). Precise regulation of this response is critical to avoid pathological inflammation and autoimmunity, but the molecular mechanisms that restrain IFN signaling remain incompletely defined. Here, we performed a human whole-genome cDNA library screen and identified ZC3H10 as a negative regulator of the type I IFN response. Overexpression of ZC3H10 suppressed ISG expression following IFNβ stimulation and increased susceptibility to infection by Newcastle disease virus, human rhinovirus 16, Enterovirus A71, and SARS-CoV-2, whereas genetic deletion of ZC3H10 enhanced ISG expression and antiviral resistance. Mechanistically, ZC3H10 required nuclear localization, a functional nucleic acid-binding domain, and its coiled-coil domain to exert its inhibitory function. Furthermore, chromatin immunoprecipitation assays revealed that ZC3H10 directly binds to the TTTC motif within ISG promoters, thereby preventing their activation. Together, these findings establish ZC3H10 as a critical negative regulator of IFN signaling that functions to balance antiviral immunity.

Abstract Background The continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) highlights the value of broad-spectrum antiviral strategies. Antibody-engineering approaches targeting conserved regions of the Spike protein may enhance neutralizing potency and breadth. Methods A human antibody (P23) against the Spike protein of SARS-CoV-2 was identified using a human antibody phage display library panning and screening for binding affinity and breadth against multiple coronavirus Spike proteins using surface plasmon resonance (SPR). The epitope of P23 was characterized using the S1 and S2 subunits of SARS-CoV-2 Spike protein and hydrogen–deuterium exchange mass spectrometry (HDX-MS). An IgG–like bispecific fusion protein (Bs-ACE2-P23) was engineered by fusing the extracellular domain (ECD) of human angiotensin-converting enzyme 2 (ACE2) to the N-terminus of the P23 heavy chain (HC). Neutralizing activity was evaluated against both pseudotyped and authentic SARS-CoV-2 variants. Results P23 cross-bound Spike proteins from SARS-CoV-2 wild type (WT), D614G and JN.1 variants, Pangolin-CoV, Bat coronavirus RaTG13, and SARS-CoV-1, recognizing an epitope on the S2 subunit adjacent to the fusion peptide (FP). While P23 was ineffective against D614G-containing SARS-CoV-2 variants, Bs-ACE2-P23 exhibited markedly enhanced neutralization potency. This bispecific architecture also improved the neutralizing activity of another FP-targeting antibody. Conclusion We developed a bispecific fusion protein with potent broad-spectrum neutralizing activity against SARS-CoV-2 variants. This architecture provides a promising strategy for next-generation coronavirus biologics.

ABSTRACT Enteroviruses (EVs), encompassing over 200 sero/genotypes, cause diseases ranging from mild illness to severe systemic infections. Galectin-9 (Gal-9) is an immunomodulatory lectin implicated in various viral infections, yet its role in EVs remains unexplored. Here, we identify Gal-9 as a novel host restriction factor against a broad spectrum of EVs, including EV-A71, EV-D68, and Coxsackievirus B2. LGALS9 deficiency increased viral replication in cells and pathogenicity in a mouse model of EV-A71 infection, while its overexpression inhibited viral replication. Mechanistically, Gal-9 specifically interacts with the viral VP2 protein, and mapping identified residues 179–194 of Gal-9 as critical for this interaction. A Gal-9 Δ179–194 mutant lost VP2-binding capacity and antiviral activity. These findings reveal that Gal-9 is a key component of the host antiviral response against EVs, functioning through a direct interaction with the viral VP2 protein.IMPORTANCEEnteroviruses (EVs) cause a wide spectrum of disease and present a persistent global health challenge, highlighted by the cyclical resurgence of strains like EV-D68 and EV-A71. However, due to a lack of sufficient understanding of their pathogenesis, no EV-specific antiviral drugs are available. This study demonstrates that galectin-9 (Gal-9) is a key host factor that broadly antagonizes EVs, including EV-A71, EV-D68, and Coxsackievirus B2. We show that Gal-9 deficiency enhances viral replication both in cell culture and in an animal model. By identifying Gal-9 as a crucial restriction factor against EVs, our study provides foundational insight for the future development of antiviral strategies.

Animal sarbecoviruses, relatives of SARS-CoV or SARS-CoV-2, pose a significant zoonotic threat driven by their ability to bind the human ACE2 (hACE2) receptor. To address challenges in evaluating these threats, we developed RAISE (Receptor binding domain-hACE2 Interaction Scoring Evaluation), a computational framework that integrates structural predictions with interaction scoring. By scoring predicted hACE2 interactions, our RAISE model categorized sarbecoviruses into three groups: high potential (hACE2-binding), negligible potential (hACE2-nonbinding), and an intermediate "poised" state (a state defined by either weak binding activity or a high potential to evolve it). Mutation screening of two "hACE2-poised" sarbecoviruses, PDF-2370 and Khosta-1 using RAISE, revealed mutations such as T498Y/W that enabled human ACE2 utilization and expanded their ability to bind to ACE2 receptors from a broader range of species. The model's generalizability was further demonstrated through prospective application to merbecoviruses, highlighting its utility in preemptively assessing zoonotic threats across coronavirus lineages. RAISE provides a predictive roadmap for prioritizing risk viruses and guiding pandemic preparedness.

An outbreak of mpox has triggered concerns regarding the adequacy of intervention strategies. Passive immunity conferred by neutralizing antibodies exhibits potential in the prophylaxis and treatment of orthopoxvirus infections. Despite this, the investigations of effective antibody therapeutics have been hindered by the varied nature of orthopoxvirus envelope proteins and the intricate mechanisms underpinning viral invasion. Our study involves the production of six mpox virus (MPXV) envelope proteins, which are relatively conservative and considered to play a role in the neutralization process. We employed a synthetic nanobody (Nb) library to derive a broad array of specific Nbs against these viral proteins. We identified a cross-reactive Nb, termed M1R-01, which targets the M1R protein and effectively neutralizes both vaccinia virus (VACV) and MPXV. Notably, the M1R-01-based antibody strategy provided optimal protection against a lethal VACV challenge in mice. Additionally, we determined the crystal structure of the M1R–Nb complex, uncovering novel binding attributes of M1R-01 and detailed conformational epitope information. This work provides a promising candidate for the therapy and prophylaxis of orthopoxvirus infections.

The influenza A virus evades the host innate immune response to establish infection by inhibiting RIG-I activation through its nonstructural protein 1 (NS1). Here, we reported that receptor-transporting protein 4 (RTP4), an interferon-stimulated gene (ISG), targets NS1 to inhibit influenza A virus infection. Depletion of RTP4 significantly increased influenza A virus multiplication, while NS1-deficient viruses were unaffected. Mechanistically, RTP4 interacts with NS1 in an RNA-dependent manner and sequesters it from the TRIM25-RIG-I complex, thereby restoring TRIM25-mediated RIG-I K63-linked ubiquitination and subsequent activation of IRF3. Antiviral activity of RTP4 requires the evolutionarily conserved CXXC motifs and an H149 residue in the zinc finger domain, mutations of which disrupted RTP4-NS1 interaction and abrogated the ability of RTP4 to rescue RIG-I-mediated signaling. Collectively, our findings provided insights into the mechanism by which an ISG restricts influenza A virus replication by reactivating host antiviral signaling.