Porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine delta-coronavirus (PDCoV), and porcine rotavirus-A (PoRV) G9 are major swine pathogens primarily responsible for gastrointestinal diseases, particularly affecting lactating piglets and resulting in significant economic losses, especially in China. This study reports a novel CRISPR-based nucleic acid detection method that integrates the high specificity of huLbCas12a with the sensitivity of loop-mediated isothermal amplification (LAMP) technology. Central to this method, the crRNA/Cas12a complex, enhances diagnostic accuracy through targeted gene editing. In this approach, the nucleic acids of the four viruses are amplified in parallel by LAMP and subsequently detected in four singleplex CRISPR–Cas12a reactions performed in separate tubes, with the incorporation of fluorescent reporter probes and a lateral flow dipstick assay establishing a visual detection system capable of separately identifying each of the four viruses. It enables the visual detection of viral genomes from as low as 1 copy/µL without cross-reactivity. In comparative testing of 95 clinical samples, our quadruplex LAMP-CRISPR assay demonstrated 100

Background/Objectives: Canine papillomavirus (CPV) is an important viral pathogen associated with papillomatosis in dogs, with canine papillomavirus type 1 (CPV1) and type 2 (CPV2) among the most prevalent and clinically relevant genotypes. The L1 capsid protein is a major immunogenic antigen of papillomaviruses; however, conserved linear B-cell epitopes shared between CPV genotypes remain poorly defined. This study aimed to identify conserved cross-reactive B-cell epitopes within CPV1 and CPV2 L1 proteins and to evaluate their preliminary immunoreactivity. Methods: Conserved linear B-cell epitopes were predicted through integrated bioinformatic and structural analyses based on sequence conservation and surface accessibility. Three candidate epitopes were selected. Recombinant CPV1 and CPV2 L1 proteins were expressed in Escherichia coli (E. coli), purified, used as recombinant L1 antigens, together with BSA-conjugated synthetic epitope peptides for mouse immunization. Antigen-specific IgG responses were assessed by ELISA, antigen-associated IFN-γ responses were evaluated by ELISpot, and cross-reactive antibody recognition was assessed by Western blot. Results: Recombinant L1 proteins induced strong antigen-specific IgG responses in mice. The selected peptides induced detectable but weaker humoral responses compared with the recombinant L1 proteins. Among the three epitopes, TPSGSLV and TVVDNTR elicited antibodies that recognized both CPV1 and CPV2 L1 proteins, while the epitope VIVPKVS showed minimal or no detectable immunoreactivity. ELISpot analysis showed only modest antigen-associated IFN-γ responses, particularly in peptide-immunized groups. Conclusions: This study identified conserved cross-reactive linear B-cell epitope candidates within CPV1 and CPV2 L1 proteins and provided preliminary immunological evidence supporting their potential relevance for CPV antigen design. However, peptide-induced responses were weaker than those induced by recombinant L1 proteins, and VLP formation, antibody neutralizing activity, and protective efficacy were not evaluated. Further studies in dogs, including optimized antigen-display platforms, neutralization assays, and protection studies, are required to determine the practical value of these epitopes for CPV vaccine development.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still going on, and as the epidemic situation continues, the genome of SARS-CoV-2 is also mutating and evolving, resulting in more and more SARS-CoV-2 mutant strains, which have brought serious pressure on the prevention and control of COVID-19. Given that the COVID-19 is still spreading, it is extremely important to rapidly identify SARS-CoV-2 variants by nucleic acid assays. Thus, developing highly sensitive and specific assays that are suitable for field testing, high-throughput, and automation, as well as other diagnostic applications for SARS-CoV-2 variants, is urgently needed. This paper reviews the research progress of novel CRISPR-based diagnostic methods for SARS-CoV-2 variants.

Synthetic antibody libraries have been developed as an efficient source for the discovery of the heavy chain variable (VH) domain, which exhibits low immunogenicity, high tissue penetration, and diverse binding epitopes in therapeutic biopharmaceuticals. In this study, the human IGHV3-23*04 germline gene was chosen as the scaffold with a high expression level and favorable thermal stability. Amino acid diversity was introduced into the complementarity determining region 3 (CDR3) to exclude potential sequence liabilities. A library containing 2.6 × 1011 independent clones was successfully constructed. The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, interleukin-17A (IL17A), B-cell maturation antigen (BCMA), and G-protein coupled receptor family C group 5 member D (GPRC5D) were used as target antigens to screen and identify VHs. In each case, Thirty-one to fifty-five VHs were screened out. The VH-Fc antibodies showed superior affinities (as high as 4.6 nM) to the corresponding antigens but did not bind to antigen-irrelevant cell CHO-S. Furthermore, the anti-RBD and anti-IL17A VH-Fc antibodies showed strong functional activity in the receptor-blocking assays. The VH-Fc antibodies from the synthetic library exhibited favorable developability (thermal stability, colloidal stability, hydrophilicity, anti-aggregation ability, and no interaction with human IgGs). We demonstrated that high-affinity and highly functional VH domain antibodies were generated from the rationally designed library with desired physicochemical properties. This approach is generally universal to target any antigen and has significant potential to accelerate candidate selection.

Porcine circovirus type 2 (PCV2) causes substantial economic losses globally. Although glycosaminoglycans (GAGs) have been identified as the general cell receptors responsible for PCV2 binding and subsequent cell infection, other critical protein(s) may also be involved. Our objective was to explore key host proteins that mediate PCV2 infection. The host protein annexin A2 (ANXA2) was observed to interact with PCV2 virus-like particles (VLPs) through immunoprecipitation (IP) and liquid chromatography‒tandem mass spectrometry (LC‒MS/MS) experiments. Furthermore, knockdown of ANXA2 or the inhibitor A2ti-1 significantly reduced PCV2 replication in host cells. Notably, the addition of ANXA2-specific antibodies to cell culture or the preincubation of PCV2 with recombinant ANXA2 significantly reduced viral infection, primarily by weakening viral attachment to cells. Confocal microscopy further confirmed the colocalization of PCV2 Cap with endogenous ANXA2 in infected cells, and in vitro GST pull-down assays also demonstrated a direct interaction between these two proteins, confirming the role of ANXA2 as an attachment factor for PCV2 cellular entry. In addition, molecular docking revealed that an interface and multiple residues between PCV2 Cap and ANXA2 were involved in the interaction, which was also verified by truncation assays. In conclusion, ANXA2 on the cell surface may function as an attachment site, promoting viral binding and increasing PCV2 infectivity through interactions with Cap. These findings provide novel insights into the molecular mechanisms of PCV2 infection and new molecular targets for the development of vaccines and therapeutic strategies.

Porcine circovirus type 3(PCV3)was initially identified in 2016 in pigs exhibiting unexplained cardiac and multi-organ inflammation in the USA(Palinski et al.2017).PCV3 has subsequently been identified in numerous countries,including China,Brazil,Italy,and others,demonstrating widespread viral dissemination(Tan et al.2021).Notably,recent investigations have revealed PCV3 infection across multiple species,including pigs,cattle,dogs,wild boars,chamois,roe deer,and others(Tan et al.2021).This evidence suggests potential viral propagation beyond its primary host(pigs).

BACKGROUND:Checkpoint inhibitor-related pneumonitis (CIP) represents a highly lethal immune-related adverse event. Early diagnosis of CIP is crucial for timely intervention and improved prognosis; however, the absence of precise and effective diagnostic techniques often leads to underdiagnosis and misdiagnosis. This study aims to identify microRNA (miRNA) features from serum and extracellular vesicles (EVs) for the early CIP detection and prognosis. METHODS:Small RNA sequencing identified candidate miRNAs in 27 serum-derived EV samples from persons with lung cancer and CIP (CIP group) and those without, including immunotherapy-treated persons with lung cancer without CIP (immune checkpoint inhibitor, ICI group) and patients with infectious pneumonia (PNE group). These miRNAs were validated in EV samples in a discovery cohort (n=48) using a quantitative reverse transcription-PCR (qRT-PCR). Diagnostic models for the biomarkers were developed using a training cohort (ICI:47, PNE:28, CIP:31) and validated in a separate validation cohort (ICI:32, PNE:19, CIP:21) using qRT-PCR in both EV and serum samples, and logistic regression. Using a Cox regression model, we built a prognostic risk stratification for patients with CIP based on three miRNAs. RESULTS:Sequencing analysis initially screened and identified 13 overexpressed miRNAs in patients with CIP. Subsequently, qRT-PCR demonstrated that three miRNAs (EVs miR-193a-5p, serum miR-193a-5p, and serum miR-378a-3p) effectively distinguished CIP from non-CIP individuals (training cohort: area under the curve (AUC)=0.870; validation cohort: AUC=0.837). Notably, this miRNA signature was equally robust in differentiating CIP from ICI (training cohort: AUC=0.823; validation cohort: AUC=0.845) and PNE groups (training cohort: AUC=0.892; validation cohort: AUC=0.907). Furthermore, when combined with lymphocyte levels, the miRNA signature significantly enhanced the overall diagnostic accuracy in distinguishing CIP from the non-CIP group (training cohort: AUC=0.900; validation cohort: AUC=0.932), and maintained its robustness in distinguishing CIP from the ICI group (training cohort: AUC=0.898; validation cohort: AUC=0.946) and the PNE group (training cohort: AUC=0.938; validation cohort: AUC=0.959). Additionally, the three-miRNA panel was independently and significantly associated with overall survival in patients with CIP (HR: 2.827; p=0.040). CONCLUSIONS:Our circulating miRNA-based signature represents a non-invasive and robust diagnostic tool for patients with CIP and could accurately predict their prognosis. This signature may facilitate early detection and personalized management of these patients.

Porcine circovirus type 2 (PCV2), the causative agent of porcine circovirus-associated diseases (PCVAD), has caused huge economic losses in the swine industry. Despite a worldwide disease distribution and numerous reports of the field epidemiology of PCV2, the molecular epidemiology and genetic evolution of PCV2 are not well characterized. In this study, 72 complete genomes of PCV2 strains sequenced from 2016 to 2022 in China were produced; phylogenetic analyses demonstrated three genotypes (PCV2a, PCV2b, and PCV2d). Strains PCV2b and PCV2d were equally represented (30/72, 41.6%) whereas the remainder were PCV2a strains (12/72, 16.6%). Therefore, PCV2b and PCV2d have become dominant genotypes in China. Based on the 1682 capsid protein (Cap) sequences, 27 high-frequency amino acid mutations occurred in Cap, with 18 of 27 mutated amino acids exposed on the capsid surface. That amino acid mutations with increasing positively charged polar amino acids occurred on the capsid surface implied PCV2 may have evolved to better adapt to hosts by enhancing the binding capacity of PCV2 to negatively charged cell receptors. Moreover, these mutations probably enable PCV2 to evade host immune responses by changing epitope antigenicity and decreasing epitope accessibility to the immune system. This study characterized the genotypic evolution of PCV2 and assessed the adaptive value of viral mutations in evading host defences, providing powerful insights to elucidate potential mechanisms of immune evasion and evidence to inform effective prevention and control strategies.

Nanoparticles (NPs) have shown great potential as advanced vaccines and immunotherapy platforms due to their size and polyvalent epitopes. However, the immune responses elicited by glycosylated antigens conjugated to NPs with variable antigen densities remain poorly understood. In this study, we analyzed the glycosylation profile of the CD2v ectodomain of African swine fever virus, identifying 16 potential N-glycosylation sites among 192 residues, which markedly reduced its antigenicity. To enhance the antigenicity of CD2v, we designed three protein-based NPs derived from Ferritin, porcine circovirus type 2 (PCV2) capsid protein, and AP205 coat protein. Antigens were conjugated to the NP surfaces using the SpyTag/SpyCatcher system. Immunoassays demonstrated that these NPs rapidly induced higher levels of antigen-specific IgG compared to unconjugated antigens, with the effect being most pronounced for the highly glycosylated CD2v. All NPs significantly promoted IgG2a production, indicating a Th1-biased immune response. Furthermore, PCV2 NP reached the popliteal lymph node within 5 min post-injection and persisted for 21 days, extensively interacting with B cells. These findings provide the potential of tailoring NP design to enhance antigenicity, providing a foundation for developing glycosylated antigen-targeted vaccines and immunotherapies.

In this study, we fully sequenced and analyzed the genome of strain 12219 and identified it as Streptomyces thermocarboxydus. The genome contained a single linear chromosome, 6,950,031 bp in size, with a GC content of 72.21 %. This study predicted a total of 6295 genes, including 128 glycoside hydrolase genes, 21 carbohydrate esterase genes, and 54 carbohydrate-binding module genes. When corncob was used as inducer, strain 12219 secreted cellulases and hemicellulases, with xylanase activity reaching 31.15 U/mL. During the hydrolysis of sodium hydroxide treated corn stover, a notable synergistic effect between the 12219 enzyme cocktail and commercial cellulase was observed. And the maximum degree of synergism reached 1.60. When the amount of the 12219 enzyme cocktail added to the commercial cellulase was 5 mg/g, the release of glucose, xylose, and cellobiose increased by 121.35 %, 178.58 %, and 29.33 %, respectively. These findings suggested that the 12219 enzyme cocktail held great potential for industrial applications.

Porcine deltacoronavirus (PDCoV), an emerging swine pathogen causing severe enteric disease in piglets, poses cross-species transmission risks, including humans. The C-terminal domain (CTD) of its spike protein harbors a key receptor-binding region with antigenic specificity and cross-protective potential. Here, we developed a novel nanoparticle-based CTD vaccine (CTDnps) by conjugating PDCoV S1-CTD to bacteriophage AP205 capsids, leveraging subunit vaccine advantages in safety, scalability, and affordability, to address urgent needs for PDCoV control. Compared to the CTD monomer, the CTDnps vaccine induced a markedly faster antigen-specific IgG response and greater neutralizing antibody (NAb) titers in mice. In immunized sows, the CTDnps vaccine elicited sustained IgG and secretory IgA (sIgA) responses, with serum NAbs persisting up to 60 days post-farrowing at titers exceeding 1:64. Passive transfer of maternal antibodies to newborn piglets significantly reduced viral loads and clinical signs upon PDCoV challenge, whereas histopathological and immunohistochemical analyses confirmed reduced viral presence and intestinal damage in the CTDnps-vaccinated group. Furthermore, CTDnps enhanced dendritic cell antigen uptake and upregulated expression of major histocompatibility complex II and co-stimulatory molecules (CD80 and CD86) to activate humoral and cellular immunity. We concluded that the PDCoV S1-CTD nanoparticle vaccine has much potential for robust and prolonged PDCoV prevention. Finally, the formed nanoparticle platform has potentially broad applications for developing multivalent vaccines against diverse coronaviruses. IMPORTANCE:Although porcine deltacoronavirus (PDCoV) poses a potential threat to public health, effective vaccines against PDCoV remain lacking. Here, we developed a novel nanoparticle-based C-terminal domain vaccine (CTDnps) targeting the conserved S1-CTD domain of the PDCoV spike protein. Unlike traditional subunit vaccines, CTDnps displayed AP205 capsids to enhance antigen presentation, induced rapid and robust neutralizing antibodies in sows, and conferred passive immunity to piglets via maternal antibody transfer. Mechanistically, CTDnps promoted dendritic cell activation and cellular immunity by upregulating major histocompatibility complex II and co-stimulatory molecules, a feature absent in monomeric CTD vaccines. We not only established CTDnps as a potent PDCoV intervention, but also pioneered a scalable, fast platform adaptable to emerging or multivalent coronavirus vaccines. This study provided actionable strategies to mitigate PDCoV outbreaks and broader coronavirus threats.

B-1a cells, a self-renewing B cell subset essential for innate immunity, produce natural IgM antibodies that defend against pathogens, yet mechanisms sustaining their maintenance during aging remain unclear. We report that aging B-1a cells exhibit hallmarks of decline, including DNA damage, apoptosis, and reduced proliferation, with striking sex-specific disparities: aged females retain higher B-1a cell numbers than males, correlating with enhanced glycolysis and chromatin accessibility. Motif analysis of accessible regions identified the transcription factor Bcl11a, which shows elevated chromatin accessibility and expression in aged female B-1a cells but declines in males. Bcl11a deletion reduced B-1a cell numbers, impaired viability, and increased apoptosis across sexes and ages. Mechanistically, Bcl11a sustains survival by upregulating antiapoptotic genes (Mcl1, Mdm2, and Mdm4) to suppress p53-mediated apoptosis, as evidenced by partial rescue of viability defects in Bcl11a-deficient B-1a cells upon p53 deletion. Conversely, Bcl11a overexpression or Bcl11a-high B-1a cells from aged Bcl11a-eGFP reporter mice enhanced stress resistance. These findings establish Bcl11a as a key regulator of B-1a cell maintenance during aging and reveal its role in mitigating sex-dimorphic immune decline through transcriptional control of survival pathways.

Pseudorabies virus (PRV) represents a considerable infectious threat to the swine industry in China and poses potential health risks to humans. However, there is a notable lack of specific antiviral agents aimed at combating PRV. Haspin is involved in histone phosphorylation during mitosis, while the role of swine Haspin in PRV infection has not been previously investigated. In the present study, we demonstrated that Haspin expression was significantly enhanced in response to PRV infection. Overexpression of the haspin gene notably enhanced PRV infection, while genetic inhibition of haspin gene resulted in a substantial reduction in viral infection. Further investigations indicated that the Haspin kinase inhibitor CHR-6494 effectively suppressed PRV infection in a concentration-dependent manner, primarily by inhibiting viral virus replication rather than interfering with the processes of binding, entry, or release. Additionally, treatment with CHR-6494 effectively restricted Herpes simplex virus type 1 infection in Vero cells. Collectively, these findings indicate that Haspin may serve as a novel therapeutic target for the management of infections caused by Alphaherpesvirinae.

Canine Papillomavirus (CPV) is a prevalent viral infection in dogs, characterized by the formation of benign warts or papillomas on the skin and mucous membranes. While most CPV types result in non-malignant growths, certain strains, particularly in immunocompromised dogs (e.g., sick or elderly animals), can lead to malignant transformations. This highlights the need for early, accurate diagnosis, alongside preventive vaccination, to manage the disease effectively. Diagnostic methods leverage CPV’s unique characteristics, including histopathology with hematoxylin and eosin (H E) staining for assessing neoplastic tissue growth and cytopathy, molecular techniques like polymerase chain reaction (PCR), rolling circle amplification (RCA), DNA in situ hybridization (ISH), and next-generation sequencing (NGS) for detecting CPV genomic DNA, immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA) for identifying viral antigen such as the L1 protein, as well as transmission electron microscopy (TEM) for visualizing viral particles in lesions. These approaches display appreciable sensitivity and specificity and are often utilized in CPV research, though they also have certain intrinsic limitations, such as accessibility, technical complexity. Advancements in CPV vaccine development, including inactivated, live-attenuated, DNA-based, and recombinant protein-based formulations, show promise in achieving effective protection. However, a commercially available vaccine has yet to be developed. Furthermore, challenges persist in developing convenient, cost-effective diagnostics suitable for diverse clinical applications and in formulating affordable, cross-protective vaccines. This review emphasizes the importance of continued innovation in CPV diagnostics and vaccine development to mitigate both benign and malignant papillomatosis, enhance disease prevention, and safeguard canine health.

Porcine circovirus type 3 (PCV3) is a globally emerging circovirus affecting pigs and other animals. The capsid protein (Cap) is the sole structural protein of PCV, with a crucial role in virus evolution and pathogenesis. Through interactions with host factors, Cap enables viral entry, transport, and replication while modifying various cellular processes. Cap protein-induced apoptosis has important implications for viral pathogenesis, but remains poorly defined. Herein, we demonstrated for the first time that PCV3 Cap induced cell cycle arrest of PK-15 cells in S-phase and initiated apoptosis via a mitochondrial Caspase-9-dependent pathway. Truncation analysis localized the apoptotic determinant to the N-terminal 1-34 aa of PCV3 Cap and heterogeneous nuclear ribonucleoprotein K (hnRNP K) was identified as a host protein that binds to PCV3 Cap. Overexpression of hnRNP K reduced PCV3 Cap-induced release of Cyt-c into the cytoplasm, implying a regulatory role in apoptosis. Based on structural modelling and molecular docking, amino acids at sites 24 and 27 of Cap from PCV3 variants, which define genotypes (PCV3a/b/c), affected binding with hnRNP K. Specifically, PCV3c Cap (V24/K27 and V24/R27) had higher affinity than PCV3a Cap (A24/R27) or PCV3b Cap (A24/K27), consistent with its superior apoptosis-inducing capacity compared to PCV3a/b variants, highlighting the importance of Cap interactions with hnRNP K. In summary, we identified novel molecular determinants of PCV3 pathogenesis that will inform development of vaccines and diagnostics.

Deubiquitinases are a group of proteins that identify and digest monoubiquitin chains or polyubiquitin chains attached to substrate proteins, preventing the substrate protein from being degraded by the ubiquitin-proteasome system. Deubiquitinases regulate cellular autophagy, metabolism and oxidative stress by acting on different substrate proteins. Recent studies have revealed that deubiquitinases act as a critical regulator in various cardiac diseases, and control the onset and progression of cardiac disease through a board range of mechanism. This review summarizes the function of different deubiquitinases in cardiac disease, including cardiac hypertrophy, myocardial infarction and diabetes mellitus-related cardiac disease. Besides, this review briefly recapitulates the role of deubiquitinases modulators in cardiac disease, providing the potential therapeutic targets in the future.

Transmissible gastroenteritis virus (TGEV) is an etiological agent of enteric disease that results in high mortality rates in piglets. The economic impact of the virus is considerable, causing significant losses to the pig industry. The development of an efficacious subunit vaccine to provide promising protection against TGEV is of the utmost importance. The viral antigen, spike glycoprotein (S), is widely regarded as one of the most effective antigenic components for vaccine research. In this study, we employed immunoinformatics and molecular dynamics approaches to develop an ‘ideal’ multi-epitope vaccine. Firstly, the dominant, non-toxic, highly antigenic T (Th, CTL) and B cell epitopes predicted from the TGEV S protein were artificially engineered in tandem to design candidate subunit vaccines. Molecular docking and dynamic simulation results demonstrate that it exhibits robust interactions with toll-like receptor 4 (TLR4). Of particular significance was the finding that the vaccine was capable of triggering an immune response in mammals, as evidenced by the immune simulation results. The humoral aspect is typified by elevated levels of IgG and IgM, whereas the cellular immune aspect is capable of eliciting the robust production of interleukins and cytokines (IFN-γ and IL-2). Furthermore, the adoption of E. coli expression systems for the preparation of vaccines will also result in cost savings. This study offers logical guidelines for the development of a secure and efficacious subunit vaccine against TGEV, in addition to providing a novel theoretical foundation and strategy to prevent associated CoV infections.

Porcine reproductive and respiratory syndrome virus (PRRSV), the causative agent of porcine reproductive and respiratory syndrome (PRRS), continues to significantly impact on the global swine industry. GP5 and M are the primary structural proteins of PRRSV, playing crucial roles in the processes of virus attachment, entry, assembly and budding. The co-expression of GP5 and M can result in the formation of virus-like particles (VLPs). However, the underlying mechanisms remain incompletely understood. This study investigated the role of GP5-M interaction in VLPs secretion and cell binding. VLPs were generated by co-expressing GP5 and M via recombinant baculoviruses in Sf9 cells and confirmed by transmission electron microscopy. The secretion of VLPs was modulated by the expression levels of GP5 and M. Using the BirA technique, the GP5-M interaction was confirmed in Sf9 cells. Disruption of the N-terminally intermolecular disulfide bond between GP5 and M weakened, but did not completely abolish, the interaction between the proteins, leading to reduced VLPs secretion. Notably, the absence of this intermolecular disulfide bond resulted in the loss of VLPs’ ability to bind to MARC-145 cells. In summary, our findings reveal the critical function of the intermolecular disulfide bond in GP5-M interaction, which significantly contributes to VLPs secretion and cell binding, and suggest potential interaction sites between GP5 and M.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has filled a gap in our knowledge regarding the prevention of CoVs. Swine coronavirus (CoV) is a significant pathogen that causes huge economic losses to the global swine industry. Until now, anti-CoV prevention and control have been challenging due to the rapidly generated variants. Silver nanoparticles (AgNPs) with excellent antimicrobial activity have attracted great interest for biosafety prevention and control applications. In this study, we synthesized chitosan-modified AgNPs (Chi-AgNPs) with good biocompatibility to investigate their antiviral effects on swine CoVs. In vitro assays showed that Chi-AgNPs could significantly impaired viral entry. The direct interaction between Chi-AgNPs and CoVs can destroy the viral surface spike (S) protein secondary structure associated with viral membrane fusion, which is caused by the cleavage of disulfide bonds in the S protein. Moreover, the mechanism showed that Chi-AgNPs reduced the virus-induced apoptosis of Vero cells via the ROS/p53 signaling activation pathway. Our data suggest that Chi-AgNPs can serve as a preventive strategy for CoVs infection and provide a molecular basis for the viricidal effect of Chi-AgNPs on CoVs.

The outbreak of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has shaken the global health system. Various nanotechnology-based strategies for vaccine development have played pivotal roles in fighting against SARS-CoV-2. Among them, the safe and effective protein-based nanoparticle (NP) platforms display a highly repetitive array of foreign antigens on their surface, which is urgent for improving the immunogenicity of vaccines. These platforms greatly improved antigen uptake by antigen presenting cells (APCs), lymph node trafficking, and B cell activation, due to the optimal size, multivalence, and versatility of NPs. In this review, we summarize the advances of protein-based NP platforms, strategies of antigen attachment, and the current progress of clinical and preclinical trials in the development of SARS-CoV-2 vaccines based on protein-based NP platforms. Importantly, the lessons learnt and design approaches developed for these NP platforms against SARS-CoV-2 also provide insights into the development of protein-based NP strategies for preventing other epidemic diseases.