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Newcastle disease virus (NDV), a member of the Paramyxoviridae family, can activate PKR/eIF2α signaling cascade to shutoff host and facilitate viral mRNA translation during infection, however, the mechanism remains unclear. In this study, we revealed that NDV infection up-regulated host cap-dependent translation machinery by activating PI3K/Akt/mTOR and p38 MAPK/Mnk1 pathways. In addition, NDV infection induced p38 MAPK/Mnk1 signaling participated 4E-BP1 hyperphosphorylation for efficient viral protein synthesis when mTOR signaling is inhibited. Furthermore, NDV NP protein was found to be important for selective cap-dependent translation of viral mRNAs through binding to eIF4E during NDV infection. Taken together, NDV infection activated multiple signaling pathways for selective viral protein synthesis in infected cells, via interaction between viral NP protein and host translation machinery. Our results may help to design novel targets for therapeutic intervention against NDV infection and to understand the NDV anti-oncolytic mechanism.

Lonicera japonica Thunb , rich in chlorogenic acid (CHA), is used for viral upper respiratory tract infection treatment caused by influenza virus, parainfluenza virus, and respiratory syncytial virus, ect in China. It was reported that CHA reduced serum hepatitis B virus level and death rate of influenza virus-infected mice. However, the underlying mechanisms of CHA against the influenza A virus have not been fully elucidated. Here, the antiviral effects and potential mechanisms of CHA against influenza A virus were investigated. CHA revealed inhibitory against A/PuertoRico/8/1934(H1N1) (EC 50  = 44.87 μM), A/Beijing/32/92(H3N2) (EC 50  = 62.33 μM), and oseltamivir-resistant strains. Time-course analysis showed CHA inhibited influenza virus during the late stage of infectious cycle. Indirect immunofluorescence assay indicated CHA down-regulated the NP protein expression. The inhibition of neuraminidase activity confirmed CHA blocked release of newly formed virus particles from infected cells. Intravenous injection of 100 mg/kg/d CHA possessed effective antiviral activity in mice, conferring 60% and 50% protection from death against H1N1 and H3N2, reducing virus titres and alleviating inflammation in the lungs effectively. These results demonstrate that CHA acts as a neuraminidase blocker to inhibit influenza A virus both in cellular and animal models. Thus, CHA has potential utility in the treatment of the influenza virus infection.

For the clinical application of semi-quantitative anti-SARS-CoV-2 antibody tests, the analytical performance and titer correlation of the plaque reduction neutralization test (PRNT) need to be investigated. We evaluated the analytical performance and PRNT titer-correlation of one surrogate virus neutralization test (sVNT) kit and three chemiluminescent assays. We measured the total antibodies for the receptor-binding domain (RBD) of the spike protein, total antibodies for the nucleocapsid protein (NP), and IgG antibodies for the RBD. All three chemiluminescent assays showed high analytical performance for the detection of SARS-CoV-2 infection, with a sensitivity ≥ 98% and specificity ≥ 99%; those of the sVNT were slightly lower. The representativeness of the neutralizing activity of PRNT ND 50 ≥ 20 was comparable among the four immunoassays (Cohen’s kappa ≈ 0.80). Quantitative titer correlation for high PRNT titers of ND 50 ≥ 50, 200, and 1,000 was investigated with new cut-off values; the anti-RBD IgG antibody kit showed the best performance. It also showed the best linear correlation with PRNT titer in both the acute and convalescent phases (Pearson’s R 0.81 and 0.72, respectively). Due to the slowly waning titer of anti-NP antibodies, the correlation with PRNT titer at the convalescent phase was poor. In conclusion, semi-quantitative immunoassay kits targeting the RBD showed neutralizing activity that was correlated by titer; measurement of anti-NP antibodies would be useful for determining past infections.

Newcastle disease virus (NDV) has been extensively studied as a promising oncolytic virus for killing tumor cells in vitro and in vivo in clinical trials. However, the viral components that regulate the oncolytic activity of NDV remain incompletely understood. In this study, we systematically compared the replication ability of different NDV genotypes in various tumor cells and identified NP protein determines the oncolytic activity of NDV. On the one hand, NDV strains with phenylalanine (F) at the 450th amino acid position of the NP protein (450th-F-NP) exhibit a loss of oncolytic activity. This phenotype is predominantly associated with genotype VII NDVs. In contrast, the NP protein with a leucine amino acid at this site in other genotypes (450th-L-NP) can facilitate the loading of viral mRNA onto ribosomes more effectively than 450th-F-NP. On the other hand, the NP protein from NDV strains that exhibit strong oncogenicity interacts with eIF4A1 within its 366–489 amino acid region, leading to the inhibition of cellular mRNA translation with a complex 5’ UTR structure. Our study provide mechanistic insights into how highly oncolytic NDV strains selectively promote the translation of viral mRNA and will also facilitate the screening of oncolytic strains for oncolytic therapy.

Background Sensitive and specific antibodies can be used as essential probes to develop competitive enzyme-linked immunosorbent assay (cELISA). However, traditional antibodies are difficult to produce, only available in limited quantities, and ineffective as enzymatic labels. Nanobodies, which are single-domain antibodies (sdAbs), offer an alternative, more promising tool to circumvent these limitations. In the present work, a cELISA using nanobody-horseradish peroxidase (HRP) fusion protein firstly designed as a probe was developed for detecting anti-Newcastle disease virus (NDV) antibodies in chicken sera. Results In the study, a platform for the rapid and simple production of nanobody-HRP fusion protein was constructed. First, a total of 9 anti-NDV-NP protein nanobodies were screened from a immunised Bactrian camel. Then, the Nb5-HRP fusions were produced with the platform and used for the first time as sensitive reagents for developing cELISA to detect anti-NDV antibodies. The cut-off value of the cELISA was 18%, and the sensitivity and specificity were respectively 100% and 98.6%. The HI test and commercial ELISA kit (IDEXX) separately agreed 97.83% and 98.1% with cELISA when testing clinical chicken sera and both agreed 100% when testing egg yolks. However, for detecting anti-NDV antibodies in the sequential sera from the challenged chickens, cELISA demonstrated to be more sensitive than the HI test and commercial ELISA kit. Moreover, a close correlation (R 2  = 0.914) was found between the percent competitive inhibition values of cELISA and HI titers. Conclusions A platform was successfully designed to easily and rapidly produce the nanobody-HRP fusion protein, which was the first time to be used as reagents for establishing cELISA. Results suggest that the platform supports the development of a cELISA with high sensitivity, simplicity, and rapid detection of anti-NDV antibodies. Overall, we believe that the platform based on nanobody-HRP fusions can be widely used for future investigations and treatment other diseases and viruses.

As a natural antiviral regulator, phospholipid scramblase 1 (PLSCR1) has been shown to inhibit influenza virus replication in infected cells through interacting with NP of influenza A virus (IAV). But its antiviral function as well as the underlying regulatory mechanism has not been examined in vivo. In the present work, we show that PLSCR1 expression is decreased in H1N1 SIV-infected mice, and Plscr1 −/− mice are more susceptible to H1N1 SIV infection. By performing yeast two-hybrid screening, we identified immunoglobulin-like domain-containing receptor 1 (ILDR1) as a novel PLSCR1-binding partner. ILDR1 is highly expressed in the lungs, and its expression level is increased after virus infection. Interestingly, ILDR1 could not directly interact with virus NP protein, but could combine with PLSCR1 competitively. Our data indicates that there is a previously unidentified PLSCR1-ILDR1-NP regulatory pathway playing a vital role in limiting IAV infection, which provides novel insights into IAV-host interactions.

We are committed to finding host targets for influenza A therapeutics. The nucleoprotein (NP) plays an important role in influenza A virus replication and is an indispensable part of viral transcription and replication. Exploring endogenous substances that can modulate NP is critical for finding host targets. MicroRNAs (miRNAs, miR) are a novel class of powerful, endogenous gene expression regulators. Herein, we used miRanda to analyse the base complementarity between the NP gene and the 14 host miRNAs reported previously by us. MiRanda predicted that miR‐431‐5p, miR‐744‐3p and miR‐205‐5p could complement the NP gene. To understand the effect of these miRNAs on NP expression, we co‐transfected 293 T cells with NP gene sequence containing above miRNAs binding site or full sequence of NP gene (transfected into pmirGlo or pcDNA3.1 vectors, respectively), and mimics of miR‐205‐5p, miR‐431‐5p and miR‐744‐3p. Dual luciferase reporter gene or Western blotting assays confirmed that miR‐205‐5p and miR‐431‐5p inhibit NP expression by binding with the miRNA binding site of NP gene. Further, we infected Mouse Lung Epithelial (MLE‐12) cells overexpressing miR‐205‐5p and miR‐431‐5p with influenza A virus and performed Western blotting to examine NP expression. We found that NP expression was significantly reduced in MLE‐12 cells overexpressing miR‐205‐5p during influenza A infection. The miR‐205‐5p overexpression‐induced inhibition of influenza A replication could be attributed to the inhibition of NP expression. Further, we administered oseltamivir and Jinchai Antiviral Capsules (JC, an anti‐influenza Chinese medicine) to influenza A virus‐infected MLE‐12 cells and mice. We found that miR‐205‐5p was significantly decreased increased in infected cells and lung tissues, and oseltamivir and JC could up‐regulate miR‐205‐5p. In conclusion, we provide new evidence that miR‐205‐5p plays a role in regulating viral NP protein expression in combating influenza A and may be a potential target for influenza A therapy.

The use of nanotechnology in agriculture, often referred to as “phyto-nanotechnology,” has received greater attention in recent years because of its potential to expand food production sustainably. Growing body of evidence suggests that nanoparticles (NPs) can be efficiently used as biosensors, gene/nutrient carriers, fertilizers, and growth augmenters, among others. Upon the entry of NPs in a biological environment, biomolecules, majorly proteins, rapidly cover the NP surface to form an interface called “protein corona” (PC) which determines the behavior of NPs, including their uptake, transport, localization, and interaction in biological systems. Moreover, some of the recent studies showed that the corona formation affects the cellular processes like energy synthesis, pathogenesis, leaf senescence, and salt stress response in plants. Besides, it also influences the heat that affected the gastrointestinal fate of consumed proteins. Therefore, understanding of PC is of critical importance for efficient utilization of NPs in phyto-nanotechnology and for the safety of living organisms. While the PC study has seen years of progress in research fields like nanomedicine, nanotoxicology, and environmental biology, it is relatively unexplored in phyto-nanotechnology. Given its significance, the employment and progress of analytical methods to analyze NP-protein complexes are crucial to comprehend the impacts of NPs on plants. In this review, we introduce the concept of PC to a large section of plant biologists along with discussing the analytical techniques, factors governing corona composition, the status of PC exploration across fields, major challenges, and the future perspectives concerning plants. Graphical Abstract

Thousands of outbreaks of the highly pathogenic avian influenza A(H5N1) virus in birds and an increasing number of mammal infections are registered annually. In 2023, multiple avian influenza outbreaks were registered among wild birds, poultry and seals in Russia. The genetic characterization of seventy-seven avian viruses and three viruses from seals showed that they belonged to the 2.3.4.4b clade and represented four distinct reassortant genotypes. The majority of viruses represented genotype BB, which was widespread in Europe in 2023. Viruses from seals and four viruses from birds, isolated from outbreaks in the Far East region, belonged to the G1 (A3) genotype and had the amino acid substitution N319K in the NP protein, previously associated with an increased virulence for mammals. In addition, one virus of the G10 genotype and two viruses, representing a previously undescribed genotype (designated as Ru-23-G4) were identified. The viruses analyzed showed normal inhibition by neuraminidase inhibitors. Seven viruses had genetic markers of amantadine resistance. All the influenza A(H5N1) viruses studied showed a binding preference for α2-3-linked sialic acids, suggesting a low risk of transmission among humans. Nevertheless, monitoring of reassortment and mammalian adaptation mutations is essential for the timely identification of viruses with increased pandemic potential.

Objective To conduct an epidemiological investigation on a case of severe fever with thrombocytopenia syndrome (SFTS) reported in Longyou County, Zhejiang Province in April 2025, and to perform nucleic acid detection and genetic characterization of Dabie bandavirus (DBV) in the patient’s serum sample, aiming to provide scientific evidence and technical support for local SFTS prevention and control. Methods An epidemiological investigation was conducted on the case. Serum samples from the confirmed case and close contacts, as well as related vector host specimens, were collected. DBV-specific nucleic acid was detected using real-time fluorescent quantitative PCR. The viral genome was amplified by RT-PCR and subjected to whole-genome sequencing. Professional computer software (SeqMan Ultra 17.2, Clustal X 2.1, BioEdit V7.2.6.1, and MEGA V7.0.26, etc.) was used for nucleotide and amino acid sequence alignment, phylogenetic tree construction, and calculation of genetic distances and homology percentages. Results The case had a history of tick bite and no history of travel outside the area. Fluorescence quantitative PCR detection showed that only the case’s serum sample was positive for DBV nucleic acid, while serum samples from close contacts and related vector host specimens were all negative for DBV nucleic acid. After amplification and sequencing, the three fragments L, M, and S were successfully obtained. Genetic evolution analysis showed that they belonged to genotypes L (C), M (C), and S (A), respectively. Compared with the closest reference strain HZ2023-16 in the phylogenetic tree, the nucleotide homologies of the L, M, NS, and NP genes were 99.74%, 99.53%, 99.66%, and 99.19%, respectively, and the amino acid homologies were 100%, 99.72%, 99.66%, and 99.59%, respectively. Compared with the type C reference strain AHL/China/2011 (L(C)/M(C)/S(D)), the nucleotide homologies of the L, M, NS, and NP genes were 96.87%, 96%, 93.76%, and 95.66%, respectively, and the amino acid homologies were 99.42%, 98.51%, 98.29%, and 99.18%, respectively. Compared with the type A reference strain JX23XSH (L(A)/M(A)/S(A)), the nucleotide homologies of the L, M, NS, and NP genes were 96.24%, 95.97%, 95.35%, and 97.02%, respectively, and the amino acid homologies were 99.52%, 98.14%, 99.32%, and 99.18%, respectively. The average genetic distances of the L, M, and S genes compared with the HZ2023-16 reference strain were 0.003, 0.005, and 0.005, respectively; compared with the type C reference strain AHL/China/2011 (L(C)/M(C)/S(D)), they were 0.031, 0.04, and 0.053, respectively; compared with the type A reference strain JX23XSH (L(A)/M(A)/S(A)), they were 0.038, 0.04, and 0.038, respectively. Amino acid variation analysis showed that compared with the reference strains, this strain had 0–12 amino acid substitutions in the L protein (e.g., V68I, A140V), 3–20 substitutions in the M protein (e.g., D151E, G863S), 1–5 substitutions in the NS protein, and 1–2 substitutions in the NP protein. Conclusion Combining the clinical manifestations, epidemiological history, and laboratory test results of the case, this outbreak can be determined as a local case of severe fever with thrombocytopenia syndrome. The strain is genetically closely related to human-derived reference strains and possesses specific genomic characteristics.