The melanin pigment gene black mediates body pigmentation and courtship behaviour in the German cockroach Blattella germanica.

Genes involved in melanin production directly impact insect pigmentation and can affect diverse physiology and behaviours. The role these genes have on sex behaviour, however, is unclear. In the present study, the crucial melanin pigment gene black was functionally characterised in an urban pest, the German cockroach, Blattella germanica. RNAi knockdown of B. germanica black (Bgblack) had no effect on survival, but did result in black pigmentation of the thoraxes, abdomens, heads, wings, legs, antennae, and cerci due to cuticular accumulation of melanin. Sex-specific variation in the pigmentation pattern was apparent, with females exhibiting darker coloration on the abdomen and thorax than males. Bgblack knockdown also resulted in wing deformation and negatively impacted the contact sex pheromone-based courtship behaviour of males. This study provides evidence for black function in multiple aspects of B. germanica biology and opens new avenues of exploration for novel pest control strategies.

RNAi of yellow-y, required for normal cuticle pigmentation, impairs courtship behavior and oviposition in the German cockroach (Blattella germanica).

The insect cuticle plays a key role in maintaining the insect's physiological function and behavior. Herein, the yellow-y protein is required to produce black melanin, and is expressed in a pattern that correlates with the distribution of this pigment. However, yellow-y can also have other functions, for instance, in insect behavior, but not much is known. In this study, we have studied the yellow-y gene in one important model and pest species, namely the German cockroach (Blattella germanica), which is to our knowledge the first time reported. In essence, we identified the yellow-y gene (BgY-y) and characterized its function by using RNA interference (RNAi). Silencing of BgY-y gene led to different developmental abnormalities (body weight and wings) in both genders. Specifically, there was an abundant decrease in melanin, turning the body color in pale yellow and the cuticle softer and more transparent. Interestingly, we also observed that the knockdown of BgY-y impaired the male cockroaches to display a weaker response to female-emitted contact sex pheromones, and also that the oviposition ability was weakened in the RNAi females. This study comprehensively analyzed the biological functions of the yellow-y gene in German cockroaches from the perspectives of development, body color, courtship behavior and oviposition, and as a consequence, this may opens new avenues to explore it as a novel pest control gene.

Identification of host proteins interacting with the E protein of porcine epidemic diarrhea virus.

Introduction: Porcine epidemic diarrhea (PED) is an acute, highly contagious, and high-mortality enterophilic infectious disease caused by the porcine epidemic diarrhea virus (PEDV). PEDV is globally endemic and causes substantial economic losses in the swine industry. The PEDV E protein is the smallest structural protein with high expression levels that interacts with the M protein and participates in virus assembly. However, how the host proteins interact with E proteins in PEDV replication remains unknown. Methods: We identified host proteins that interact with the PEDV E protein using a combination of PEDV E protein-labeled antibody co-immunoprecipitation and tandem liquid-chromatography mass-spectroscopy (LC-MS/MS). Results: Bioinformatical analysis showed that in eukaryotes, ribosome biogenesis, RNA transport, and amino acid biosynthesis represent the three main pathways that are associated with the E protein. The interaction between the E protein and isocitrate dehydrogenase [NAD] ß-subunit (NAD-IDH-ß), DNA-directed RNA polymerase II subunit RPB9, and mRNA-associated protein MRNP 41 was validated using co-immunoprecipitation and confocal assays. NAD-IDH-ß overexpression significantly inhibited viral replication. Discussion: The antiviral effect of NAD-IDH-ß suggesting that the E protein may regulate host metabolism by interacting with NAD-IDH-ß, thereby reducing the available energy for viral replication. Elucidating the interaction between the PEDV E protein and host proteins may clarify its role in viral replication. These results provide a theoretical basis for the study of PEDV infection mechanism and antiviral targets.

Nanoparticle-delivered RNAi-based pesticide target screening for the rice pest white-backed planthopper and risk assessment for a natural predator.

Vacuolar-type (H+)-ATPase (vATPase) is a conserved multi-subunit eukaryotic enzyme composed of 14 subunits that form a functional complex consisting of an ATP-hydrolytic domain (V1) and a proton-translocation domain (V0). ATP hydrolysis and subsequent H+ translocation rely heavily on a fully assembled V1/V0 complex. Since vATPase is crucial for insect survival, it is a viable molecular target for pest control. However, detailed functional analyses of the 14 subunits and their suitability for pest control have not been fully explored in a single insect species. In this study, we identified 22 vATPase subunit transcripts that correspond to 13 subunits (A1, A2, B, C, D, E, F, G, H, a1, a2, c and d) in the white-backed planthopper (WBPH), Sogatella furcifera, a major hemipteran pest of rice. RNAi screens using microinjection and spray-based methods revealed that the SfVHA-F, SfVHA-a2 and SfVHA-c2 subunits are critical. Furthermore, star polymer (SPc) nanoparticles were utilized to conduct spray-induced and nanoparticle-delivered gene silencing (SI-NDGS) to evaluate the pest control efficacy of RNAi targeting the SfVHA-F, SfVHA-a2 and SfVHA-c2 transcripts. Target mRNA levels and vATPase enzymatic activity were both reduced. Honeydew excreta was likewise reduced in WBPH treated with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. To assess the environmental safety of the nanoparticle-wrapped dsRNAs, Cyrtorhinus lividipennis Reuter, a major natural enemy of planthoppers, was also sprayed with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. Post-spray effects of dsSfVHA-a2 and dsSfVHA-c2 on C. lividipennis were innocuous. This study identifies SfVHA-a2 and SfVHA-c2 as promising targets for biorational control of WBPH and lays the foundation for developing environment-friendly RNAi biopesticides.

Porcine alveolar macrophages host proteins interacting with African swine fever virus p72.

Introduction: African swine fever virus (ASFV) is a highly contagious virus that spreads rapidly and has a mortality rate of up to 100% in domestic pigs, leading to significant economic losses in the pig industry. The major capsid protein p72 of ASFV plays a critical role in viral invasion and immune evasion. Methods: In this study, we used yeast two-hybrid screening to identify host proteins interacting with p72 in porcine alveolar macrophages (PAMs) and verified these proteins using confocal microscopy and immunoprecipitation techniques. Results and Discussion: We validated 13 proteins that interact with p72, including CD63, B2M, YTHDF2, FTH1, SHFL, CDK5RAP3, VIM, PELO, TIMP2, PHYH, C1QC, CMAS, and ERCC1. Enrichment analysis and protein-protein interaction network analysis of these interacting proteins revealed their involvement in virus attachment, invasion, replication, assembly, and immune regulation. These findings provide new insights into the function of p72 and valuable information for future research on the interaction between ASFV and host proteins.

Deoxycholic acid inhibits ASFV replication by inhibiting MAPK signaling pathway.

African swine fever (ASF) is an acute, febrile, highly contagious infection of pigs caused by the African swine fever virus (ASFV). The purpose of this study is to understand the molecular mechanism of ASFV infection and evaluate the effect of DCA on MAPK pathway, so as to provide scientific basis for the development of new antiviral drugs. The transcriptome analysis found that ASFV infection up-regulated the IL-17 and MAPK signaling pathways to facilitate viral replication. Metabolome analysis showed that DCA levels were up-regulated after ASFV infection, and that exogenous DCA could inhibit activation of the MAPK pathway by ASFV infection and thus inhibit viral replication. Dual-luciferase reporter assays were used to screen the genes of ASFV and revealed that I73R could significantly up-regulate the transcription level of AP-1 transcription factor in the MAPK pathway. Confocal microscopy demonstrated that I73R could promote AP-1 entry into the nucleus, and that DCA could inhibit the I73R-mediated nuclear entry of AP-1, inhibiting MAPK pathway, and I73R interacts with AP-1. These results indicated that DCA can inhibit ASFV-mediated activation of the MAPK pathway, thus inhibiting ASFV replication. This study provides a theoretical basis for research on ASF pathogenesis and for antiviral drug development.

ALIX and TSG101 are essential for cellular entry and replication of two porcine alphacoronaviruses.

Alphacoronaviruses are the primary coronaviruses responsible for causing severe economic losses in the pig industry with the potential to cause human outbreaks. Currently, extensive studies have reported the essential role of endosomal sorting and transport complexes (ESCRT) in the life cycle of enveloped viruses. However, very little information is available about which ESCRT components are crucial for alphacoronaviruses infection. By using RNA interference in combination with Co-immunoprecipitation, as well as fluorescence and electron microscopy approaches, we have dissected the role of ALIX and TSG101 for two porcine alphacoronavirus cellular entry and replication. Results show that infection by two porcine alphacoronaviruses, including porcine epidemic diarrhea virus (PEDV) and porcine enteric alphacoronavirus (PEAV), is dramatically decreased in ALIX- or TSG101-depleted cells. Furthermore, PEDV entry significantly increases the interaction of ALIX with caveolin-1 (CAV1) and RAB7, which are crucial for viral endocytosis and lysosomal transport, however, does not require TSG101. Interestingly, PEAV not only relies on ALIX to regulate viral endocytosis and lysosomal transport, but also requires TSG101 to regulate macropinocytosis. Besides, ALIX and TSG101 are recruited to the replication sites of PEDV and PEAV where they become localized within the endoplasmic reticulum and virus-induced double-membrane vesicles. PEDV and PEAV replication were significantly inhibited by depletion of ALIX and TSG101 in Vero cells or primary jejunal epithelial cells, indicating that ALIX and TSG101 are crucial for PEDV and PEAV replication. Collectively, these data highlight the dual role of ALIX and TSG101 in the entry and replication of two porcine alphacoronaviruses. Thus, ESCRT proteins could serve as therapeutic targets against two porcine alphacoronaviruses infection.

African swine fever virus maintains de novo global cellular protein synthesis and inhibits stress granules formation via dephosphorylating eIF2α.

African swine fever virus (ASFV) has caused enormous economic losses since its first reported detection, and there is still no effective vaccines or drug treatment. During infection, viruses may employ various strategies, such as regulating the host endoplasmic reticulum stress/unfolded protein response or the formation of stress granules (SGs), to form an optimal environment for virus replication. However, how ASFV infection regulates host endoplasmic reticulum stress, eIF2α-regulated protein synthesis, and the formation of SGs remains unclear. Here, we evaluated the activation of ER stress and its three downstream axes during ASFV infection and identified a powerful dephosphorylation of eIF2α by ASFV ex vivo. This strong dephosphorylation property could maintain the efficiency of eIF2α-mediated de novo global protein synthesis, thus ensuring efficient viral protein synthesis at early stage. In addition, the powerful dephosphorylation of eIF2α by ASFV upon infection could also inhibit the formation of SGs induced by sodium arsenite. In addition, a specific eIF2α dephosphorylation inhibitor, salubrinal, could partially counteract ASFV-mediated eIF2α dephosphorylation and inhibit viral replication. Our results provide new insights into the areas of ASFV`s escape from host immunity and hijacking of the host protein translation system.

Pathogenicity and horizontal transmission evaluation of a novel isolated African swine fever virus strain with a three-large-fragment-gene deletion.

African swine fever has caused substantial economic losses to China`s pig industry in recent years. Currently, the highly pathogenic African swine fever virus strain of genotype II is predominantly circulating in China, accompanied by a series of emerging isolates displaying unique genetic variations. The pathogenicity of these emerging strains is still unclear. Recently, a novel ASFV strain with a distinguishable three-large-fragment gene deletion was obtained from the field specimens, and its in vivo pathogenicity and transmission were evaluated in this study. The animal experiment involved inoculating a high dose of YNFN202103 and comparing its effects with those of the highly pathogenic strain GZ201801_2. Results showed that pigs infected by YNFN202103 exhibited significantly prolonged onset and survival time, lower viremia levels, and less severe histopathological lesions compared to GZ201801_2. These findings contributed valuable insights into the pathogenicity and transmission of ASFV and its prevention and eradication strategies in practical settings.

RNA Interference-Screening of Potentially Lethal Gene Targets in the White-Backed Planthopper Sogatella furcifera via a Spray-Induced and Nanocarrier-Delivered Gene Silencing System.

RNA interference (RNAi) is a widespread post-transcriptional silencing mechanism that targets homologous mRNA sequences for specific degradation. An RNAi-based pest management strategy is target-specific and considered a sustainable biopesticide. However, the specific genes targeted and the efficiency of the delivery methods can vary widely across species. In this study, a spray-induced and nanocarrier-delivered gene silencing (SI-NDGS) system that incorporated gene-specific dsRNAs targeting conserved genes was used to evaluate phenotypic effects in white-backed planthopper (WBPH). At 2 days postspraying, transcript levels for all target genes were significantly reduced and knockdown of two gene orthologs, hsc70-3 and PP-α, resulted in an elevated mortality (>60%) and impaired ecdysis. These results highlight the utility of the SI-NDGS system for identifying genes involved in WBPH growth and development that could be potentially exploitable as high mortality target genes to develop an alternative method for WBPH control.

Inhibitory effects of quercetin on porcine epidemic diarrhea virus in vitro and in vivo.

Porcine epidemic diarrhea (PED) is an acute, severe, highly contagious disease. Porcine epidemic diarrhea virus (PEDV) strains are prone to mutation, and the immune response induced by traditional vaccines may not be strong enough to be effective against the virus. Therefore, there is an urgent need to develop novel anti-PEDV drugs. This study aimed to explore the therapeutic effects of quercetin in PEDV infections in vitro (Vero cells) and in vivo (suckling piglets). Using transmission electron microscopy and laser confocal microscopy, we found that PEDV infection promotes the accumulation of lipid droplets (LDs). In vitro, studies showed that quercetin inhibits LD accumulation by down-regulating NF-κB signaling and IL-1ß, IL-8, and IL-6 levels, thereby inhibiting viral replication. In vivo, studies in pigs demonstrated that quercetin can effectively relieve the clinical symptoms and intestinal injury caused by PEDV. Collectively, our findings suggest that quercetin inhibits PEDV replication both in vivo and in vitro, which provides a new direction for the development of PED antiviral drugs.

KPNA2 suppresses porcine epidemic diarrhea virus replication by targeting and degrading virus envelope protein through selective autophagy.

IMPORTANCE: Porcine epidemic diarrhea, characterized by vomiting, dehydration, and diarrhea, is an acute and highly contagious enteric disease caused by porcine epidemic diarrhea virus (PEDV) in neonatal piglets. This disease has caused large economic losses to the porcine industry worldwide. Thus, identifying the host factors involved in PEDV infection is important to develop novel strategies to control PEDV transmission. This study shows that PEDV infection upregulates karyopherin α 2 (KPNA2) expression in Vero and intestinal epithelial (IEC) cells. KPNA2 binds to and degrades the PEDV E protein via autophagy to suppress PEDV replication. These results suggest that KPNA2 plays an antiviral role against PEDV. Specifically, knockdown of endogenous KPNA2 enhances PEDV replication, whereas its overexpression inhibits PEDV replication. Our data provide novel KPNA2-mediated viral restriction mechanisms in which KPNA2 suppresses PEDV replication by targeting and degrading the viral E protein through autophagy. These mechanisms can be targeted in future studies to develop novel strategies to control PEDV infection.

A Hybrid Missing Data Imputation Method for Batch Process Monitoring Dataset.

Batch process monitoring datasets usually contain missing data, which decreases the performance of data-driven modeling for fault identification and optimal control. Many methods have been proposed to impute missing data; however, they do not fulfill the need for data quality, especially in sensor datasets with different types of missing data. We propose a hybrid missing data imputation method for batch process monitoring datasets with multi-type missing data. In this method, the missing data is first classified into five categories based on the continuous missing duration and the number of variables missing simultaneously. Then, different categories of missing data are step-by-step imputed considering their unique characteristics. A combination of three single-dimensional interpolation models is employed to impute transient isolated missing values. An iterative imputation based on a multivariate regression model is designed for imputing long-term missing variables, and a combination model based on single-dimensional interpolation and multivariate regression is proposed for imputing short-term missing variables. The Long Short-Term Memory (LSTM) model is utilized to impute both short-term and long-term missing samples. Finally, a series of experiments for different categories of missing data were conducted based on a real-world batch process monitoring dataset. The results demonstrate that the proposed method achieves higher imputation accuracy than other comparative methods.

Efficient DIPA-CRISPR-mediated knockout of an eye pigment gene in the white-backed planthopper, Sogatella furcifera.

Although CRISPR/Cas9 has been widely used in insect gene editing, the need for the microinjection of preblastoderm embryos can preclude the technique being used in insect species with eggs that are small, have hard shells, and/or are difficult to collect and maintain outside of their normal environment. Such is the case with Sogatella furcifera, the white-backed planthopper (WBPH), a significant pest of Oryza sativa (rice) that oviposits inside rice stems. Egg extraction from the stem runs the risk of mechanical damage and hatching is heavily influenced by the micro-environment of the rice stem. To bypass these issues, we targeted embryos prior to oviposition via direct parental (DIPA)-CRISPR, in which Cas9 and single-guide RNAs (sgRNAs) for the WBPH eye pigment gene tryptophan 2,3-dioxygenase were injected into the hemocoel of adult females. Females at varying numbers of days posteclosion were evaluated to determine at what stage their oocyte might be most capable of taking up the gene-editing components. An evaluation of the offspring indicated that the highest G0 gene-edited efficacy (56.7%) occurred in females injected 2 d posteclosion, and that those mutations were heritably transmitted to the G1 generation. This study demonstrates the potential utility of DIPA-CRISPR for future gene-editing studies in non-model insect species and can facilitate the development of novel pest management applications.

Origin, genomic diversity and evolution of African swine fever virus in East Asia.

Since 2018, the outbreaks of genotype II African swine fever virus (ASFV) in China and several eastern Asian countries have caused a huge impact on the local swine industry, resulting in huge economic losses. However, little is known about the origin, genomic diversity, evolutionary features, and epidemiological history of the genotype II ASFV. Here, 14 high-quality complete genomes of ASFVs were generated via sequencing of samples collected from China over the course of 3 years, followed by phylogenetic and phylodynamic analyses. The strains identified were relatively homogeneous, with a total of 52 SNPs and 11 indels compared with the prototype strain HLJ/2018, among which there were four exceptionally large deletions (620-18,023 nt). Evolutionary analyses revealed that ASFV strains distributed in eastern Asia formed a monophyly and a 'star-like' structure centered around the prototype strain, suggesting a single origin. Additionally, phylogenetic network analysis and ancestral reconstruction of geographic state indicated that genotype II ASFV strains in eastern Asia likely originated from Western Europe. Overall, these results contribute to the understanding of the history and current status of genotype II ASFV strains in eastern Asian, which could be of considerable importance in disease control and prevention.

Isolation, identification, and pathogenicity of porcine epidemic diarrhea virus.

Porcine epidemic diarrhea (PED) is an enterophilic infectious disease caused by the porcine epidemic diarrhea virus (PEDV), which can lead to dehydration-like diarrhea in piglets with a mortality rate of up to 100%, causing huge economic losses to the global pig industry. In this study, we isolated two PEDV strains, FS202201 and JY202201, from diarrheal samples collected from two new PED outbreak farms in 2022. We performed phylogenetic analysis of the S gene and whole gene sequence. The effects of the different mutations on viral pathogenicity were investigated using piglet challenge experiments. The results showed that both strains belong to the G2c subtype, a widely prevalent virulent strain. Compared with FS202201, JY202201 harbored substitution and deletion mutations in nsp1. Both FS202201 and JY202201 infected piglets showed severe diarrhea and significant intestinal tissue lesions at an infection dose of 104 TCID50/mL, with a mortality rate of 50%; however, JY202201 required an additional day to reach mortality stabilization. An infection dose of 103 TCID50/mL reduced diarrhea and intestinal tissue lesions in piglets, with mortality rates of the two strains at 16.7% and 0%, respectively. In addition, PEDV was detected in the heart, liver, spleen, lungs, kidneys, mesenteric lymph nodes, stomach, large intestine, duodenum, jejunum, and ileum, with the highest levels in the intestinal tissues. In conclusion, this study enriches the epidemiology of PEDV and provides a theoretical basis for the study of its pathogenic mechanism and prevention through virus isolation, identification, and pathogenicity research on newly identified PED in the main transmission hub area of PEDV in China (Guangdong).

Rhein suppresses African swine fever virus replication in vitro via activating the caspase-dependent mitochondrial apoptosis pathway.

African swine fever (ASF) is a virulent infectious diseases of pigs caused by the African swine fever virus (ASFV) that can spread widely and cause high fatality rates. Currently, there is no effective way to treat the disease, and there is no effective vaccine to prevent it. Rhein, an anthraquinone compound extracted from many traditional Chinese medicines, exhibits anti-inflammatory, anti-tumor, and anti-viral activities. However, the anti-viral effects of rhein on ASFV remain unclear. Therefore, this study aimed to investigate the anti-ASFV activity of rhein in porcine alveolar macrophages (PAMs) and the underlying mechanisms. In this study, we confirmed that rhein inhibits ASFV replication significantly in a dose-dependent manner in vitro. Moreover, rhein could alter the susceptibility of PAMs to ASFV and promoted the production of superoxide in the mitochondria, which induced the loss of mitochondrial membrane potential, leading to the activation of caspase-9, caspase-3, and apoptosis. Mito-TEMPO, a mitochondria-targeted antioxidant, blocked rhein-induced mitochondrial superoxide generation and loss of mitochondrial membrane potential, prevented caspase-9 and caspase-3 activation, alleviated apoptosis, and suppressed the anti-ASFV activity of rhein. Altogether, our results suggested that rhein could play an anti-ASFV role by inducing apoptosis through the activation of the caspase-dependent mitochondrial apoptotic pathway and may provide a novel compound for developing anti-ASFV drugs.

Isolation, identification, and pathogenicity of a NADC30-like porcine reproductive and respiratory disorder syndrome virus strain affecting sow production.

Since it was first reported in 1987, porcine reproductive and respiratory syndrome virus (PRRSV) has caused several economic crises worldwide. The current prevalence of PRRSV NADC30-like stains causing clinical disease outbreaks in Chain is highly concerning. Immunization against and the prevention of this infection are burdensome for farming organizations as the pathogen frequently mutates and undergoes recombination. Herein, the genetic characterization of a NADC30-like strain (termed BL2019) isolated from a farm in Guangdong Province, China, was analyzed and its pathogenicity for piglets and sows was assessed. Results revealed that BL2019 exhibits a nucleotide homology of 93.7% with NADC30 PRRSV and its NSP2 coding region demonstrates the same 131aa deletion pattern as that of NADC30 and NADC30-like. Furthermore, we identified two recombination breakpoints located nt5804 of the NSP5-coding region and nt6478 of NSP2-coding region, the gene fragment between the two breakpoints showed higher homology to the TJ strain(a representative strain of highly pathogenic PRRSV) compared to the NADC30 strain. In addition, BL2019 infection in piglets caused fever lasting for 1 week, moderate respiratory clinical signs and obvious visual and microscopic lung lesions; infection in gestating sows affected their feed intake and increased body temperature, abortion rates, number of weak fetuses, and other undesirable phenomena. Therefore, we report a NADC30-like PRRSV strain with partial recombination and a representative strain of HP-PRRSV, strain TJ, that can provide early warning and support for PRRS immune prevention and control.

Dihydromyricetin inhibits African swine fever virus replication by downregulating toll-like receptor 4-dependent pyroptosis in vitro.

African swine fever (ASF), caused by ASF virus (ASFV) infection, poses a huge threat to the pork industry owing to ineffective preventive and control measures. Hence, there is an urgent need to develop strategies, including antiviral drugs targeting ASFV, for preventing ASFV spread. This study aimed to identify novel compounds with anti-ASFV activity. To this end, we screened a small chemical library of 102 compounds, among which the natural flavonoid dihydromyricetin (DHM) exhibited the most potent anti-ASFV activity. DHM treatment inhibited ASFV replication in a dose- and time-dependent manner. Furthermore, it inhibited porcine reproductive and respiratory syndrome virus and swine influenza virus replication, which suggested that DHM exerts broad-spectrum antiviral effects. Mechanistically, DHM treatment inhibited ASFV replication in various ways in the time-to-addition assay, including pre-, co-, and post-treatment. Moreover, DHM treatment reduced the levels of ASFV-induced inflammatory mediators by regulating the TLR4/MyD88/MAPK/NF-κB signaling pathway. Meanwhile, DHM treatment reduced the ASFV-induced accumulation of reactive oxygen species, further minimizing pyroptosis by inhibiting the ASFV-induced NLRP3 inflammasome activation. Interestingly, the effects of DHM on ASFV were partly reversed by treatment with polyphyllin VI (a pyroptosis agonist) and RS 09 TFA (a TLR4 agonist), suggesting that DHM inhibits pyroptosis by regulating TLR4 signaling. Furthermore, targeting TLR4 with resatorvid (a specific inhibitor of TLR4) and small interfering RNA against TLR4 impaired ASFV replication. Taken together, these results reveal the anti-ASFV activity of DHM and the underlying mechanism of action, providing a potential compound for developing antiviral drugs targeting ASFV.

Emodin and rhapontigenin inhibit the replication of African swine fever virus by interfering with virus entry.

Africa swine fever (ASF) is a highly pathogenic contagion caused by African swine fever virus (ASFV), which not only affects the development of domestic pig industry, but also causes huge losses to the world agricultural economy. Vaccine development targeting ASFV remains elusive, which leads to severe difficulties in disease prevention and control. Emodin (EM) and rhapontigenin (RHAG), which are extracted from the dried rhizome of Polygonum knotweed, have various biological properties such as anti-neoplastic and anti-bacterial activities, but no studies have reported that they have anti-ASFV effects. This study discovered that EM and RHAG at different concentrations had a significant dose-dependent inhibitory effect on the ASFV GZ201801 strain in porcine alveolar macrophages (PAMs), and at the specified concentration, EM and RHAG showed continuous inhibition at 24 h, 48 h and 72 h. Not only did they strongly impact virion attachment and internalization, but also inhibit the early stages of ASFV replication. Further research proved that the expression level of Rab 7 protein was reduced by EM and RHAG, and treatments with EM and RHAG induced the accumulation of free cholesterol in endosomes and inhibited endosomal acidification, which prevented the virus from escaping and shelling from late endosomes. This study summarized the application of EM and RHAG in inhibiting ASFV replication in-vitro. Similarly, EM and RHAG targeted Rab 7 in the viral endocytosis pathway, inhibited viral infection, and induced the accumulation of cholesterol in the endosomes and the acidification of the endosomes to inhibit uncoating. A reference could be made to the results of this study when developing antiviral drugs and vaccines.