African Swine Fever Virus Bearing an I226R Gene Deletion Elicits Robust Immunity in Pigs to African Swine Fever.

African swine fever (ASF) is a severe hemorrhagic infectious disease in pigs caused by African swine fever virus (ASFV), leading to devastating economic losses in epidemic regions. Its control currently depends on thorough culling and clearance of the diseased and surrounding suspected pigs. An ASF vaccine has been extensively explored for years worldwide, especially in hog-intensive areas where it is highly desired, but it is still unavailable for numerous reasons. Here, we report another ASF vaccine candidate, named SY18ΔI226R, bearing a deletion of the I226R gene with a replacement of an enhanced green fluorescent protein (eGFP) expression cassette at the right end of the viral genome. This deletion results in the complete loss of virulence of SY18 as the gene-deleted strain does not cause any clinical symptoms in all pigs inoculated with a dosage of either 104.0 or 107.0 50% tissue culture infective doses (TCID50). Apparent viremia with a gradual decline was monitored, while virus shedding was detected only occasionally in oral or anal swabs. ASFV-specific antibody appeared at 9 days postinoculation. After intramuscular challenge with its parental strain ASFV SY18 at 21 days postinoculation, all the challenged pigs survived, without obvious febrile or abnormal clinical signs. No viral DNA could be detected upon the dissection of any tissue when viremia disappeared. These results indicated that SY18ΔI226R is safe in swine and elicits robust immunity to virulent ASFV infection. IMPORTANCE Outbreaks of African swine fever have resulted in devastating losses to the swine industry worldwide, but there is currently no commercial vaccine available. Although several vaccine candidates have been reported, none has been approved for use for several reasons, especially ones concerning biosafety. Here, we identified a new undescribed functional gene, I226R. When deleted from the ASFV genome, the virus completely loses its virulence in swine. Importantly, pigs infected with this gene-deleted virus were resistant to infection by intramuscular challenge with 102.5 or 104.0 TCID50 of its virulent parental virus. Furthermore, the nucleic acid of the gene-deleted virus and its virulent parental virus was rarely detected from oral or anal swabs. Viruses could not be detected in any tissues after necropsy when viremia became negative, indicating that robust immunity was achieved. Therefore, SY18ΔI226R is a novel, ideal, and efficacious vaccine candidate for genotype II ASF.

PHACTR1 gene polymorphism with the risk of coronary artery disease in Chinese Han population.

BACKGROUND: Coronary artery disease (CAD) is the most frequent multifactorial disease worldwide and is characterised by endothelial injury, lipid deposition and coronary artery calcification. The purpose of this study was to determine the allelic and genotypic frequencies of two loci (rs2026458 and rs9349379) of phosphatase and actin regulator 1 (PHACTR1) to the risk of developing CAD in the Chinese Han population. METHODS: A case-control study was conducted including 332 patients with CAD and 119 controls. Genotype analysis was performed by PCR and Sanger sequencing. Genetic model analysis was performed to evaluate the association between single nucleotide polymorphisms and CAD susceptibility using Pearson's χ2 test and logistic regression analysis. RESULTS: The GG genotype of rs9349379 represented 50% and 29% of patients with CAD and controls, respectively (p<0.001). The CC genotype of rs2026458 was more prevalent in the controls than in patients with CAD compared with TT genotype (OR=0.548, 95% CI 0.351 to 0.856, p=0.008). Logistic regression analyses revealed that PHACTR1 rs9349379 GG genotype was significantly associated with increased risk of CAD in the recessive model (OR=2.359, 95% CI 1.442 to 3.862, p=0.001), even after adjusting for age gender, hypertension, type 2 diabetes, hyperlipidaemia and smoking habit. Heterogeneity test proved that rs9349379's risk effects on CAD were more significant among women. CONCLUSIONS: Our study indicate that the PHACTR1 rs9349379 polymorphism is associated with the increased risk for CAD in the female Chinese Han population.

Red cell distribution width in coronary heart disease: prediction of restenosis and its relationship with inflammatory markers and lipids.

BACKGROUND: Red cell distribution width (RDW) is associated with a poor prognosis and adverse events in cardiovascular diseases. The aims of this study were to investigate the relationship between serum RDW levels and outcomes after percutaneous coronary intervention and to identify potential novel laboratory markers for evaluating the risk of in-stent restenosis (ISR) with stable angina pectoris. METHODS: A total of 261 patients with coronary heart disease from Dongfeng General Hospital implanted with a coronary drug-eluting stent (DES) were enrolled in the study. We retrospectively analysed the role and prognosis values of serum parameters that were measured before angiography at the first admission. According to the results of the second angiogram, the patients were divided into two groups as follows: the non-ISR group (n=143) and the ISR group (n=118). The clinical characteristics and all laboratory data were considered for univariate and multivariate logistic regression analyses. RESULTS: The white cell count, RDW, neutrophil count, C-reactive protein (CRP), total cholesterol, low-density lipoprotein cholesterol (LDL-C), blood urea nitrogen and uric acid levels were higher in the ISR group than in the non-ISR group. There were no differences in the rates of hypertension, fasting plasma glucose, red cell count, neutrophil to lymphocyte ratio, platelet count, triglyceride, high-density lipoprotein cholesterol and creatinine levels. In the univariate regression analysis, age, diabetes, white cell count, neutrophil count, RDW, CRP, total cholesterol, LDL-C, blood urea nitrogen, Gensini score and number of stents were predictors of ISR. According to the multiple logistic regression analysis, age, RDW and number of stents were independent predictors of ISR. CONCLUSIONS: Preprocedural blood parameters can independently predict ISR. Our study results demonstrated that a high preprocedural RDW is an independent predictor of DES restenosis.

Effects of compound chemical activators on the hydration of low-carbon ferrochrome slag-based composite cement.

Low-carbon ferrochrome slag (LCFS), a by-product of the ferrochrome alloy industry, has potential for use as a cementitious material due to its pozzolanic characteristic. The objective of the present study was to determine the optimum compound chemical activators for LCFS-based composite cement using an orthogonal test, in which 7 d and 28 d compressive strengths were used as the evaluating indices. The influences of compound chemical activators on the hydration of a composite cement mix were investigated using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and thermogravimetry-differential scanning calorimetry (TG-DSC). The optimum activator to activate the composite cement was a compound of NaCl (NC) at a dosage of 0.6%, Na2SO4 (NS) at a dosage of 1.2%, NaF (NF) at a dosage of 0.6% and Al2(SO4)3 (AS) at a dosage of 0.9% or 0.7%. The compressive strengths of the optimum composite cement mix at ages of 3, 28 and 180 d increased by 50.1%, 22.4% and 16.5%, respectively. More hydration products including ettringite and calcium silicate hydrate were formed at an early age of hydration. The compound chemical activators effectively activated the ferrochrome slag (FS), blast-furnace slag (BFS) and fly ash (FA) in the composite cement.

Chemical Synthesis of Sulfated Yeast (Saccharomyces cerevisiae) Glucans and Their In Vivo Antioxidant Activity.

The effects of sulfation of yeast glucans was optimized using response surface methodology. The degree of sulfation was evaluated from 0.11 to 0.75 using ion-chromatography. The structural characteristics of SYG (sulfation of yeast glucans) with a DS = 0.75 were determined using high-performance liquid chromatography/gel-permeation chromatography and finally by Fourier transform infrared spectrometry. The SYG had lower viscosity and greater solubility than the native yeast glucans, suggesting that the conformation of the SYG had significantly changed. The results also showed that SYG had a significantly greater antioxidant activity in vivo compared to native yeast glucans.

Development and validation of multiple linear regression models for predicting total hip arthroplasty acetabular prosthesis.

PURPOSE: To establish a multivariate linear equation to predict the diameter (outer diameter) of the acetabular prosthesis used in total hip arthroplasty. METHODS: A cohort of 258 individuals who underwent THA at our medical facility were included in this study. The independent variables encompassed the patients' height, weight, foot length, gender, age, and surgical access. The dependent variable in this study was the diameter of the acetabular prosthesis utilized during the surgical procedure. The entire cohort dataset was randomly partitioned into a training cohort and a validation cohort, with a ratio of 7:3, employing the SPSS 26.0 software. Pearson correlation analysis was conducted to examine the relationships between the patients' height, weight, foot length, gender, age, surgical access, and the diameter of the acetabular prosthesis in the training cohort. Additionally, a multiple linear regression equation was developed using the independent variables from the training cohort and the diameter of the acetabular prosthesis as the dependent variable. This equation aimed to predict the diameter of the acetabular prosthesis based on the patients' characteristics. The accuracy of the equation was evaluated by substituting the data of the validation cohort into the multiple linear equation. The predicted acetabular prosthesis diameters were then compared with the actual diameters used in the operation. RESULTS: The correlation analysis conducted on the training cohort revealed that surgical access (r = 0.054) and age (r = -0.120) exhibited no significant correlation with the diameter of the acetabular prosthesis utilized during the intraoperative procedure. Conversely, height (r = 0.687), weight (r = 0.654), foot length (r = 0.687), and sex (r = 0.354) demonstrated a significant correlation with the diameter of the acetabular prosthesis used intraoperatively. Furthermore, a predictive equation, denoted as Y (acetabular prosthesis diameter in mm) = 20.592 + 0.548 × foot length (cm) + 0.083 × height (cm) + 0.077 × weight (kg), was derived. This equation accurately predicted the diameter within one size with an accuracy rate of 64.94% and within two sizes with an accuracy rate of 94.81%. CONCLUSION: Anthropometric data can accurately predict the diameter of acetabular prosthesis during total hip arthroplasty.

Deleting the C84L Gene from the Virulent African Swine Fever Virus SY18 Does Not Affect Its Replication in Porcine Primary Macrophages but Reduces Its Virulence in Swine.

(1) Background: African swine fever (ASF) is a highly contagious disease that causes high pig mortality. Due to the absence of vaccines, prevention and control are relatively challenging. The pathogenic African swine fever virus (ASFV) has a complex structure and encodes over 160 proteins, many of which still need to be studied and verified for their functions. In this study, we identified one of the unknown functional genes, C84L. (2) Methods: A gene deficient strain was obtained through homologous recombination and several rounds of purification, and its replication characteristics and virulence were studied through in vitro and in vivo experiments, respectively. (3) Results: Deleting this gene from the wild-type virulent strain SY18 did not affect its replication in porcine primary macrophages but reduced its virulence in pigs. In animal experiments, we injected pigs with a 102 TCID50, 105 TCID50 deletion virus, and a 102 TCID50 wild-type strain SY18 intramuscularly. The control group pigs reached the humane endpoint on the ninth day (0/5) and were euthanized. Two pigs in the 102 TCID50(2/5) deletion virus group survived on the twenty-first day, and one in the 105 TCID50(1/5) deletion virus group survived. On the twenty-first day, the surviving pigs were euthanized, which was the end of the experiment. The necropsies of the survival group and control groups' necropsies showed that the surviving pigs' liver, spleen, lungs, kidneys, and submaxillary lymph nodes did not show significant lesions associated with the ASFV. ASFV-specific antibodies were first detected on the seventh day after immunization; (4) Conclusions: This is the first study to complete the replication and virulence functional exploration of the C84L gene of SY18. In this study, C84L gene was preliminarily found not a necessary gene for replication, gene deletion strain SY18ΔC84L has similar growth characteristics to SY18 in porcine primary alveolar macrophages. The C84L gene affects the virulence of the SY18 strain.

Identification of L11L and L7L as virulence-related genes in the African swine fever virus genome.

Introduction: African swine fever (ASF) is an infectious disease that causes considerable economic losses in pig farming. The agent of this disease, African swine fever virus (ASFV), is a double-stranded DNA virus with a capsid membrane and a genome that is 170-194 kb in length encoding over 150 proteins. In recent years, several live attenuated strains of ASFV have been studied as vaccine candidates, including the SY18ΔL7-11. This strain features deletion of L7L, L8L, L9R, L10L and L11L genes and was found to exhibit significantly reduced pathogenicity in pigs, suggesting that these five genes play key roles in virulence. Methods: Here, we constructed and evaluated the virulence of ASFV mutations with SY18ΔL7, SY18ΔL8, SY18ΔL9, SY18ΔL10, and SY18ΔL11L. Results: Our findings did not reveal any significant differences in replication efficiency between the single-gene deletion strains and the parental strains. Pigs inoculated with SY18ΔL8L, SY18ΔL9R and SY18ΔL10L exhibited clinical signs similar to those inoculated with the parental strains. Survival rate of pigs inoculated with 103.0TCID50 of SY18ΔL7L was 25%, while all pigs inoculated with 103.0TCID50 of SY18ΔL11L survived, and 50% inoculated with 106.0TCID50 SY18ΔL11L survived. Discussion: The results indicate that L8L, L9R and L10L do not affect ASFV SY18 virulence, while the L7L and L11L are associated with virulence.

Deletion of the B125R gene in the African swine fever virus SY18 strain leads to an A104R frameshift mutation slightly attenuating virulence in domestic pigs.

African swine fever (ASF), caused by the ASF virus (ASFV), is a hemorrhagic and fatal viral disease that affects Eurasian wild boars and domestic pigs, posing a substantial threat to the global pig breeding industry. ASFV, a double-stranded DNA virus, possesses a large genome containing up to 160 open reading frames, most of which exhibit unknown functions. The B125R gene of ASFV, located at the 105595-105972 bp site in the ASFV-SY18 genome, remains unexplored. In this study, we discovered that B125R deletion did not affect recombinant virus rescue, nor did it hinder viral replication during the intermediate growth phase. Although the virulence of the recombinant strain harboring this deletion was attenuated, intramuscular inoculation of the recombinant virus in pigs at doses of 102 or 104 TCID50 resulted in mortality. Moreover, sequencing analysis of six recombinant strains obtained from three independent experiments consistently revealed an adenine insertion at the 47367-47375 bp site in the A104R gene due to the B125R deletion, leading to premature termination of this gene. Intriguingly, this insertion did not influence the transcription of the A104R gene between the recombinant and parental strains. Consequently, we postulate that the deletion of the B125R gene in ASFV-SY18 or other genotype II strains may marginally attenuate virulence in domestic pigs.

Comparison of Genotype II African Swine Fever Virus Strain SY18 Challenge Models.

African swine fever (ASF) is a viral haemorrhagic disease found in domestic and wild boars caused by the African swine fever virus (ASFV). A highly virulent strain was used to evaluate the efficacy of newly developed vaccine candidates. The ASFV strain SY18 was isolated from the first ASF case in China and is virulent in pigs of all ages. To evaluate the pathogenesis of ASFV SY18 following intraoral (IO) and intranasal (IN) infections, a challenge trial was conducted in landrace pigs, with intramuscular (IM) injection as a control. The results showed that the incubation period of IN administration with 40-1000 50 % tissue culture infective dose (TCID50) was 5-8 days, which was not significantly different from that of IM inoculation with 200 TCID50. A significantly longer incubation period, 11-15 days, was observed in IO administration with 40-5000 TCID50. Clinical features were similar among all infected animals. Symptoms, including high fever (≥40.5 °C), anorexia, depression, and recumbency, were observed. No significant differences were detected in the duration of viral shedding during fever. There was no significant difference in disease outcome, and all animals succumbed to death. This trial showed that IN and IO infections could be used for the efficacy evaluation of an ASF vaccine. The IO infection model, similar to that of natural infection, is highly recommended, especially for the primary screening of candidate vaccine strains or vaccines with relatively weak immune efficacy, such as live vector vaccines and subunit vaccines.

Evaluation of African Swine Fever Virus E111R Gene on Viral Replication and Porcine Virulence.

African swine fever (ASF) is an acute infectious disease of domestic pigs and wild boars caused by the African swine fever virus (ASFV), with up to a 100% case fatality rate. The development of a vaccine for ASFV is hampered by the fact that the function of many genes in the ASFV genome still needs to be discovered. In this study, the previously unreported E111R gene was analyzed and identified as an early-expressed gene that is highly conserved across the different genotypes of ASFV. To further explore the function of the E111R gene, a recombinant strain, SY18ΔE111R, was constructed by deleting the E111R gene of the lethal ASFV SY18 strain. In vitro, the replication kinetics of SY18ΔE111R with deletion of the E111R gene were consistent with those of the parental strain. In vivo, high-dose SY18ΔE111R (105.0 TCID50), administered intramuscularly to pigs, caused the same clinical signs and viremia as the parental strain (102.0 TCID50), with all pigs dying on days 8-11. After being infected with a low dose of SY18ΔE111R (102.0 TCID50) intramuscularly, pigs showed a later onset of disease and 60% mortality, changing from acute to subacute infection. In summary, deletion of the E111R gene has a negligible effect on the lethality of ASFV and does not affect the viruses' ability to replicate, suggesting that E111R could not be the priority target of ASFV live-attenuated vaccine candidates.

SY18ΔL60L: a new recombinant live attenuated African swine fever virus with protection against homologous challenge.

Introduction: African swine fever (ASF) is an acute and highly contagious disease and its pathogen, the African swine fever virus (ASFV), threatens the global pig industry. At present, management of ASF epidemic mainly relies on biological prevention and control methods. Moreover, due to the large genome of ASFV, only half of its genes have been characterized in terms of function. Methods: Here, we evaluated a previously uncharacterized viral gene, L60L. To assess the function of this gene, we constructed a deletion strain (SY18ΔL60L) by knocking out the L60L gene of the SY18 strain. To evaluate the growth characteristics and safety of the SY18ΔL60L, experiments were conducted on primary macrophages and pigs, respectively. Results: The results revealed that the growth trend of the recombinant strain was slower than that of the parent strain in vitro. Additionally, 3/5 (60%) pigs intramuscularly immunized with a 105 50% tissue culture infectious dose (TCID50) of SY18ΔL60L survived the 21-day observation period. The surviving pigs were able to protect against the homologous lethal strain SY18 and survive. Importantly, there were no obvious clinical symptoms or viremia. Discussion: These results suggest that L60L could serve as a virulence- and replication-related gene. Moreover, the SY18ΔL60L strain represents a new recombinant live-attenuated ASFV that can be employed in the development of additional candidate vaccine strains and in the elucidation of the mechanisms associated with ASF infection.

A label-free oligonucleotide based thioflavin-T fluorescent switch for Ag+ detection with low background emission.

A novel fluorescent Ag(+) sensor was developed based on the label-free silver (I) specific oligonucleotide (SSO) and Thioflavine T (ThT) monomer-excimer switch. C-rich SSO which contain C-C mismatched base pairs can selectively bind to Ag(+) ions and the formed duplexes which constructed by C-Ag(+)-C structure are thermally stabilized without largely altering the double helical structure. ThT give very weak fluorescent in bulk solution and/or in the presence of SSO. However ThT shows high fluorescence in the presence of SSO and Ag(+) at the same time mainly because ThT excimer, which has the high quantum yield, formed and stabilized in the minor or major groove. Based on the discovery, we developed the novel Ag(+) sensor. Under the optimum condition, the selectivity of this system for Ag(+) over other metal ions in aqueous solution is remarkably high, and Ag(+) can be quantified over the dynamic range of 30-450 nM, with a limit of detection of ~16 nM and a linear correlation coefficient of 0.995.

Removal and immobilization of arsenic from wastewater via arsenonatroalunite formation.

Removal and immobilization of highly toxic arsenic form industrial wastewater using simple and effective methods is of important practical significance. Although the formation of natroalunite phase NaAl3(SO4)2(OH)6 has been demonstrated to be an effective method for arsenic immobilization in model system with chemical reagent grade arsenates as arsenic source, the further study is needed to investigate its immobilization for real industrial wastewater. This work reported the synthesis of natroalunite phase NaAl3(SO4)2(OH)6 using arsenic-containing industrial wastewater from benzyl acid production. The synthesis temperature and time were optimized to obtain the pure natroalunite phase composites with high crystallinity. When n(Al/As)aq was greater than 3.0, the arsenic could almost precipitate exclusively as natroalunite phase after 60 min hydrothermal reaction at 200°C, with a maximum arsenic immobilization amount of 7.0 mol%. A maximum leaching concentration of 0.50 mg/L was observed at pH = 3.0 during the short-term (24 h) leaching test, which was lower than the US EPA TCLP test limit of 1 mg/L. The long-term leaching test up to 90 days revealed that the arsenonatroalunite could be a safe immobilization material for arsenic in pH 5.0-8.0 environments.

Influence of Phosphorus Sources on the Compressive Strength and Microstructure of Ferronickel Slag-Based Magnesium Phosphate Cement.

Electric furnace ferronickel slag (EFS) is a typical magnesium-rich industrial by-product discharged from the manufacture of nickel and iron-nickel alloys. The approach to use it as the raw material for the preparation of magnesium phosphate cement (MPC) has potential and proves effective. In this study, three different phosphorus sources (PS) including phosphoric acid (H3PO4, PA), sodium dihydrogen phosphate (NaH2PO4, SDP) and potassium dihydrogen phosphate (KH2PO4, PDP) were used to react with EFS to prepare the EFS-based MPC (EMPC), and the effects of raw material mass ratio (EFS/PA, EFS/SDP, EFS/PDP) on the compressive strength, early hydration temperature and microstructure of EMPC pastes were investigated. Results showed that the compressive strength of EMPC paste is significantly impacted by the type of phosphorus source and the raw materials mass ratio. When the EFS/PDP ratio is 4.0, the compressive strength of the MPC paste reaches up to 18.8, 22.8 and 27.5 MPa at 3, 7 and 28 d, respectively. Cattiite (Mg3(PO4)2·22H2O), K-struvite (KMgPO4·6H2O) and/or Na-struvite (NaMgPO4·6H2O) were identified as the main hydration products of EMPC. The development of EMPC mainly involves the dissolution of a phosphorus source, MgO and Mg2SiO4, formation of hydration product as binder, and combination of the unreacted raw materials together by binders to build a compact form.

Synergistic effect of the responses of different tissues against African swine fever virus.

African swine fever is an acute, haemorrhagic fever and contagious disease of pigs caused by African swine fever virus (ASFV), which has a great impact on the pig farming industry and related international trade. Understanding the response processes of various tissues in pigs after ASFV infection may help to address current major concerns, such as the exploration of key genes for vaccine development, the cooperative mechanism of the host response and the possibility of establishing active herd immunity. ASFV is able to infect core tissues and is associated with acute death. RNA and protein samples were obtained and verified from five tissues, including the lung, spleen, liver, kidney and lymph nodes. Multiple duplicate samples were quantitatively analyzed by corresponding transcriptomic and proteomic comparison. The results showed that different tissues cooperated in responses to ASFV infection and coordinated the defence against ASFV in the form of an inflammatory cytokine storm and interferon activation. The lung and spleen were mainly involved (dominant) in the innate immune response pathway; the liver and kidney were involved in the metabolic regulatory pathway and the inflammatory response; and the lymph nodes cooperated with the liver to complete energy metabolism regulation. The key pathways and responsive genes in each tissue of the contracted pigs were comprehensively mapped by infectomics, providing further evidence to investigate the complicated tie between ASFV and host cells.

The Mink Circovirus Capsid Subunit Expressed by Recombinant Baculovirus Protects Minks against Refractory Diarrhea in Field.

Mink refractory diarrhea is a seasonal disease that occurs in many mink farms in China. Mink circovirus (MiCV) has been recognized as the causative agent of the disease. The aim of the study was to develop a subunit vaccine against mink refractory diarrhea. A recombinant baculovirus strain expressing the capsid protein was constructed using the baculovirus expression vector system (BEVS). A subunit vaccine was developed based on the capsid protein with appropriate adjuvant. Then, a field trial was carried out in two districts in order to evaluate the efficiency of the subunit vaccine. The field trial indicated that in total, only 1.8% of the minks developed typical diarrhea in the vaccinated group compared with 74.5% in the control group. The vaccination could significantly reduce the infection rate of MiCV among the mink herds and could restrain the virus' shedding from feces. Furthermore, the vaccinated group had a higher average litter size in the following year compared to the control group. Collectively, the results indicated that the subunit vaccine based on the capsid protein can provide reliable protection against MiCV infection.

Evaluation of Cellular Immunity with ASFV Infection by Swine Leukocyte Antigen (SLA)-Peptide Tetramers.

African swine fever virus (ASFV) causes acute hemorrhagic fever in domestic pigs and wild boars, resulting in incalculable economic losses to the pig industry. As the mechanism of viral infection is not clear, protective antigens have not been discovered or identified. In this study, we determined that the p30, pp62, p72, and CD2v proteins were all involved in the T cell immune response of live pigs infected with ASFV, among which p72 and pp62 proteins were the strongest. Panoramic scanning was performed on T cell epitopes of the p72 protein, and three high-frequency positive epitopes were selected to construct a swine leukocyte antigen (SLA)-tetramer, and ASFV-specific T cells were detected. Subsequently, the specific T cell and humoral immune responses of ASFV-infected pigs and surviving pigs were compared. The results demonstrate that the specific T cellular immunity responses gradually increased during the infection and were higher than that in the surviving pigs in the late stages of infection. The same trend was observed in specific humoral immune responses, which were highest in surviving pigs. In general, our study provides key information for the exploration of ASFV-specific immune responses and the development of an ASFV vaccine.

I267L Is Neither the Virulence- Nor the Replication-Related Gene of African Swine Fever Virus and Its Deletant Is an Ideal Fluorescent-Tagged Virulence Strain.

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF) which reaches up to 100% case fatality in domestic pigs and wild boar and causes significant economic losses in the swine industry. Lack of knowledge of the function of ASFV genes is a serious impediment to the development of the safe and effective vaccine. Herein, I267L was identified as a relative conserved gene and an early expressed gene. A recombinant virus (SY18ΔI267L) with I267L gene deletion was produced by replacing I267L of the virulent ASFV SY18 with enhanced green fluorescent protein (EGFP) cassette. The replication kinetics of SY18ΔI267L is similar to that of the parental isolate in vitro. Moreover, the doses of 102.0 TCID50 (n = 5) and 105.0 TCID50 (n = 5) SY18ΔI267L caused virulent phenotype, severe clinical signs, viremia, high viral load, and mortality in domestic pigs inoculated intramuscularly as the virulent parental virus strain. Therefore, the deletion of I267L does not affect the replication or the virulence of ASFV. Utilizing the fluorescent-tagged virulence deletant can be easy to gain a visual result in related research such as the inactivation effect of some drugs, disinfectants, extracts, etc. on ASFV.

Deletion of the L7L-L11L Genes Attenuates ASFV and Induces Protection against Homologous Challenge.

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a major epidemic disease endangering the swine industry. Although a number of vaccine candidates have been reported, none are commercially available yet. To explore the effect of unknown genes on the biological characteristics of ASFV and the possibility of a gene-deleted isolate as a vaccine candidate, the strain SY18ΔL7-11, with deletions of L7L-L11L genes from ASFV SY18, was constructed, and its biological properties were analyzed. The results show that deletion of genes L7L-L11L did not affect replication of the virus in vitro. Virulence of SY18△L7-11 was significantly reduced, as 11 of the 12 pigs survived for 28 days after intramuscular inoculation with a low dose (103 TCID50) or a high dose (106 TCID50) of SY18ΔL7-11. All 11 surviving pigs were completely protected against challenge with the parental ASFV SY18 on 28 days postinoculation (dpi). Transient fever and/or irregularly low levels of genomic DNA in the blood were monitored in some pigs after inoculation. No ASF clinical signs or viremia were monitored after challenge. Antibodies to ASFV were induced in all pigs from 14 to 21 days postinoculation. IFN-γ was detected in most of the inoculated pigs, which is usually inhibited in ASFV-infected pigs. Overall, the results demonstrate that SY18ΔL7-11 is a candidate for further constructing safer vaccine(s), with better joint deletions of other gene(s) related to virulence.