Search Results (717)

African swine fever (ASF) is an acute, febrile, and lethal pig disease induced by the African swine fever virus (ASFV). In the absence of an effective vaccine, early diagnosis is essential for the prevention and control of ASF disease. The p54 protein is important for ASFV diagnosis and vaccine design. In this study, ASFV p54 protein was constructed, expressed, purified, and used to generate three mAbs, namely 9A3, 5H2, and 2G6. Epitope mapping was performed using alanine mutants; the minimal linear epitope recognized by 9A3 and 5H2 was ⁵⁶KKKAAAI⁶², and the minimal linear epitope recognized by 2G6 was ¹⁰⁸TNRPATN¹¹⁴. Of these, ⁵⁶KKKAAAI⁶² was identified as a new linear epitope for the first time. The epitopes were highly conserved in at least genotypes I and II. Alanine-scanning mutagenesis further revealed that residues 56K, 57K, 60A, 61A, 62L, 108T, 110R, 111P, 113T, and 114N were the core sites involved in antibody recognition. Overall, the mAbs and epitopes of the p54 protein identified in this study provide theoretical support for the development of ASFV vaccines based on the B cell epitope, the development of ASFV therapeutic antibody drugs, and the development of ASFV diagnostic tools. Full article

Background/Objectives: African swine fever (ASF) is a highly lethal disease of domestic pigs and wild suids that continues to cause substantial economic losses worldwide. Despite recent progress in live attenuated ASF vaccine development, evidence supporting durable protection under repeated exposure conditions representative of endemic settings remains limited. Here, we assessed the long-term safety and protective efficacy of a live attenuated ASFV-G-ΔI177L/ΔLVR vaccine using a repeated-challenge experimental design intended to model re-exposure in ASF-endemic regions. Methods: Vaccinated pigs were subjected to homologous virulent ASF virus challenges at multiple intervals, including repeated challenges (three sequential inoculations) and single challenges administered at 8 and 12 weeks post-vaccination. Results: Across all challenge regimens, vaccinated animals survived and remained clinically healthy, including those receiving three challenges, supporting sustained protection under repeated exposure pressure. Animals challenged at 8 or 12 weeks post-vaccination likewise exhibited complete survival, indicating maintained efficacy through at least 12 weeks. No vaccine-associated adverse clinical outcomes were detected over the study period, and post-challenge viral shedding was minimal. Conclusions: Overall, these data demonstrate that the candidate live attenuated ASF vaccine provides excellent protective efficacy and confers sustained protection against homologous ASF virus infection. This result is expected to be equally applicable under repeated exposure conditions in regions with unstable ASF biosecurity, making it a sufficiently promising model experiment for field application in ASF epidemic areas. However, this is still a vaccine variant, and further studies are planned to evaluate its genomic stability and transmissibility. Full article

Wild boar populations are increasingly recognized as important hosts in the ecology of swine viruses, yet data from Croatia remain limited. This study aimed to establish baseline information on the presence of porcine bocavirus (PBoV) and porcine cytomegalovirus (PCMV) in Croatian wild boar within the framework of the national African swine fever (ASF) surveillance program. Spleen and blood samples from 184 ASF-negative wild boar collected across 11 counties were tested using real-time PCR. PCMV DNA was detected in 16 animals (8.69%), with similar detection frequencies in spleen (7.69%) and blood (9.52%). PBoV DNA was identified in seven animals (3.80%), all from spleen samples. Positive animals were distributed across several counties, but no significant associations were observed between virus detection and age, sex, or geographic origin. Coinfection with both viruses was detected in a single animal (0.05%). These findings provide the first molecular evidence of PBoV and PCMV in Croatian wild boar and indicate low-level viral circulation across multiple regions. Although both viruses are typically subclinical, their detection contributes to understanding pathogen diversity in free-living suids and establishes a foundation for future epidemiological and molecular studies in the region. Full article

African swine fever in both domestic and wild pig populations is caused by the extremely infectious African swine fever virus (ASFV). It seriously endangers biodiversity and results in large financial losses for the worldwide pork sector. The major capsid protein p72 is molecularly chaperoned by the ASFV pB602L protein, which is essential to viral assembly. Furthermore, as a nonstructural protein expressed at late stages of infection, pB602L induces a distinct antibody response that may complement existing serological assays based on structural proteins. Given its strong immunogenicity, pB602L represents a promising antigen for developing supplementary diagnostic tools for African swine fever (ASF). In this study, we successfully generated and separated the ASFV pB602L protein, and we verified its responsiveness using serum from pigs infected with ASFV. Additionally, we produced four monoclonal antibody-specific hybridoma cell lines that targeted the pB602L protein exclusively. These cell lines demonstrated high immunoreactivity and responsiveness toward ASFV pB602L. These results highlight the potential enhancement of diagnostic skills. We have detected two previously unknown linear B-cell epitopes (¹³⁸TIDSFL¹⁴³ and ¹⁶⁴TNVDTC¹⁶⁹) using overlapping peptide and truncated protein fragment analysis. Due to their high degree of conservation across various ASFV strains, these epitopes offer trustworthy candidates for the creation of particular diagnostic instruments. This study expands the known ASFV antigenic repertoire by systematically mapping immunodominant epitopes of pB602L. The identified epitopes provide potential molecular targets for the rational design of multi-epitope subunit vaccines. Full article

Proactive disease transmission pathway analyses break complex transmission routes into simpler steps, making risks and uncertainties easier to identify. This approach is especially valuable for African Swine Fever (ASF), a difficult-to-control disease in low-biosecurity settings or when biosecurity practices are inconsistently applied. To support targeted biosecurity planning, a pathway analysis was conducted that is specific to pork harvest facilities in the United States. The analysis focused on two federally inspected plants that slaughter market hogs and produce primal cuts. Inputs, outputs, and potential transmission pathways were identified through a literature review, site visits, and facility personnel interviews. Because ASF virus remains stable at low temperatures and in many pork products, particular attention was given to pathways involving storage conditions, waste materials, and processing steps such as heating or pH modification. Processing steps were evaluated against existing process control plans and ASF inactivation thresholds to determine mitigation status. Of 42 identified pathways, 39 were classified as unmitigated or of unknown mitigation status. These unmitigated or unknown pathways—broadly involving pigs, people, vehicles, and waste—represent the highest priorities for further risk assessment work and for exploring ways to develop or strengthen biosecurity protocols that reduce ASF transmission. Full article

African swine fever (ASF) is a highly fatal, febrile infectious disease of domestic pigs and wild boars caused by the African swine fever virus (ASFV). Recently, highly virulent recombinant ASFVs with chimeric genomes derived from p72 genotype I and II viruses have emerged in China, Vietnam, and Russia. These genotype I/II recombinants can evade immunity induced by genotype II–based vaccines, thereby complicating disease control efforts. To address this challenge, a novel duplex quantitative PCR (qPCR) assay was developed to simultaneously detect and differentiate genotypes I, II, and I/II recombinants in a single reaction. The assay exhibited high sensitivity and specificity, with a reliable detection limit of 10 copies/reaction for genotype I and II ASFV DNA. Validation using clinical samples collected in northern Vietnam in 2025 confirmed a robust performance in accurately distinguishing circulating genotype II viruses from recombinant genotype I/II viruses, including the detection of potential co-infection. Whole-genome sequencing of selected positive samples further corroborated these findings. Overall, this qPCR assay provides a precise and efficient tool for identifying currently circulating ASFV genotypes, thereby facilitating improved disease surveillance and supporting a comprehensive understanding of the evolving epidemiological landscape of ASF in regions with increasing viral genetic diversity. Full article

African swine fever (ASF), caused by African swine fever virus (ASFV), is a devastating swine disease. To date, no commercial ASF vaccine has been authorized for global marketing except in Vietnam, and emerging genotype I/II recombinant ASFV strains pose severe new challenges to ASF control. Live-attenuated vaccines (LAVs) are widely recognized as the most promising strategy for ASF control. This review systematically summarizes three conventional development strategies for ASF LAVs, dissects the molecular mechanisms of two core bottlenecks—intergenotypic ASFV recombination and vaccine strain reversion to virulence—and elaborates rational design strategies for next-generation LAVs based on cutting-edge technologies. These strategies can fundamentally mitigate the aforementioned risks, offering promising solutions for addressing the major limitations of conventional ASF LAVs. Full article

Background/Objectives: African Swine Fever (ASF) represents one of the most serious threats to animal health and global food security. The causative agent of ASF is the African swine fever virus (ASFV), a DNA virus belonging to the Asfarviridae family. Here, we describe ex vivo results for an original anti-ASFV vaccine approach based on the cellular immune response induced by extracellular vesicles (EVs) engineered to express four ASFV proteins. EV engineering was achieved by expressing a DNA vector encoding a biologically inactive HIV-1 Nef protein (Nef^mut), which exhibits unusually high efficiency of incorporation into EVs, even when fused to foreign proteins. Previous studies have demonstrated that intramuscular injection of Nef^mut-based vectors leads to the engineering of Evs, spontaneously released by muscle cells, and induction of antigen-specific CD8⁺ T cell immunity. Methods: We designed DNA vectors expressing the fusion products between Nef^mut and each of the four ASFV structural proteins p30, p54, pp62, and p72. Engineered EVs were molecularly characterized by Western blot and nanotrack analysis, and their potential immunogenicity was assessed by priming and cross-presentation assays. Results: We assessed that the four fusion proteins were successfully expressed in transfected mammalian cells, with the release of valuable amounts of engineered EVs. When immature swine dendritic cells were challenged with the engineered EVs and then co-cultivated with autologous peripheral blood lymphocytes in priming assays, lymphocyte subpopulations specifically reacting against each ASFV antigen were elicited, as detected by an IFN-γ ELISpot assay. In addition, we provide evidence that the Nef^mut-based fusion products incorporated into the engineered EVs can be cross-presented by professional antigen-presenting cells, leading to cross-priming of autologous lymphocytes. Conclusions: These results represent the best premise to go forward with experiments examining immunogenicity and antiviral efficiency in pigs. Full article

African swine fever (ASF) is a highly lethal viral disease of pigs caused by the African swine fever virus (ASFV). The mortality rate is nearly 100%. Currently, it is known that the ASFV has a complex structure, and its genome encodes various immune escape proteins. However, the pathogenic mechanism of ASFV remains to be studied. This study found that ASFV pD345L significantly inhibits the activation of the ISRE promoter triggered by interferon (IFN) β and the production of downstream IFN-stimulated genes (ISG). We further reveal that pD345L may degrade STAT1 via the autophagy pathway and impede its nuclear translocation; this inhibitory effect is closely associated with its exonuclease activity. Our research results have clarified the impact of ASFV pD345L on the JAK/STAT signaling pathway, expanding our understanding of the inhibitory effect of ASFV-encoded proteins on the host’s innate immunity, and to some extent, contributing to the development of an African swine fever vaccine. Full article

Recombinant genotype I–II African swine fever virus (ASFV) strains with high virulence have been increasingly reported in China and Vietnam since 2023, raising significant concerns for disease control. In this study, we characterized the hematological, virological, pathological, and immunological dynamics in ASFV-inoculated pigs, with particular emphasis on temporal changes associated with mortality following the onset of viremia. Specific-pathogen-free pigs were intramuscularly inoculated with 1 × 10³ or 1 × 10⁵ HAD₅₀/mL of ASFV LS100 virus strain and developed acute disease characterized by high fever and severe hemorrhagic manifestations. The incubation period ranged from 3 to 5 days, with mortality occurring between 6 and 10 days post-inoculation (dpi). Viral genomic DNA was detected in blood, oral swabs, and rectal swabs as early as 2–4 dpi. Pathological examination revealed prominent necrotic skin lesions and joint swelling. Although hematological parameters and serum biochemical profiles were comparable between high- and low-dose groups, differences in viral load distribution were observed. Notably, cytokine profiling in whole blood revealed a strong and persistent upregulation of pro-inflammatory mediators, including IL-1β, IL-6, IL-12p40, TNF-α, IFN-γ, CCL2, CCL3, CCL14, CXCL9, and CXCL10, which correlated with persistent fever from 2 to 7 dpi. Collectively, these findings confirm that naturally occurring recombinant genotype I–II ASFV strains are highly virulent and capable of inducing severe systemic inflammation. Their continued circulation poses substantial challenges for ASF control and prevention in Vietnam and threatens the global swine industry. Full article

African swine fever virus (ASFV) is an evolving threat to global swine health and food security, driven by its complex epidemiology, multi-host transmission cycles, and ongoing spread across countries. This review summarizes the global scenario and transmission pathways of ASFV, highlighting the outbreaks associated with evolving risk patterns to support effective disease prevention and control. ASF has been reported in pig-producing regions across Africa, Europe, and, more recently, Asia, largely driven by the spread of genotype II strains. The virus is transmitted through direct contact with infected pigs or pig-products, indirectly via contaminated materials, and through soft ticks of the genus Ornithodoros spp., with epidemiological patterns varying according to wildlife reservoirs and regional factors. Control measures mainly rely on early detection, movement control, strict quarantine, robust biosecurity measures, and international trade regulations. Despite significant advances, persistent challenges, including the absence of a widely available commercial vaccine, long-term stability of the virus, human activities, and inconsistencies in global response capacities, continue to hinder disease eradication efforts. This review underscores the need for transnational strategies and policies that integrate economically sustainable disease management systems and reduce the long-term impact of ASFV. Full article

African swine fever (ASF) poses a persistent and escalating threat to global swine production. To comprehensively characterize its global spatiotemporal dynamics from 1996 to 2025, we developed an integrated framework combining multi-distance spatial analysis and advanced time series forecasting, utilizing a dataset of 57,253 outbreak records. Our findings reveal a clear divergence in transmission patterns: wild boar accounted for approximately 70% of outbreaks and predominantly sustained transmission in Eastern Europe, whereas domestic pig outbreaks were largely concentrated in Southeast Asia. A pronounced epidemiological shift occurred between 2017 and 2020, during which ASF spread transitioned from a predominantly north–south axis linking Africa and the Caucasus to a broad east–west expansion across Eurasia, coinciding with rapid dissemination throughout Asia. In the Northern Hemisphere, ASF outbreaks exhibited a bimodal seasonal pattern, with peaks observed in January–March and July–August. Comparative forecasting analyses demonstrated that machine learning approaches consistently outperformed both traditional statistical and deep learning models. Among these, the random forest algorithm achieved the highest predictive accuracy, surpassing SARIMA, Prophet, XGBoost, and GRU. Collectively, these findings underscore the pivotal role of wild boar in maintaining global ASF transmission and highlight the necessity of integrated surveillance at wildlife–livestock interfaces. Furthermore, they support the application of machine learning-based approaches for improving early warning systems and enhancing the effectiveness of global ASF control strategies. Full article

Highly virulent African swine fever virus (ASFV) genotype II strains have been responsible for the global epidemic in domestic pigs and are typically characterized by a hemadsorption (HAD)-positive phenotype mediated by the CD2v protein encoded by the EP402R gene. Here, we report the detection and genetic characterization of three non-HAD genotype II ASFV isolates (VNUA/ASFV/VP2023-isolate1, VNUA/ASFV/TB2024-isolate2, and VNUA/ASFV/HY2024-isolate3) recovered from whole-blood samples collected from pigs exhibiting prolonged clinical signs in northern Vietnam. Whole-genome analysis revealed nonsense mutations in the EP402R gene (G57A in isolates VNUA/ASFV/TB2024-isolate2 and VNUA/ASFV/HY2024-isolate3, and G132A in VNUA/ASFV/VP2023-isolate1), resulting in premature stop codons and a HAD-negative phenotype. Furthermore, additional genetic alterations, including deletions and frameshift mutations, were identified within multigene families (MGF110, MGF360, and MGF505), which are known to play critical roles in virulence, host range, and immune evasion. Notably, VNUA/ASFV/VP2023-isolate1 harbored a partial deletion of the I177L gene along with the insertion of an mCherry marker gene, suggesting possible evolution of the modified live ASFV-G-ΔI177L vaccine strain under field conditions. Collectively, these findings underscore the ongoing evolution and genomic plasticity of ASFV strains circulating in Vietnam. Full article

In 2023, ASF was recognized in Lombardy in wild boars, but shortly thereafter the disease was also identified in pig farms, with serious economic repercussions for the entire national pig sector. To identify factors related to the introduction of the infection into pig farms, a case–control study was conducted with the aim of gaining knowledge on the risk and protective factors involved in the introduction of the ASF virus into intensive pig farms. To this end, a questionnaire was developed on risk factors related to ASFV transmission into pig farms and on good management and biosecurity practices. The results of the study showed that measures aimed at strengthening the segregation of the farm from the external environment (external biosecurity), such as the mandatory passage through a hygiene lock upon entry, the presence of a hygiene lock for farm personnel and external visitors, the presence of special equipment and disinfection points at the entrance to the sheds, the loading of dead pigs outside the animal housing area and the ownership of non-adjacent agricultural land, were associated with a reduced risk. This information, if effectively communicated, could be of direct practical value to farmers to ensure the successful implementation of farm biosecurity. Full article

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF), a fatal and highly contagious disease, resulting in enormous losses to the global swine industry. No licensed vaccines or effective therapeutics are currently available to control ASFV infection. Interferons (IFNs) serve as key mediators of host antiviral immunity by inducing interferon-stimulated genes (ISGs), but the specific mechanisms by which individual ISGs restrict ASFV replication remain unclear. Interferon-induced protein with tetratricopeptide repeats 3 (IFIT3, also called ISG60) has been shown to exhibit antiviral activity against various viruses, but its role in ASFV infection has not been previously studied. Here, we used porcine alveolar macrophages (PAMs), the primary target cells of ASFV, to investigate IFIT3’s function in ASFV replication. We found that overexpression of IFIT3 inhibited ASFV replication, while its knockdown enhanced viral propagation. Mechanistically, IFIT3 directly blocked ASFV adsorption to host cells, thereby suppressing all subsequent stages of the viral cycle. IFIT3 also specifically interacted with ASFV F334L, an early viral gene product that encodes the small subunit of ribonucleotide reductase, a key enzyme for viral DNA synthesis. Additionally, IFIT3 positively regulated the STAT1/TBK1/IRF3 signaling axis: its overexpression increased phosphorylation of TBK1 and IRF3, as well as the protein level of STAT1, while IFIT3 knockdown attenuated activation of these molecules. Transcriptomic analysis of IFIT3-knockout PAMs revealed significant suppression of innate immune pathways, including type I interferon, JAK-STAT, and RIG-I-like receptor pathways, along with downregulated expression of core antiviral molecules such as ISG15, MX1, and STAT1. Conversely, pathways related to viral adsorption, endocytosis, and cytoskeleton were activated, and pathways involved in protein translation initiation, endoplasmic reticulum stress, and autophagy were dysregulated, creating a favorable intracellular environment for ASFV replication. In conclusion, IFIT3 restricts ASFV replication possibly by inhibiting viral adsorption and promoting innate immune signaling, identifying it as a potential therapeutic target against ASFV. This study’s limitation is its in vitro PAM model; future work will validate IFIT3’s role in vivo and develop targeted inhibitors. Full article