Search Results (422)

African swine fever (ASF) continues to spread, threatening the global swine industry and endangered swine species. Sri Lanka is a tropical island situated south of India in the Indian Ocean. Here, we report the first detection of ASF in Sri Lanka. In September 2024, increased pig mortality was reported across the country, with initial confirmation of porcine reproductive and respiratory syndrome (PRRS). Despite vaccination for PRRS, the mortalities continued to increase and therefore, tissue samples collected from dead pigs were subjected to ASF real-time PCR. ASFV genomic material was detected in most of the samples. The real-time PCR-positive samples were then subjected to genotyping by partial genome sequencing. All p72 and p54 sequences were found to be aligned with ASFV genotype II viruses, and CD2v sequences were found to be aligned with ASFV serogroup 8 viruses. The real-time PCR-positive samples were inoculated onto primary porcine leukocytes for virus isolation, and a selected number of tissues collected from dead pigs were subjected to histopathology. Histopathological studies revealed widespread loss of lymphocytes together with inflammation and extensive staining of ASFV antigens in tissue samples. Hemadsorption (HAD)-positive isolates were obtained from seven clinical samples, and three of them were subjected to whole-genome sequencing. Phylogeographic analysis of the whole-genome sequences showed that the virus is closely related to ASFV strains circulating in China and Hong Kong. Full article

Background/Objectives: Inadequate characterization of protective antigens poses a significant challenge to the development of vaccines for African swine fever (ASF), particularly for antigen-dependent formulations such as subunit, mRNA, and recombinant viral vector vaccines. To address this, we aimed to screen African swine fever virus (ASFV) antigens and enhance their immunogenicity using a nanoparticle delivery platform. Methods: Here, six ASFV antigens (p30, p54, pE120R, pH124R, pE184L, and CD2v) were purified and used to immunize pigs individually. The effects of antibodies induced by these six antigens on ASFV replication or hemadsorption was evaluated in primary porcine alveolar macrophages (PAMs). These six antigens were, respectively, conjugated to ferritin via SpyTag/SpyCatcher to prepare six ferritin nanoparticles. A cocktail of the six mixed antigens or a cocktail of the six mixed nanoparticles was used to immunize pigs separately, and the differences in induced humoral and cellular immune responses were compared. Results: Antibodies generated against p30, p54, pE120R, pH124R, and pE184L in immunized pigs significantly inhibited ASFV replication in PAMs, while anti-CD2v antibodies specifically obstructed the hemadsorption of ASFV. Notably, immunization with a cocktail of these antigen-conjugated nanoparticles elicited a stronger virus-inhibitory antibody response compared to immunization with a cocktail of antigen monomers. Furthermore, nanoparticle immunization induced robust cellular immunity, evidenced by elevated serum IFN-γ, increased numbers of ASFV-specific IFN-γ-secreting cells, and an expanded CD8⁺ T cell population. Conclusions: Our study identifies a set of promising ASFV antigen candidates and demonstrates that ferritin nanoparticle delivery synergistically enhances both humoral and cellular immune responses against ASFV, providing a rational strategy for multi-antigen ASF vaccine design. Full article

African swine fever (ASF) is a transboundary viral disease that has heavily impacted Southeast Asia since its introduction in 2019. Smallholder pig production systems in Cambodia and the Lao People’s Democratic Republic (the Lao PDR), characterized by low biosecurity, free-ranging practices, and limited veterinary oversight, remain particularly vulnerable. To assess farmers’ awareness and practices regarding ASF, a knowledge, attitudes, and practices (KAP) survey was implemented between March and September 2023 by Agronomes et Vétérinaires Sans Frontières within the framework of the Biosecurity in Pig Farming (BIG) project. A total of 471 pig farmers, including 56% women, were interviewed across eight provinces using a standardized questionnaire (188 in Cambodia and 283 in the Lao PDR). Results showed that ASF awareness was generally high (92% in Cambodia, 66% in the Lao PDR), yet 15% of Cambodian and 30% of Lao respondents expressed doubts about the presence of ASF in their country. While recognition of ASF symptoms was moderate and positively correlated with farmers’ perceived capacity to identify the disease, knowledge of transmission pathways was low and often misaligned with perceptions. Airborne transmission was frequently cited as a risk, and the risks related to visitors and fomites were underestimated by more than 50% of the farmers. Implementation of biosecurity measures (BSM) was limited, with mean scores of 43% in Cambodia and 27% in the Lao PDR. Risky practices such as swill feeding, free-ranging, sharing of boars, traders, and inadequate carcass disposal remained widespread. Statistical analysis identified education level, herd size, knowledge, perceived risks, and perceived benefits of BSM as the main determinants of biosecurity implementation. Farmers with larger herds or stronger commercial orientation demonstrated higher biosecurity adoption, while misconceptions and knowledge gaps remained frequent among smallholder farmers. Strengthening awareness, promoting low-cost and feasible biosecurity practices, and integrating farmer-centred approaches are essential for reducing ASF transmission risks and improving the resilience of smallholder pig production systems in the region. Full article

African Swine Fever (ASF) control is severely hampered by the reliance on slow, laboratory-bound diagnostics. While rapid, field-deployable lateral flow assays (LFAs) are urgently needed, the comparative performance of key single-antigen targets remains poorly characterized. This study aimed to develop and systematically evaluate the diagnostic performance of three in-house single-antigen LFAs targeting ASF virus P30, P54, and P72, using swine field samples from Thailand, including a panel of 143 quantitative polymerase chain reaction-negative swine serum samples. The performance of each LFA was compared against a commercial multi-antigen (P32/P62/P72) indirect ELISA, which served as the reference standard, classifying 64 samples as positive and 79 as negative. The P72-based LFA demonstrated perfect diagnostic performance (100% sensitivity, 100% specificity) and perfect agreement (κ = 1.0) with the enzyme-linked immunosorbent assay (ELISA). Similarly, the P30 LFA demonstrated high performance (100% sensitivity, 98.7% specificity) with ‘Almost Perfect’ agreement (κ = 0.9859). In contrast, the P54 LFA was unsuitable, achieving 100% sensitivity but unacceptably low specificity (88.6%) due to a high rate of false positives. Overall, the single-antigen P72 and P30 LFAs demonstrated excellent concordance with the multi-antigen ELISA, supporting their reliable for detecting antibodies against ASFV. Although these assays do not replace molecular methods for acute infection detection, they represent valuable complementary tools for serosurveillance. Full article

Background/Objectives: African swine fever (ASF) causes massive global swine industry losses with no effective vaccine available. This study constructed T7 phages displaying key ASFV proteins to evaluate their potential as an ASF vaccine by assessing viral shedding and immune responses in pigs. Methods: Five ASFV proteins were displayed on T7 phages to form VLPs (ASFV-SC-T7 group), with soluble proteins (ASFV-SC group) and PBS as controls; 9 piglets were immunized, boosted at 28 days, challenged with virulent ASFV, and assessed via ELISA, flow cytometry, and real-time PCR. Results: ASFV-SC-T7 induced more high-titer antibodies and elevated monocytes/CD8⁺ T cells, but all groups developed ASF lesions, with ASFV-SC-T7 having higher lung/mesenteric lymph node viral loads and no survival improvement (only delayed fever). Conclusions: T7 phage-displayed ASFV proteins activate strong immunity, confirming T7 phages as a viable delivery platform, but failed to protect against virulent ASFV, requiring future optimization of antigens and regimens. Full article

African swine fever virus (ASFV) poses a significant threat to the global pig industry due to high mortality rates and complex genetic variation. Live attenuated vaccines (LAVs) provide protection against ASFV. Previously, MGF505-2R was identified as a potent inhibitor of innate immunity in vitro. This study evaluates the pathogenicity of a recombinant Eurasian genotype II strain with the MGF505-2R gene deleted (ASFV-ΔMGF505-2R) in piglets. Twelve five-week-old crossbred piglets were divided into two groups, with one group of eight piglets inoculated with ASFV-ΔMGF505-2R (n = 8) and the other group of four piglets inoculated with the same dose of parental ASFV CN/GS 2018 (n = 4). Clinical symptoms, viral loads, and immune responses were monitored over 30 days. ASFV-ΔMGF505-2R-inoculated piglets exhibited transient fever and low viremia only in the beginning of the challenge, while the control group developed high levels of viremia and hyperthermia at day 2 and 8 post-challenge, respectively. Meanwhile, the control group demonstrated more severe post-mortem signs and immuno-histochemistry injury when compared to the ΔMGF505-2R group. ELISA analysis displayed higher levels of IFN-β and IL-1β in the ΔMGF505-2R group, further solidating the immunosuppressive role of MGF505-2R. All ASFV-ΔMGF505-2R-inoculated piglets developed high titers of ASFV-specific P30 antibodies at 10 days post-challenge. These findings rationalized the potential of ASFV-ΔMGF505-2R as a live attenuated candidate for ASF infection. Full article

African swine fever is a highly contagious and deadly disease of both domestic and wild pigs. In developing countries such as Ghana, the diagnosis and control of ASF are very challenging. In this paper, we discussed factors that account for ASF endemicity in many developing nations, with special focus on Ghana. We identified possible ASF spread via pig value chain through the transportation of live pigs across regions in Ghana. Major factors contributing to ASF spread in Ghana include lack of farmer compensation during ASF outbreaks, free range system of pig farming, porous country borders, lack of rapid on-site diagnostic test kits, unsafe sample collection and transportation to diagnostic laboratories, long diagnostic test turnaround, and improper carcass disposal. We also discuss available diagnostic options for ASF and their limitations. We propose a more holistic approach to ASF control in Ghana. These measures include applying a muti-sectoral approach, rehabilitation of inactive regional laboratories and expansion of services to six newly established regions, promoting point of care testing and developing and implementing farmer compensation plan during outbreaks. These proposed ASF control measures will provide field veterinarians with effective means to make informed decisions while awaiting laboratory confirmation of outbreaks. Full article

Background/Objectives: African swine fever (ASF) is a devastating disease affecting the swine industry globally. Development of safe and effective vaccines is an urgent need. This study aimed to evaluate, caASFV001-MA52, a cell-adapted ASFV strain derived from serial passaging in MA-104 cells, as a promising live-attenuated vaccine (LAV) candidate against virulent ASFV infection. Methods: Seven-week-old, crossbred pigs were immunized with caASFV001-MA52 (at a dose of 10⁵ TCID₅₀) and subsequently challenged with a lethal dose of virulent ASFV. Vaccine efficacy was measured through clinical monitoring, immunological and virological analyses, and pathological assessments of tissue protection and viral load reduction. Safety was critically assessed, particularly regarding its profile in animals with concurrent endemic porcine infections, including PCV, PRRSV and S. suis. Results: caASFV001-MA52 exhibits partial protection (70–80%) against the lethal challenge. Vaccinated and challenged survivors exhibited reduced viral loads and significantly alleviated pathological lesions compared to controls. Safety evaluations revealed that the vaccine’s profile is susceptible to concurrent infection. Pigs co-infected with endemic porcine pathogens showed increased virulence and mortality following vaccination. Although vaccination temporarily reactivated latent viral infections (PCV2, PCV3, and PRRSV), most surviving pigs effectively controlled and eliminated these co-infections. Conclusions: The caASFV001-MA52 strain demonstrates promising immunogenicity and protection against lethal challenges, supporting its continued development as an LAV candidate. However, the observed safety concerns regarding concurrent infections emphasize the critical need for veterinary health surveillance during its future practical application. Full article

African swine fever virus (ASFV) is a high-consequence pathogen that causes African swine fever (ASF), for which mortality rates can reach 90–100%, with death typically occurring within 14 days. ASF is currently a highly contagious pandemic disease responsible for extensive losses in pig production in multiple affected countries suffering from extended outbreaks. While a limited number of vaccines to prevent ASF are in use in south-east Asia, vaccines are not widely available, are only effective against highly homologous strains of ASFV, and must be used prior to an outbreak on a farm. Currently, there is no treatment for ASF and culling affected farms is the only response to outbreaks on farms to try and prevent spreading. CRISPR/Cas systems evolved as an adaptive immune response in bacteria and archaea that function by cleaving and disrupting the genomes of invading bacteriophage pathogens. CRISPR technology has since been leveraged into an array of endonuclease-based systems used for nucleic acid detection, targeting, genomic cleavage, and gene editing, making them particularly well-suited for development as sequence-specific therapeutic modalities. The programmability of CRISPR-based therapeutics offers a compelling new way to rapidly and specifically target pathogenic viral genomes simply by using different targeting guide RNAs (gRNA) as an adaptable antiviral modality. Here, we demonstrate for the first time a specific CRISPR/Cas9 multiplexed gRNA system that targets the African swine fever viral genome, resulting in sequence-specific cleavage, leading to the reduction in the viral load in infected animals, and subsequent recovery from an otherwise lethal dose of ASFV. Moreover, animals that recovered had protective immunity to subsequent homologous ASFV infection. Full article

African swine fever (ASF) is a highly fatal viral disease of domestic pigs and wild boar that continues to threaten pig production across Europe. Genotype II African swine fever virus (ASFV) has been present in Serbia since 2019 and was first confirmed in Bosnia and Herzegovina in 2023, yet recent genetic data from the region have been lacking. This study aimed to update the genetic characterization of ASFV strains circulating in Serbia between 2023 and 2025 and to provide the first sequence data from Bosnia and Herzegovina. A total of 110 isolates were analyzed by partial sequencing of seven genomic regions recommended by the European Union Reference Laboratory. Good-quality sequences were obtained for at least two loci per isolate. All isolates belonged to genotype II and were classified as CVR variant I, IGR-II, O174L-I, MGF I, K145R-I, and ECO2-II, corresponding to cluster 19. No novel genetic changes were identified in the sequenced fragments. These findings indicate the stable, endemic circulation of cluster 19 in both domestic pigs and wild boar, maintained through ecological and human-mediated transmission at the wildlife–livestock interface. The detection of cluster 19 in Bosnia and Herzegovina underscores transboundary spread and highlights the need for continued molecular surveillance and regional cooperation. Full article

African swine fever (ASF), induced by the African swine fever virus (ASFV), is an acute hemorrhagic disease characterized by high fever, systemic hemorrhages, and elevated mortality. Current diagnostic techniques including PCR and ELISA present limitations in field applications due to requirements for specialized equipment and prolonged processing duration. Therefore, rapid and accurate detection of ASFV has become a key link in ASF prevention and control. This study established a rapid and precise visual diagnostic approach by integrating the CRISPR/AapCas12b system with lateral flow strip (LFS) technology, specifically targeting the B646L gene encoding the major capsid protein p72. The CRISPR/AapCas12b-LFS platform achieved a sensitivity threshold of 6 copies/µL for B646L gene detection, completing analysis within an hour. Validation study confirmed exceptional specificity against common porcine pathogens including PRRSV, CSFV, PRV, PPV4, and PCV3. The developed assay demonstrated complete concordance with real-time PCR results when analyzing 34 clinical specimens including three heart samples, three liver samples, three spleen samples, three lung samples, three kidney samples, three lymph node samples, five serum samples, five blood samples, and five oral swab samples for ASFV detection. Overall, this method is sensitive, specific, and practicable onsite for ASFV detection, showing a great application potential for monitoring ASFV in the field. Full article

African Swine Fever (ASF) control is severely limited by a diagnostic gap, as laboratory-based quantitative polymerase chain reaction (qPCR) is highly sensitive but slow, whereas field-deployable immunochromatographic assays (ICAs) are rapid but unreliable. To address this limitation, this study evaluated a novel, rapid isothermal assay, RNase hybridization-assisted amplification (RHAM), as a high-sensitivity, point-of-need diagnostic solution. This study compared the performance of RHAM and a conventional p72-based ICA against the qPCR reference standard using 106 diverse clinical field samples, including oral swabs, blood, serum, and organs, collected from suspected ASF cases in Thailand. The ICA exhibited markedly low diagnostic performance, achieving only 56.76% sensitivity and showing moderate agreement (κ = 0.421) with qPCR, highlighting the need for a more reliable alternative. In contrast, the RHAM assay achieved 94.59% sensitivity and 96.88% specificity, providing results rapidly within 35 min. This statistically superior performance (McNemar’s test, p < 0.0001) demonstrated almost perfect agreement (κ = 0.891) with the qPCR reference standard, missing only four samples with very high Ct values (>30). In conclusion, RHAM is a powerful, accurate, and field-deployable diagnostic tool that effectively bridges the diagnostic gap, offering qPCR-like sensitivity for the rapid containment of ASF outbreaks. Full article

African swine fever (ASF) continues to spread across the globe, causing a severe impact on the swine industry. Passive surveillance based on testing dead pigs is one of the most effective methods for early detection of ASF incursions. We have previously shown that the superficial inguinal lymph node (SILN) is a convenient and effective sample type for ASF virus (ASFV) genome detection in pigs succumbed to highly or moderately virulent ASFV infections. In this study, we explored the distribution kinetics of ASFV into SILN and other lymphoid tissues in pigs exposed to moderately virulent ASFV strains (ASFV Estonia 2014 and ASFV Malta’78), oronasally. The ASFV genome was detected in SILNs as early as 2–3 days post-infection (dpi), peaking around 5–9 dpi. The detection of ASFV Estonia 2014 started early, and the pigs succumbed to infection faster compared to the ASFV Malta’78 infected pigs that remained longer. All pigs that succumbed to ASF had comparable levels of ASFV genomic material in the spleen and SILNs. The levels of ASFV genomic material gradually started to decrease in pigs that did not succumb to ASF, indicating possible virus clearance. In contrast, ASFV genome levels in blood and spleen samples remained relatively steady during the study period. Immunohistochemistry and in situ hybridization of spleen and SILN samples supported real-time PCR results. This study demonstrates the distribution kinetics of moderately virulent ASFV in peripheral lymph nodes and highlights the utility of SILNs for dead pig screening. Full article

African swine fever (ASF), caused by African swine fever virus (ASFV), has inflicted severe economic losses on China’s pig industry. Existing ASFV nucleic acid detection methods struggle to identify infected pigs in the pre-viremic stage, especially for recently emerged recombinant ASFV strains that exhibit delayed clinical symptoms and prolonged virus shedding, posing great challenges to ASF prevention and control. To fit the problem, this study established a TaqMan duplex quantitative polymerase chain reaction (qPCR) assay targeting the ASFV p72 gene and porcine Hp gene for early diagnosis of ASFV infection. The qPCR reaction system (20 μL) and conditions were optimized and showed high sensitivity, with detection limits of 1.42 × 10¹ copies/μL for Hp and 2.23 × 10¹ copies/μL for ASFV, as well as excellent specificity and reproducibility. Serum cDNA samples from pigs infected with virulent or recombinant ASFV strains were tested, and the result showed that Hp was detectable as early as 1 day post-infection (DPI), however ASFV remained undetectable until 3DPI. Then cDNA samples from cohabitation infection were tested and 80% samples were Hp-positive, although ASFV test was negative.In conclusion, this duplex qPCR assay for simultaneous detection of Hp and ASFV enables pre-viremia diagnosis of ASF, providing a valuable tool for early screening of ASFV-infected pigs. Full article