African Swine Fever Research Articles

Detection of African swine fever virus and wild boar eDNA in soil and turbid water samples: towards environmental surveillance

Since 2007, an ongoing African swine fever (ASF) pandemic has significantly impacted Eurasia. Extensive field evidence and modeling confirm the central role of wild boar in ASF epidemiology. To effectively control and eradicate the infection, rapid detection of the ASF virus (ASFV) is crucial for prompt intervention in areas of recent viral introduction or ongoing outbreaks. Environmental DNA (eDNA) is a cost-effective and non-invasive technique that has shown promising results in monitoring animal species and their pathogens and has the potential to be used for wildlife disease surveillance. In this study, we designed and evaluated an eDNA sampling method for highly turbid water and soil samples to detect ASFV and wild boar (Sus scrofa) DNA as a control using qPCR while ensuring biosafety measures and evaluating ASF epidemiology. To validate our method, we obtained samples from La Mandria Regional Park (LMRP) in northwestern Italy, an area free of ASFV, and spiked them in a laboratory setting with an ASFV’s synthetic DNA template. Our findings highlight the potential of eDNA monitoring as a reliable, rapid, and safe method for early detection of ASFV from soil and turbid water samples.

The p30 protein of the African swine fever virus behaves as an RNase

The African Swine Fever Virus (ASFV) is responsible for causing African Swine Fever (ASF), a severe contagious disease characterized by hemorrhagic symptoms. The p30 protein of ASFV is the most abundantly expressed viral protein. It is reported to be antigenic and has recognized phosphorylation, glycosylation, and membrane attachment sites, which also shows that the C-terminal region of p30 is more active than the N-terminal region. The present study reports the unique RNase activity of recombinant p30. The RNase activity of p30 was stable at an optimum temperature of 37 °C, and the maximum activity was recorded at pH 7–9 in the presence of monovalent salts. The mutant of p30 (p30m), where cysteine was mutated to alanine at position 109, showed a loss of RNase activity. Our understanding of ASFV biology is significantly less; until now, we have little knowledge about the functions of its proteins. The results of the present study will assist in exploring the biology of ASFV and the role of its protein in counteracting the host immune response.

African swine fever virus E120R inhibited cGAS‐STING‐mediated IFN‐β and NF‐κB pathways

AbstractAfrican swine fever (ASF) is an acute and severe contagious disease triggered by the African swine fever virus (ASFV), which severely threatens the global swine industry. At present, no safe and efficacious vaccine has been provided to prevent and control this disease. The pathogenesis and immune evasion mechanism of ASFV are still unknown, which seriously hinders the development of safe and effective ASF vaccines. Certain proteins of ASFV involved in immunosuppression helped to evade the host innate immune response. The cGAS‐STING signaling pathway is important to the innate immune system. It induces the production of type I interferons (IFNs) and other cytokines by recognizing cytoplasmic DNA, mediating antimicrobial innate immunity through type I IFN, and nuclear factor‐κB (NF‐κB) pathways. In the present study, E120R, a late‐phase expression protein and a key virulent factor of ASFV inhibited cGAS‐STING mediated promoter activities of IFN‐β and NF‐κB in HEK293T cells. The ectopic expression of E120R down‐regulated IFN‐β pathway by targeting interferon regulatory factor 3 (IRF3) and p65, inhibited the phosphorylation of STING, and further inhibited the phosphorylation of TANK‐binding kinase 1 (TBK1) and IRF3, with no significant effects on p65 phosphorylation. Additionally, E120R also inhibited the NF‐κB pathways by inhibiting the nuclear translocation of p50 and p65, which was mediated by Sendai virus (SeV). Further, the study showed that the 61–80 amino acids sites in the C‐terminal domain of E120R were crucial for these functions. In conclusion, our work preliminarily elucidated a novel mechanism of inhibiting host innate immune response by ASFV E120R, which will provide a new target for the ASFV live gene deletion vaccine development and the theoretical basis for ASFV prevention.

Current detection methods of African swine fever virus.

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a highly contagious and notifiable animal disease in domestic pigs and wild boars, as designated by the World Organization for Animal Health (WOAH). The effective diagnosis of ASF holds great importance in promptly controlling its spread due to its increasing prevalence and the continuous emergence of variant strains. This paper offers a comprehensive review of the most common and up-to-date methods established for various genes/proteins associated with ASFV. The discussed methods primarily focus on the detection of viral genomes or particles, as well as the detection of ASFV associated antibodies. It is anticipated that this paper will serve as a reference for choosing appropriate diagnostic methods in diverse application scenarios, while also provide direction for the development of innovative technologies in the future.

Fencing, Biosecurity and Wild Boar Politics in the Danish-German Borderland

ABSTRACTThis paper investigates the spatial strategies of fencing and the politics of biosecurity in a European borderland setting. It considers the way in which national spaces and borders are co-produced through spatial strategies of fencing, discourses of biosecurity, and notions of the intrusive other. Based on ethnographic fieldwork in the Danish-German borderlands, the paper examines the physical and discursive creation of a (bio)security fence stretching the entire length of the border – constructed to prevent the migration of Eurasian wild boars and the spread of the highly contagious viral disease African Swine Fever. A disease that could potentially contaminate domestic farmed pigs and severely affect pork exports. Although government narratives justifying the border fence focus on external factors like African Swine Fever, the paper argues that this physical security barrier is not only a biosecurity defense against external threats, but to some also a reflection of symbolism, political imaginaries and ideas of belonging (for both humans and non-humans).

African swine fever antibody detection and status in pigs in Apa, Ohimini and Okpokwu local government areas of Benue State, Nigeria

Since African Swine Fever (ASF) is a notifiable, highly contagious, lethal haemorrhagic disease in domestic pigs. studies were undertaken to investigate the presence of antibody against African Swine Fever Virus (ASFV) among pig population in Apa, Ohimini and Okpokwu LGAs of Benue State, Nigeria . Eight, five, and seven serum were sampled from suspected pigs’ populations in Apa, Ohimini and Okpokwu Local Governments Areas of Benue state respectively. One serum sample from Ohimini tested positive (ie 20%) but none of the samples from Apa and Okpokwu LGAs tested positive for the test (ie 0%). Since pigs with demonstrable antibody are normally considered as chronic carriers of the virus because it is doubtful if true recovery ever occurred. Control measures such as use of quarantine , test and culling of animals that tested positive for ASF antibody with commensurable level of compensation.
  
  
  
  
 La peste porcine africaine (PPA) étant une maladie hémorragique à déclaration obligatoire, hautement contagieuse et mortelle chez les porcs domestiques. des études ont été entreprises pour étudier la présence d'anticorps contre le virus de la peste porcine africaine (VPPA) parmi la population porcine des LGA d'Apa, Ohimini et Okpokwu de l'État de Benue, au Nigéria. Huit, cinq et sept sérums ont été échantillonnés dans des populations de porcs suspectées respectivement dans les zones de gouvernement local d'Apa, d'Ohimini et d'Okpokwu, dans l'État de Benue. Un échantillon de sérum d'Ohimini s'est révélé positif (soit 20 %), mais aucun des échantillons des LGA d'Apa et d'Okpokwu n'a été testé positif (soit 0 %). Étant donné que les porcs présentant des anticorps démontrables sont normalement considérés comme des porteurs chroniques du virus, car il est douteux qu’une véritable guérison ne se soit jamais produite. Desmesures de contrôle telles que le recours à la quarantaine, les tests et l'abattage des animaux testés positifs aux anticorps anti-PPA avec un niveau de compensation proportionné.

Natural co-infection of pigs with African swine fever virus and porcine reproductive and respiratory syndrome virus in India.

Porcine reproductive and respiratory syndrome (PRRS) and African swine fever (ASF) are economically important diseases of pigs throughout the world. During an outbreak, all age groups of animals except piglets < 1 month of age were affected with symptoms of high fever, cutaneous hemorrhages, vomition with blood, diarrhea, poor appetite, ataxia, and death. The outbreak was confirmed by the detection of the N gene of the porcine reproductive and respiratory syndrome virus (PRRSV) and the VP72 gene of the African swine fever virus (ASFV) by PCR in representative blood samples from affected pigs followed by Sanger sequencing. Mixed infection was also confirmed by simultaneous detection of both the viruses using multiplex PCR. Phylogenetic analysis of both the viruses revealed that the outbreak was related to ASFV and PRRSV strains from China which were also closely related to the PRRSV and ASFV strains from the recent outbreak from India. The study confirmed the involvement of genotype II of ASFV and genotype 2 of PRRSV in the present outbreak. Interestingly, PRRSV associated with the present outbreak was characterized as a highly pathogenic PRRSV. Therefore, the present study indicates the possibility of future waves or further outbreaks of these diseases (PRRS and ASF) in this region. This is the first report of ASFV and PRRSV co-infection in pigs from India.

ASFV epitope mapping by high density peptides microarrays

African swine fever (ASF) is an acute, highly contagious and deadly infectious disease. It is a threat to animal health with major potential economic and societal impact. Despite decades of ASF vaccine research, still some gaps in knowledge are hindering the development of a functional vaccine. Worth mentioning are gaps in understanding the mechanism of ASF infection and immunity, as well as the fact that - in case of this disease - virus proteins, so-called protective antigens, responsible for inducing protective immune responses in pigs are not identified yet. In this paper we elaborate on a methodology to identify protective antigens based on epitope mapping by microarray technology. High density peptide microarrays, combined with fluorescence scanning, have been used to analyze the interaction of peptide sequences of African swine fever virus (ASFV) proteins with antibodies present in inactivated serum from infected and healthy animals. The study evidenced ASFV proteins already under the radar for vaccine development, such as p54, and identified specific sequences in those proteins that may become the focus for future vaccine candidates. Such methodology is amenable to automation and high-throughput and may help developing better targeting for next generation vaccines.

Analysis Of Factors Affecting Swine Farmers’ Income During African Swine Fever (ASF) In North Sumatera

In the year 2019, a significant outbreak of pig mortalities caused by African Swine Fever (ASF) transpired inside the North Sumatra province This study aims to determine differences in the income of pig farmers before and during the ASF pandemic in North Sumatra, to analyze the factors that affect the income of pig farmers in North Sumatra, and to analyze the factors that affect the productivity of pig farmers in North Sumatra. This research was carried out in Deli Serdang, Humbang Hansudutan, and Dairi Regencies in March-July 2023 with a total of 96 respondents. Data analysis used is using multiple linear analysis. The results showed that the income of pig farmers in North Sumatra before the African Swine Fever (ASF) outbreak was higher, namely IDR 135,351,041.67 compared to the income of pig farmers during the ASF outbreak, which was IDR 98,484,895.83. The results of multiple regression analysis show that harvest weight, labor costs, feed cost, and sources of income have a significant effect on the income of pig farmers in North Sumatra.

Genetic analysis reveals multiple intergenic region and central variable region in the African swine fever virus variants circulating in Serbia.

This study provides the first comprehensive report on the molecular characteristics of African swine fever virus (ASFV) variants in Serbia between 2019 and 2022. Since its first observation in July 2019, the disease has been found in wild boar and domestic swine. The study involved the analysis of 95 ASFV-positive samples collected from 12 infected administrative districts in Serbia. Partial four genomic regions were genetically characterized, including B646L, E183L, B602L, and the intergenic region (IGR) between the I73R-I329L genes. The results of the study suggest that multiple ASFV strains belonging to genotype II are circulating in Serbia, as evidenced by the analysis of the IGR between I73R-I329L genes that showed the most differences. Furthermore, the phylogenetic analysis of the B602L gene showed three different clades within the CVR I group of ASFV strains. Regarding the IGR, 98.4% were grouped into IGR II, with only one positive sample grouped into the IGR III group. These findings provide essential insights into the molecular characteristics of ASFV variants in Serbia and contribute to the knowledge of circulating strains of ASFV in Europe. However, further research is necessary to gain a better understanding of ASFV spread and evolution.

Detection of African Swine Fever Virus from Wild Boar, Singapore, 2023.

We detected African swine fever virus (ASFV) from a wild boar in Singapore. In <72 hours, we confirmed and reported ASFV p72 genotype II, CD2v serogroup 8, and IGR-II variant by using a combination of real-time PCR and whole-genome sequencing. Continued biosurveillance will be needed to monitor ASFV in Singapore.

Epidemiological Assessment of African Swine Fever Spread in the Dominican Republic.

Since African Swine Fever (ASF) was detected in the Dominican Republic in July 2021, it has negatively impacted the country's swine industry. Assessing the epidemiological situation is crucial to helping local authorities and industry stakeholders control the disease. Here, data on 155 reported outbreaks in the Dominican Republic from November 2022 to June 2023 were evaluated. Descriptive spatiotemporal analysis was performed to characterize disease distribution and spread, and between-herd R0 was calculated for the study period. The Knox test and a space-time permutation model were used to evaluate clustering. Data on clinical presentation, biosecurity measures, and suspected reasons for introduction were categorized and summarized. The majority (78%) of outbreaks occurred on backyard farms which generally had low biosecurity. Across farm types, the majority of pigs were still alive at the time of depopulation. Spatiotemporal findings and R0 estimates suggest an endemic pattern of disease geographically located centrally within the country. Clustering was detected even at small temporal and spatial distances due to outbreaks amongst neighboring backyard farms. These results provide critical information on the current state of the ASF epidemic in the Dominican Republic and will aid government officials and swine industry leaders in developing effective ASF control strategies.

Efficient delivery of the immunodominant genes of African swine fever virus by adeno-associated virus serotype 2.

Adeno-associated virus serotype 2 (AAV2) represents a promising basis for developing a virus-vector vaccine against African swine fever (ASF). This study aimed to create genetic constructs based on AAV2 to deliver the immunodominant genes of ASF virus (ASFV) and to evaluate their functionality in vitro. The efficiency and specificity of transgene expression, as well as their non-toxicity in cells of target animals, were evaluated. Bioinformatics analysis methods were used to identify the immunodominant genes of ASFV. The target genes B646L, E183L, CP204L, and CP530R were identified and subsequently cloned into the pAAV-MCS vector. Assembly of recombinant AAV2 (rAAV2) was performed by cotransfection of AAV293 cells with the following plasmids: pAAV-MCS with the gene of interest, envelope, and packaging. Quantitative polymerase chain reaction was used to determine the AAV2 titer. The functionality of the constructs was evaluated in HEK293 and SPEV cells by determining the presence of mature proteins in the cell lysate and the expression levels of messenger RNA. The specificity of the target proteins in cell lysates was confirmed by Western blotting. The proposed AAV2 assembly protocol makes it possible to achieve a concentration of mature viral particles of at least 280 billion/mL of virus-containing material. The rAAV2 could effectively transduce host SPEV cells. The expression of both cistrons was detectable during the transduction of cells; therefore, the combined expression of immunogens in the cells of target animals should be possible using this method. This study demonstrated the potential of using genetic constructs based on AAV2 for the delivery of ASFV genes in vitro.

Molecular contamination of an animal facility during and after African swine fever virus infection.

The molecular contamination of an animal facility was investigated during and after an infection with highly pathogenic African swine fever virus (ASFV) among domestic pigs. The investigation evaluated the risk of indirect transmission of the disease and indicated points that may facilitate cleaning and disinfection processes. Six domestic pigs were infected oronasally with the highly pathogenic Georgia 2007 strain. Environmental samples from the floors, walls, rubber floor mats, feeders, drinkers, high-efficiency particulate-absorbing filter covers and doors were collected 7 days post infection (dpi), 7 days later and 24 h after disinfection of the facility. The samples were investigated by real-time PCR and in vitro assays to find genetic traces of ASFV and infectious virus. Typical clinical outcomes for ASF (i.e. fever, apathy, recumbency and bloody diarrhoea) were observed, and all animals died or required euthanasia before or at 9 dpi. No infectious virus was found in environmental samples at the sampling time points. Genetic traces of ASFV were found in all locations except the doors. The initial virus load was calculated using real-time PCR threshold cycle values and was the highest at the drain. A statistically significant decrease of virus load over time was found on non-porous surfaces mechanically cleaned by water (the floor and drain). The gathered data confirmed different routes of virus excretion (oral and nasal, faeces and urine, and aerosol) and showed virus locations and different initial concentrations in the animal facility. Maintaining the facility with mechanical cleaning and using personal protection (gloves) and hand disinfection may efficiently minimise the risk of further virus spread. Together with the results of previously published studies, the present investigations' failure to isolate infectious virus may suggest that if stable environmental conditions are assured, the time needed before the introduction of new herds into previously ASF-affected farm facilities could be shortened and in this way the economic losses caused by the disease outbreak mitigated.

Research progress on African swine fever in China

Research progress on African swine fever in China

Application of Protein Crystallography and Machine Learning Data for the Development of a Peptide Vaccine against African Swine Fever

Application of Protein Crystallography and Machine Learning Data for the Development of a Peptide Vaccine against African Swine Fever

Search for Potential Epitopes in the Envelope Protein of the African Swine Fever Virus

Search for Potential Epitopes in the Envelope Protein of the African Swine Fever Virus

Rapid Visual Detection of African Swine Fever Virus with a CRISPR/Cas12a Lateral Flow Strip Based on Structural Protein Gene D117L

African swine fever virus (ASFV) is a large double-stranded DNA virus that is highly infectious and seriously affects domestic pigs and wild boars. African swine fever (ASF) has caused huge economic losses to endemic countries and regions. At present, there is still a lack of effective vaccines and therapeutics. Therefore, rapid and accurate detection is essential for the prevention and control of ASF. The portable DNA endonuclease (Cas12a)-mediated lateral flow strip detection method (Cas12a-LFS) combined with recombinant polymerase amplification (RPA) has been gradually recognized as effective for virus detection including ASFV. In this study, based on the ASFV structural protein p17 gene (D117L), an RPA-Cas12a-LFS detection method was established. The detection method exhibits a sensitivity of up to two gene copies and has no cross-reaction with nine other swine viruses. Thus, the method is highly sensitive and specific. In 68 clinical samples, the coincidence rate of the p17 strip was 100%, compared to the traditional quantitative PCR (qPCR). In conclusion, we have developed a simple, rapid, sensitive, and specific ASFV visual detection method and demonstrated the potential of on-site detection of ASFV.

African Swine Fever: A Review of Current Disease Management Strategies and Risks Associated with Exhibition Swine in the United States

African swine fever is a high-consequence foreign animal disease endemic to sub-Saharan Africa and the island of Sardinia. The U.S. is the world’s third largest pork producer, and ASF introduction would severely disrupt the pork supply chain, emphasizing the need to protect market access for U.S. proteins. However, niche producers raising swine intended for exhibition may not follow stringent biosecurity protocols, and livestock show circuits may promote untracked animal movement across the country, potentially exacerbating virus’ spread in the event of ASF incursion into the U.S. Youth membership in state or national swine organizations offers a route for outreach and educational activities to enhance foreign animal disease preparedness, and adult presence at swine exhibitions allows a wide variety of programming for all ages to better serve all levels of understanding.

Analysis of Factors Influencing the Spread of Asian Swine Fever (ASF) Disease in Samosir District, North Sumatera Province

In Samosir, socio-cultural elements are closely related to pig farming and traditional wisdom which makes pig farming an important part of traditional ceremonies for Christians. In 2019 to 2020 ASF disease is spreading on Samosir Island. African Swine Fever (ASF) is a highly contagious viral disease of pigs, causing various internal bleeding and accompanied by a very high mortality rate. This study used a survey method (interviews) and data analysis using multiple linear regression analysis to obtain the factors that influence the cause of the spread of Asian Swine Fever (ASF) in pigs in Samosir Regency. Based on the results of the study it was found that there was a significant effect of the vaccination variable, the biosecurity variable and the livestock transportation variable, while the variables that had no significant effect were the feed variable and the cage variable on the spread of Asian Swine Fever (ASF) in pigs in Samosir Regency