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Modular framework to assess the risk of African swine fever virus entry into the European Union.

ABSTRACT: BACKGROUND: The recent occurrence and spread of African swine fever (ASF) in Eastern Europe is perceived as a serious risk for the pig industry in the European Union (EU). In order to estimate the potential risk of ASF virus (ASFV) entering the EU, several pathways of introduction were previously assessed separately. The present work aimed to integrate five of these assessments (legal imports of pigs, legal imports of products, illegal imports of products, fomites associated with transport and wild boar movements) into a modular tool that facilitates the visualization and comprehension of the relative risk of ASFV introduction into the EU by each analyzed pathway. RESULTS: The framework's results indicate that 48% of EU countries are at relatively high risk (risk score 4 or 5 out of 5) for ASFV entry for at least one analyzed pathway. Four of these countries obtained the maximum risk score for one pathway: Bulgaria for legally imported products during the high risk period (HRP); Finland for wild boar; Slovenia and Sweden for legally imported pigs during the HRP. Distribution of risk considerably differed from one pathway to another; for some pathways, the risk was concentrated in a few countries (e.g., transport fomites), whereas other pathways incurred a high risk for 4 or 5 countries (legal pigs, illegal imports and wild boar). CONCLUSIONS: The modular framework, developed to estimate the risk of ASFV entry into the EU, is available in a public domain, and is a transparent, easy-to-interpret tool that can be updated and adapted if required. The model's results determine the EU countries at higher risk for each ASFV introduction route, and provide a useful basis to develop a global coordinated program to improve ASFV prevention in the EU.

SUBMITTER: Mur L

PROVIDER: S-EPMC4112856 | biostudies-other | 2014

REPOSITORIES: biostudies-other

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Modular framework to assess the risk of African swine fever virus entry into the European Union.

Mur Lina L Martínez-López Beatriz B Costard Solenne S de la Torre Ana A Jones Bryony A BA Martínez Marta M Sánchez-Vizcaíno Fernando F Muñoz María Jesús MJ Pfeiffer Dirk U DU Sánchez-Vizcaíno José Manuel JM Wieland Barbara B

BMC veterinary research 20140703

<h4>Background</h4>The recent occurrence and spread of African swine fever (ASF) in Eastern Europe is perceived as a serious risk for the pig industry in the European Union (EU). In order to estimate the potential risk of ASF virus (ASFV) entering the EU, several pathways of introduction were previously assessed separately. The present work aimed to integrate five of these assessments (legal imports of pigs, legal imports of products, illegal imports of products, fomites associated with transpor ...[more]

PMID: 24992824

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Project description:This report provides a descriptive analysis of the African swine fever (ASF) Genotype II epidemic in the affected Member States in the EU and two neighbouring countries for the period from 1 September 2020 to 31 August 2021. ASF continued to spread in wild boar in the EU, it entered Germany in September 2020, while Belgium became free from ASF in October 2020. No ASF outbreaks in domestic pigs nor cases in wild boar have been reported in Greece since February 2020. In the Baltic States, overall, there has been a declining trend in proportions of polymerase chain reaction (PCR)-positive samples from wild boar carcasses in the last few years. In the other countries, the proportions of PCR-positive wild boar carcasses remained high, indicating continuing spread of the disease. A systematic literature review revealed that the risk factors most frequently significantly associated with ASF in domestic pigs were pig density, low levels of biosecurity and socio-economic factors. For wild boar, most significant risk factors were related to habitat, socio-economic factors and wild boar management. The effectiveness of different control options in the so-named white zones, areas where wild boar densities have been drastically reduced to avoid further spread of ASF after a new introduction, was assessed with a stochastic model. Important findings were that establishing a white zone is much more challenging when the area of ASF incursion is adjacent to an area where limited control measures are in place. Very stringent wild boar population reduction measures in the white zone are key to success. The white zone needs to be far enough away from the affected core area so that the population can be reduced in time before the disease arrives and the timing of this will depend on the wild boar density and the required population reduction target in the white zone. Finally, establishing a proactive white zone along the demarcation line of an affected area requires higher culling efforts, but has a higher chance of success to stop the spread of the disease than establishing reactive white zones after the disease has already entered in the area.

Project description:An update on the African swine fever (ASF) situation in the 10 affected Member States (MS) in the EU and in two neighbouring countries from the 1 September 2019 until the 31 August 2020 is provided. The dynamics of the proportions of PCR- and ELISA-positive samples since the first ASF detection in the country were provided and seasonal patterns were investigated. The impact of the ASF epidemic on the annual numbers of hunted wild boar in each affected MS was investigated. To evaluate differences in the extent of spread of ASF in the wild boar populations, the number of notifications that could be classified as secondary cases to a single source was calculated for each affected MS and compared for the earliest and latest year of the epidemic in the country. To evaluate possible risk factors for the occurrence of ASFV in wild boar or domestic pigs, a literature review was performed. Risk factors for the occurrence of ASF in wild boar in Romanian hunting grounds in 2019 were identified with a generalised linear model. The probability to find at least one PCR-confirmed ASF case in wild boar in a hunting ground in Romania was driven by environmental factors, wild boar abundance and the density of backyard pigs in the hunting ground area, while hunting-related variables were not retained in the final model. Finally, measures implemented in white zones (ASF-free zones that are geographically adjacent to an area where ASF is present in wild boar) to prevent further spread of ASF were analysed with a spatially, explicit stochastic individual-based model. To be effective, the wild boar population in the white zone would need to be drastically reduced before ASF arrives at the zone and it must be wide enough. To achieve the necessary pre-emptive culling targets of wild boar in the white zone, at the start of the establishment, the white zone should be placed sufficiently far from the affected area, considering the speed of the natural spread of the disease. This spread is faster in denser wild boar populations. After a focal ASF introduction, the white zone is always close to the infection hence pre-emptive culling measures in the white zone must be completed in short term, i.e. in a few months.

Project description:African swine fever (ASF) is an acute and hemorrhagic infectious disease caused by African swine fever virus (ASFV), which is listed as an animal epidemic disease that must be reported by The World Organization for Animal Health and that causes serious economic losses to China and even the whole world. Currently, the entry mechanism of ASFV is not fully understood. Especially in the early stages of virus entry, the host factors required for ASFV entry have not yet been identified and characterized. In this study, we demonstrated that ASFV externalized phosphatidylserine (PS) on the envelope functioned as viral apoptotic mimicry, which interacts with AXL, a tyrosine kinase receptor, to mediate ASFV entry into porcine alveolar macrophages (PAMs). We found that AXL was the most pronounced phosphatidylserine receptor (PSR) affecting ASFV entry in PAMs by RNA interference screening. Knockout AXL gene expression remarkably decreased ASFV internalization and replication in MA104 cells. Furthermore, the antibody against AXL extracellular domains effectively inhibited the ASFV entry. Consistent with these results, the deletion of the intracellular kinase domain of AXL and the treatment of the AXL inhibitor, R428, significantly inhibited the internalization of ASFV. Mechanistically, AXL facilitated the internalization of ASFV virions via macropinocytosis. Collectively, we provide evidence that AXL is a coreceptor for ASFV entry into PAMs, which expands our knowledge of ASFV entry and provides a theoretical basis for identifying new antiviral targets. IMPORTANCE African swine fever (ASF) is a highly contagious infectious disease caused by the ASF virus (ASFV), with a mortality rate of up to 100%. ASFV has caused huge economic losses to pig farming worldwide. Specific cellular surface receptors are considered crucial determinants of ASFV tropism. However, the host factors required for ASFV entry have not yet been identified, and the molecular mechanism of its entry remains unclear. Here, we found that ASFV utilized phosphatidylserine (PS) on the surface of virions to masquerade as apoptotic mimicry and facilitated virus entry by interacting with host factor AXL. We found that knockout of AXL remarkably decreased ASFV internalization and replication. The antibody against AXL extracellular domains and AXL inhibitor R428 significantly inhibited the internalization of ASFV via macropinocytosis. The current work deepens our understanding of ASFV entry and provides clues for the development of antiviral drugs to control ASFV infection.

Dataset Information

Modular framework to assess the risk of African swine fever virus entry into the European Union.

Publications

Modular framework to assess the risk of African swine fever virus entry into the European Union.

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