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Li X, Hu Z, Tian X, Fan M, Liu Q, Wang X. A suitable sampling strategy for the detection of African swine fever virus in living and deceased pigs in the field: a retrospective study. Front Vet Sci 2024; 11:1419083. [PMID: 38988987 PMCID: PMC11234165 DOI: 10.3389/fvets.2024.1419083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 06/12/2024] [Indexed: 07/12/2024] Open
Abstract
African swine fever (ASF) is a fatal disease that threatens the health status of the swine population and thus can impact the economic outcome of the global pig industry. Monitoring the ASF virus (ASFV) is of utmost concern to prevent and control its distribution. This study aims to identify a suitable sampling strategy for ASFV detection in living and deceased pigs under field conditions. A range of samples, comprising tissues obtained from deceased pigs, as well as serum and tonsil swab samples from live pigs, were gathered and subjected to detection using the qPCR method. The findings revealed that the mandibular lymph nodes demonstrated the highest viral loads among superficial tissues, thereby indicating their potential suitability for detecting ASFV in deceased pigs. Additionally, the correlations between virus loads in various tissues have demonstrated that tonsil swab samples are a viable specimen for monitoring live pigs, given the strong associations observed with other tissues. These findings indicated two dependable sample types for the detection of ASFV: mandibular lymph nodes for deceased pigs and tonsil swabs for live pigs, which supply some references for the development of efficacious preventive measures against ASFV.
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Affiliation(s)
- Xiaowen Li
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
- China Agriculture Research System-Yangling Comprehensive Test Station, Xianyang, China
| | - Zhiqiang Hu
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
- College of Animal Science, Xichang University, Xichang, China
| | - Xiaogang Tian
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
| | - Mingyu Fan
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
| | - Qingyuan Liu
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
| | - Xinglong Wang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, China
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Li Y, Wang Z, Qing J, Hu D, Vo HT, Thi KT, Wang X, Li X. Application of propidium monoazide quantitative PCR to discriminate of infectious African swine fever viruses. Front Microbiol 2024; 14:1290302. [PMID: 38268706 PMCID: PMC10805820 DOI: 10.3389/fmicb.2023.1290302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024] Open
Abstract
Introduction The detection of African swine fever virus (ASFV) is commonly performed using quantitative real-time PCR (qPCR), a widely used virological method known for its high sensitivity and specificity. However, qPCR has a limitation in distinguishing between infectious and inactivated virus, which can lead to an overestimation of viral targets. Methods To provide insights into ASFV infectivity, we evaluated the suitability of PMAxx, an improved version of propidium monoazide (PMA), as a means to differentiate between infectious and non-infectious ASFV. Pre-treatment with 50 μM PMAxx for 15 min significantly reduced the qPCR signal of ASFV in the live vaccine. Additionally, thermal treatment at 85°C for 5 min effectively inactivated the live ASFV in the vaccine. Based on a standard curve, the sensitivity of the PMAxx-qPCR assay was estimated to be approximately 10 copies/μL. Furthermore, we observed a strong agreement between the results obtained from PMAxx-qPCR and pig challenge experiments. Moreover, we utilized the PMAxx-qPCR assay to investigate the persistence of ASFV, revealing a close relationship between viral persistence and factors such as temperature and type of piggery materials. Conclusion The findings of this study suggest that pre-treating viruses with PMAxx prior to qPCR is a reliable method for distinguishing between infectious and non-infectious ASFV. Thus, integrating of PMAxx-qPCR into routine diagnostic protocols holds potential for improving the interpretation of positive ASFV results obtained through qPCR.
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Affiliation(s)
- Yang Li
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., (Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology), Dezhou, China
| | - Zewei Wang
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., (Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology), Dezhou, China
| | - Jie Qing
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., (Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology), Dezhou, China
| | - Dajun Hu
- New Hope Binh Phuoc livestock Co., Ltd., Huyen Hon Quan, Vietnam
| | - Hong Trang Vo
- New Hope Binh Phuoc livestock Co., Ltd., Huyen Hon Quan, Vietnam
| | - Kim Thanh Thi
- New Hope Binh Phuoc livestock Co., Ltd., Huyen Hon Quan, Vietnam
| | - Xinglong Wang
- College of Veterinary Medicine, Northwest A&F University, Xianyang, Yangling, China
| | - Xiaowen Li
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., (Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology), Dezhou, China
- New Hope Binh Phuoc livestock Co., Ltd., Huyen Hon Quan, Vietnam
- College of Veterinary Medicine, Northwest A&F University, Xianyang, Yangling, China
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Li X, Hu Z, Fan M, Tian X, Wu W, Gao W, Bian L, Jiang X. Evidence of aerosol transmission of African swine fever virus between two piggeries under field conditions: a case study. Front Vet Sci 2023; 10:1201503. [PMID: 37323846 PMCID: PMC10267313 DOI: 10.3389/fvets.2023.1201503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023] Open
Abstract
African swine fever (ASF) is a devastating and economically significant infectious disease that has caused enormous losses in the commercial pig sector in China since 2018. The primary transmission routes of the African swine fever virus (ASFV), the causative agent of ASF, are direct pig-to-pig contact or indirect contact with virus-contaminated objects. While aerosol transmission of ASFV has been previously reported under experimental conditions, no reports have described it under field conditions. In this case study, aerosol-associated samples were collected over a monitoring period of 24 days in an ASFV-positive farm. A complete and clear chain of ASFV transmission through aerosols was observed: pigs in Room A on Day 0-aerosol in Room A on Day 6-dust of air outlets in Room A on Day 9-outdoor aerosols on Day 9-dust of air inlets in Room B on Day 15-aerosols/pigs in Room B on Day 21. Furthermore, a fluorescent powder experiment confirmed the transmission of dust from Room A to Room B. This study represents the first report providing evidence of aerosol transmission of ASFV under field conditions. Further research is needed to study the laws of aerosol transmission in ASFV and develop effective strategies such as air filtration or disinfection to create a low-risk environment with fresh air for pig herds.
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Affiliation(s)
- Xiaowen Li
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
- China Agriculture Research System-Yangling Comprehensive Test Station, Xianyang, China
| | - Zhiqiang Hu
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
- China Agriculture Research System-Yangling Comprehensive Test Station, Xianyang, China
| | - Mingyu Fan
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
- China Agriculture Research System-Yangling Comprehensive Test Station, Xianyang, China
| | - Xiaogang Tian
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
| | - Weisheng Wu
- Xiajin New Hope Liuhe Agriculture and Animal Husbandry Co., Ltd., Dezhou, China
| | - Wenchao Gao
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
- China Agriculture Research System-Yangling Comprehensive Test Station, Xianyang, China
| | - Lujie Bian
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
| | - Xiaoxue Jiang
- Shandong New Hope Liuhe Agriculture and Animal Husbandry Technology Co., Ltd. (NHLH Academy of Swine Research), Dezhou, China
- Shandong Engineering Laboratory of Pig and Poultry Healthy Breeding and Disease Diagnosis Technology, Qingdao, China
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Penrith ML, van Heerden J, Pfeiffer DU, Oļševskis E, Depner K, Chenais E. Innovative Research Offers New Hope for Managing African Swine Fever Better in Resource-Limited Smallholder Farming Settings: A Timely Update. Pathogens 2023; 12:355. [PMID: 36839627 PMCID: PMC9963711 DOI: 10.3390/pathogens12020355] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/17/2023] [Accepted: 02/19/2023] [Indexed: 02/23/2023] Open
Abstract
African swine fever (ASF) in domestic pigs has, since its discovery in Africa more than a century ago, been associated with subsistence pig keeping with low levels of biosecurity. Likewise, smallholder and backyard pig farming in resource-limited settings have been notably affected during the ongoing epidemic in Eastern Europe, Asia, the Pacific, and Caribbean regions. Many challenges to managing ASF in such settings have been identified in the ongoing as well as previous epidemics. Consistent implementation of biosecurity at all nodes in the value chain remains most important for controlling and preventing ASF. Recent research from Asia, Africa, and Europe has provided science-based information that can be of value in overcoming some of the hurdles faced for implementing biosecurity in resource-limited contexts. In this narrative review we examine a selection of these studies elucidating innovative solutions such as shorter boiling times for inactivating ASF virus in swill, participatory planning of interventions for risk mitigation for ASF, better understanding of smallholder pig-keeper perceptions and constraints, modified culling, and safe alternatives for disposal of carcasses of pigs that have died of ASF. The aim of the review is to increase acceptance and implementation of science-based approaches that increase the feasibility of managing, and the possibility to prevent, ASF in resource-limited settings. This could contribute to protecting hundreds of thousands of livelihoods that depend upon pigs and enable small-scale pig production to reach its full potential for poverty alleviation and food security.
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Affiliation(s)
- Mary-Louise Penrith
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria 0110, South Africa
| | - Juanita van Heerden
- Transboundary Animal Diseases, Onderstepoort Veterinary Research, Agricultural Research Council, Pretoria 0110, South Africa
| | - Dirk U. Pfeiffer
- Centre for Applied One Health Research and Policy Advice, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Department of Pathobiology and Population Sciences, Veterinary Epidemiology, Economics, and Public Health Group, Royal Veterinary College, Hatfield AL9 7TA, UK
| | - Edvīns Oļševskis
- Food and Veterinary Service, LV-1050 Riga, Latvia
- Institute of Food Safety, Animal Health and Environment, “BIOR“, LV-1076 Riga, Latvia
| | - Klaus Depner
- Friedrich-Loeffler-Institute, Greifswald-Insel Riems, 17493 Greifswald, Germany
| | - Erika Chenais
- Department of Disease Control and Epidemiology, National Veterinary Institute, S-751 89 Uppsala, Sweden
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