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Ruedas-Torres I, Thi to Nga B, Salguero FJ. Pathogenicity and virulence of African swine fever virus. Virulence 2024; 15:2375550. [PMID: 38973077 PMCID: PMC11232652 DOI: 10.1080/21505594.2024.2375550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 06/28/2024] [Indexed: 07/09/2024] Open
Abstract
African swine fever (ASF) is a devastating disease with a high impact on the pork industry worldwide. ASF virus (ASFV) is a very complex pathogen, the sole member of the family Asfaviridae, which induces a state of immune suppression in the host through infection of myeloid cells and apoptosis of lymphocytes. Moreover, haemorrhages are the other main pathogenic effect of ASFV infection in pigs, related to the infection of endothelial cells, as well as the activation and structural changes of this cell population by proinflammatory cytokine upregulation within bystander monocytes and macrophages. There are still many gaps in the knowledge of the role of proteins produced by the ASFV, which is related to the difficulty in producing a safe and effective vaccine to combat the disease, although few candidates have been approved for use in Southeast Asia in the past couple of years.
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Affiliation(s)
- Ines Ruedas-Torres
- Vaccine Development and Evaluation Centre (VDEC), United Kingdom Health Security Agency, Salisbury, UK
| | - Bui Thi to Nga
- Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi, Vietnam
| | - Francisco J. Salguero
- Vaccine Development and Evaluation Centre (VDEC), United Kingdom Health Security Agency, Salisbury, UK
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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Obanda V, Akinyi M, King'ori E, Nyakundi R, Ochola G, Oreng P, Mugambi K, Waiguchu GM, Chege M, Rosenbaum W, Ylitalo EB, Bäck AT, Pettersson L, Mukunzi OS, Agwanda B, Stenberg-Lewerin S, Lwande OW. Epidemiology and ecology of the sylvatic cycle of African Swine Fever Virus in Kenya. Virus Res 2024; 348:199434. [PMID: 39004284 PMCID: PMC11325071 DOI: 10.1016/j.virusres.2024.199434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 07/07/2024] [Accepted: 07/07/2024] [Indexed: 07/16/2024]
Abstract
African Swine Fever (ASF) is caused by a DNA virus (AFSV) maintained and transmitted by the Argasid ticks. The re-emergence of the disease in Africa coupled with its rapid spread globally is a threat to the pig industry, food security and livelihoods. The ecology and epidemiology of the ASFV sylvatic cycle, especially in the face of changing land use and land cover, further compounds the menace and impacts of this disease in Kenya. The study aimed to determine the occurrence and distribution of ASFV seroprevalence in warthog populations, the tick vectors and extent of tick infestation of warthog burrows, and the genotypes of ASFV in soft ticks in Kenya. Warthogs from different parts of Kenya were captured and venous blood was centrifuged to harvest sera. Warthog burrows were examined for their conditions and to extract ticks. Sera were analyzed for antibodies against ASFV using a commercial ELISA kit coated with p32 ASFV recombinant protein. Ticks were pooled, DNA extracted and the p72 gene of the ASFV was amplified by qPCR and conventional PCR. The overall seroprevalence of ASFV in warthogs was 87.5 %. A total of 228 warthog burrows were examined and 2154 argasid ticks were extracted from the burrows. Tick pools from Kigio Farm and Lewa Wildlife Conservancies were ASFV-positive by qPCR and conventional PCR. ASFV was further confirmed by the Twist Comprehensive Viral Research Panel (TCVRP), which also identified the argasid ticks as Ornithodoros porcinus. The ticks were infected with virus genotype IX, and their occurrence overlaps with regions of previous ASF outbreaks in domestic pigs. Further, Viruses that could be tick endosymbionts/commensals or due to bloodmeal were detected in ticks by TCVRP; Porcine type-C oncovirus; Pandoravirus neocaledonia; Choristoneura fumiferana granulovirus; Enterobacteria phage p7; Leporid herpesvirus 4 isolate; 5; Human Lymphotropic virus; Human herpesvirus 5. In conclusion, our results suggest that infected Ornithodoros spp. seems to have a rich virome, which has not been explored but could be exploited to inform ASF control in Kenya. Further, the ecology of Ornithodoros spp. and burrow-use dynamics are complex and more studies are needed to understand these dynamics, specifically in the spread of ASFV at the interface of wild and domestic pigs. Further, our results provide evidence of genotype IX ASFV sylvatic cycle which through O. porcinus tick transmission has resulted in high exposure of adult common warthogs. Finally, the co-circulation of ASFV genotype IX in the same location with past ASF outbreaks in domestic pigs and presently in ticks brings to focus the role of the interface and ticks on virus transmission to pigs and warthogs.
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Affiliation(s)
- Vincent Obanda
- Veterinary Science and Laboratories Department, Wildlife Research and Training Institute, P.O Box 842-20117, Naivasha, Kenya
| | - Mercy Akinyi
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - Edward King'ori
- Veterinary Services Department, Kenya Wildlife Service, P.O. Box 54582 00200, Nairobi, Kenya
| | - Ruth Nyakundi
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - Griphin Ochola
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - Purity Oreng
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - Kevin Mugambi
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - Grace Mwihaki Waiguchu
- Center for Savannah, Arid and Semi-Arid Ecosystems, Wildlife Research and Training Institute, Tsavo, P.O Box 842-20117, Naivasha, Kenya
| | - Mary Chege
- Institute of Primate Research, P.O. Box 24481 Karen 00502, Nairobi, Kenya
| | - William Rosenbaum
- Department of Medical Biosciences, Clinical Genomics, 901 87, Umeå University, Umeå, Sweden
| | | | | | - Lisa Pettersson
- Department of Clinical Microbiology, Umeå University, 901 85, Umeå, Sweden
| | - Opanda Silvanos Mukunzi
- Centre for Virus Research, Kenya Medical Research Training Institute, P.O. BOX 54628-00200, Nairobi, Kenya
| | - Bernard Agwanda
- Zoology Department, National Museums of Kenya, P.O. BOX 40658- 00100, Nairobi, Kenya
| | - Susanna Stenberg-Lewerin
- Department of Animal Biosciences, Swedish University of Agricultural Sciences, P.O Box 7023 75007, Uppsala, Sweden
| | - Olivia Wesula Lwande
- Department of Clinical Microbiology, Umeå University, 901 85, Umeå, Sweden; Umeå Centre for Microbiology Research, Umeå University, 901 87, Umeå, Sweden.
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Taraveau F, Bru D, Quembo CJ, Jourdan-Pineau H. Development of microsatellite markers for the soft tick Ornithodoros phacochoerus. Parasit Vectors 2024; 17:301. [PMID: 38992704 PMCID: PMC11238500 DOI: 10.1186/s13071-024-06382-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 06/28/2024] [Indexed: 07/13/2024] Open
Abstract
BACKGROUND Soft ticks of the genus Ornithodoros are responsible for the maintenance and transmission of the African swine fever (ASF) virus in the sylvatic and domestic viral cycles in Southern Africa. They are also the main vectors of the Borrelia species causing relapsing fevers. Currently, no genetic markers are available for Afrotropical Ornithodoros ticks. As ASF spreads globally, such markers are needed to assess the role of ticks in the emergence of new outbreaks. The aim of this study is to design microsatellite markers that could be used for ticks of the Ornithodoros moubata complex, particularly Ornithodoros phacochoerus, to assess population structure and tick movements in ASF endemic areas. METHODS A total of 151 markers were designed using the O. moubata and O. porcinus genomes after elimination of repeated sequences in the genomes. All designed markers were tested on O. phacochoerus and O. porcinus DNA to select the best markers. RESULTS A total of 24 microsatellite markers were genotyped on two populations of O. phacochoerus and on individuals from four other Ornithodoros species. Nineteen markers were selected to be as robust as possible for population genetic studies on O. phacochoerus. CONCLUSIONS The microsatellite markers developed here represent the first genetic tool to study nidicolous populations of O. phacochoerus.
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Affiliation(s)
- Florian Taraveau
- UMR ASTRE, CIRAD, INRAE, Campus de Baillarguet, 34398, Montpellier, France.
| | - David Bru
- UMR ASTRE, CIRAD, INRAE, Campus de Baillarguet, 34398, Montpellier, France
| | - Carlos João Quembo
- Central Region Office-Regional Veterinary Laboratory, Agricultural Research Institute of Mozambique, Chimoio, EN6.CP42, Mozambique
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Kayaga EB, Wampande EM, Ekakoro JE, Okwasiimire R, Nassali A, Ochoa K, Hauser C, Ndoboli D, Havas KA. Detection of antibodies against Ornithodoros moubata salivary antigens and their association with detection of African swine fever virus in pigs slaughtered in central Uganda. Front Vet Sci 2024; 11:1328040. [PMID: 38605921 PMCID: PMC11007201 DOI: 10.3389/fvets.2024.1328040] [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: 10/26/2023] [Accepted: 03/14/2024] [Indexed: 04/13/2024] Open
Abstract
Introduction African swine fever (ASF) is an important disease of pigs in sub-Saharan Africa and Uganda and is threatening the pig population and agricultural economy of other continents. ASF virus (ASFV) can be transmitted from wild suids to domestic pigs through soft ticks of the Ornithodoros species. The aim of this study was to understand the relationship between domestic pigs' O. moubata tick exposure and ASFV status. Methods Pigs were sampled from six abattoirs in the Kampala metropolitan area of Uganda from May 2021 through June 2022. Blood, serum, and tissue samples were collected. Serum was tested for antibodies against the rtTSGP1 salivary antigens of O. moubata ticks using an indirect ELISA assay. Blood and tissue samples from pigs were tested to detect ASFV using qPCR. Probability of tick exposure was categorized based on sample-to-positive ratio cut-off points. Results Out of 1,328 serum samples tested, there were 828 (62.3%) samples with a negligible probability; 369 (27.8%) with a medium probability; 90 (6.8%) with a high probability, and 41 (3.1%) with a very high probability of exposure to the O. moubata salivary antigen. There was a statistically significant association between the pigs' O. moubata exposure and ASFV status with a higher proportion of pigs having a very high probability of infection if they were ASFV positive by blood, tonsil, and lymph nodes. Discussion These results suggested that tick exposure was associated with ASFV transmission in Uganda. There were ASFV qPCR positive pigs that had no O. moubata exposure as well, which highlights that pig-to-pig and indirect contact transmission still play a significant role. This work highlights the need for further work in Uganda to investigate these transmission factors related to the O. moubata tick and ASFV transmission.
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Affiliation(s)
- Edrine B. Kayaga
- Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources, and Biosecurity, Makerere University, Kampala, Uganda
| | - Eddie M. Wampande
- Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources, and Biosecurity, Makerere University, Kampala, Uganda
| | - John E. Ekakoro
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Rodney Okwasiimire
- Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources, and Biosecurity, Makerere University, Kampala, Uganda
| | - Aisha Nassali
- Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources, and Biosecurity, Makerere University, Kampala, Uganda
| | - Krista Ochoa
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Cole Hauser
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Dickson Ndoboli
- Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources, and Biosecurity, Makerere University, Kampala, Uganda
| | - Karyn A. Havas
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
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Orosco FL. Host immune responses against African swine fever virus: Insights and challenges for vaccine development. Open Vet J 2023; 13:1517-1535. [PMID: 38292721 PMCID: PMC10824091 DOI: 10.5455/ovj.2023.v13.i12.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/22/2023] [Indexed: 02/01/2024] Open
Abstract
The African swine fever virus (ASFV) poses a serious threat to global swine populations, underscoring the urgent need for effective preventive strategies. This comprehensive review investigates the intricate interplay between innate, cellular, and humoral immunity against ASFV, with a focus on their relevance to vaccine development. By delving into immunopathogenesis and immunological challenges, this review article aims to provide a holistic perspective on the complexities of ASFV infections and immune evasion. Key findings underscore the critical role of innate immune recognition in shaping subsequent adaptive immune defenses, potential protective antigens, and the multifaceted nature of ASFV-specific antibodies and cytotoxic T-cell responses. Despite advancements, the unique attributes of ASFV present hurdles in the development of a successful vaccine. In conclusion, this review examines the current state of ASFV immune responses and offers insights into future research directions, fostering the development of effective interventions against this devastating pathogen.
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Affiliation(s)
- Fredmoore L. Orosco
- Virology and Vaccine Institute of the Philippines Program, Department of Science and Technology, Industrial Technology Development Institute, Taguig, Philippines
- S&T Fellows Program, Department of Science and Technology, Taguig, Philippines
- Department of Biology, College of Arts and Sciences, University of the Philippines Manila, Manila, Philippines
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Ogundijo OA, Omotosho OO, Al-Mustapha AI, Abiola JO, Awosanya EJ, Odukoya A, Owoicho S, Oyewo M, Ibrahim A, Orum TG, Nanven MB, Bolajoko MB, Luka P, Adeyemo OK. A multi-state survey of farm-level preparedness towards African swine fever outbreak in Nigeria. Acta Trop 2023; 246:106989. [PMID: 37507080 DOI: 10.1016/j.actatropica.2023.106989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 07/04/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023]
Abstract
Outbreaks of African Swine Fever (ASF) have severe economic implications for Nigeria and result in significant loss of livelihoods. The non-availability of vaccines makes biosecurity the reliable key to reducing ASF outbreaks. This study evaluated preparedness for ASF outbreaks at the farm level among 247 pig farmers randomly selected from Abia, Akwa-Ibom, Edo, Kwara, and Oyo states. We categorized each pig farmer's ASF preparedness rating (ASF - PR) as "poor", "moderate", and "satisfactory" based on their score on an 11-item scale. Finally, a multivariable logistic regression analysis was conducted to assess the association between the socio-demographic variables and farm-level ASF preparedness. The awareness of ASF among pig farmers was very high (87.9%, n = 217). Most farmers knew the clinical signs of the disease, the modes of transmission of ASF, and correctly identified the risk factors. They also considered the need for thorough cleaning and disinfection of piggeries (87.1%, n = 189), tightened biosecurity (85.7%, n = 186), culling all ASF-affected pigs (77.9%, n = 169) as well as the ban on the transport of pigs and their products (49.8%, n = 108) as very important in ASF control. Conversely, 27.6%, (n = 60) of the farmers thought ASF could affect humans, 12% (n = 27) of them openly discarded the carcasses of dead pigs, and there was a high antibiotic usage. Most of the pig farmers used antibiotics as prophylaxis (63.6%, n = 157), chemotherapeutics (66.4%, n = 164), growth promoters (15.4%, n = 38), and wrongly so, 13% (n = 32) of them thought that antibiotics could be used to prevent and treat ASF. At the farm level, two-thirds (68.8%, n = 170) of the farmers had strict movement restrictions, and 48.6% (n = 120) routinely quarantine new pigs before introduction into their herd. Across the five states, 36% (n = 89) of the farmers had witnessed sudden death with signs consistent with ASF amongst their pigs and only 10.1% (n = 27) had confirmatory ASF diagnosis. The mean score for the farm-level ASF-PR was 6.95 ± 2.7. Approximately one-quarter of the 247 pig farmers had satisfactory ASF - PR that might help to prevent the incursion of ASF into their farms. Most farmers had moderate ASF - PR (59.5%, n = 147) whereas 17% (n = 42) had very poor ASF-PR and were most prone to an ASF outbreak. Of the sociodemographic variables, only age was significantly associated with farm-level ASF preparedness as older pig farmers especially those aged between 50 and 59 years (OR: 4.83; 95% CI: 1.10, 21.22; p = 0.037) were more likely to have satisfactory ASF - PR than the others. Our findings showed pig farmers were not adequately prepared and the next ASF outbreak could pose more significant threat to pig populations across Nigeria. Government should urgently establish minimum biosecurity measures and improve its ASF surveillance mechanisms for commercial and backyard pig production.
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Affiliation(s)
- Oluwaseun A Ogundijo
- Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria
| | - Oladipo O Omotosho
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria
| | - Ahmad I Al-Mustapha
- Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria; Department of Veterinary Services, Kwara State Ministry of Agriculture and Rural Development, Ilorin, Kwara State, Nigeria; Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Finland.
| | - John O Abiola
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria
| | - Emmanuel J Awosanya
- Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria
| | - Adesoji Odukoya
- Federal Ministry of Agriculture and Rural Development, Abuja, Nigeria; Nigerian Field Epidemiology and Laboratory Training program, Abuja, Nigeria
| | - Samuel Owoicho
- Federal Ministry of Agriculture and Rural Development, Abuja, Nigeria; Nigerian Field Epidemiology and Laboratory Training program, Abuja, Nigeria
| | - Muftau Oyewo
- Department of Veterinary Services, Kwara State Ministry of Agriculture and Rural Development, Ilorin, Kwara State, Nigeria; Nigerian Field Epidemiology and Laboratory Training program, Abuja, Nigeria
| | - Ahmed Ibrahim
- Department of Veterinary Services, Kwara State Ministry of Agriculture and Rural Development, Ilorin, Kwara State, Nigeria
| | - Terese G Orum
- Regional Disease Surveillance Systems Enhancement Project, Abuja, Nigeria
| | - Magdalene B Nanven
- Nigerian Field Epidemiology and Laboratory Training program, Abuja, Nigeria
| | | | - Pam Luka
- National Veterinary Research Institute, Vom, Plateau State, Nigeria
| | - Olanike K Adeyemo
- Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Ibadan, Oyo State, Nigeria
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