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Yamashita M, Iwamoto S, Ochiai M, Yamamoto A, Sudo K, Narushima R, Nagasaka T, Saito A, Oba M, Omatsu T, Mizutani T, Yamamoto K. Pathogenicity of genotype 2.1 classical swine fever virus isolated from Japan in 2019 in pigs. Microbiol Immunol 2024; 68:267-280. [PMID: 38946035 DOI: 10.1111/1348-0421.13160] [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: 12/25/2023] [Revised: 05/13/2024] [Accepted: 06/09/2024] [Indexed: 07/02/2024]
Abstract
Classical swine fever (CSF) re-emerged in Japan in 2018 for the first time in 26 years. The disease has been known to be caused by a moderately pathogenic virus, rather than the highly pathogenic virus that had occurred in the past. However, the underlying pathophysiology remains unknown. This study conducted an experimental challenge on specific pathogen-free (SPF) pigs in a naïve state for 2, 4, and 6 weeks and confirmed the disease state during each period by clinical observation, virus detection, and pathological necropsy. We revealed the pathological changes and distribution of pathogens and virus-specific antibodies at each period after virus challenge. These results were comprehensively analyzed and approximately 70% of the pigs recovered, especially at 4- and 6-week post-virus challenge. This study provides useful information for future countermeasures against CSF by clarifying the pathogenicity outcomes in unvaccinated pigs with moderately pathogenic genotype 2.1 virus.
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Affiliation(s)
- Maiko Yamashita
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
- Center for Infectious Disease Epidemiology and Prevention Research, Tokyo University of Agriculture and Technology (Cooperative Division of Veterinary Sciences), Tokyo, Japan
| | - Shoko Iwamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Mariko Ochiai
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Atsushi Yamamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Kasumi Sudo
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
- Livestock Industry Bureau, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Rie Narushima
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Takao Nagasaka
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
| | - Akito Saito
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
- Exotic Diseases Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Tokyo, Japan
| | - Mami Oba
- Center for Infectious Disease Epidemiology and Prevention Research, Tokyo University of Agriculture and Technology (Cooperative Division of Veterinary Sciences), Tokyo, Japan
| | - Tsutomu Omatsu
- Center for Infectious Disease Epidemiology and Prevention Research, Tokyo University of Agriculture and Technology (Cooperative Division of Veterinary Sciences), Tokyo, Japan
| | - Tetsuya Mizutani
- Center for Infectious Disease Epidemiology and Prevention Research, Tokyo University of Agriculture and Technology (Cooperative Division of Veterinary Sciences), Tokyo, Japan
| | - Kinya Yamamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, Tokyo, Japan
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2
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Fukai K, Nishi T, Masujin K, Yamada M, Ikezawa M. Quantitative analysis of viremia and viral shedding in pigs infected experimentally with classical swine fever virus isolates obtained from recent outbreaks in Japan. Vet Res 2023; 54:81. [PMID: 37759265 PMCID: PMC10523739 DOI: 10.1186/s13567-023-01215-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/04/2023] [Indexed: 09/29/2023] Open
Abstract
Although classical swine fever occurred in September 2018 for the first time in 26 years, its virulence is thought to be moderate based on field observations by veterinary authorities and our previous experimental infections. We quantified viremia and viral shedding in pigs infected with recent Japanese classical swine fever virus isolates, as well as a highly virulent strain. The results show that pigs infected with the Japanese strains exhibited lower viremia and viral shedding than those infected with the highly virulent strain. However, horizontal transmission occurred in pigs infected with the Japanese strains, similar to those infected with the highly virulent strain. Additionally, viremia and neuralization antibodies coexisted in pigs infected with the Japanese strains, presenting challenges for control measures.
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Affiliation(s)
- Katsuhiko Fukai
- WOAH Reference Laboratory for Classical Swine Fever, Kodaira Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-Honcho, Kodaira, Tokyo, 187-0022, Japan.
| | - Tatsuya Nishi
- WOAH Reference Laboratory for Classical Swine Fever, Kodaira Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-Honcho, Kodaira, Tokyo, 187-0022, Japan
| | - Kentaro Masujin
- WOAH Reference Laboratory for Classical Swine Fever, Kodaira Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-Honcho, Kodaira, Tokyo, 187-0022, Japan
| | - Manabu Yamada
- National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan
| | - Mitsutaka Ikezawa
- National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan
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3
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Pathological Characteristics of Domestic Pigs Orally Infected with the Virus Strain Causing the First Reported African Swine Fever Outbreaks in Vietnam. Pathogens 2023; 12:pathogens12030393. [PMID: 36986314 PMCID: PMC10058432 DOI: 10.3390/pathogens12030393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/14/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023] Open
Abstract
African swine fever (ASF) is currently Vietnam’s most economically significant swine disease. The first ASF outbreak in Vietnam was reported in February 2019. In this study, VNUA/HY/ASF1 strain isolated from the first ASF outbreak was used to infect 10 eight-week-old pigs orally with 103 HAD50 per animal. The pigs were observed daily for clinical signs, and whole blood samples were collected from each animal for viremia detection. Dead pigs were subjected to full post-mortem analyses. All 10 pigs displayed acute or subacute clinical signs and succumbed to the infection between 10 to 27 (19.8 ± 4.66) days post-inoculation (dpi). The onset of clinical signs started around 4–14 dpi. Viremia was observed in pigs from 6–16 dpi (11.2 ± 3.55). Enlarged, hyperemic, and hemorrhagic lymph nodes, enlarged spleen, pneumonia, and hydropericardium were observed at post-mortem examinations.
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Development of an Effective Oral Vaccine Dissemination Strategy against Classical Swine Fever for Wild Boar in Gifu Prefecture, Japan. Transbound Emerg Dis 2023. [DOI: 10.1155/2023/9484441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
In September 2018, classical swine fever (CSF) reemerged in Japan after more than a quarter of a century. After the first notification on a pig farm, wild boars positive for CSF were found continuously in the surrounding area. Gifu was the first prefecture in Japan to disseminate oral vaccines to wild boars in March 2019, with vaccines spread to approximately 14,000 sites between 2019 and 2020. While these diligent measures seemed to have shown some effectiveness, several vaccine spray sites remained without wild boar emergence. Based on the vaccine dissemination records from these periods, this study conducted a statistical analysis to propose more effective vaccine dissemination sites. First, a generalized linear mixed model was used to identify factors correlated with wild boar emergence. Then, two spatial interpolation methods, inverse distance weighted (IDW) and Kriging, were adopted to create a probability map of wild boar emergence for the entire Gifu Prefecture. The analysis showed a positive correlation between wild boar emergence and the appearance of raccoons, raccoon dogs, and crows as well as road density and wild boar distribution index. In particular, raccoon (OR: 1.83, 95%CI: 1.25–2.68,
< 0.001), raccoon dog (OR: 1.81, 95%CI: 1.25–2.66,
< 0.001), and medium level road density (OR: 1.56, 95%CI: 1.04–2.39,
= 0.04) were strongly correlated with wild boar emergence. The spatial interpolation approach resulted in better prediction accuracy for the Kriging method than for IDW by the root mean square error, but both approaches identified a high wild boar appearance probability area in southeastern Gifu and a low appearance probability area in central Gifu. Here we have demonstrated a tool to effectively disperse oral vaccine to wildlife.
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Measuring impact of vaccination among wildlife: The case of bait vaccine campaigns for classical swine fever epidemic among wild boar in Japan. PLoS Comput Biol 2022; 18:e1010510. [PMID: 36201410 PMCID: PMC9536577 DOI: 10.1371/journal.pcbi.1010510] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 08/23/2022] [Indexed: 11/07/2022] Open
Abstract
Understanding the impact of vaccination in a host population is essential to control infectious diseases. However, the impact of bait vaccination against wildlife diseases is difficult to evaluate. The vaccination history of host animals is generally not observable in wildlife, and it is difficult to distinguish immunity by vaccination from that caused by disease infection. For these reasons, the impact of bait vaccination against classical swine fever (CSF) in wild boar inhabiting Japan has not been evaluated accurately. In this study, we aimed to estimate the impact of the bait vaccination campaign by modelling the dynamics of CSF and the vaccination process among a Japanese wild boar population. The model was designed to estimate the impact of bait vaccination despite lack of data regarding the demography and movement of wild boar. Using our model, we solved the theoretical relationship between the impact of vaccination, the time-series change in the proportion of infected wild boar, and that of immunised wild boar. Using this derived relationship, the increase in antibody prevalence against CSF because of vaccine campaigns in 2019 was estimated to be 12.1 percentage points (95% confidence interval: 7.8–16.5). Referring to previous reports on the basic reproduction number (R0) of CSF in wild boar living outside Japan, the amount of vaccine distribution required for CSF elimination by reducing the effective reproduction number under unity was also estimated. An approximate 1.6 (when R0 = 1.5, target vaccination coverage is 33.3% of total population) to 2.9 (when R0 = 2.5, target vaccination coverage is 60.0% of total population) times larger amount of vaccine distribution would be required than the total amount of vaccine distribution in four vaccination campaigns in 2019. Vaccination of wildlife is important to control infectious diseases in animals. However, the impact of common vaccination of wildlife, bait vaccination, is difficult to evaluate owing to difficulty in obtaining the vaccination history at the individual level. Mathematical modelling can estimate the impact of vaccination; however, the demography and movement of hosts are required to describe disease dynamics. In this study, we aimed to estimate the impact of bait vaccination by modelling the dynamics of classical swine fever (CSF) and the vaccination among Japanese wild boar. The model was designed to estimate the impact of bait vaccination despite lack of data regarding the demography and movement of wild boar. Using our model, the increase in antibody prevalence because of vaccination in 2019 was estimated to be 12 percentage points. Furthermore, we estimated the amount of vaccine distribution required for CSF elimination by reducing the effective reproduction number under unity. Referring to previous reports on the basic reproduction number of CSF in wild boar living outside Japan, it was estimated that an approximate 1.6 to 2.9 times larger amount of vaccine distribution would be required than the total amount of vaccine distribution in four vaccination campaigns in 2019.
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6
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Haplotype of Wild Korean Boars Infected by Classical Swine Fever Virus Subgenotype 2.1d. Animals (Basel) 2022; 12:ani12192670. [PMID: 36230411 PMCID: PMC9559489 DOI: 10.3390/ani12192670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/29/2022] [Accepted: 10/01/2022] [Indexed: 11/05/2022] Open
Abstract
Simple Summary Classical swine fever is a highly contagious disease that infects both domestic pigs and wild boars. Classical swine fever virus (CSFV) has not been detected in domestic pigs in South Korea since 2016, but has been increasing in wild boars since 2017. Two cases of CSFV subgenotype 2.1d were detected in wild Korean boars in 2011, but then no cases were detected until 2016; however, 16 cases of CSFV were detected between 2017 and 2019. In this study, we report seven CSFV-positive samples obtained from wild boars in 2020. In addition, although 13 mtDNA haplotypes were detected in wild boars in South Korea, all 25 cases of CSFV that occurred in wild boars between 2011 and 2020 were detected in animals with haplotype 01. Abstract Classical swine fever virus (CSFV) is one of the major pathogens that causes severe economic damage to the swine industry. Circulation of CSFV in wild boars carries the potential risk of reintroducing the virus into CSFV-free pig farms. This study carried out a genetic analysis of CSFV isolates from wild boars and analyzed the mtDNA haplotypes of the wild boars. Blood samples (n = 2140) from wild Korean boars captured in 2020 were subjected to qRT-PCR to detect CSFV, which was classified as subgenotype 2.1d based on phylogenetic analysis. CSFV had been detected in wild boars only in northern regions (Gangwon and Gyeonggi) of South Korea between 2011 and 2019. However, CSFV was identified in wild boars in the more southern regions (Chungbuk and Gyeongbuk) in 2020. Based on mitochondrial DNA analysis, all wild boars with CSFV were haplotype 01 (H01). Thus, we presume that the H01 haplotype is more susceptible to CSFV. In the future, infection of wild boars by CSFV is expected to occur intermittently every year, and we predict that most wild boars infected with CSFV will be haplotype H01.
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Establishment of a Direct PCR Assay for Simultaneous Differential Diagnosis of African Swine Fever and Classical Swine Fever Using Crude Tissue Samples. Viruses 2022; 14:v14030498. [PMID: 35336904 PMCID: PMC8948687 DOI: 10.3390/v14030498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/17/2022] [Accepted: 02/25/2022] [Indexed: 12/04/2022] Open
Abstract
African swine fever (ASF) and classical swine fever (CSF) are contagious swine diseases that are clinically indistinguishable from each other; hence, reliable test methods for accurate diagnosis and differentiation are highly demanded. By employing a buffer system suitable for crude extraction of nucleic acids together with an impurity-tolerant enzyme, we established a multiplex assay of real-time reverse-transcription polymerase chain reaction (rRT-PCR) for simultaneous detection of ASF virus (ASFV), CSF virus (CSFV) and swine internal control derived genes in a sample without the need for prior purification of viral nucleic acids. We applied this method to test serum and tissue samples of infected pigs and wild boars and compared the statistical sensitivities and specificities with those of standard molecular diagnostic methods. When a serum was used as a test material, the newly established assay showed 94.4% sensitivity for both and 97.9 and 91.9% specificity for ASFV and CSFV detection, respectively. In contrast, the results were 100% identical with those obtained by the standard methods when a crude tissue homogenate was used as a test material. The present data indicate that this new assay offers a practical, quick, and reliable technique for differential diagnosis of ASF and CSF where geographical occurrences are increasingly overlapping.
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8
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Matsuyama R, Yamamoto T, Hayama Y, Omori R. Estimation of the Lethality Rate, Recovery Rate, and Case Fatality Ratio of Classical Swine Fever in Japanese Wild Boar: An Analysis of the Epidemics From September 2018 to March 2019. Front Vet Sci 2021; 8:772995. [PMID: 34977211 PMCID: PMC8714742 DOI: 10.3389/fvets.2021.772995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
Understanding the morbidity and lethality of diseases is necessary to evaluate the effectiveness of countermeasure against the epidemics (e.g., vaccination). To estimate them, detailed data on host population dynamics are required; however, estimating the population size for wildlife is often difficult. We aimed to elucidate the morbidity and lethality of classical swine fever (CSF) currently highly prevalent in the wild boar population in Japan. To this end, we estimated lethality rate, recovery rate, and case fatality ratio (CFR) of CSF without detailed data on the population estimates of wild boar. A mathematical model was constructed to describe the CSF dynamics and population dynamics of wild boar. We fitted the model to the (i) results of the reverse transcription polymerase chain reaction (RT-PCR) test for the CSFV gene and the (ii) results of the enzyme-linked immunosorbent assay (ELISA) test for the antibody against CSFV in sampled wild boar. In the 280 wild boar sampled from September 2018 to March 2019 in the major CSF-affected area in Japan, the lethality rate and recovery rate of CSF per week were estimated as 0.165 (95% confidence interval: 0.081–0.250) and 0.004 (0–0.009), respectively. While the estimate of lethality rate of CSF was similar with the estimates in previous studies, the recovery rate was lower than those reported previously. CFR was estimated as 0.959 (0.904–0.981) using our estimate of recovery rate. This study is the first to estimate lethality rate of CSF from the dynamics of CSF epidemics in the wild boar population. Since the value of CFR is sensitive to the value of recovery rate, the accuracy in the estimate of recovery rate is a key for the accurate estimation of CFR. A long-term transmission experiment of moderately virulent strains may lead to more accurate estimation of the recovery rate and CFR of CSF.
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Affiliation(s)
- Ryota Matsuyama
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takehisa Yamamoto
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Yoko Hayama
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Ryosuke Omori
- International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
- *Correspondence: Ryosuke Omori
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9
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Oki M, Ikezawa M, Nishi T, Fukai K, Yamada M. Immunohistochemical analysis of the distribution of classical swine fever (CSF) viral antigen in boar-pig hybrids and pigs four weeks after infection. J Vet Med Sci 2021; 84:48-52. [PMID: 34789589 PMCID: PMC8810325 DOI: 10.1292/jvms.21-0226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We detected the classical swine fever virus (CSFV) antigen in three boar-pig hybrids (hybrids) and three pigs. All animals were experimentally infected with CSFV strain JPN/27/2019 to optimize diagnostic sampling and risk assessment of virus dissemination. Two hybrids died 17- and 19-days post-inoculation (dpi). The other animals were euthanized at 28 dpi. The detection of CSFV antigen at 28 dpi in epithelial cells of the apocrine sweat and sebaceous glands in the skin, salivary glands, mucosal epithelial cells in the rectum, and epithelial cells in the kidney and urinary bladder, suggests that CSFV persists in these tissues and spreads via sweat, saliva, feces, and urine for at least 4 weeks. These findings reveal that hybrids and pigs represent a high risk of virus dissemination four weeks after infection with CSFV strain JPN/27/2019. Prominent CSFV antigens were also detected in hair follicles of the skin. These results suggest that postmortem sampling of animal skin may be effective for CSF diagnosis and can be used to develop a rapid and easy diagnostic method using hair follicles.
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Affiliation(s)
| | - Mitsutaka Ikezawa
- National Institute of Animal Health, National Agriculture and Food Research Organization
| | - Tatsuya Nishi
- National Institute of Animal Health, National Agriculture and Food Research Organization
| | - Katsuhiko Fukai
- National Institute of Animal Health, National Agriculture and Food Research Organization
| | - Manabu Yamada
- National Institute of Animal Health, National Agriculture and Food Research Organization
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Characteristics of Classical Swine Fever Virus Variants Derived from Live Attenuated GPE - Vaccine Seed. Viruses 2021; 13:v13081672. [PMID: 34452536 PMCID: PMC8402697 DOI: 10.3390/v13081672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 11/17/2022] Open
Abstract
The GPE- strain is a live attenuated vaccine for classical swine fever (CSF) developed in Japan. In the context of increasing attention for the differentiating infected from vaccinated animals (DIVA) concept, the achievement of CSF eradication with the GPE- proposes it as a preferable backbone for a recombinant CSF marker vaccine. While its infectious cDNA clone, vGPE-, is well characterized, 10 amino acid substitutions were recognized in the genome, compared to the original GPE- vaccine seed. To clarify the GPE- seed availability, this study aimed to generate and characterize a clone possessing the identical amino acid sequence to the GPE- seed. The attempt resulted in the loss of the infectious GPE- seed clone production due to the impaired replication by an amino acid substitution in the viral polymerase NS5B. Accordingly, replication-competent GPE- seed variant clones were produced. Although they were mostly restricted to propagate in the tonsils of pigs, similarly to vGPE-, their type I interferon-inducing capacity was significantly lower than that of vGPE-. Taken together, vGPE- mainly retains ideal properties for the CSF vaccine, compared with the seed variants, and is probably useful in the development of a CSF marker vaccine.
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11
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Liu ZH, Xu HL, Han GW, Tao LN, Lu Y, Zheng SY, Fang WH, He F. Self-Assembling Nanovaccine Enhances Protective Efficacy Against CSFV in Pigs. Front Immunol 2021; 12:689187. [PMID: 34367147 PMCID: PMC8334734 DOI: 10.3389/fimmu.2021.689187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/01/2021] [Indexed: 01/01/2023] Open
Abstract
Classical swine fever virus (CSFV) is a highly contagious pathogen, which pose continuous threat to the swine industry. Though most attenuated vaccines are effective, they fail to serologically distinguish between infected and vaccinated animals, hindering CSFV eradication. Beneficially, nanoparticles (NPs)-based vaccines resemble natural viruses in size and antigen structure, and offer an alternative tool to circumvent these limitations. Using self-assembling NPs as multimerization platforms provides a safe and immunogenic tool against infectious diseases. This study presented a novel strategy to display CSFV E2 glycoprotein on the surface of genetically engineered self-assembling NPs. Eukaryotic E2-fused protein (SP-E2-mi3) could self-assemble into uniform NPs as indicated in transmission electron microscope (TEM) and dynamic light scattering (DLS). SP-E2-mi3 NPs showed high stability at room temperature. This NP-based immunization resulted in enhanced antigen uptake and up-regulated production of immunostimulatory cytokines in antigen presenting cells (APCs). Moreover, the protective efficacy of SP-E2-mi3 NPs was evaluated in pigs. SP-E2-mi3 NPs significantly improved both humoral and cellular immunity, especially as indicated by the elevated CSFV-specific IFN-γ cellular immunity and >10-fold neutralizing antibodies as compared to monomeric E2. These observations were consistent to in vivo protection against CSFV lethal virus challenge in prime-boost immunization schedule. Further results revealed single dose of 10 μg of SP-E2-mi3 NPs provided considerable clinical protection against lethal virus challenge. In conclusion, these findings demonstrated that this NP-based technology has potential to enhance the potency of subunit vaccine, paving ways for nanovaccine development.
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Affiliation(s)
- Ze-Hui Liu
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Hui-Ling Xu
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Guang-Wei Han
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Li-Na Tao
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Ying Lu
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Su-Ya Zheng
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Wei-Huan Fang
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China.,Department of Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
| | - Fang He
- Institute of Preventive Veterinary Sciences & College of Animal Sciences, Zhejiang University, Hangzhou, China.,Department of Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China
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12
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Clemmons EA, Alfson KJ, Dutton JW. Transboundary Animal Diseases, an Overview of 17 Diseases with Potential for Global Spread and Serious Consequences. Animals (Basel) 2021; 11:2039. [PMID: 34359167 PMCID: PMC8300273 DOI: 10.3390/ani11072039] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 12/21/2022] Open
Abstract
Animals provide food and other critical resources to most of the global population. As such, diseases of animals can cause dire consequences, especially disease with high rates of morbidity or mortality. Transboundary animal diseases (TADs) are highly contagious or transmissible, epidemic diseases, with the potential to spread rapidly across the globe and the potential to cause substantial socioeconomic and public health consequences. Transboundary animal diseases can threaten the global food supply, reduce the availability of non-food animal products, or cause the loss of human productivity or life. Further, TADs result in socioeconomic consequences from costs of control or preventative measures, and from trade restrictions. A greater understanding of the transmission, spread, and pathogenesis of these diseases is required. Further work is also needed to improve the efficacy and cost of both diagnostics and vaccines. This review aims to give a broad overview of 17 TADs, providing researchers and veterinarians with a current, succinct resource of salient details regarding these significant diseases. For each disease, we provide a synopsis of the disease and its status, species and geographic areas affected, a summary of in vitro or in vivo research models, and when available, information regarding prevention or treatment.
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Affiliation(s)
- Elizabeth A. Clemmons
- Southwest National Primate Research Center, Texas Biomedical Research Institute, 8715 W. Military Drive, San Antonio, TX 78227, USA;
| | - Kendra J. Alfson
- Texas Biomedical Research Institute, 8715 W. Military Drive, San Antonio, TX 78227, USA
| | - John W. Dutton
- Southwest National Primate Research Center, Texas Biomedical Research Institute, 8715 W. Military Drive, San Antonio, TX 78227, USA;
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13
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Nishi T, Fukai K, Kato T, Sawai K, Yamamoto T. Genome variability of classical swine fever virus during the 2018-2020 epidemic in Japan. Vet Microbiol 2021; 258:109128. [PMID: 34058522 DOI: 10.1016/j.vetmic.2021.109128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/20/2021] [Indexed: 11/18/2022]
Abstract
Although RNA viruses exhibit extensive sequence diversity, the mutation rate must be limited to ensure protein functions that maintain the viral life cycle. Here, we compared the whole genome sequences of 150 isolates of classical swine fever virus (CSFV), obtained from a single epidemic that occurred in Japan during 2018-2020. After the detection of the first case, the disease spread among both farm pigs and wild boars and caused severe impact on the pig industry. To evaluate the diversification of the CSFV genome that eliminated mutations negatively affecting viral transmission, the substitution sets inherited by at least two isolates were separately evaluated as shared single nucleotide variants (SNVs) or shared single amino acid variants (SAVs). Comparisons of 12 protein-coding regions indicated that the percentages of SNVs and SAVs in the multifunctional nonstructural protein NS3 were the lowest, and shared SAVs were not detected in another nonstructural protein, NS4A. This demonstrated purifying negative selection suppressing changes in the protein sequences of NS3 and NS4A during virus transmission in the field. In contrast, a high possibility of nonsynonymous substitution among shared SNVs was detected only in genes encoding the secreted protein Erns and the nonstructural protein NS2, suggesting positive selection during the epidemic. Mapping of shared SAVs to the three-dimensional structure of Erns revealed that shared SAVs were not present in the substrate-binding sites but were instead localized to the peripheral region of the protein. These data will support efforts toward the development of diagnostic methods, recombinant vaccines, and antiviral agents targeting conserved and indispensable viral genes.
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Affiliation(s)
- Tatsuya Nishi
- Exotic Disease Research Unit, Division of Transboundary Animal Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Tokyo, Japan
| | - Katsuhiko Fukai
- Exotic Disease Research Unit, Division of Transboundary Animal Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Tokyo, Japan
| | - Tomoko Kato
- Exotic Disease Research Unit, Division of Transboundary Animal Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Kodaira, Tokyo, Japan
| | - Kotaro Sawai
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan
| | - Takehisa Yamamoto
- Epidemiology Research Unit, Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan.
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14
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Epidemiological analysis of classical swine fever in wild boars in Japan. BMC Vet Res 2021; 17:188. [PMID: 33975588 PMCID: PMC8111369 DOI: 10.1186/s12917-021-02891-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/28/2021] [Indexed: 12/03/2022] Open
Abstract
Background Classical swine fever (CSF) is a contagious disease of pigs and wild boars that is transmitted through direct/indirect contact between animals or CSF virus-contaminated fomites. When the disease re-emerged in 2018 in Japan, a CSF-infected wild boar was reported shortly after the initial pig farm outbreak; subsequently, the disease spread widely. To control the disease spread among wild boars, intensive capturing, fencing, and oral bait vaccination were implemented with concomitant virological and serological surveillance. This study aimed to describe the disease spread in the wild boar population in Japan from September 2018, when the first case was reported, to March 2020, based on the surveillance data. We conducted statistical analyses using a generalized linear mixed model to identify factors associated with CSF infection among wild boars. Moreover, we descriptively assessed the effect of oral bait vaccination, which started in March 2019 in some municipalities in the affected areas. Results We observed a faster CSF infection spread in the wild boar population in Japan compared with the CSF epidemics in European countries. The infection probability was significantly higher in dead and adult animals. The influence of the multiple rounds of oral bait vaccination was not elucidated by the statistical modeling analyses. There was a decrease and increase in the proportion of infected and immune animals, respectively; however, the immunization in piglets remained insufficient after vaccination for 1 year. Conclusions Conditions regarding the wild boar habitat, including forest continuity, higher wild boar population density, and a larger proportion of susceptible piglets, were addressed to increase the infection risk in the wild boar population. These findings could improve the national control strategy against the CSF epidemic among wild boars. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-021-02891-0.
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15
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Sudo K, Yamada M, Ochiai M, Iwamoto S, Sakaki H, Kushida C, Yamashita M, Yamamoto A, Nagasaka T, Oidemizu M, Saito A, Yamamoto K. The formation process of button ulcers in pigs experimentally infected with a subgenotype 2.1 isolate of classical swine fever virus. J Vet Med Sci 2021; 83:990-993. [PMID: 33867396 PMCID: PMC8267204 DOI: 10.1292/jvms.20-0654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated the role of classical swine fever virus (CSFV) in the formation of button ulcers in the mucosa of the gastrointestinal tract. Histopathological and immunohistochemical analyses of pigs experimentally infected with a subgenotype 2.1 isolate of CSFV, which was isolated in Japan in 2019, revealed follicular necrosis in the submucosal mucosa-associated lymphoid tissue and herniation of crypts as factors that contribute to the development of button ulcers during CSFV infection. These findings indicate that CSFV induces follicular necrosis and is one of the causative agents of button ulcers in pigs.
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Affiliation(s)
- Kasumi Sudo
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan.,Present address: Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00153 Rome, Italy
| | - Manabu Yamada
- National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannodai, Tsukuba, Ibaraki 305-0856, Japan
| | - Mariko Ochiai
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Shoko Iwamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Hajime Sakaki
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Chiho Kushida
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Maiko Yamashita
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Atsushi Yamamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Takao Nagasaka
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Mikio Oidemizu
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Akito Saito
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
| | - Kinya Yamamoto
- National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
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16
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Fan J, Liao Y, Zhang M, Liu C, Li Z, Li Y, Li X, Wu K, Yi L, Ding H, Zhao M, Fan S, Chen J. Anti-Classical Swine Fever Virus Strategies. Microorganisms 2021; 9:microorganisms9040761. [PMID: 33917361 PMCID: PMC8067343 DOI: 10.3390/microorganisms9040761] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/24/2021] [Accepted: 04/02/2021] [Indexed: 12/23/2022] Open
Abstract
Classical swine fever (CSF), caused by CSF virus (CSFV), is a highly contagious swine disease with high morbidity and mortality, which has caused significant economic losses to the pig industry worldwide. Biosecurity measures and vaccination are the main methods for prevention and control of CSF since no specific drug is available for the effective treatment of CSF. Although a series of biosecurity and vaccination strategies have been developed to curb the outbreak events, it is still difficult to eliminate CSF in CSF-endemic and re-emerging areas. Thus, in addition to implementing enhanced biosecurity measures and exploring more effective CSF vaccines, other strategies are also needed for effectively controlling CSF. Currently, more and more research about anti-CSFV strategies was carried out by scientists, because of the great prospects and value of anti-CSFV strategies in the prevention and control of CSF. Additionally, studies on anti-CSFV strategies could be used as a reference for other viruses in the Flaviviridae family, such as hepatitis C virus, dengue virus, and Zika virus. In this review, we aim to summarize the research on anti-CSFV strategies. In detail, host proteins affecting CSFV replication, drug candidates with anti-CSFV effects, and RNA interference (RNAi) targeting CSFV viral genes were mentioned and the possible mechanisms related to anti-CSFV effects were also summarized.
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Affiliation(s)
- Jindai Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Yingxin Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Mengru Zhang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Chenchen Liu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Zhaoyao Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Yuwan Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Xiaowen Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Keke Wu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Lin Yi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Hongxing Ding
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Mingqiu Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
| | - Shuangqi Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Correspondence: (S.F.); (J.C.); Tel.: +86-20-8528-8017 (J.C.)
| | - Jinding Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; (J.F.); (Y.L.); (M.Z.); (C.L.); (Z.L.); (Y.L.); (X.L.); (K.W.); (L.Y.); (H.D.); (M.Z.)
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou 510642, China
- Correspondence: (S.F.); (J.C.); Tel.: +86-20-8528-8017 (J.C.)
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Bazarragchaa E, Isoda N, Kim T, Tetsuo M, Ito S, Matsuno K, Sakoda Y. Efficacy of Oral Vaccine against Classical Swine Fever in Wild Boar and Estimation of the Disease Dynamics in the Quantitative Approach. Viruses 2021; 13:v13020319. [PMID: 33672749 PMCID: PMC7924559 DOI: 10.3390/v13020319] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/09/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022] Open
Abstract
Classical swine fever virus (CSFV) in the wild boar population has been spreading in Japan, alongside outbreaks on pigs, since classical swine fever (CSF) reemerged in September 2018. The vaccination using oral bait vaccine was initially implemented in Gifu prefecture in March 2019. In the present study, antibodies against CSFV in wild boar were assessed in 1443 captured and dead wild boars in Gifu prefecture. After the implementation of oral vaccination, the increase of the proportion of seropositive animals and their titer in wild boars were confirmed. Quantitative analysis of antigen and antibodies against CSFV in wild boar implies potential disease diversity in the wild boar population. Animals with status in high virus replication (Ct < 30) and non- or low-immune response were confirmed and were sustained at a certain level after initial oral vaccination. Through continuous vaccination periods, the increase of seroprevalence among wild boar and the decrease of CSFV-positive animals were observed. The epidemiological analysis based on the quantitative virological outcomes could provide more information on the efficacy of oral vaccination and dynamics of CSF in the wild boar population, which will help to improve the implementation of control measures for CSF in countries such as Japan and neighboring countries.
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Affiliation(s)
- Enkhbold Bazarragchaa
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Hokkaido, Japan; (E.B.); (T.K.); (M.T.)
| | - Norikazu Isoda
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Hokkaido, Japan; (E.B.); (T.K.); (M.T.)
- Unit of Risk Analysis and Management, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Hokkaido, Japan; (S.I.); (K.M.)
- Correspondence: (N.I.); (Y.S.); Tel.: +81-11-706-5208 (N.I.); +81-11-706-5207 (Y.S.)
| | - Taksoo Kim
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Hokkaido, Japan; (E.B.); (T.K.); (M.T.)
| | - Madoka Tetsuo
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Hokkaido, Japan; (E.B.); (T.K.); (M.T.)
| | - Satoshi Ito
- Unit of Risk Analysis and Management, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Hokkaido, Japan; (S.I.); (K.M.)
| | - Keita Matsuno
- Unit of Risk Analysis and Management, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Hokkaido, Japan; (S.I.); (K.M.)
- International Collaboration Unit, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Hokkaido, Japan
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Hokkaido, Japan; (E.B.); (T.K.); (M.T.)
- International Collaboration Unit, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Hokkaido, Japan
- Correspondence: (N.I.); (Y.S.); Tel.: +81-11-706-5208 (N.I.); +81-11-706-5207 (Y.S.)
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18
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Murato Y, Hayama Y, Shimizu Y, Sawai K, Yamamoto T. Evaluation of sampling methods for effective detection of infected pig farms during a disease outbreak. PLoS One 2020; 15:e0241177. [PMID: 33091063 PMCID: PMC7580991 DOI: 10.1371/journal.pone.0241177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/12/2020] [Indexed: 11/19/2022] Open
Abstract
Emergency surveillance following an outbreak of transboundary animal diseases such as classical swine fever (CSF), is conducted to find another new infection as early as possible. Although larger sample sizes can help achieve higher disease surveillance sensitivity, the sample size is limited by the availability of resources in an emergency situation. Moreover, the recent CSF outbreak reported in Japan was associated with fewer clinical signs; this emphasizes the importance of detecting infected farms by surveillance. In this study, we aimed to identify effective and labor-efficient sampling methods showing high probabilities of detecting infection, by simulating infection and sampling in pigsties. We found that impartial sampling, which involves selection of pigs to be sampled from the four corners and the center of the pigsty, and random sampling showed comparable probabilities of detection. Impartial sampling involves sample collection without pig identification and random selection. Owing to its simplicity, impartial sampling is labor-efficient and thus a possible substitute for random sampling. In a group-housing pigsty, testing five pigs from five pens showed a higher detection probability than testing five pigs from one pen. These results suggest preferable surveillance methods for conducting emergency surveillance of infectious diseases.
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Affiliation(s)
- Yoshinori Murato
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Yoko Hayama
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Yumiko Shimizu
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Kotaro Sawai
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Takehisa Yamamoto
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
- * E-mail:
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19
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Shimizu Y, Hayama Y, Murato Y, Sawai K, Yamaguchi E, Yamamoto T. Epidemiology of Classical Swine Fever in Japan-A Descriptive Analysis of the Outbreaks in 2018-2019. Front Vet Sci 2020; 7:573480. [PMID: 33195567 PMCID: PMC7536261 DOI: 10.3389/fvets.2020.573480] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/18/2020] [Indexed: 11/13/2022] Open
Abstract
This study describes the epidemiological characteristics of classical swine fever (CSF) outbreaks in Japan. The first case was confirmed in September 2018, 26 years after the last known case. Outbreaks occurred on 39 farms, 34 commercial farms, and 5 non-commercial farms, between September 2018 and August 2019. In this study, a descriptive analysis was conducted of the epidemiological data on the characteristics of the affected farms, clinical manifestations, intra-farm transmission, association with infected wild boars, and control measures implemented on the farms. Twenty-eight of the 34 affected commercial farms were farrow-to-finish farms. It was assumed that the major risk factors were frequent human-pig interactions and the movement of pigs between farms. Fever and leukopenia were commonly observed in infected pigs. In 12 out of 18 farms where clinical manifestations among fattening pigs was the reason for notification, death was the most frequent clinical manifestation, but the proportion of dead animals did not exceed 0.5% of the total number of animals at most of the affected farms. Therefore, the clinical form of CSF in Japan was considered to be sub-acute. Twenty-three of the 29 farms (79%) with pigs at multiple stages (i.e., piglets, fattening pigs, and sows), had infection across the multiple stages. Many of these farms were within 5 km of the site where the first infected wild boars had been discovered, suggesting that infected wild boars were the source of infection. Infections still occurred at farms that had implemented measures at their farm boundaries to prevent the introduction of the virus into their farms, such as disinfection of vehicles and people, changing boots of the workers, and installation of perimeter fences. It is necessary to continue to strengthen biosecurity measures for farms located in areas with infected wild boars and to continue monitoring the distribution of infected wild boars so that any abnormalities can be reported and inspected at an early stage.
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Affiliation(s)
- Yumiko Shimizu
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Yoko Hayama
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Yoshinori Murato
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Kotaro Sawai
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Emi Yamaguchi
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Takehisa Yamamoto
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
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20
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Fukai K, Nishi T, Yamada M, Ikezawa M. Toward better control of classical swine fever in wild boars: susceptibility of boar-pig hybrids to a recent Japanese isolate and effectiveness of a bait vaccine. Vet Res 2020; 51:96. [PMID: 32736657 PMCID: PMC7393845 DOI: 10.1186/s13567-020-00821-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/16/2020] [Indexed: 11/22/2022] Open
Abstract
We analyzed the pathogenicity of a recent Japanese classical swine fever virus (CSFV) to wild boars via an experimental infection using boar-pig hybrids as an alternative to wild boars. We also investigated the effectiveness of a bait vaccine against the CSFV. Naïve boar-pig hybrids and pigs showed clinical signs such as fever, leucopenia, anorexia and conjunctivitis following the experimental infection. In contrast, the boar-pig hybrids administered the bait vaccine did not show any clinical signs. Our data indicated that boar-pig hybrids and domestic pigs have similar susceptibility to the recent Japanese CSFV. Additionally, the bait vaccine is effective against the CSFV.
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Affiliation(s)
- Katsuhiko Fukai
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo, 187-0022, Japan.
| | - Tatsuya Nishi
- Exotic Disease Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1 Josui-honcho, Kodaira, Tokyo, 187-0022, Japan
| | - Manabu Yamada
- National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan
| | - Mitsutaka Ikezawa
- National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan
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Ikeda T, Asano M, Kuninaga N, Suzuki M. Monitoring relative abundance index and age ratios of wild boar (Sus scrofa) in small scale population in Gifu prefecture, Japan during classical swine fever outbreak. J Vet Med Sci 2020; 82:861-865. [PMID: 32435014 PMCID: PMC7324824 DOI: 10.1292/jvms.20-0083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the first cases of classical swine fever were reported in 2018, no studies have
explored this impact on wild boar populations in Japan. Comparing the relative abundance
indices and age ratios in the wild boar population before and after the outbreak, we
investigated the impact of classical swine fever virus on wild boar population dynamics in
August 2017–December 2019. Relative abundance indices declined from 2017 to 2019
drastically, while there were no significant differences in age ratios throughout the
study period. Consequently, wildlife managers should consider that wild boars continue to
contract classical swine fever virus, and they should intensively implement
countermeasures in agricultural lands and in pig farms, in addition to wild boar
population management.
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Affiliation(s)
- Takashi Ikeda
- Research Center for Wildlife Management, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan
| | - Makoto Asano
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan
| | - Naotoshi Kuninaga
- Research Center for Wildlife Management, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan
| | - Masatsugu Suzuki
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan
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Risk Assessment of African Swine Fever Virus Exposure to Sus scrofa in Japan Via Pork Products Brought in Air Passengers' Luggage. Pathogens 2020; 9:pathogens9040302. [PMID: 32326040 PMCID: PMC7238144 DOI: 10.3390/pathogens9040302] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/18/2020] [Accepted: 04/18/2020] [Indexed: 02/01/2023] Open
Abstract
In recent years, African swine fever (ASF) has become prevalent in many areas, including Asia. The repeated detection of the ASF virus (ASFV) genome in pork products brought in air passenger’s luggage (PPAP) was also reported from Japanese airports. In the present study, the risk of ASFV exposure to susceptible hosts in Japan via three different pathways was assessed. Two quantitative stochastic risk assessment models were built to estimate the annual probability of ASFV exposure to domestic pigs, which could be attributed to foreign job trainees or foreign tourists. A semi-quantitative stochastic model was built to assess the risk of ASFV exposure to wild boar caused by foreign tourists. The overall mean annual probability of ASFV exposure to domestic pigs via PPAP carried by foreign job trainees was 0.169 [95% confidence interval (CI): 0.000–0.600], whereas that by foreign tourists was 0.050 [95% CI: 0.000–0.214], corresponding to approximately one introduction every 5.9 and 20 years, respectively. The risk of ASFV exposure to domestic pigs was dispersed over the country, whereas that of wild boar was generally higher in the western part of Japan, indicating that the characteristics of the potential ASF risk in each prefecture were varied.
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Bohórquez JA, Muñoz-González S, Pérez-Simó M, Muñoz I, Rosell R, Coronado L, Domingo M, Ganges L. Foetal Immune Response Activation and High Replication Rate during Generation of Classical Swine Fever Congenital Infection. Pathogens 2020; 9:pathogens9040285. [PMID: 32295279 PMCID: PMC7238013 DOI: 10.3390/pathogens9040285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/09/2020] [Accepted: 04/14/2020] [Indexed: 12/16/2022] Open
Abstract
Classical swine fever virus (CSFV) induces trans-placental transmission and congenital viral persistence; however, the available information is not updated. Three groups of sows were infected at mid-gestation with either a high, moderate or low virulence CSFV strains. Foetuses from sows infected with high or low virulence strain were obtained before delivery and piglets from sows infected with the moderate virulence strain were studied for 32 days after birth. The low virulence strain generated lower CSFV RNA load and the lowest proportion of trans-placental transmission. Severe lesions and mummifications were observed in foetuses infected with the high virulence strain. Sows infected with the moderately virulence strain showed stillbirths and mummifications, one of them delivered live piglets, all CSFV persistently infected. Efficient trans-placental transmission was detected in sows infected with the high and moderate virulence strain. The trans-placental transmission occurred before the onset of antibody response, which started at 14 days after infection in these sows and was influenced by replication efficacy of the infecting strain. Fast and solid immunity after sow vaccination is required for prevention of congenital viral persistence. An increase in the CD8+ T-cell subset and IFN-alpha response was found in viremic foetuses, or in those that showed higher viral replication in tissue, showing the CSFV recognition capacity by the foetal immune system after trans-placental infection.
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Affiliation(s)
- José Alejandro Bohórquez
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
| | - Sara Muñoz-González
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
| | - Marta Pérez-Simó
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
| | - Iván Muñoz
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
| | - Rosa Rosell
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
- Departament d’Agricultura, Ramadería, Pesca, Alimentació I Medi Natural i Rural (DAAM), 08007 Generalitat de Catalunya, Spain
| | - Liani Coronado
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
- Centro Nacional de Sanidad Agropecuaria (CENSA), Mayabeque 32700, Cuba
| | - Mariano Domingo
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
- Servei de Diagnòstic de Patologia Veterinària (SDPV), Departament de Sanitat I d’Anatomia Animals, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Llilianne Ganges
- OIE Reference Laboratory for Classical Swine Fever, IRTA-CReSA, 08193 Barcelona, Spain; (J.A.B.); (S.M.-G.); (M.P.-S.); (I.M.); (R.R.); (L.C.); (M.D.)
- Correspondence:
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Choe S, Cha RM, Yu DS, Kim KS, Song S, Choi SH, Jung BI, Lim SI, Hyun BH, Park BK, An DJ. Rapid Spread of Classical Swine Fever Virus among South Korean Wild Boars in Areas near the Border with North Korea. Pathogens 2020; 9:E244. [PMID: 32218239 PMCID: PMC7238106 DOI: 10.3390/pathogens9040244] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/24/2020] [Accepted: 03/24/2020] [Indexed: 11/16/2022] Open
Abstract
There has been a rapid increase in the number of classical swine fever (CSF) sero-positive wild boars captured near the demilitarized zone (DMZ), located the border with North Korea. In 2015-2016, few CSFV-positive antibody boars were detected; however, the number has increased steeply since 2017. Most occurred in the northern region of Gyeonggi before spreading slowly to Gangwon (west to east) in 2018-2019. Multi-distance spatial cluster analysis provided an indirect estimate of the time taken for CSFV to spread among wild boars: 46.7, 2.6, and 2.49 days/km. The average CSF serum neutralization antibody titer was 4-10 (log 2), and CSFV Ab B-ELISA PI values ranged from 65.5 to 111.5, regardless of the age and sex of wild boars. Full genome analysis revealed that 16 CSFV strains isolated from wild boars between 2017 and 2019 were identical to the YC16CS strain (sub-genotype 2.1d) isolated from an outbreak in breeding pigs near the border with North Korea in 2016. The rapid increase in CSF in wild boars may be due to a continuously circulating infection within hub area and increased population density. The distribution pattern of CSFV in Korean wild boars moves from west to southeast, affected by external factors, including small-scale hunting, geographical features and highways.
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Affiliation(s)
- SeEun Choe
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Ra Mi Cha
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Dae-Sung Yu
- Division of Veterinary Epidemiological, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea;
| | - Ki-Sun Kim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Sok Song
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Sung-Hyun Choi
- Korea Pork Producers Association, Seocho-gu, Seoul 06643, Korea; (S.-H.C.); (B.-I.J.)
| | - Byung-Il Jung
- Korea Pork Producers Association, Seocho-gu, Seoul 06643, Korea; (S.-H.C.); (B.-I.J.)
| | - Seong-In Lim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Bang-Hun Hyun
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
| | - Bong-Kyun Park
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
- College of Veterinary Medicine, Seoul University, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
| | - Dong-Jun An
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do 39660, Korea; (S.C.); (R.M.C.); (K.-S.K.); (S.S.); (S.-I.L.); (B.-H.H.); (B.-K.P.)
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Tetsuo M, Matsuno K, Tamura T, Fukuhara T, Kim T, Okamatsu M, Tautz N, Matsuura Y, Sakoda Y. Development of a High-Throughput Serum Neutralization Test Using Recombinant Pestiviruses Possessing a Small Reporter Tag. Pathogens 2020; 9:E188. [PMID: 32143534 PMCID: PMC7157198 DOI: 10.3390/pathogens9030188] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 11/16/2022] Open
Abstract
A serum neutralization test (SNT) is an essential method for the serological diagnosis of pestivirus infections, including classical swine fever, because of the cross reactivity of antibodies against pestiviruses and the non-quantitative properties of antibodies in an enzyme-linked immunosorbent assay. In conventional SNTs, an immunoperoxidase assay or observation of cytopathic effect after incubation for 3 to 7 days is needed to determine the SNT titer, which requires labor-intensive or time-consuming procedures. Therefore, a new SNT, based on the luciferase system and using classical swine fever virus, bovine viral diarrhea virus, and border disease virus possessing the 11-amino-acid subunit derived from NanoLuc luciferase was developed and evaluated; this approach enabled the rapid and easy determination of the SNT titer using a luminometer. In the new method, SNT titers can be determined tentatively at 2 days post-infection (dpi) and are comparable to those obtained by conventional SNTs at 3 or 4 dpi. In conclusion, the luciferase-based SNT can replace conventional SNTs as a high-throughput antibody test for pestivirus infections.
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Affiliation(s)
- Madoka Tetsuo
- Laboratory of Microbiology, Division of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; (M.T.); (K.M.); (T.K.); (M.O.)
| | - Keita Matsuno
- Laboratory of Microbiology, Division of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; (M.T.); (K.M.); (T.K.); (M.O.)
- Global Station for Zoonosis Control, Global Institute for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan
| | - Tomokazu Tamura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (T.T.); (T.F.); (Y.M.)
- Department of Molecular Biology, Princeton University, Washington Road, Princeton, NJ 08540, USA
| | - Takasuke Fukuhara
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (T.T.); (T.F.); (Y.M.)
| | - Taksoo Kim
- Laboratory of Microbiology, Division of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; (M.T.); (K.M.); (T.K.); (M.O.)
| | - Masatoshi Okamatsu
- Laboratory of Microbiology, Division of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; (M.T.); (K.M.); (T.K.); (M.O.)
| | - Norbert Tautz
- Institute of Virology and Cell Biology, University of Lübeck, D-23562 Lübeck, Germany;
| | - Yoshiharu Matsuura
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; (T.T.); (T.F.); (Y.M.)
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Division of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan; (M.T.); (K.M.); (T.K.); (M.O.)
- Global Station for Zoonosis Control, Global Institute for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan
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Isoda N, Baba K, Ito S, Ito M, Sakoda Y, Makita K. Dynamics of Classical Swine Fever Spread in Wild Boar in 2018-2019, Japan. Pathogens 2020; 9:pathogens9020119. [PMID: 32069897 PMCID: PMC7169391 DOI: 10.3390/pathogens9020119] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 11/16/2022] Open
Abstract
The prolongation of the classic swine fever (CSF) outbreak in Japan in 2018 was highly associated with the persistence and widespread of the CSF virus (CSFV) in the wild boar population. To investigate the dynamics of the CSF outbreak in wild boar, spatiotemporal analyses were performed. The positive rate of CSFV in wild boar fluctuated dramatically from March to June 2019, but finally stabilized at approximately 10%. The Euclidean distance from the initial CSF notified farm to the farthest infected wild boar of the day constantly increased over time since the initial outbreak except in the cases reported from Gunma and Saitama prefectures. The two-month-period prevalence, estimated using integrated nested Laplace approximation, reached >80% in half of the infected areas in March–April 2019. The area affected continued to expand despite the period prevalence decreasing up to October 2019. A large difference in the shapes of standard deviational ellipses and in the location of their centroids when including or excluding cases in Gunma and Saitama prefectures indicates that infections there were unlikely to have been caused simply by wild boar activities, and anthropogenic factors were likely involved. The emergence of concurrent space–time clusters in these areas after July 2019 indicated that CSF outbreaks were scattered by this point in time. The results of this epidemiological analysis help explain the dynamics of the spread of CSF and will aid in the implementation of control measures, including bait vaccination.
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Affiliation(s)
- Norikazu Isoda
- Unit of Risk Analysis and Management, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Japan; (N.I.); (S.I.)
- Global Station for Zoonosis Control, Global Institute for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan;
| | - Kairi Baba
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, 582, Bunkyodai Midorimachi, Ebetsu 069-8501, Japan;
| | - Satoshi Ito
- Unit of Risk Analysis and Management, Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-Ku, Sapporo 001-0020, Japan; (N.I.); (S.I.)
| | - Mitsugi Ito
- Akabane Animal Clinic, Co. Ltd., 55 Ishizoe, Akabane-Cho, Tahara 441-3502, Japan;
| | - Yoshihiro Sakoda
- Global Station for Zoonosis Control, Global Institute for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan;
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-Ku, Sapporo 060-0818, Japan
| | - Kohei Makita
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, 582, Bunkyodai Midorimachi, Ebetsu 069-8501, Japan;
- Correspondence: ; Tel.: +81-11-388-4761
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Hayama Y, Shimizu Y, Murato Y, Sawai K, Yamamoto T. Estimation of infection risk on pig farms in infected wild boar areas-Epidemiological analysis for the reemergence of classical swine fever in Japan in 2018. Prev Vet Med 2019; 175:104873. [PMID: 31896501 DOI: 10.1016/j.prevetmed.2019.104873] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 12/09/2019] [Accepted: 12/17/2019] [Indexed: 11/30/2022]
Abstract
In September 2018, classical swine fever (CSF) reemerged in Japan after 26 years' absence. The first case was detected at a pig farm in Gifu Prefecture, in the center of Japan, and the disease spread to both domestic pigs and wild boar (Sus scrofa). The spread of CSF in wild boar is extremely difficult to control and is thus a great threat to domestic pig farms, and understanding the transmission risk from wild boar to domestic pigs is essential to implement effective control measures that will prevent domestic pig infection. Therefore, this study elucidates the transmission risk from wild boar to domestic pigs by introducing a transmission kernel that is dependent on the distance between infected wild boar and pig farms, and then estimating the risk area of infection from wild boar by describing the transmission probability. The study used epidemiological data from Gifu Prefecture in the period from September 2018 to March 2019, including a total of 171 1-km grid cells where an infected wild boar was detected and pig farm data from 13 infected and 34 uninfected farms. The estimated infection risk area within 28 days matched well with the observed data. The risk area widened gradually during the epidemic, and at the end of March, the risk area extended over a range of approximately 75 km from east to west and 40 km from north to south (almost 3000 km2). Ten out of the 13 infected farms and four out of the 34 uninfected farms were located within the high-risk area (>60 % infection probability). In contrast, one infected farm and 18 uninfected farms were located within the low-risk area (<5 % infection probability). When several infected grid cells were detected within 5 km of a pig farm, the risk of infection from wild boar within 28 days was more than 5 %. This analysis provides an estimate of the potential spatial range over which CSF virus can spread between wild boar and domestic pig farms, and can be used to inform the early detection of CSF-suspected pigs and the strengthening of biosecurity measures that will effectively prevent and control the disease based on the infection risk level.
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Affiliation(s)
- Yoko Hayama
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan.
| | - Yumiko Shimizu
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan
| | - Yoshinori Murato
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan
| | - Kotaro Sawai
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan
| | - Takehisa Yamamoto
- Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan
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Ito S, Jurado C, Bosch J, Ito M, Sánchez-Vizcaíno JM, Isoda N, Sakoda Y. Role of Wild Boar in the Spread of Classical Swine Fever in Japan. Pathogens 2019; 8:pathogens8040206. [PMID: 31653072 PMCID: PMC6963481 DOI: 10.3390/pathogens8040206] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 11/21/2022] Open
Abstract
Since September 2018, nearly 900 notifications of classical swine fever (CSF) have been reported in Gifu Prefecture (Japan) affecting domestic pig and wild boar by the end of August 2019. To determine the epidemiological characteristics of its spread, a spatio-temporal analysis was performed using actual field data on the current epidemic. The spatial study, based on standard deviational ellipses of official CSF notifications, showed that the disease likely spread to the northeast part of the prefecture. A maximum significant spatial association estimated between CSF notifications was 23 km by the multi-distance spatial cluster analysis. A space-time permutation analysis identified two significant clusters with an approximate radius of 12 and 20 km and 124 and 98 days of duration, respectively. When the area of the identified clusters was overlaid on a map of habitat quality, approximately 82% and 75% of CSF notifications, respectively, were found in areas with potential contact between pigs and wild boar. The obtained results provide information on the current CSF epidemic, which is mainly driven by wild boar cases with sporadic outbreaks on domestic pig farms. These findings will help implement control measures in Gifu Prefecture.
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Affiliation(s)
- Satoshi Ito
- Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Hokkaido, 001-0020, Japan.
- VISAVET Center and Animal Health Department, University Complutense of Madrid, 28040 Madrid, Spain.
| | - Cristina Jurado
- VISAVET Center and Animal Health Department, University Complutense of Madrid, 28040 Madrid, Spain.
| | - Jaime Bosch
- VISAVET Center and Animal Health Department, University Complutense of Madrid, 28040 Madrid, Spain.
| | - Mitsugi Ito
- Akabane Animal Clinic, Co. Ltd., 55 Ishizoe, Akabane-cho, Tahara, Aichi-ken, 441-3502, Japan.
| | | | - Norikazu Isoda
- Research Center for Zoonosis Control, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Hokkaido, 001-0020, Japan.
- Global Station for Zoonosis Control, Global Institute for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo 001-0020, Japan.
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-0018, Japan.
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