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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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Choe S, Park GN, Kim KS, Shin J, Lim SI, An BH, Hyun BH, An DJ. Efficacy of an orally administered classical swine fever live marker vaccine (Flc-LOM-BE rns strain) in pigs. Vaccine 2023; 41:7377-7386. [PMID: 37973511 DOI: 10.1016/j.vaccine.2023.10.071] [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: 06/14/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/19/2023]
Abstract
In several countries, classical swine fever (CSF) has not been detected in domestic pigs, but has been detected in wild boars, making the disease difficult to control. To overcome this problem, we inoculated pigs with a CSF live marker vaccine (Flc-LOM-BErns strain), which has "distinguish infection from vaccinated animals (DIVA)" function, to determine whether it is suitable as an oral vaccine specifically for wild boars. Pigs inoculated intramuscularly or orally with the Flc-LOM-BErns vaccine were challenged 2 or 4 weeks later, respectively, with virulent CSFV. Pigs administered the oral Flc-LOM-BErns strain (105.0 and 6.0 TCID50/dose), and those vaccinated intramuscularly (103.0 TCID50/dose), had normal numbers of leukocytes and normal body temperature. Also, they generated protective neutralizing antibodies and anti-BVDV Erns antibodies. In addition, all pigs in these groups survived, with no CSFV RNA detected in feces, spleen, or other organs. Thus, the Flc-LOM-BErns vaccine shows excellent safety and efficacy, while having DIVA function and suitability for oral inoculation.
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Affiliation(s)
- SeEun Choe
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Gyu-Nam Park
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Ki-Sun Kim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Jihye Shin
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Seong-In Lim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Byung-Hyun An
- Department of Virology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Bang-Hun Hyun
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
| | - Dong-Jun An
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk-do 39660, Republic of Korea.
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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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Coronado L, Perera CL, Rios L, Frías MT, Pérez LJ. A Critical Review about Different Vaccines against Classical Swine Fever Virus and Their Repercussions in Endemic Regions. Vaccines (Basel) 2021; 9:154. [PMID: 33671909 PMCID: PMC7918945 DOI: 10.3390/vaccines9020154] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/31/2021] [Accepted: 02/09/2021] [Indexed: 12/24/2022] Open
Abstract
Classical swine fever (CSF) is, without any doubt, one of the most devasting viral infectious diseases affecting the members of Suidae family, which causes a severe impact on the global economy. The reemergence of CSF virus (CSFV) in several countries in America, Asia, and sporadic outbreaks in Europe, sheds light about the serious concern that a potential global reemergence of this disease represents. The negative aspects related with the application of mass stamping out policies, including elevated costs and ethical issues, point out vaccination as the main control measure against future outbreaks. Hence, it is imperative for the scientific community to continue with the active investigations for more effective vaccines against CSFV. The current review pursues to gather all the available information about the vaccines in use or under developing stages against CSFV. From the perspective concerning the evolutionary viral process, this review also discusses the current problematic in CSF-endemic countries.
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Affiliation(s)
- Liani Coronado
- National Centre for Animal and Plant Health (CENSA), OIE Collaborating Centre for Disaster Risk Reduction in Animal Health, San José de las Lajas 32700, Cuba; (L.C.); (C.L.P.); (M.T.F.)
| | - Carmen L. Perera
- National Centre for Animal and Plant Health (CENSA), OIE Collaborating Centre for Disaster Risk Reduction in Animal Health, San José de las Lajas 32700, Cuba; (L.C.); (C.L.P.); (M.T.F.)
| | - Liliam Rios
- Reiman Cancer Research Laboratory, Faculty of Medicine, University of New Brunswick, Saint John, NB E2L 4L5, Canada;
| | - María T. Frías
- National Centre for Animal and Plant Health (CENSA), OIE Collaborating Centre for Disaster Risk Reduction in Animal Health, San José de las Lajas 32700, Cuba; (L.C.); (C.L.P.); (M.T.F.)
| | - Lester J. Pérez
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois at Urbana–Champaign, Champaign, IL 61802, USA
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Choe S, Le VP, Shin J, Kim JH, Kim KS, Song S, Cha RM, Park GN, Nguyen TL, Hyun BH, Park BK, An DJ. Pathogenicity and Genetic Characterization of Vietnamese Classical Swine Fever Virus: 2014-2018. Pathogens 2020; 9:pathogens9030169. [PMID: 32121079 PMCID: PMC7157220 DOI: 10.3390/pathogens9030169] [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: 01/31/2020] [Revised: 02/26/2020] [Accepted: 02/26/2020] [Indexed: 11/20/2022] Open
Abstract
Here, we examined the pathogenicity and genetic differences between classical swine fever viruses (CSFV) isolated on pig farms in North Vietnam from 2014–2018. Twenty CSFV strains from 16 pig farms were classified as genotype 2 (sub-genotypes 2.1b, 2.1c, and 2.2). The main sub-genotype, 2.1c, was classified phylogenetically as belonging to the same cluster as viruses isolated from the Guangdong region in South China. Strain HY58 (sub-genotype 2.1c), isolated from pigs in Vietnam, caused higher mortality (60%) than the Vietnamese ND20 strain (sub-genotype 2.2). The Vietnamese strain of sub-genotype 2.1b was estimated to have moderate virulence; indeed, genetic analysis revealed that it belongs to the same cluster as Korean CSFV sub-genotype 2.1b. Most CSFVs circulating in North Vietnam belong to sub-genotype 2.1c. Geographical proximity means that this genotype might continue to circulate in both North Vietnam and Southern China (Guangdong, Guangxi, and Hunan).
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Affiliation(s)
- SeEun Choe
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Van Phan Le
- College of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi 100000, Vietnam; (V.P.L.); (T.L.N.)
| | - Jihye Shin
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Jae-Hoon Kim
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea;
| | - Ki-Sun Kim
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Sok Song
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Ra Mi Cha
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Gyu-Nam Park
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Thi Lan Nguyen
- College of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi 100000, Vietnam; (V.P.L.); (T.L.N.)
| | - Bang-Hun Hyun
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
| | - Bong-Kyun Park
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
- College of Veterinary Medicine, Seoul University, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea
| | - Dong-Jun An
- Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongbuk 39660, Korea; (S.C.); (J.S.); (K.-S.K.); (S.S.); (R.M.C.); (G.-N.P.); (B.-H.H.); (B.-K.P.)
- Correspondence: ; Tel.: +82-54-912-0795
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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: 33] [Impact Index Per Article: 6.6] [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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Gong W, Li J, Wang Z, Sun J, Mi S, Lu Z, Cao J, Dou Z, Sun Y, Wang P, Yuan K, Zhang L, Zhou X, He S, Tu C. Virulence evaluation of classical swine fever virus subgenotype 2.1 and 2.2 isolates circulating in China. Vet Microbiol 2019; 232:114-120. [PMID: 31030834 DOI: 10.1016/j.vetmic.2019.04.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/31/2019] [Accepted: 04/02/2019] [Indexed: 01/01/2023]
Abstract
Classical swine fever (CSF) remains an important pig disease in China, where it usually presents with mild or atypical clinical manifestations, with large scale outbreaks rarely seen. This has led to speculation about the possible circulation of viral strains of low virulence. To investigate this possibility, five field isolates within the predominant genotype 2 (2.1b, 2.1c, 2.1 h and 2.2) were evaluated and compared by experimental infection of naturally farrowed but colostrum-deprived piglets. All infected piglets displayed clinical signs, including persistent high fever, depression, anorexia, dyspnea, conjunctivitis, constipation, and hesitant gait. Typical pathological lesions, including pulmonary edema, hemorrhagic or cellulosic exudation, and swelling and hemorrhage of lymph nodes, were observed. Viremia and Erns protein expression in the blood of all infected animals were detectable from 3 to 5 days post infection (DPI), their presence correlating with the onset of fever, clinical signs and leukopenia. E2 antibody did not develop in any of the field CSFV-infected piglets during the disease course, while Erns antibody was detectable in 4-56% of infected animals at various time points. Mortalities ranged from 20 to 80% within 21 DPI, progressing to 100% by 43 DPI. Based on clinical scores and fatalities within 21 DPI, 2 of the 5 field isolates were classified as of moderate virulence and 3 of high virulence; i.e., no field isolates of low virulence were identified. The study has provided data supporting the use of these isolates as challenge viruses to evaluate the efficacy of current CSF vaccines.
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Affiliation(s)
- Wenjie Gong
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, PR China
| | - Junhui Li
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Zunbao Wang
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Jiumeng Sun
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, PR China
| | - Shijiang Mi
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, PR China
| | - Zongji Lu
- College of Life Sciences and Engineering, Foshan University, Foshan, PR China
| | - Jian Cao
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Zhihua Dou
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Yanjun Sun
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Pengjiang Wang
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Ke Yuan
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Liying Zhang
- College of Animal Sciences, Jilin University, Changchun, PR China
| | - Xubin Zhou
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China
| | - Sun He
- Tecon Biology Joint Stock Company Limited, Urumqi, PR China.
| | - Changchun Tu
- Institute of Military Veterinary Medicine, Academy of Military Medical Sciences, Changchun, PR China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, PR China.
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An DJ, Lim SI, Choe S, Kim KS, Cha RM, Cho IS, Song JY, Hyun BH, Park BK. Evolutionary dynamics of classical swine fever virus in South Korea: 1987-2017. Vet Microbiol 2018; 225:79-88. [PMID: 30322538 DOI: 10.1016/j.vetmic.2018.09.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 01/29/2023]
Abstract
The 5' UTR (n=102) and full-length E2 (n=37) genes of classical swine fever viruses (CSFVs) circulating in South Korea over the past 30 years (1987-2017) were examined to determine the evolutionary rate and estimated time of the most recent common ancestor (tMRCA). From 2000, the Korean classical swine fever (CSF) antigen changed from genotype 3 to 2, which comprises subgenotypes 2.1b (2002-2013) and 2.1d (2011-2017). There are genotypic variations in the full-length E2 gene of Korean CSFV genotypes 2.1b and 2.1d (seven separate amino acid substitutions); these are useful distinguishing markers. The mean substitution rate (×103 substitutions/site/year) for Korean CSFV was estimated to be 2.2088 (95% highest posterior density (HPD): lower, 1.7045; upper, 2.7574) and the mean tMRCA was estimated to be 1901 (95% HPD: lower, 1865; upper, 1933). The effective population size of Korean CSFV genotype 2 increased rapidly from 2002 to 2003, after which it remained constant. The occurrence of CSF in Korea is expected to decline in the future; however, it will likely be more prevalent in wild boar than in domestic pigs. Thus, there is a risk of transmission from wild boar to breeding pigs.
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Affiliation(s)
- Dong-Jun An
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Seong-In Lim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - SeEun Choe
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Ki-Sun Kim
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Ra Mi Cha
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - In-Soo Cho
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Jae-Young Song
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Bang-Hun Hyun
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea
| | - Bong-Kyun Park
- Virus Disease Division, Animal and Plant Quarantine Agency, Gimchen, Gyeongbuk-do, 39660, South Korea; Department of Veterinary Medicine Virology Laboratory, College of Veterinary Medicine, Seoul University, Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
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