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Taffarel AI, Barrios Benito MY, Hung VV, Cardillo S, Phuong NT, Caldevilla C, Galdo Novo S. Foot-and-mouth disease virus strains isolated in Vietnam during 2010-2019: genetic characterization and antigenic relatedness to the Euro SA vaccine. Arch Virol 2024; 169:44. [PMID: 38341400 DOI: 10.1007/s00705-024-05960-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 12/01/2023] [Indexed: 02/12/2024]
Abstract
Foot-and-mouth disease is a highly contagious disease that affects cloven-hoofed animals. It has an important socio-economic impact on the livestock industry because it produces a drastic decrease of productivity. The disease has been successfully eradicated from some regions, including North America and Western Europe, but it is still endemic in developing countries. Agriculture plays an important role in the national economy of Vietnam, to which animal production contributes a great proportion. The concurrent circulation of foot-and-mouth disease virus (FMDV) serotypes O, A, and Asia 1 has been detected in recent years, but serotype O remains the most prevalent and is responsible for the highest numbers of outbreaks. Appropriate vaccine strain selection is an important element in the control of FMD and is necessary for the application of vaccination programs in FMD-affected regions. Here, we present updated information about the genetic and antigenic characteristics of circulating strains, collected from endemic outbreaks involving types O and A, between 2010 and 2019. Neutralizing assays showed a good in vitro match between type O strains and the monovalent O1 Campos vaccine strain. High r1 values were obtained (above 0.7) when testing a swine serum pool collected 21 days after vaccination, but the O/VTN/2/2019 strain was an exception. An EPP estimation resulted in a median neutralizing titre of about 1.65 log10, indicating that good protection could be achieved. For type A Asia SEA 97 lineage strains, acceptable individual neutralizing titres were obtained with estimated EPP values over 80% for different combinations of vaccine strains. Taking into account that the r1 value is one tool of a battery of tests that should be considered for estimating the cross-protection of a field strain against a vaccine strain, an in vivo challenge experiment was also performed, yielding a PD50 value of 8.0. The results indicate that South American strains could be potentially used for controlling outbreaks involving these lineages. This study demonstrates the importance of considering strain characteristics when choosing vaccine strains and controls.
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Affiliation(s)
- Ana I Taffarel
- Laboratorio de Referencia OMSA Para Fiebre Aftosa, Dirección de Laboratorio Animal, SENASA, CP1640, Martínez Buenos Aires, Argentina
| | - Melanie Y Barrios Benito
- Laboratorio de Referencia OMSA Para Fiebre Aftosa, Dirección de Laboratorio Animal, SENASA, CP1640, Martínez Buenos Aires, Argentina
| | - Vo V Hung
- Department of Animal Health, Regional Animal Health Office (RAHO) No 6, Ho Chi Min, QMW4, Vietnam
| | | | - Nguyen T Phuong
- Department of Animal Health, Regional Animal Health Office (RAHO) No 6, Ho Chi Min, QMW4, Vietnam
| | | | - Sabrina Galdo Novo
- Laboratorio de Referencia OMSA Para Fiebre Aftosa, Dirección de Laboratorio Animal, SENASA, CP1640, Martínez Buenos Aires, Argentina.
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Abdullah SW, Han S, Wu J, Zhang Y, Bai M, Jin Y, Zhi X, Guan J, Sun S, Guo H. The DDX23 Negatively Regulates Translation and Replication of Foot-and-Mouth Disease Virus and Is Degraded by 3C Proteinase. Viruses 2020; 12:E1348. [PMID: 33255534 PMCID: PMC7760909 DOI: 10.3390/v12121348] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/16/2020] [Accepted: 11/20/2020] [Indexed: 12/12/2022] Open
Abstract
DEAD-box helicase 23 (DDX23) is a host nuclear helicase, which is a part of the spliceosomal complex and involved in pre-mRNA splicing. To investigate whether DDX23, an internal ribosomal entry sites transacting factor (ITAF) affects foot-and-mouth disease virus (FMDV) replication and translation through internal ribosome entry site (IRES)-dependent manner. For this, we utilized a pull-down assay, Western blotting, quantitative real-time PCR, confocal microscopy, overexpression and small interfering RNA knockdown, as well as the median tissue culture infective dose. Our findings showed that FMDV infection inhibited DDX23 expression and the overexpression of DDX23 reduced viral replication, however, CRISPR Cas9 knockout/small interfering RNA knockdown increased FMDV replication. FMDV IRES domain III and IV interacted with DDX23, whereas DDX23 interacted with FMDV 3C proteinase and significantly degraded. The enzymatic activity of FMDV 3C proteinase degraded DDX23, whereas FMDV degraded DDX23 via the lysosomal pathway. Additionally, IRES-driven translation was suppressed in DDX23-overexpressing cells, and was enhanced in DDX23 knocked down. Collectively, our results demonstrated that DDX23 negatively affects FMDV IRES-dependent translation, which could be a useful target for the design of antiviral drugs.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Shiqi Sun
- State Key Laboratory of Veterinary Etiological Biology, O.I.E./China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (S.W.A.); (S.H.); (J.W.); (Y.Z.); (M.B.); (Y.J.); (X.Z.); (J.G.)
| | - Huichen Guo
- State Key Laboratory of Veterinary Etiological Biology, O.I.E./China National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China; (S.W.A.); (S.H.); (J.W.); (Y.Z.); (M.B.); (Y.J.); (X.Z.); (J.G.)
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3
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Complete Genome Sequence of O/VN1/2014, a Foot-and-Mouth Disease Virus of Serotype O Isolated in Vietnam in 2014. Microbiol Resour Announc 2019; 8:MRA01343-18. [PMID: 30746514 PMCID: PMC6368649 DOI: 10.1128/mra.01343-18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 12/24/2018] [Indexed: 11/24/2022] Open
Abstract
In this article, we report the complete genome sequence of foot-and-mouth disease virus (FMDV) strain O/VN1/2014 isolated in Vietnam (Lao Cai) in 2014. The virus belongs to serotype O, topotype South East Asia (SEA), and genotype Mya-98 (O/SEA/Mya-98). In this article, we report the complete genome sequence of foot-and-mouth disease virus (FMDV) strain O/VN1/2014 isolated in Vietnam (Lao Cai) in 2014. The virus belongs to serotype O, topotype South East Asia (SEA), and genotype Mya-98 (O/SEA/Mya-98). It is the latest complete genome information for the genotype O/SEA/Mya-98 in Vietnam since 2009.
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Ahmed Z, Pauszek SJ, Ludi A, LaRocco M, Khan EUH, Afzal M, Arshed MJ, Farooq U, Arzt J, Bertram M, Brito B, Naeem K, Abubakar M, Rodriguez LL. Genetic diversity and comparison of diagnostic tests for characterization of foot-and-mouth disease virus strains from Pakistan 2008-2012. Transbound Emerg Dis 2017; 65:534-546. [PMID: 29034593 DOI: 10.1111/tbed.12737] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Indexed: 02/06/2023]
Abstract
We report the laboratory analysis of 125 clinical samples from suspected cases of foot-and-mouth disease (FMD) in cattle and Asian buffalo collected in Pakistan between 2008 and 2012. Of these samples, 89 were found to contain viral RNA by rRT-PCR, of which 88 were also found to contain infectious FMD virus (FMDV) by virus isolation (VI), with strong correlation between these tests (κ = 0.96). Samples that were VI-positive were serotyped by antigen detection ELISA (Ag-ELISA) and VP1 sequence acquisition and analysis. Sequence data identified FMDV serotypes A (n = 13), O (n = 36) and Asia-1 (n = 41), including three samples from which both serotypes Asia-1 and O were detected. Serotype A viruses were classified within three different Iran-05 sublineages: HER-10, FAR-11 and ESF-10. All serotype Asia-1 were within Group VII (Sindh-08 lineage), in a genetic clade that differs from viruses isolated prior to 2010. All serotypes O were classified as PanAsia-2 within two different sublineages: ANT-10 and BAL-09. Using VP1 sequencing as the gold standard for serotype determination, the overall sensitivity of Ag-ELISA to correctly determine serotype was 74%, and serotype-specific sensitivity was 8% for serotype A, 88% for Asia-1 and 89% for O. Serotype-specific specificity was 100% for serotype A, 93% for Asia-1 and 94% for O. Interestingly, 12 of 13 serotype A viruses were not detected by Ag-ELISA. This study confirms earlier accounts of regional genetic diversity of FMDV in Pakistan and highlights the importance of continued validation of diagnostic tests for rapidly evolving pathogens such as FMDV.
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Affiliation(s)
- Z Ahmed
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - S J Pauszek
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA
| | - A Ludi
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - M LaRocco
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA
| | - E-U-H Khan
- Progressive Control of Foot and Mouth Disease in Pakistan, Food & Agriculture Organization of the United Nations Office, NARC Premises, Islamabad, Pakistan
| | - M Afzal
- Progressive Control of Foot and Mouth Disease in Pakistan, Food & Agriculture Organization of the United Nations Office, NARC Premises, Islamabad, Pakistan
| | - M J Arshed
- Progressive Control of Foot and Mouth Disease in Pakistan, Food & Agriculture Organization of the United Nations Office, NARC Premises, Islamabad, Pakistan
| | - U Farooq
- Animal Health Program, Animal Sciences Institute, National Agricultural Research Center, Islamabad, Pakistan
| | - J Arzt
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA
| | - M Bertram
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - B Brito
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - K Naeem
- Animal Health Program, Animal Sciences Institute, National Agricultural Research Center, Islamabad, Pakistan
| | - M Abubakar
- National Veterinary Laboratories, Islamabad, Pakistan
| | - L L Rodriguez
- USDA/ARS Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Greenport, NY, USA
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Le VP, Vu TTH, Duong HQ, Than VT, Song D. Evolutionary phylodynamics of foot-and-mouth disease virus serotypes O and A circulating in Vietnam. BMC Vet Res 2016; 12:269. [PMID: 27894299 PMCID: PMC5126991 DOI: 10.1186/s12917-016-0896-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 11/22/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Foot-and-mouth disease virus (FMDV) is one of the highest risk factors that affects the animal industry of the country. The virus causes production loss and high ratio mortality in young cloven-hoofed animals in Vietnam. The VP1 coding gene of 80 FMDV samples (66 samples of the serotype O and 14 samples of the serotype A) collected from endemic outbreaks during 2006-2014 were analyzed to investigate their phylogeny and genetic relationship with other available FMDVs globally. RESULTS Phylogenetic analysis indicated that the serotype O strains were clustered into two distinct viral topotypes (the SEA and ME-SA), while the serotype A strains were all clustered into the genotype IX. Among the study strains, the amino acid sequence identities were shared at a level of 90.1-100, 92.9-100, and 92.8-100% for the topotypes SEA, ME-SA, and genotype IX, respectively. Substitutions leading to changes in the amino acid sequence, which are critical for the VP1 antigenic sites were also identified. Our results showed that the studied strains are most closely related to the recent FMDV isolates from Southeast Asian countries (Myanmar, Thailand, Cambodia, Malaysia, and Laos), but are distinct from the earlier FMDV isolates within the genotypes. CONCLUSIONS This study provides important evidence of recent movement of FMDVs serotype O and A into Vietnam within the last decade and their genetic accumulation to be closely related to strains causing FMD in surrounding countries.
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Affiliation(s)
- Van Phan Le
- Department of Microbiology and Infectious Disease, Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi, Vietnam.
| | - Thi Thu Hang Vu
- Research and Development Laboratory, Rural Technology Development JSC, Hung Yen, Vietnam
| | - Hong-Quan Duong
- Institute of Research and Development, Duy Tan University, Danang, Vietnam
| | - Van Thai Than
- Department of Microbiology, Chung-Ang University College of Medicine, Seoul, South Korea.
| | - Daesub Song
- College of Pharmacy, Korea University, Sejong, South Korea
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de Carvalho Ferreira HC, Pauszek SJ, Ludi A, Huston CL, Pacheco JM, Le VT, Nguyen PT, Bui HH, Nguyen TD, Nguyen T, Nguyen TT, Ngo LT, Do DH, Rodriguez L, Arzt J. An Integrative Analysis of Foot-and-Mouth Disease Virus Carriers in Vietnam Achieved Through Targeted Surveillance and Molecular Epidemiology. Transbound Emerg Dis 2015; 64:547-563. [PMID: 26301461 DOI: 10.1111/tbed.12403] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Indexed: 11/28/2022]
Abstract
Foot-and-mouth disease (FMD) is a major constraint to transboundary trade in animal products, yet much of its natural ecology and epidemiology in endemic regions is still poorly understood. To address this gap, a multidisciplinary, molecular and conventional epidemiological approach was applied to an investigation of endemic FMD in Vietnam. Within the study space, it was found that 22.3% of sampled ruminants had previously been infected with FMD virus (FMDV), of which 10.8% were persistent, asymptomatic carriers (2.4% of the total population). Descriptive data collected from targeted surveillance and a farm questionnaire showed a significantly lower prevalence of FMDV infection for dairy farms. In contrast, farms of intermediate size and/or history of infection in 2010 were at increased risk of FMD exposure. At the individual animal level, buffalo had the highest exposure risk (over cattle), and there was spatial heterogeneity in exposure risk at the commune level. Conversely, carrier prevalence was higher for beef cattle, suggesting lower susceptibility of buffalo to persistent FMDV infection. To characterize virus strains currently circulating in Vietnam, partial FMDV genomic (VP1) sequences from carrier animals collected between 2012 and 2013 (N = 27) and from FMDV outbreaks between 2009 and 2013 (N = 79) were compared by phylogenetic analysis. Sequence analysis suggested that within the study period, there were two apparent novel introductions of serotype A viruses and that the dominant lineage of serotype O in Vietnam shifted from SEA/Mya-98 to ME-SA/PanAsia. FMDV strains shared close ancestors with FMDV from other South-East Asian countries indicating substantial transboundary movement of the predominant circulating strains. Close genetic relationships were observed between carrier and outbreak viruses, which may suggest that asymptomatic carriers of FMDV contribute to regional disease persistence. Multiple viral sequences obtained from carrier cattle over a 1-year period had considerable within-animal genetic variation, indicating within-host virus evolution.
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Affiliation(s)
- H C de Carvalho Ferreira
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - S J Pauszek
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA
| | - A Ludi
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA.,Oak Ridge Institute for Science and Education, PIADC Research Participation Program, Oak Ridge, TN, USA
| | - C L Huston
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - J M Pacheco
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA
| | - V T Le
- Regional Animal Health Office No. 6, Department of Animal Health, Ministry of Agriculture and Rural Development, Ho Chi Minh City, Vietnam
| | - P T Nguyen
- Regional Animal Health Office No. 6, Department of Animal Health, Ministry of Agriculture and Rural Development, Ho Chi Minh City, Vietnam
| | - H H Bui
- Regional Animal Health Office No. 6, Department of Animal Health, Ministry of Agriculture and Rural Development, Ho Chi Minh City, Vietnam
| | - T D Nguyen
- National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - T Nguyen
- National Centre for Veterinary Diagnostics, Hanoi, Vietnam
| | - T T Nguyen
- Department of Animal Health, Ministry of Agriculture and Rural Development, Hanoi, Vietnam
| | - L T Ngo
- Regional Animal Health Office No. 6, Department of Animal Health, Ministry of Agriculture and Rural Development, Ho Chi Minh City, Vietnam
| | - D H Do
- Department of Animal Health, Ministry of Agriculture and Rural Development, Hanoi, Vietnam
| | - L Rodriguez
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA
| | - J Arzt
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, USA
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Brito BP, Rodriguez LL, Hammond JM, Pinto J, Perez AM. Review of the Global Distribution of Foot-and-Mouth Disease Virus from 2007 to 2014. Transbound Emerg Dis 2015; 64:316-332. [DOI: 10.1111/tbed.12373] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 01/23/2023]
Affiliation(s)
- B. P. Brito
- Agricultural Research Service; U.S. Department of Agriculture; Plum Island Animal Disease Center; Greenport NY USA
| | - L. L. Rodriguez
- Agricultural Research Service; U.S. Department of Agriculture; Plum Island Animal Disease Center; Greenport NY USA
| | - J. M. Hammond
- Centre for Animal & Plant Biosecurity; NSW Department of Primary Industries; Elizabeth Macarthur Agricultural Institute; Menangle NSW Australia
| | - J. Pinto
- Animal Health Service; Food and Agriculture Organization of the United Nations (FAO); Rome Italy
| | - A. M. Perez
- Department of Veterinary Population Medicine; College of Veterinary Medicine; University of Minnesota; Saint Paul MN USA
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Le VP, Lee KN, Nguyen T, Kim SM, Cho IS, Khang DD, Hien NB, Van Quyen D, Park JH. A rapid molecular strategy for early detection and characterization of Vietnamese foot-and-mouth disease virus serotypes O, A, and Asia 1. J Virol Methods 2011; 180:1-6. [PMID: 22172973 DOI: 10.1016/j.jviromet.2011.11.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 11/22/2011] [Accepted: 11/28/2011] [Indexed: 11/29/2022]
Abstract
A one-step RT-PCR method using newly designed primers VN-VP1F/VN-VP1R targeting the full VP1 capsid protein-coding gene, combined with direct sequencing of its PCR product, has been developed successfully for universal detection and characterization of Vietnamese FMDV serotypes O, A, and Asia 1 directly from clinical samples. The one-step RT-PCR amplified 821-bp dsDNA products covering the entire VP1 gene of FMDV serotypes O, A, and Asia 1. The obtained dsDNA products were suitable for direct sequencing, cloning, and other molecular epidemiology studies of Vietnamese FMDV strains, which eliminated the need for cell culture and virus purification. This one-step RT-PCR system was applied to detect and characterize 55 field FMDV strains, including 34 serotype O, 17 serotype A, and 4 serotype Asia 1 isolates collected from endemic outbreaks in Vietnam from 2005 to 2010. Interestingly, the PCR products obtained from the present PCR method could be used as DNA templates for the second PCR typing method using serotypes O, A, and Asia 1-specific primers (Le et al., 2011). The use of the second PCR amplification increased markedly the sensitivity of the test for FMDV detection. The present RT-PCR method promises to be an effective tool for molecular epidemiological studies of FMD in Vietnam.
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Affiliation(s)
- Van Phan Le
- Department of Microbiology and Infectious Disease, Hanoi University of Agriculture, Hanoi, Viet Nam.
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RETRACTED ARTICLE: The complete nucleotide sequences of serotype ‘O’ and ‘A’ Indian vaccine strains of foot-and-mouth disease virus. Arch Virol 2011; 156:2117. [DOI: 10.1007/s00705-011-1073-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 07/06/2011] [Indexed: 10/18/2022]
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Development of one-step multiplex RT-PCR method for simultaneous detection and differentiation of foot-and-mouth disease virus serotypes O, A, and Asia 1 circulating in Vietnam. J Virol Methods 2011; 175:101-8. [PMID: 21550367 DOI: 10.1016/j.jviromet.2011.04.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 04/01/2011] [Accepted: 04/05/2011] [Indexed: 11/22/2022]
Abstract
A one-step multiplex RT-PCR method using new primers was developed for the simultaneous detection and differentiation of Vietnamese FMDV serotypes O, A, and Asia 1 directly from clinical samples. The RT-PCR method used a cocktail of one universal minus-sense primer designed in the 2B gene and three serotype-specific plus-sense primers designed in the hypervariable regions of the capsid VP1 coding gene of FMDV. These serotype-specific primer pairs amplified 658, 535, and 427 bp PCR products corresponding to FMDV serotypes O, Asia 1, and A, respectively. In this study, six well-characterized FMDV strains belonging to serotypes O, A, and Asia 1 were used as reference strains for validation tests. Among these six FMDV strains were three vaccine strains for type O (O1/Manisa), A (A22/Iraq), and Asia 1 (As1/Shamir/89). The other reference strains included one pandemic strain of FMDV serotype Asia 1 (Asia1/MOG/05) and two pandemic strains of FMDV serotype O (O/UKG/34/2001 and O/SKR/2000). For field application, 37 positive-clinical samples and 18 cell culture-adapted viruses belonging to serotypes O, A, and Asia 1, as confirmed previously by antigen ELISA for FMDV detection, were used. The present method showed high sensitivity and specificity and can be adapted for detection and typing of FMDV serotypes O, A, and Asia 1 circulating in Vietnam.
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