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Chang W, Wang J, Wu F, Zhang H, Yang M. Antiviral activity and underlying mechanisms of baicalin against porcine reproductive and respiratory syndrome virus in vitro. Microb Pathog 2024:106712. [PMID: 38851360 DOI: 10.1016/j.micpath.2024.106712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/11/2024] [Accepted: 05/24/2024] [Indexed: 06/10/2024]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is a major challenge for the global swine industry, causing huge economic losses worldwide. To date, there are no effective measures to prevent and control the spread of PRRS virus (PRRSV). Baicalin (BA) is a natural flavonoid with various pharmacological effects, including antiviral, anti-inflammatory, antioxidant and immunomodulatory. Here, we demonstrate that BA exhibits potent anti-PRRSV activity in vitro, BA concentrations in the range of 5-20 μg/mL significantly inhibited PRRSV infection in a dose-dependent manner and were independent of PRRSV strain. Mechanistically, BA inhibited PRRSV replication by directly interacting with virions, thereby affecting multiple stages of the virus life cycle. Meanwhile, the preventive effect of BA on PRRSV could be realized by inhibiting CD151 and CD163 expression. Furthermore, BA reduced the PRRSV-induced expression of PAMs cytokines (IFN-α, IL-6, IL-8, and TNF-α), suggesting that BA-induced antiviral cytokines may help BA inhibit PRRSV infection. Taken together, BA can be used as an inhibitor of PRRSV infection in vitro, which provides a theoretical basis for the clinical application of BA and the prevention and control of PRRSV infection, which is worthy of further in vivo studies in swine.
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Affiliation(s)
- Weichen Chang
- Zhengzhou Key Laboratory for Pig Disease Prevention and Control, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan province, People's Republic of China
| | - Jing Wang
- Henan Agricultural University, Zhengzhou, 450046, Henan province, People's Republic of China
| | - Feifan Wu
- Henan Agricultural University, Zhengzhou, 450046, Henan province, People's Republic of China
| | - Hongying Zhang
- Henan Agricultural University, Zhengzhou, 450046, Henan province, People's Republic of China
| | - Mingfan Yang
- Zhengzhou Key Laboratory for Pig Disease Prevention and Control, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan province, People's Republic of China.
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Xia Z, Long D, Hong X, Lan Y, Xie L. Tissue expression of porcine transient receptor potential mucolipin protein channels and their differential responses to porcine reproductive and respiratory syndrome virus infection in vitro. J Vet Res 2024; 68:45-53. [PMID: 38525220 PMCID: PMC10960329 DOI: 10.2478/jvetres-2024-0014] [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: 09/15/2023] [Accepted: 03/06/2024] [Indexed: 03/26/2024] Open
Abstract
Introduction Porcine reproductive and respiratory syndrome virus (PRRSV) infection results in a serious disease, posing a huge economic threat to the global swine industry. The transient receptor potential mucolipin proteins (TRPMLs) have been shown to be strongly associated with virus infection and other physiological processes in humans, but their tissue distribution and responses to PRRSV in pigs remain unknown. Material and Methods Quantitative reverse-transcription PCR analysis was undertaken to determine the optimal primer for TRPML expression detection and for quantifying that expression individually in different pig tissue samples. Meat Animal Research Center 145 (MARC-145) monkey kidney cells and the TRPML-specific activator mucolipin synthetic agonist 1 (ML-SA1) were used to reveal the relationship between TRPML and PRRSV-2 infection. Results The best primers for each TRPML gene used in a fluorescence-based quantitative method were identified and TRPML1 was found to be highly expressed in the kidneys and liver of pigs, while TRPML2 and TRPML3 were observed to be primarily expressed in the kidney and spleen tissues. The expression of TRPML2 was upregulated with the rise in PRRSV-2 infection titre but not the expression of TRPML1 or TRPML3, and ML-SA1 inhibited PRRSV-2 in a dose-dependent manner. Conclusion Our research revealed the gene expression of TRPMLs in pigs and identified that TRPML channels may act as key host factors against PRRSV infection, which could lead to new targets for the prevention and treatment of pig infectious diseases.
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Affiliation(s)
- Zhiqiang Xia
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian463000, China
- Zhumadian Huazhong Chia Tai Co., Ltd., Zhumadian463000, China
- Henan Topfond Pharmaceutical Company Limited, Zhumadian463000, China
| | - Denggao Long
- Sixteenth Middle School of Yiyang City, Yiyang413064, Hunan Province, China
| | - Xinyi Hong
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian463000, China
| | - Ying Lan
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian463000, China
| | - Lixia Xie
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian463000, China
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Rawal G, Krueger KM, Yim-im W, Li G, Gauger PC, Almeida MN, Aljets EK, Zhang J. Development, Evaluation, and Clinical Application of PRRSV-2 Vaccine-like Real-Time RT-PCR Assays. Viruses 2023; 15:2240. [PMID: 38005917 PMCID: PMC10675446 DOI: 10.3390/v15112240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 11/05/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
In this study, we developed and validated (1) singleplex real-time RT-PCR assays for specific detection of five PRRSV-2 MLV vaccine viruses (Ingelvac MLV, Ingelvac ATP, Fostera, Prime Pac, and Prevacent) and (2) a four-plex real-time RT-PCR assay (IngelvacMLV/Fostera/Prevacent/XIPC) including the internal positive control XIPC for detecting and distinguishing the three most commonly used vaccines in the USA (Prevacent, Ingelvac MLV, and Fostera). The singleplex and 4-plex vaccine-like PCRs and the reference PCR (VetMAXTM PRRSV NA&EU, Thermo Fisher Scientific, Waltham, MA, USA) did not cross-react with non-PRRSV swine viral and bacterial pathogens. The limits of detection of vaccine-like PCRs ranged from 25 to 50 genomic copies/reactions. The vaccine-like PCRs all had excellent intra-assay and inter-assay repeatability. Based on the testing of 531 clinical samples and in comparison to the reference PCR, the diagnostic sensitivity, specificity, and agreement were in the respective range of 94.67-100%, 100%, and 97.78-100% for singleplex PCRs and 94.94-100%, 100%, and 97.78-100% for the 4-plex PCR, with a CT cutoff of 37. In addition, 45 PRRSV-2 isolates representing different genetic lineages/sublineages were tested with the vaccine-like PCRs and the results were verified with sequencing. In summary, the vaccine-like PCRs specifically detect the respective vaccine-like viruses with comparable performances to the reference PCR, and the 4-plex PCR allows to simultaneously detect and differentiate the three most commonly used vaccine viruses in the same sample. PRRSV-2 vaccine-like PCRs provide an additional tool for detecting and characterizing PRRSV-2.
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Affiliation(s)
| | | | | | | | | | | | | | - Jianqiang Zhang
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA; (G.R.); (K.M.K.); (W.Y.-i.); (G.L.); (P.C.G.); (M.N.A.); (E.K.A.)
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Chen W, Wang W, Wang X, Li Z, Wu K, Li X, Li Y, Yi L, Zhao M, Ding H, Fan S, Chen J. Advances in the differential molecular diagnosis of vesicular disease pathogens in swine. Front Microbiol 2022; 13:1019876. [PMID: 36386633 PMCID: PMC9641196 DOI: 10.3389/fmicb.2022.1019876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 09/30/2022] [Indexed: 11/23/2022] Open
Abstract
Foot-and-mouth disease virus (FMDV), Senecavirus A (SVA) and swine vesicular disease virus (SVDV) are members of the family Picornaviridae, which can cause similar symptoms - vesicular lesions in the tissues of the mouth, nose, feet, skin and mucous membrane of animals. Rapid and accurate diagnosis of these viruses allows for control measures to prevent the spread of these diseases. Reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR are traditional and reliable methods for pathogen detection, while their amplification reaction requires a thermocycler. Isothermal amplification methods including loop-mediated isothermal amplification and recombinase polymerase amplification developed in recent years are simple, rapid and do not require specialized equipment, allowing for point of care diagnostics. Luminex technology allows for simultaneous detection of multiple pathogens. CRISPR-Cas diagnostic systems also emerging nucleic acid detection technologies which are very sensitivity and specificity. In this paper, various nucleic acid detection methods aimed at vesicular disease pathogens in swine (including FMDV, SVA and SVDV) are summarized.
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Affiliation(s)
- Wenxian Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Weijun Wang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Xinyan Wang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Zhaoyao Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Keke Wu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Xiaowen Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Yuwan Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Lin Yi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Mingqiu Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Hongxing Ding
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, Guangzhou, China
| | - Shuangqi Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- *Correspondence: Shuangqi Fan, ; Jinding Chen,
| | - Jinding Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
- *Correspondence: Shuangqi Fan, ; Jinding Chen,
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Yim-Im W, Huang H, Zheng Y, Li G, Rawal G, Gauger P, Krueger K, Main R, Zhang J. Characterization of PRRSV in clinical samples and the corresponding cell culture isolates. Transbound Emerg Dis 2022; 69:e3045-e3059. [PMID: 35838985 DOI: 10.1111/tbed.14661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 11/27/2022]
Abstract
Isolation of porcine reproductive and respiratory syndrome virus (PRRSV) in cell culture is a primary means of obtaining virus isolates for autogenous vaccine production and other applications. However, it has not been well characterized whether cell culture isolate and the virus in clinical sample are equivalent. This study compared PRRSV ORF5 sequences from 1,024 clinical samples (995 PRRSV-2, 26 PRRSV-1, and 3 PRRSV-1 and PRRSV-2 PCR-positive) and their isolates in MARC-145 and/or ZMAC cells. For 3 PRRSV-1 and PRRSV-2 PCR-positive clinical samples, both PRRSV-1 and PRRSV-2 were isolated in ZMAC cells whereas either PRRSV-1 or PRRSV-2, but not both, was isolated in MARC-145 cells, with isolate sequences matching the respective viruses in clinical samples. Twenty-six PRRSV-1 and most of 995 PRRSV-2 PCR-positive clinical samples had matching viral ORF5 sequences with their cell culture isolates. However, 14 out of 995 PRRSV-2 cases (1.4%) had non-matching viral sequences between clinical samples and MARC-145 isolates although viral sequences from clinical samples and ZMAC isolates matched. This is concerning because, if the MARC-145 isolate is directly used for autogenous vaccine production without sequencing confirmation against the virus in the clinical sample, it is possible that the produced autogenous vaccine does not include the desired wild-type virus strain found on the farm and instead contains vaccine-like virus. Vaccine-specific PCR and next-generation sequencing performed on six selected cases indicated presence of ≥2 PRRSV-2 strains (mixed infection) in such clinical samples. In summary, PRRSV ORF5 sequences from clinical samples and cell culture isolates matched each other for majority of the cases. However, PRRSV sequences between clinical sample and MARC-145 cell culture isolate could occasionally be different when the clinical sample contains ≥2 PRRSV-2 strains. Characterizing PRRSV sequences from clinical samples and cell culture isolates should be conducted before using isolates for producing autogenous vaccines or other applications. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Wannarat Yim-Im
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Haiyan Huang
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Ying Zheng
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Ganwu Li
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Gaurav Rawal
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Phillip Gauger
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Karen Krueger
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Rodger Main
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
| | - Jianqiang Zhang
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA
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Opriessnig T, Rawal G, McKeen L, Filippsen Favaro P, Halbur PG, Gauger PC. Evaluation of the intranasal route for porcine reproductive and respiratory disease modified-live virus vaccination. Vaccine 2021; 39:6852-6859. [PMID: 34706840 DOI: 10.1016/j.vaccine.2021.10.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND In pigs, modified live virus (MLV) vaccines against porcine reproductive and respiratory syndrome virus (PRRSV) are commonly used and administered by intramuscular (IM) injection. In contrast, PRRSV, as a primary respiratory pathogen, is mainly transmitted via the intranasal (IN) route. The objective of this study was to evaluate the efficacy of a commonly used commercial PRRSV MLV delivered IN compared to the IM route. METHODS Fifty-four pigs were divided into five treatment groups. All vaccinated groups received the same MLV vaccine but administered via different routes. Group IN-JET-VAC was vaccinated with an automated high pressure prototype nasal jet device (IN-JET-VAC, n = 12), group IN-MAD-VAC was vaccinated with a mucosal atomization device (IN-MAD-VAC, n = 12), group IM-VAC was vaccinated intramuscularly (IM-VAC; n = 12) according to label instructions, while the NEG-CONTROL (n = 6) and the POS-CONTROL (n = 12) groups were both unvaccinated. At 28 days post vaccination all vaccinated groups and the POS-CONTROL pigs were challenged with a pathogenic US PRRSV isolate. Blood and nasal swabs were collected at regular intervals, and all pigs were necropsied at day 10 post challenge (dpc) when gross and microscopic lung lesions were assessed. RESULTS Prior to challenge most vaccinated pigs had seroconverted to PRRSV. Clinical signs (fever, inappetence) were most obvious in the POS-CONTROL group from dpc 7 onwards. The vaccinated groups were not different for PRRSV viremia, seroconversion, or average daily weight gain. However, IN-JET-VAC and IN-MAD-VAC had significantly higher neutralizing antibody levels against the vaccine virus at challenge. CONCLUSIONS Comparable vaccine responses were obtained in IN and IM vaccinated pigs, suggesting the intranasal administration route as an alternative option for PRRSV vaccination.
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Affiliation(s)
- Tanja Opriessnig
- The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK; Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
| | - Gaurav Rawal
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Lauren McKeen
- Department of Statistics, Iowa State University, Ames, IA, USA
| | | | - Patrick G Halbur
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Phillip C Gauger
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
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Duan E, Zhang B, Liang X, Jing H, Liu C, Zhang F, Huang J, Su L, Wang J. Effects of glycyrrhizin on the growth cycle and ATPase activity of PRRSV-2-infected MARC-145 cells. Res Vet Sci 2021; 138:30-38. [PMID: 34091227 DOI: 10.1016/j.rvsc.2021.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 05/10/2021] [Accepted: 05/18/2021] [Indexed: 11/29/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is a viral infectious disease caused by the porcine reproductive and respiratory syndrome virus (PRRSV) and is devastating the swine industry. MARC-145 cells, an African green monkey kidney cell line, are sensitive to PRRSV-2, and are often used for in vitro studies on PRRSV-2. Preliminary research has shown that glycyrrhizin, an important active component extracted from traditional Chinese medicinal licorice, significantly inhibits the proliferation of PRRSV-2 in MARC-145 cells; however, the in-depth molecular mechanism remains unclear. By determining the cell growth cycle, this study found that PRRSV-2 infection first increased the content of G1-phase MARC-145 cells and then decreased the content of G1-phase cells. Moreover, glycyrrhizin affected the role of PRRSV-2 in regulating the cell cycle. Furthermore, PRRSV-2 had the highest proliferation titer in G0/G1-phase MARC-145 cells, and glycyrrhizin reduced the content of PRRSV-2 in synchronized MARC-145 cells. According to the results of ATPase detection, PRRSV-2 infection weakened the Na+/K+-ATPase and Ca2+/Mg2+-ATPase activities in MARC-145 cells, while glycyrrhizin significantly enhanced their activities in PRRSV-2-infected MARC-145 cells. The above results provide theoretical support toward clarifying the mechanism by which glycyrrhizin inhibits the proliferation of PRRSV-2 in MARC-145 cells. Moreover, these results offer references for the development and use of glycyrrhizin and the clinical treatment of PRRSV-2 infection.
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Affiliation(s)
- Erzhen Duan
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Beibei Zhang
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Xiaoqing Liang
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Huiyuan Jing
- Key Laboratory of Veterinary Biological Products, College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan 450046, China
| | - Cen Liu
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Fenghua Zhang
- Kaifeng Center for Animal Disease Control and Prevention, Kaifeng, Henan, China
| | - Jin Huang
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Lanli Su
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China
| | - Jinrong Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou, Henan 450001, China.
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Rawal G, Yim-Im W, Chamba F, Smith C, Okones J, Francisco C, Zhang J. Development and validation of a reverse transcription real-time PCR assay for specific detection of PRRSGard vaccine-like virus. Transbound Emerg Dis 2021; 69:1212-1226. [PMID: 33763963 DOI: 10.1111/tbed.14084] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/14/2021] [Accepted: 03/22/2021] [Indexed: 01/30/2023]
Abstract
Increasing use of modified live virus (MLV) vaccines presents challenges to interpret positive results of porcine reproductive and respiratory syndrome virus (PRRSV) screening PCR that can detect both wild-type and vaccine strains. Instead, vaccine-specific PCR provides a convenient tool to detect vaccine-like virus from a sample. Here we report the development and validation of a real-time RT-PCR specific for PRRSGard® , a newly available commercial PRRSV-2 MLV vaccine. Analytical specificity, sensitivity and diagnostic performance of PRRSGard PCR were evaluated and compared to a commercial PRRSV screening PCR (reference PCR). PRRSGard and reference PCRs did not cross-react with any of the 27 non-PRRSV swine pathogens. PRRSGard PCR did not cross-react with other PRRSV-2 vaccine viruses and 31 laboratory and field PRRSV-2 isolates representing various genetic lineages of PRRSV-2. PRRSGard and reference PCRs consistently detected up to 10-6 and 10-5 dilutions of PRRSGard vaccine virus, respectively. Based on testing serial dilutions of in vitro transcribed RNA, the 95% limit of detection of PRRSGard PCR was 16 genomic copies/reaction with CT cut-off value of 36 and 7 genomic copies/reaction with CT cut-off value of 37. Diagnostic performance of PRRSGard PCR was evaluated using 846 clinical samples (684 serum and 162 oral fluid samples). Compared to the reference screening PCR, diagnostic sensitivity, specificity and agreement of PRRSGard PCR were 95.34%, 98.85% and 97.52% with cut-off CT value of 36 and 98.14%, 96.56% and 97.16% with cut-off CT value of 37. In addition, PRRSGard PCR was able to detect PRRSGard vaccine virus in a sample even with the co-presence of another PRRSV strain. In summary, in contrast to a reference screening PCR that detects both vaccine and field PRRSV strains, PRRSGard PCR provides a convenient tool to specifically detect PRRSGard vaccine-like virus and to inform PRRSV vaccination protocols.
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Affiliation(s)
- Gaurav Rawal
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Wannarat Yim-Im
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | | | - Chad Smith
- Pharmgate Animal Health, Wilmington, NC, USA
| | - Jeff Okones
- Pharmgate Animal Health, Wilmington, NC, USA
| | | | - Jianqiang Zhang
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
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