Abstract: Equine influenza (EI) is an acute, highly contagious viral respiratory disease of equids. Currently, equine influenza virus (EIV) subtype H3N8 continues to be the most important respiratory pathogen of horses in many countries around the world. The need to achieve a rapid diagnosis and to implement effective quarantine and movement restrictions is critical in controlling the spread of EIV. In this study, a novel, inexpensive and user-friendly assay based on an insulated isothermal RT-PCR (iiRT-PCR) method on the POCKIT™, a field-deployable device, was described and validated for point-of-need detection of EIV-H3N8 in clinical samples. The newly established iiRT-PCR assay targeting the EIV HA3 gene was evaluated for its sensitivity using in vitro transcribed (IVT) RNA, as well as ten-fold serial dilutions of RNA extracted from the prototype H3N8 strain A/equine/Miami/1/63. Inclusivity and exclusivity panels were tested for specificity evaluation. Published real-time RT-PCR (rRT-PCR) assays targeting the NP and HA3 genes were used as the reference standards for comparison of RNA extracted from field strains and from nasal swab samples collected from experimentally infected horses, respectively. Limit of detection with a 95% probability (LoD95%) was estimated to be 11copies of IVT RNA. Clinical sensitivity analysis using RNA prepared from serial dilutions of a prototype EIV (Miami 1/63/H3N8) showed that the iiRT-PCR assay was about 100-fold more sensitive than the rRT-PCR assay targeting the NP gene of EIV subtype H3N8. The iiRT-PCR assay identified accurately fifteen EIV H3N8 strains and two canine influenza virus (CIV) H3N8 strains, and did not cross-react with H6N2, H7N7, H1N1 subtypes or any other equine respiratory viral pathogens. Finally, 100% agreement was found between the iiRT-PCR assay and the universal influenza virus type A rRT-PCR assay in detecting the EIV A/equine/Kentucky/7/07 strain in 56 nasal swab samples collected from experimentally inoculated horses. Therefore, the EIV H3N8 subtype specific iiRT-PCR assay along with the portable POCKIT™ Nucleic Acid Analyzer provides a highly reliable, sensitive and specific on-site detection system of both equine and canine influenza viruses.
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The study presents a new an inexpensive, rapid, and user-friendly technique for the detection of equine influenza virus subtype H3N8 using a method called insulated isothermal RT-PCR (iiRT-PCR) on a portable device called POCKIT™.
About Equine Influenza Virus and its Detection
Equine influenza is a highly infectious respiratory disease that affects horses. This disease is caused by the Equine Influenza Virus (EIV), and H3N8 is its most significant subtype.
The rapid diagnosis of this illness is crucial to effectively implement quarantine measures and to control the virus’s spread.
The study aimed to develop a new technique suitable for point-of-need detection in the field using the insulated isothermal RT-PCR method.
About the Insulated Isothermal RT-PCR Method
The insulated isothermal RT-PCR (iiRT-PCR) method is a type of polymerase chain reaction that happens at a constant temperature (isothermal).
The technique was evaluated using in vitro transcribed (IVT) RNA and ten-fold serial dilutions of RNA extracted from the H3N8 strain.
The iiRT-PCR assay was developed to target the EIV HA3 gene and its sensitivity was analyzed. It was also tested for specificity using inclusivity and exclusivity panels.
Results and Conclusion
The iiRT-PCR assay was around 100 times more sensitive than reference standard assays in detecting the H3N8 subtype of EIV.
The assay accurately identified fifteen different strains of EIV H3N8, two strains of Canine Influenza Virus H3N8, and did not cross-react with other subtypes or any other equine respiratory viral pathogens.
The method showed a 100% agreement in detecting the EIV A/equine/Kentucky/7/07 strain, with 56 nasal swab samples collected from experimentally inoculated horses.
In conclusion, this new iiRT-PCR assay can provide a reliable, highly sensitive, and specific on-site detection system for Equine and Canine Influenza Viruses when used with a portable POCKIT™ Nucleic Acid Analyzer.
Cite This Article
APA
Balasuriya UB, Lee PY, Tiwari A, Skillman A, Nam B, Chambers TM, Tsai YL, Ma LJ, Yang PC, Chang HF, Wang HT.
(2014).
Rapid detection of equine influenza virus H3N8 subtype by insulated isothermal RT-PCR (iiRT-PCR) assay using the POCKIT™ Nucleic Acid Analyzer.
J Virol Methods, 207, 66-72.
https://doi.org/10.1016/j.jviromet.2014.06.016
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA. Electronic address: ubalasuriya@uky.edu.
Lee, Pei-Yu Alison
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
Tiwari, Ashish
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
Skillman, Ashley
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
Nam, Bora
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
Chambers, Thomas M
Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
Tsai, Yun-Long
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
Ma, Li-Juan
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
Yang, Pai-Chun
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
Chang, Hsiao-Fen Grace
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
Wang, Hwa-Tang Thomas
Department of Research and Development, GeneReach USA, Lexington, MA, USA.
MeSH Terms
Animals
Horses
Influenza A Virus, H3N8 Subtype / genetics
Influenza A Virus, H3N8 Subtype / isolation & purification
Yao SM, Wu ML, Hung TH. On-site detection system of Candidatus Liberibacter asiaticus by using TaqMan probe-based insulated isothermal polymerase chain reaction (iiPCR). PLoS One 2023;18(6):e0287699.
Chang TD, Huang LN, Lin YJ, Wu ZB, Tsai SH, Lin YH. Rapid Detection of Fusarium oxysporum Using Insulated Isothermal PCR and a Rapid, Simple DNA Preparation Protocol. Int J Mol Sci 2022 Oct 31;23(21).
Inui K, Nguyen T, Tseng HJ, Tsai CM, Tsai YL, Chung S, Padungtod P, Zhu H, Guan Y, Kalpravidh W, Claes F. A field-deployable insulated isothermal RT-PCR assay for identification of influenza A (H7N9) shows good performance in the laboratory. Influenza Other Respir Viruses 2019 Nov;13(6):610-617.
Ren Y, Yue H, Zhu L, Tang C, Zhang B. Development and evaluation of reverse transcription-insulated isothermal PCR assay to detect duck hepatitis A virus type A in liver samples using the POCKIT(TM) system. J Vet Med Sci 2019 Oct 24;81(10):1533-1539.
Schar D, Padungtod P, Tung N, O'Leary M, Kalpravidh W, Claes F. New frontiers in applied veterinary point-of-capture diagnostics: Toward early detection and control of zoonotic influenza. Influenza Other Respir Viruses 2019 Nov;13(6):618-621.
Zhang J, Nfon C, Tsai CF, Lee CH, Fredericks L, Chen Q, Sinha A, Bade S, Harmon K, Piñeyro P, Gauger P, Tsai YL, Wang HT, Lee PA. Development and evaluation of a real-time RT-PCR and a field-deployable RT-insulated isothermal PCR for the detection of Seneca Valley virus. BMC Vet Res 2019 May 24;15(1):168.
Tsai JJ, Liu WL, Lin PC, Huang BY, Tsai CY, Chou PH, Lee FC, Ping CF, Lee PA, Liu LT, Chen CH. An RT-PCR panel for rapid serotyping of dengue virus serotypes 1 to 4 in human serum and mosquito on a field-deployable PCR system. PLoS One 2019;14(3):e0214328.
Tsai JJ, Liu LT, Lin PC, Tsai CY, Chou PH, Tsai YL, Chang HG, Lee PA. Validation of the Pockit Dengue Virus Reagent Set for Rapid Detection of Dengue Virus in Human Serum on a Field-Deployable PCR System. J Clin Microbiol 2018 May;56(5).
Go YY, Kim YS, Cheon S, Nam S, Ku KB, Kim M, Cho NH, Park H, Alison Lee PY, Lin YC, Tsai YL, Thomas Wang HT, Balasuriya UBR. Evaluation and Clinical Validation of Two Field-Deployable Reverse Transcription-Insulated Isothermal PCR Assays for the Detection of the Middle East Respiratory Syndrome-Coronavirus. J Mol Diagn 2017 Nov;19(6):817-827.
Wilkes RP, Anis E, Dunbar D, Lee PA, Tsai YL, Lee FC, Chang HG, Wang HT, Graham EM. Rapid and sensitive insulated isothermal PCR for point-of-need feline leukaemia virus detection. J Feline Med Surg 2018 Apr;20(4):362-369.
Ambagala A, Fisher M, Goolia M, Nfon C, Furukawa-Stoffer T, Ortega Polo R, Lung O. Field-Deployable Reverse Transcription-Insulated Isothermal PCR (RT-iiPCR) Assay for Rapid and Sensitive Detection of Foot-and-Mouth Disease Virus. Transbound Emerg Dis 2017 Oct;64(5):1610-1623.
Lin YH, Lin YJ, Chang TD, Hong LL, Chen TY, Chang PF. Development of a TaqMan Probe-Based Insulated Isothermal Polymerase Chain Reaction (iiPCR) Assay for Detection of Fusarium oxysporum f. sp. cubense Race 4. PLoS One 2016;11(7):e0159681.
Kuo HC, Lo DY, Chen CL, Tsai YL, Ping JF, Lee CH, Lee PA, Chang HG. Rapid and sensitive detection of Mycoplasma synoviae by an insulated isothermal polymerase chain reaction-based assay on a field-deployable device. Poult Sci 2017 Jan 1;96(1):35-41.
Soltan MA, Tsai YL, Lee PA, Tsai CF, Chang HG, Wang HT, Wilkes RP. Comparison of electron microscopy, ELISA, real time RT-PCR and insulated isothermal RT-PCR for the detection of Rotavirus group A (RVA) in feces of different animal species. J Virol Methods 2016 Sep;235:99-104.
Zhang J, Tsai YL, Lee PY, Chen Q, Zhang Y, Chiang CJ, Shen YH, Li FC, Chang HF, Gauger PC, Harmon KM, Wang HT. Evaluation of two singleplex reverse transcription-Insulated isothermal PCR tests and a duplex real-time RT-PCR test for the detection of porcine epidemic diarrhea virus and porcine deltacoronavirus. J Virol Methods 2016 Aug;234:34-42.
Go YY, Rajapakse RPVJ, Kularatne SAM, Lee PA, Ku KB, Nam S, Chou PH, Tsai YL, Liu YL, Chang HG, Wang HT, Balasuriya UBR. A Pan-Dengue Virus Reverse Transcription-Insulated Isothermal PCR Assay Intended for Point-of-Need Diagnosis of Dengue Virus Infection by Use of the POCKIT Nucleic Acid Analyzer. J Clin Microbiol 2016 Jun;54(6):1528-1535.
Wilkes RP, Lee PY, Tsai YL, Tsai CF, Chang HH, Chang HF, Wang HT. An insulated isothermal PCR method on a field-deployable device for rapid and sensitive detection of canine parvovirus type 2 at points of need. J Virol Methods 2015 Aug;220:35-8.