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Colburn ME, Delaney MA, Anchor GC, Terio KA. Effect of formalin-fixation and paraffin-embedded tissue storage times on RNAscope in situ hybridization signal amplification. J Vet Diagn Invest 2024; 36:498-505. [PMID: 38650110 PMCID: PMC11185121 DOI: 10.1177/10406387241245777] [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] [Indexed: 04/25/2024] Open
Abstract
RNAscope in situ hybridization (ISH) detects target RNA in formalin-fixed, paraffin-embedded (FFPE) tissues. Protocols suggest that prolonged FFPE storage and formalin fixation may impact signal detection, potentially limiting the utility of RNAscope ISH in retrospective studies. To develop parameters for RNAscope use with archived specimens, we evaluated the effect of formalin-fixation time by measuring the signal of a reference gene (16srRNA) in selected tissues fixed in 10% neutral-buffered formalin for 1, 2, 3, 5, 7, 10, 14, 21, 28, 60, 90, 180, and 270 d. The signal intensity and percent area of signal decreased after 180 d. Tissues had detectable signal at 180 d but not at 270 d of formalin fixation. To assess target detection in paraffin blocks, we qualitatively compared the signal of canine distemper virus (CDV) antigen via immunohistochemistry and CDV RNA via RNAscope ISH in replicate sections from blocks stored at room temperature for 6 mo, 1, 3, 6, 8, 11, 13, and 15 y; RNA was detected in FFPE tissues stored for up to 15 y. Our results demonstrate that RNAscope ISH can detect targets in tissues with prolonged paraffin storage intervals and formalin-fixation times.
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Affiliation(s)
- Megan E. Colburn
- Zoological Pathology Program, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, IL, USA
| | - Martha A. Delaney
- Zoological Pathology Program, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, IL, USA
| | - Gretchen C. Anchor
- Zoological Pathology Program, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, IL, USA
| | - Karen A. Terio
- Zoological Pathology Program, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, IL, USA
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Wall GV, Wright IM, Barnardo C, Erasmus BJ, van Staden V, Potgieter AC. African horse sickness virus NS4 protein is an important virulence factor and interferes with JAK-STAT signaling during viral infection. Virus Res 2021; 298:198407. [PMID: 33812899 DOI: 10.1016/j.virusres.2021.198407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/25/2021] [Accepted: 03/29/2021] [Indexed: 12/24/2022]
Abstract
African horse sickness virus (AHSV) non-structural protein NS4 is a nucleocytoplasmic protein that is expressed in the heart, lung, and spleen of infected horses, binds dsDNA, and colocalizes with promyelocytic leukemia nuclear bodies (PML-NBs). The aim of this study was to investigate the role of AHSV NS4 in viral replication, virulence and the host immune response. Using a reverse genetics-derived virulent strain of AHSV-5 and NS4 deletion mutants, we showed that knockdown of NS4 expression has no impact in cell culture, but results in virus attenuation in infected horses. RNA sequencing (RNA-seq) was used to investigate the transcriptional response in these horses, to see how the lack of NS4 mediates the transition of the virus from virulent to attenuated. The presence of NS4 was shown to result in a 24 hour (h) delay in the transcriptional activation of several immune system processes compared to when the protein was absent. Included in these processes were the RIG-I-like, Toll-like receptor, and JAK-STAT signaling pathways, which are key pathways involved in innate immunity and the antiviral response. Thus, it was shown that AHSV NS4 suppresses the host innate immune transcriptional response in the early stages of the infection cycle. We investigated whether AHSV NS4 affects the innate immune response by impacting the JAK-STAT signaling pathway specifically. Using confocal laser scanning microscopy (CLSM) we showed that AHSV NS4 disrupts JAK-STAT signaling by interfering with the phosphorylation and/or translocation of STAT1 and pSTAT1 into the nucleus. Overall, these results showed that AHSV NS4 is a key virulence factor in horses and allows AHSV to overcome host antiviral responses in order to promote viral replication and spread.
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Affiliation(s)
- Gayle V Wall
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
| | - Isabella M Wright
- Deltamune (Pty) Ltd, Moraine House - The Braes, 193 Bryanston Drive, Bryanston, Gauteng, 2191, South Africa
| | - Carin Barnardo
- Deltamune (Pty) Ltd, Moraine House - The Braes, 193 Bryanston Drive, Bryanston, Gauteng, 2191, South Africa
| | - Baltus J Erasmus
- Deltamune (Pty) Ltd, Moraine House - The Braes, 193 Bryanston Drive, Bryanston, Gauteng, 2191, South Africa
| | - Vida van Staden
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, 0002, South Africa
| | - A Christiaan Potgieter
- Deltamune (Pty) Ltd, Moraine House - The Braes, 193 Bryanston Drive, Bryanston, Gauteng, 2191, South Africa; Department of Biochemistry, Focus Area for Human Metabolomics, North-West University, Potchefstroom, South Africa.
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Whitehead Z, Roux C, O'Dell N, Hanekom J. Clinical presentation and management of African horse sickness in two dogs. VETERINARY RECORD CASE REPORTS 2018. [DOI: 10.1136/vetreccr-2018-000664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Zandri Whitehead
- Companion Animal Clinical StudiesUniversity of PretoriaPretoriaSouth Africa
- Specialist Medicine ClinicTygerberg Animal HospitalCape TownSouth Africa
| | - Christelle Roux
- Companion Animal Clinical StudiesUniversity of PretoriaPretoriaSouth Africa
| | - Nicolize O'Dell
- Paraclinical SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Josef Hanekom
- Companion Animal Clinical StudiesUniversity of PretoriaPretoriaSouth Africa
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Zwart L, Potgieter CA, Clift SJ, van Staden V. Characterising Non-Structural Protein NS4 of African Horse Sickness Virus. PLoS One 2015; 10:e0124281. [PMID: 25915516 PMCID: PMC4411093 DOI: 10.1371/journal.pone.0124281] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/12/2015] [Indexed: 01/07/2023] Open
Abstract
African horse sickness is a serious equid disease caused by the orbivirus African horse sickness virus (AHSV). The virus has ten double-stranded RNA genome segments encoding seven structural and three non-structural proteins. Recently, an additional protein was predicted to be encoded by genome segment 9 (Seg-9), which also encodes VP6, of most orbiviruses. This has since been confirmed in bluetongue virus and Great Island virus, and the non-structural protein was named NS4. In this study, in silico analysis of AHSV Seg-9 sequences revealed the existence of two main types of AHSV NS4, designated NS4-I and NS4-II, with different lengths and amino acid sequences. The AHSV NS4 coding sequences were in the +1 reading frame relative to that of VP6. Both types of AHSV NS4 were expressed in cultured mammalian cells, with sizes close to the predicted 17–20 kDa. Fluorescence microscopy of these cells revealed a dual cytoplasmic and nuclear, but not nucleolar, distribution that was very similar for NS4-I and NS4-II. Immunohistochemistry on heart, spleen, and lung tissues from AHSV-infected horses showed that NS4 occurs in microvascular endothelial cells and mononuclear phagocytes in all of these tissues, localising to the both the cytoplasm and the nucleus. Interestingly, NS4 was also detected in stellate-shaped dendritic macrophage-like cells with long cytoplasmic processes in the red pulp of the spleen. Finally, nucleic acid protection assays using bacterially expressed recombinant AHSV NS4 showed that both types of AHSV NS4 bind dsDNA, but not dsRNA. Further studies will be required to determine the exact function of AHSV NS4 during viral replication.
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Affiliation(s)
- Lizahn Zwart
- Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Christiaan A. Potgieter
- Deltamune (Pty) Ltd, Lyttelton, Centurion, South Africa
- Department of Biochemistry, Centre for Human Metabonomics, North-West University, Potchefstroom, South Africa
| | - Sarah J. Clift
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - Vida van Staden
- Department of Genetics, University of Pretoria, Pretoria, South Africa
- * E-mail:
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Van Sittert SJ, Drew TM, Kotze JL, Strydom T, Weyer CT, Guthrie AJ. Occurrence of African horse sickness in a domestic dog without apparent ingestion of horse meat. J S Afr Vet Assoc 2013. [DOI: 10.4102/jsava.v84i1.948] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
This is the first case of African horse sickness (AHS) in a dog where there was no apparent ingestion of horse meat. Significantly, the dog was part of a colony that resides in a Good Clinical Practice and Good Laboratory Practice accredited facility where complete history, weather and feeding records are maintained. The dog died after a week-long illness despite therapy. The principal post-mortem findings were severe hydrothorax and pulmonary consolidation (red hepatisation of the lungs). Histopathology revealed severe oedema and congestion of the lungs, hyaline degeneration of the myocardium and congestion of the liver sinusoids. Immunohistochemistry detected AHS-positive staining granules in the myocardium, whilst a real-time reverse transcription quantitative Polymerase chain reaction assay of tissue samples was strongly positive for African horse sickness virus nucleic acid. Other dogs on the property showed a 43%seroconversion rate to AHS.
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Bwala DG, Clift S, Duncan NM, Bisschop SP, Oludayo FF. Determination of the distribution of lentogenic vaccine and virulent Newcastle disease virus antigen in the oviduct of SPF and commercial hen using immunohistochemistry. Res Vet Sci 2012; 93:520-8. [DOI: 10.1016/j.rvsc.2011.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 06/08/2011] [Accepted: 06/21/2011] [Indexed: 10/17/2022]
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Clift SJ, Penrith ML. Tissue and Cell Tropism of African Horse Sickness Virus Demonstrated by Immunoperoxidase Labeling in Natural and Experimental Infection in Horses in South Africa. Vet Pathol 2010; 47:690-7. [DOI: 10.1177/0300985810370010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tissues from 196 experimental and confirmed natural cases of African horse sickness (all 9 serotypes) were examined with a standardized and validated immunohistochemical assay for detection of the causative virus. The study confirmed that heart and lung are the main target tissues for African horse sickness virus (across all serotypes), followed closely by spleen. It also indicated that microvascular endothelial cells and monocyte–macrophages are the main target cells for virus replication. The importance of monocytes as target cells was emphasized, with relatively few tissue macrophages containing antigen in the lung and spleen, respectively. The results were largely in agreement with those of previous studies, but the large number of cases examined permitted more precise description of the location and distribution of antigen in different tissues. Comparison with descriptions of tissue and cell tropism of other orbiviruses indicated similarity with African horse sickness. Immunohistochemistry was shown to be a useful and consistent technique for demonstrating target cells, but the difficulty of identifying cell types—in particular, different types of monocyte–macrophages—is a limitation.
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Affiliation(s)
- S. J. Clift
- Section of Pathology, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - M.-L. Penrith
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
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