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PloS one2015; 10(4); e0124281; doi: 10.1371/journal.pone.0124281

Characterising Non-Structural Protein NS4 of African Horse Sickness Virus.

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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Publication Date: 2015-04-27 PubMed ID: 25915516PubMed Central: PMC4411093DOI: 10.1371/journal.pone.0124281Google Scholar: Lookup
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Summary

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 research article discusses the characteristics of a non-structural protein, NS4, in the African Horse Sickness Virus (AHSV). NS4 is indicated to exist in two main types and is found in certain cells of AHSV-infected horses, with potential implications for viral replication.

Objective of the Research

  • The study aimed to examine and characterise the African Horse Sickness Virus’s non-structural protein named NS4, which was recently predicted and confirmed to be part of the virus’ genome.

Understanding the Virus and Protein NS4

  • The African Horse Sickness is a severe equine disease spread by the African Horse Sickness Virus, a type of orbivirus. This virus consists of ten double-stranded RNA genome segments that encode seven structural and three non-structural proteins.
  • A recent addition to the non-structural proteins is NS4, which forms part of the genome segment 9 (Seg-9) – this same segment also encodes the structural protein VP6.

Methods and Findings

  • The researchers conducted an in silico (computer-simulated) analysis of AHSV Seg-9 sequences. This analysis revealed the existence of two primary types of AHSV NS4 – NS4-I and NS4-II, which vary in length and amino acid sequences.
  • The study shows that the NS4 coding sequences of AHSV are located in the +1 reading frame regarding VP6.
  • Both types of AHSV NS4 were expressed in mammalian cells cultured in the lab. These proteins showed sizes close to what had been previously predicted.
  • Microscopic observations showed dual cytoplasmic and nuclear, but not nucleolar, distribution for NS4-I and NS4-II in the mammalian cells.

Further Observations

  • Immunohistochemistry on tissue samples from AHSV-infected horses indicated that NS4 occurs in microvascular endothelial cells and mononuclear phagocytes, located within the heart, spleen, and lungs.
  • Interestingly, NS4 was also observed in unique and distinct stellate-shaped dendritic macrophage-like cells in the spleen’s red pulp.
  • Nucleic acid protection assays showed that both types of AHSV NS4 bind to double-stranded DNA but not to double-stranded RNA.

Implications and Future Research

  • The findings open up avenues for further examination to ascertain the exact role of AHSV NS4 during the replication of the virus, a process vital for its survival and spread within the host.

Cite This Article

APA
Zwart L, Potgieter CA, Clift SJ, van Staden V. (2015). Characterising Non-Structural Protein NS4 of African Horse Sickness Virus. PLoS One, 10(4), e0124281. https://doi.org/10.1371/journal.pone.0124281

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 10
Issue: 4
Pages: e0124281

Researcher Affiliations

Zwart, Lizahn
  • Department of Genetics, University of Pretoria, Pretoria, South Africa.
Potgieter, Christiaan A
  • Deltamune (Pty) Ltd, Lyttelton, Centurion, South Africa; Department of Biochemistry, Centre for Human Metabonomics, North-West University, Potchefstroom, South Africa.
Clift, Sarah J
  • Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.
van Staden, Vida
  • Department of Genetics, University of Pretoria, Pretoria, South Africa.

MeSH Terms

  • African Horse Sickness / pathology
  • African Horse Sickness / virology
  • African Horse Sickness Virus / classification
  • African Horse Sickness Virus / genetics
  • African Horse Sickness Virus / metabolism
  • Animals
  • Cell Line
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Viral
  • Genome, Viral
  • Genotype
  • Horses
  • Intracellular Space / metabolism
  • Open Reading Frames
  • Phylogeny
  • Protein Transport
  • Sequence Analysis, DNA
  • Serogroup
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / metabolism

Conflict of Interest Statement

Competing Interests: The authors have declared that no competing interests exist.

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Citations

This article has been cited 20 times.
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