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Veterinary research2016; 47(1); 115; doi: 10.1186/s13567-016-0400-7

Attenuation of the virulence of a recombinant influenza virus expressing the naturally truncated NS gene from an H3N8 equine influenza virus in mice.

Abstract: Equine influenza virus (EIV) causes a highly contagious disease in horses and other equids. Recently, we isolated an H3N8 EIV (A/equine/Kyonggi/SA1/2011) from a domestic horse in South Korea that exhibited symptoms of respiratory disease, and found that the EIV strain contained a naturally mutated NS gene segment encoding a truncated NS1 protein. In order to determine whether there was an association between the NS gene truncation and viral virulence, a reverse genetics system was applied to generate various NS gene recombinant viruses using the backbone of the H1N1 A/Puerto Rico/8/1934 (PR/8) virus. In a mouse model, the recombinant PR/8 virus containing the mutated NS gene of the Korean H3N8 EIV strain showed a dramatically reduced virulence: it induced no weight loss, no clinical signs and no histopathological lesions. However, the mice infected with the recombinant viruses with NS genes of PR/8 and H3N8 A/equine/2/Miami/1963 showed severe clinical signs including significant weight loss and 100% mortality. In addition, the levels of the pro-inflammatory cytokines; IL-6, CCL5, and IFN-γ, in the lungs of mice infected with the recombinant viruses expressing a full-length NS1 were significantly higher than those of mice infected with the virus with the NS gene from the Korean H3N8 EIV strain. In this study, our results suggest that the C-terminal moiety of NS1 contains a number of virulence determinants and might be a suitable target for the development of a vaccine candidate against equine influenza.
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Publication Date: 2016-11-15 PubMed ID: 27846859PubMed Central: PMC5111206DOI: 10.1186/s13567-016-0400-7Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

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 examined how manipulation of a certain gene in the equine influenza virus, causing the virus to be less harmful in mice. In particular, it explored how a naturally mutated NS gene from a particular horse influenza strain can potentially be used to create a less deadly version of the virus, which might be useful for designing vaccines.

Equine Influenza Virus and NS Gene

  • The study used an Equine Influenza Virus (EIV), a common cause of respiratory disease in horses, isolated from a horse in South Korea.
  • Researchers discovered this particular virus strain had a naturally occurring mutation in the NS gene, which resulted in a truncated NS1 protein.
  • The NS1 protein is known to be key to the influenza virus’s virulence, or ability to cause disease.

Manipulating the NS Gene

  • Utilising a system of reverse genetics, scientists constructed recombinant viruses with different NS genes, based on the backbone of the common H1N1 virus.
  • One of these recombinant viruses included the mutated NS gene from the South Korean horse virus strain.

Testing in Mice

  • Testing these recombinant viruses in mice, the team found that those mice infected with the virus which contained the mutated NS gene didn’t lose weight or exhibit symptoms, in contrast to mice infected with viruses containing the unmutated NS gene.
  • This result suggests that the NS gene mutation led to a less virulent virus.

Pro-inflammatory Cytokines

  • The study also measured levels of pro-inflammatory cytokines in the mice – these are signalling molecules that play a role in the body’s immune response.
  • Mice infected with recombinant viruses with full-length NS1 showed significantly higher levels of these cytokines than mice infected with the virus containing the NS gene from the South Korean horse strain, which was another sign of the latter’s reduced virulence.

Implications and Potential Applications

  • These findings suggest that the NS1 protein, particularly its C-terminal moiety, contains a number of elements that determine the severity of the viral infection.
  • This premises the likelihood of developing a vaccine candidate against equine influenza targeting the identified section of the NS1 protein.

Cite This Article

APA
Na W, Lyoo KS, Yoon SW, Yeom M, Kang B, Moon H, Kim HK, Jeong DG, Kim JK, Song D. (2016). Attenuation of the virulence of a recombinant influenza virus expressing the naturally truncated NS gene from an H3N8 equine influenza virus in mice. Vet Res, 47(1), 115. https://doi.org/10.1186/s13567-016-0400-7

Publication

Veterinary research
ISSN: 1297-9716
NlmUniqueID: 9309551
Country: England
Language: English
Volume: 47
Issue: 1
Pages: 115
PII: 115

Researcher Affiliations

Na, Woonsung
  • College of Pharmacy, Korea University, Sejong, Republic of Korea.
Lyoo, Kwang-Soo
  • Korea Zoonosis Research Institute, Chonbuk National University, Iksan, Republic of Korea.
Yoon, Sun-Woo
  • Viral Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea.
Yeom, Minjoo
  • College of Pharmacy, Korea University, Sejong, Republic of Korea.
Kang, Bokyu
  • Research Unit, Green Cross Veterinary Products, Yong-in, Republic of Korea.
Moon, Hyoungjoon
  • Research Unit, Green Cross Veterinary Products, Yong-in, Republic of Korea.
Kim, Hye Kwon
  • Korea Zoonosis Research Institute, Chonbuk National University, Iksan, Republic of Korea.
Jeong, Dae Gwin
  • Korea Zoonosis Research Institute, Chonbuk National University, Iksan, Republic of Korea.
Kim, Jeong-Ki
  • College of Pharmacy, Korea University, Sejong, Republic of Korea. kfrancis@korea.ac.kr.
Song, Daesub
  • College of Pharmacy, Korea University, Sejong, Republic of Korea. sds1@korea.ac.kr.

MeSH Terms

  • A549 Cells
  • Animals
  • Blotting, Western
  • Cytokines / metabolism
  • Dogs
  • HEK293 Cells
  • Horse Diseases / immunology
  • Horse Diseases / virology
  • Horses
  • Humans
  • Influenza A Virus, H3N8 Subtype / genetics
  • Influenza A Virus, H3N8 Subtype / pathogenicity
  • Lung / pathology
  • Lung / virology
  • Madin Darby Canine Kidney Cells
  • Mice
  • Mice, Inbred C57BL
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / pathology
  • Orthomyxoviridae Infections / veterinary
  • Orthomyxoviridae Infections / virology
  • Recombination, Genetic / genetics
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / immunology
  • Viral Plaque Assay

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Citations

This article has been cited 6 times.
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