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Seekings AH, Howard WA, Nuñéz A, Slomka MJ, Banyard AC, Hicks D, Ellis RJ, Nuñéz-García J, Hartgroves LC, Barclay WS, Banks J, Brown IH. The Emergence of H7N7 Highly Pathogenic Avian Influenza Virus from Low Pathogenicity Avian Influenza Virus Using an in ovo Embryo Culture Model. Viruses 2020; 12:v12090920. [PMID: 32839404 PMCID: PMC7552004 DOI: 10.3390/v12090920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 01/19/2023] Open
Abstract
Outbreaks of highly pathogenic avian influenza virus (HPAIV) often result in the infection of millions of poultry, causing up to 100% mortality. HPAIV has been shown to emerge from low pathogenicity avian influenza virus (LPAIV) in field outbreaks. Direct evidence for the emergence of H7N7 HPAIV from a LPAIV precursor with a rare di-basic cleavage site (DBCS) was identified in the UK in 2008. The DBCS contained an additional basic amino acid compared to commonly circulating LPAIVs that harbor a single-basic amino acid at the cleavage site (SBCS). Using reverse genetics, outbreak HPAIVs were rescued with a DBCS (H7N7DB), as seen in the LPAIV precursor or an SBCS representative of common H7 LPAIVs (H7N7SB). Passage of H7N7DB in chicken embryo tissues showed spontaneous evolution to a HPAIV. In contrast, deep sequencing of extracts from embryo tissues in which H7N7SB was serially passaged showed retention of the LPAIV genotype. Thus, in chicken embryos, an H7N7 virus containing a DBCS appears naturally unstable, enabling rapid evolution to HPAIV. Evaluation in embryo tissue presents a useful approach to study AIV evolution and allows a laboratory-based dissection of molecular mechanisms behind the emergence of HPAIV.
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Affiliation(s)
- Amanda H. Seekings
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
- Correspondence:
| | - Wendy A. Howard
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
| | - Alejandro Nuñéz
- Pathology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (A.N.); (D.H.)
| | - Marek J. Slomka
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
| | - Ashley C. Banyard
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
- Institute for Infection and Immunity, St. George’s Hospital Medical School, University of London, London SW17 0RE, UK
| | - Daniel Hicks
- Pathology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (A.N.); (D.H.)
| | - Richard J. Ellis
- Surveillance and Laboratory Services Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (R.J.E.); (J.N.-G.)
| | - Javier Nuñéz-García
- Surveillance and Laboratory Services Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (R.J.E.); (J.N.-G.)
| | | | - Wendy S. Barclay
- Virology Department, Imperial College, London W2 1NY, UK; (L.C.H.); (W.S.B.)
| | - Jill Banks
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
| | - Ian H. Brown
- Virology Department, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey KT15 3NB, UK; (W.A.H.); (M.J.S.); (A.C.B.); (J.B.); (I.H.B.)
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