tetano
Editor, Senior Moderator
Viruses
. 2020 Aug 21;12(9):E920.
doi: 10.3390/v12090920.
The Emergence of H7N7 Highly Pathogenic Avian Influenza Virus from Low Pathogenicity Avian Influenza Virus Using an in ovo Embryo Culture Model
Amanda H Seekings[SUP] 1 [/SUP], Wendy A Howard[SUP] 1 [/SUP], Alejandro Nu??z[SUP] 2 [/SUP], Marek J Slomka[SUP] 1 [/SUP], Ashley C Banyard[SUP] 1 3 4 [/SUP], Daniel Hicks[SUP] 2 [/SUP], Richard J Ellis[SUP] 5 [/SUP], Javier Nu??z-Garc?a[SUP] 5 [/SUP], Lorian C Hartgroves[SUP] 6 [/SUP], Wendy S Barclay[SUP] 6 [/SUP], Jill Banks[SUP] 1 [/SUP], Ian H Brown[SUP] 1 [/SUP]
Affiliations
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 (H7N7[SUB]DB[/SUB]), as seen in the LPAIV precursor or an SBCS representative of common H7 LPAIVs (H7N7[SUB]SB[/SUB]). Passage of H7N7[SUB]DB[/SUB] in chicken embryo tissues showed spontaneous evolution to a HPAIV. In contrast, deep sequencing of extracts from embryo tissues in which H7N7[SUB]SB[/SUB] 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.
Keywords: H7N7; deep sequencing; embryo culture; highly pathogenic avian influenza (HPAI); immunohistochemistry; low pathogenicity avian influenza (LPAI); reverse genetics.
. 2020 Aug 21;12(9):E920.
doi: 10.3390/v12090920.
The Emergence of H7N7 Highly Pathogenic Avian Influenza Virus from Low Pathogenicity Avian Influenza Virus Using an in ovo Embryo Culture Model
Amanda H Seekings[SUP] 1 [/SUP], Wendy A Howard[SUP] 1 [/SUP], Alejandro Nu??z[SUP] 2 [/SUP], Marek J Slomka[SUP] 1 [/SUP], Ashley C Banyard[SUP] 1 3 4 [/SUP], Daniel Hicks[SUP] 2 [/SUP], Richard J Ellis[SUP] 5 [/SUP], Javier Nu??z-Garc?a[SUP] 5 [/SUP], Lorian C Hartgroves[SUP] 6 [/SUP], Wendy S Barclay[SUP] 6 [/SUP], Jill Banks[SUP] 1 [/SUP], Ian H Brown[SUP] 1 [/SUP]
Affiliations
- PMID: 32839404
- DOI: 10.3390/v12090920
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 (H7N7[SUB]DB[/SUB]), as seen in the LPAIV precursor or an SBCS representative of common H7 LPAIVs (H7N7[SUB]SB[/SUB]). Passage of H7N7[SUB]DB[/SUB] in chicken embryo tissues showed spontaneous evolution to a HPAIV. In contrast, deep sequencing of extracts from embryo tissues in which H7N7[SUB]SB[/SUB] 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.
Keywords: H7N7; deep sequencing; embryo culture; highly pathogenic avian influenza (HPAI); immunohistochemistry; low pathogenicity avian influenza (LPAI); reverse genetics.