Dataset Information

H7N7 Avian Influenza Virus Mutation from Low to High Pathogenicity on a Layer Chicken Farm in the UK.

ABSTRACT: Avian influenza virus (AIV) subtypes H5 and H7 are capable of mutating from low to high pathogenicity strains, causing high mortality in poultry with significant economic losses globally. During 2015, two outbreaks of H7N7 low pathogenicity AIV (LPAIV) in Germany, and one each in the United Kingdom (UK) and The Netherlands occurred, as well as single outbreaks of H7N7 high pathogenicity AIV (HPAIV) in Germany and the UK. Both HPAIV outbreaks were linked to precursor H7N7 LPAIV outbreaks on the same or adjacent premises. Herein, we describe the clinical, epidemiological, and virological investigations for the H7N7 UK HPAIV outbreak on a farm with layer chickens in mixed free-range and caged units. H7N7 HPAIV was identified and isolated from clinical samples, as well as H7N7 LPAIV, which could not be isolated. Using serological and molecular evidence, we postulate how the viruses spread throughout the premises, indicating potential points of incursion and possible locations for the mutation event. Serological and mortality data suggested that the LPAIV infection preceded the HPAIV infection and afforded some clinical protection against the HPAIV. These results document the identification of a LPAIV to HPAIV mutation in nature, providing insights into factors that drive its manifestation during outbreaks.

SUBMITTER: Byrne AMP

PROVIDER: S-EPMC7914596 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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H7N7 Avian Influenza Virus Mutation from Low to High Pathogenicity on a Layer Chicken Farm in the UK.

Byrne Alexander M P AMP Reid Scott M SM Seekings Amanda H AH Núñez Alejandro A Obeso Prieto Ana B AB Ridout Susan S Warren Caroline J CJ Puranik Anita A Ceeraz Vanessa V Essen Stephen S Slomka Marek J MJ Banks Jill J Brown Ian H IH Brookes Sharon M SM

Viruses 20210208 2

Avian influenza virus (AIV) subtypes H5 and H7 are capable of mutating from low to high pathogenicity strains, causing high mortality in poultry with significant economic losses globally. During 2015, two outbreaks of H7N7 low pathogenicity AIV (LPAIV) in Germany, and one each in the United Kingdom (UK) and The Netherlands occurred, as well as single outbreaks of H7N7 high pathogenicity AIV (HPAIV) in Germany and the UK. Both HPAIV outbreaks were linked to precursor H7N7 LPAIV outbreaks on the s ...[more]

PMID: 33567525

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Project description:The influenza A virus is of global concern for the poultry industry, especially the H5 and H7 subtypes as they have the potential to become highly pathogenic for poultry. In this study, the hemagglutinin (HA) of a low pathogenic avian influenza virus of the H7N7 subtype isolated from a Swedish mallard Anas platyrhynchos was sequenced, characterized and transiently expressed in Nicotiana benthamiana. Recently, plant expression systems have gained interest as an alternative for the production of vaccine antigens. To examine the possibility of expressing the HA protein in N. benthamiana, a cDNA fragment encoding the HA gene was synthesized de novo, modified with a Kozak sequence, a PR1a signal peptide, a C-terminal hexahistidine (6×His) tag, and an endoplasmic retention signal (SEKDEL). The construct was cloned into a Cowpea mosaic virus (CPMV)-based vector (pEAQ-HT) and the resulting pEAQ-HT-HA plasmid, along with a vector (pJL3:p19) containing the viral gene-silencing suppressor p19 from Tomato bushy stunt virus, was agro-infiltrated into N. benthamiana. The highest gene expression of recombinant plant-produced, uncleaved HA (rHA0), as measured by quantitative real-time PCR was detected at 6 days post infiltration (dpi). Guided by the gene expression profile, rHA0 protein was extracted at 6 dpi and subsequently purified utilizing the 6×His tag and immobilized metal ion adsorption chromatography. The yield was 0.2 g purified protein per kg fresh weight of leaves. Further molecular characterizations showed that the purified rHA0 protein was N-glycosylated and its identity confirmed by liquid chromatography-tandem mass spectrometry. In addition, the purified rHA0 exhibited hemagglutination and hemagglutination inhibition activity indicating that the rHA0 shares structural and functional properties with native HA protein of H7 influenza virus. Our results indicate that rHA0 maintained its native antigenicity and specificity, providing a good source of vaccine antigen to induce immune response in poultry species.

Dataset Information

H7N7 Avian Influenza Virus Mutation from Low to High Pathogenicity on a Layer Chicken Farm in the UK.

Publications

H7N7 Avian Influenza Virus Mutation from Low to High Pathogenicity on a Layer Chicken Farm in the UK.

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