Veterinary Archives, Vol. 87 No. 4, 2017.
Original scientific paper
https://doi.org/10.24099/vet.arhiv.170509
Novel reassortant clade 2.3.4.4 avian influenza A(H5N5) virus in wild birds and poultry, Croatia, 2016-2017
Vladimir Savić
orcid.org/0000-0003-0398-5346
; Poultry Centre, Croatian Veterinary Institute, Zagreb, Croatia
Abstract
Highly pathogenic avian influenza (HPAI) causes flock mortality as high as 100% in susceptible poultry species but it also poses a threat for humans, particularly viruses of A/goose/Guangdong/96-like (GD/96) lineage. The emergence of novel HPAI viruses in migratory birds is of concern because of the potential for virus spread during migration. In late 2016, novel GD/96 reassortant clade 2.3.4.4 group B avian influenza H5N5 virus was detected in wild birds and domestic poultry in Croatia, concurrently with numerous detections of H5N8 virus of the same clade and group. Sequencing of the full genome of the H5N8 index case isolate (October 2016) and of all three H5N5 isolates (December 2016 -March 2017) has shown that the novel H5N5 reassortant virus most likely emerged as a result of complex reassortment process in Asia from HPAI H5N8 viruses after the later viruses have became established in wild bird population. Concurrent findings of both, H5N5 and H5N8 viruses, at the same locations in Croatia indicate that the H5N5 reassortant virus was introduced from Asia as a subpopulation of H5N8 viruses by the same wild bird flyways. Although the novel H5N5 reassortant virus possesses haemagglutinin of the GD/96 lineage, the virus genome has typical avian virus traits. Apart from mutations T215A in M1 protein and P42S in NS1 protein which are associated to increased virulence in mice, none of the mutations related to increased affinity to human-type (α-2,6) receptors and mammalian host adaptation were found. Nevertheless, the virus poses a serious threat to the poultry industry since high pathogenicity for gallinaceous birds was confirmed by high intravenous pathogenicity index (2.87).
Keywords
influenza; HPAI; H5N5; reassortant; full genome sequence
Hrčak ID:
185569
URI
Publication date:
3.7.2017.
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