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As the graphic above illustrates, there are two basic paths to creating a novel HPAI virus. A normally low path (LPAI) virus - usually H5 or H7 - can enter a poultry flock and mutate into a high path virus, or two compatible flu viruses can swap genetic material (reassort) and create a hybrid.
A little over three months ago we saw Egypt's first (and so far, only) OIE Notification Of A Reassorted HPAI H5N2 Virus, which turned up at a duck farm in Dakahlia governorate.
That announcement followed similar reports from Russia, which in December of 2017 and again in August 2018, reported outbreaks of HPAI H5N2 in poultry farms in Kostroma Oblast.The OIE confirmed that the second Russian H5N2 virus was of clade 2.3.4.4. - which suggested it was a relatively new reassortment - likely from either HPAI H5N8 or HPAI H5N6.
Today we've our first detailed look at the Egypt's new H5N2 virus ( A/duck/Egypt/VG1099/2018), published in the journal Viruses. As with the Russian H5N2, it is of clade 2.3.4.4.More specifically, a reassortant between HPAI H5N8 and LPAI H9N2, both of which - along with HPAI H5N1 - co-circulate in Egypt.
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| https://www.mdpi.com/1999-4915/11/6/565/htm |
While reassortment can occur with just about any influenza A virus, H5Nx subtypes appear unusually agile in this department, and genetic contributions from LPAI H9N2 can be found inside many avian viruses (see PNAS: Reassortment Potential Of Avian H9N2).
While avian flu activity has been somewhat subdued the past year or so, the recent appearance of novel reassortants - like H5N2 in Russia and Egypt, and H7N4 last year in China - are reminders that nature's laboratory remains open 24/7 and that new viruses will continue to emerge and challenge us.I've only posted a few excerpts from today's H5N2 analysis, so follow the link to read it in its entirety.
Isolation of a Novel Reassortant Highly Pathogenic Avian Influenza (H5N2) Virus in Egypt
Naglaa M. Hagag 1, Ahmed M. Erfan 1, Mohamed El-Husseiny 1, Azhar G. Shalaby 1, Mohamed A. Saif 1, Maram M. Tawakol 1, Ahmed A. Nour 1, Abdullah A. Selim 1, Abdel-Satar Arafa 1, Mohamed K. Hassan 1, Wafaa M. M. Hassan 1, Hanan A. Fahmy 1, Essam Ibraheem 1, Mohamed Attia 2, Ali M. M. Abdelhakim 2, Momtaz A. Shahein 1 and Mahmoud M. Naguib 1,3,*
Received: 30 May 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
Abstract
Highly pathogenic avian influenza (HPAI) H5N1 and H5N8 have become endemic among domestic poultry in Egypt since 2006 and 2016, respectively. In parallel, the low pathogenic avian influenza H9N2 virus has been endemic since 2010. Despite the continuous circulation of these subtypes for several years, no natural reassortant has been detected so far among the domestic poultry population in Egypt.
In this study, the HPAI (H5N2) virus was isolated from a commercial duck farm, giving evidence of the emergence of the first natural reassortment event in domestic poultry in Egypt.
The virus was derived as a result of genetic reassortment between avian influenza viruses of H5N8 and H9N2 subtypes circulating in Egypt. The exchange of the neuraminidase segment and high number of acquired mutations might be associated with an alteration in the biological propensities of this virus.(SNIP)
Currently, Egypt faces endemic co-circulation of HPAI (H5N1, H5N8) and LPAI (H9N2) viruses, where a simultaneous detection of the three subtypes has been detected [7]. The co-circulation of those three subtypes raises fears for the generation of a new subtype/genotype with unpredictable properties, including an increased potential threat to human [1].
However, the nucleotide identity and phylogenetic distance of the Egyptian HPAI H5N2 virus (EG-VG1099) virus with other Egyptian HA genes seems low, and it is reasonable to suggest that the new reassortant EG-VG1099 resulted from a reassortant between HPAI H5N8 virus of clade 2.3.4.4 (group B) and the Egyptian LPAI (H9N2) virus of the G1-like lineage (Figure 1C).
This was supported by the phylogenetic relatedness of the NA gene segment with only viruses isolated from Egypt; however, the circulation of an additional variant of H5N8 in Egypt cannot be excluded. So far, no natural reassortant has been detected between the Egyptian H5N1/H9N2 subtypes [21], and the emerged H5N2 virus in this study indicated a higher reassortment compatibility between the Egyptian H5N8 and H9N2 viruses compared to the Egyptian H5N1/H9N2.
However, we cannot exclude the detection of new genotypes with different gene constellations in the upcoming period. This highlights the significance of obtaining the whole genome sequence of the circulating HPAI H5N1/H5N2/H5N8 viruses in Egypt.(Continue . . . )
