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Review
. 2019 May 29;7(6):156.
doi: 10.3390/microorganisms7060156.

The Emergence and Decennary Distribution of Clade 2.3.4.4 HPAI H5Nx

Khristine Joy C Antigua  1 , Won-Suk Choi  2 , Yun Hee Baek  3 , Min-Suk Song  4
Affiliations
Review

The Emergence and Decennary Distribution of Clade 2.3.4.4 HPAI H5Nx

Khristine Joy C Antigua et al. Microorganisms. .

Abstract

Reassortment events among influenza viruses occur naturally and may lead to the development of new and different subtypes which often ignite the possibility of an influenza outbreak. Between 2008 and 2010, highly pathogenic avian influenza (HPAI) H5 of the N1 subtype from the A/goose/Guangdong/1/96-like (Gs/GD) lineage generated novel reassortants by introducing other neuraminidase (NA) subtypes reported to cause most outbreaks in poultry. With the extensive divergence of the H5 hemagglutinin (HA) sequences of documented viruses, the WHO/FAO/OIE H5 Evolutionary Working Group clustered these viruses into a systematic and unified nomenclature of clade 2.3.4.4 currently known as "H5Nx" viruses. The rapid emergence and circulation of these viruses, namely, H5N2, H5N3, H5N5, H5N6, H5N8, and the regenerated H5N1, are of great concern based on their pandemic potential. Knowing the evolution and emergence of these novel reassortants helps to better understand their complex nature. The eruption of reports of each H5Nx reassortant through time demonstrates that it could persist beyond its usual seasonal activity, intensifying the possibility of these emerging viruses' pandemic potential. This review paper provides an overview of the emergence of each novel HPAI H5Nx virus as well as its current epidemiological distribution.

Keywords: H5Nx; avian; avian influenza; dissemination; epidemiology; evolution.

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Conflict of interest statement

The authors declare no conflict of interests.

Figures

Figure 1
Figure 1
H5Nx timeline of evolution and continuous emergence (2008–2018).
Figure 2
Figure 2
Distribution of reported H5Nx occurrences in various regions per specific period: (A) 2008–2013, (B) 2014, (C) 2015, (D) 2016, (E) 2017, and (F) 2018. Red pins in the map denotes a record of confirmed reported occurrence of H5Nx in the specified area. The map was generated using the collated reports recorded in the database of the Food and Agriculture Organization (FAO)’s Global Animal Disease Information System, Empress-I (http://empres-i.fao.org/eipws3g/) and was mapped using Maptive® (https://www.maptive.com/), an online mapping software utilizing Google Maps.
Figure 3
Figure 3
Epi curve of the cumulative sum of mortalities a recorded due to H5Nx from 2008 to June 2018. The data were generated based on the downloaded data from the FAO’s Global Animal Disease Information System, Empress-I (http://empres-i.fao.org/eipws3g/) [58]. *** For 2018, it should be noted that some of the poultry mortalities from the African region in 2018 were not all reflected from the collated Empress-I data. a Cumulative poultry mortalities is the total sum of all the mortalities including the number of dead, slaughtered, and destroyed due to the specified disease cause during the specified period.
See this image and copyright information in PMC

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