Complete analysis of the H5 hemagglutinin and N8 neuraminidase phylogenetic trees reveals that the H5N8 subtype has been produced by multiple reassortment events

Andrew R Dalby

doi:10.12688/f1000research.9261.1

Abstract

The analysis of the complete H5 hemagglutinin and H8 neuraminidase phylogenetic trees presented in this paper shows that the H5N8 avian influenza has been generated by multiple reassortment events. The H5N8 strain does not have a single origin and is produced when the H5 hemagglutinin and N8 neuraminidase re-assort from other H5 and N8 containing strains. While it was known that there had been a re-assortment to incorporate the Guangdong H5 hemagglutinin at the start of the Korean outbreak, the results show that there have also been multiple reassortment events amongst the non-Korean sequences.

Highlights

The H5N8 subtype of influenza A virus was first isolated in Ireland in 19831
The H5N8 hemagglutinin classifications according to the pathogenic H5N1 system Table 1 shows a summary of the H5N8 sequences that are not classified as being members of the 2.3.4.4 clade by the influenza database pathogenic H5N1 classification tool
All of the sequences from the Korean outbreak are classified as part of the 2.3.4.4 clade and this includes many of the 2014 North American sequences but not Californian quail sequence KP101004, which is part of the American non-Guangdong classification

Summary

Introduction

The H5N8 subtype of influenza A virus was first isolated in Ireland in 19831. Until the 2014 outbreak in Korea this was a relatively rare subtype that only occurred sporadically. This Korean outbreak was more sustained and over a much wider geographical region than the earlier outbreaks. The epidemiology of the Guangdong H5 containing H5N8 virus has been investigated extensively[3,4,5,6,7] but there is much less investigation of the subtypes that contain the non-Guangdong H5 which has been the predominant hemagglutinin in North America. The most significant finding from these previous studies is that the H5 Guangdong hemagglutinin has been introduced to North America via bird migratory pathways and that this H5 has not undergone subsequent reassortment into other avian influenza subtypes including H5N2

Methods

Results

Conclusion