Via Emerging Infectious Diseases: Toward a Unified Nomenclature System for Highly Pathogenic Avian Influenza Virus (H5N1). This is an "online report," but the writing style and paragraphing make it almost unreadable on a computer screen. Here's an excerpt, re-paragraphed:
Using the clade designation criteria proposed in Table 1, this study has identified 10 unique first-order numbered clades of the HPAI viruses (H5N1) in the Gs/GD-like lineage (clades 0–9).
The group of HA genes previously designated as clade 2 showed a level of diversity that far exceeds the current definition of a clade; therefore, this group was also separated into 5 additional second-order clades (clades 2.1–2.5).
Clades 2.1 (avian/human isolates from Indonesia) and 2.3 (avian/human isolates from the People's Republic of China; Hong Kong; Vietnam; Thailand; Lao People's Democratic Republic; and Malaysia) were also further delineated into third-order groups (clades 2.1.1–2.1.3 and 2.3.1–2.3.4), respectively.
The origins of isolates belonging to each clade are described in Table 2. For each clade identified, a representative prototype virus is listed to facilitate interpretation of the proposed numbering system (Table 2).
As other studies have shown, the primary clade defining factor appears to be spatio-temporal because most distinct clades consist of isolates within close geographic proximity to one another or from specific time periods (perhaps as a result of heightened transmission during outbreak periods) (2–7).
Notably, clade 2.2 comprises isolates from more widespread geographic areas (3 continents), which is likely to reflect movement of the virus through long-distance spread as a result of poultry trade or wild bird migration (2,3,6,7).
The evolution of the H5 HA in avian hosts shows a notable difference from the typical evolution of HA genes from human influenza viruses. The evolution of the H3 HA since 1968 is characterized by a limited diversity among circulating strains. This lack of diversity is clearly the consequence of rapid extinction after the emergence of new clades and lineages.
As expected, the evolutionary tree of human influenza HA genes has extended trunks and extremely short branches (14,15). In contrast, multiple avian influenza A HA clades continue to evolve and co-circulate in different regions and species; hence, the unprecedented need for a nomenclature system that has been unnecessary for human influenza genes.
The results from this study indicate that the HPAI H5N1 viruses can be grouped into several clades designated by a numbering system that can continue to be expanded as these viruses continue to evolve.
By establishing this nomenclature system and guidelines for naming clades, this information can be used in the future as criteria for assigning new clades as new lineages of HPAI H5N1 variants emerge.
I admit I'm grinding an axe here: My interest in effective writing and text display on websites makes me biased. No doubt some specialists would cruise right through the text as displayed on the EID website. But many more would probably print off the article to make it easier to read and understand.
And for most of us hapless non-experts, presenting technical information in such a format makes it almost inaccessible. If the experts really want the public to understand the problem, they should bear that in mind.
