The World Health Organization has declared that the world is now at the start of an influenza pandemic. WHO Director-General Dr. Margaret Chan said today:
I have conferred with leading influenza experts, virologists, and public health officials. In line with procedures set out in the International Health Regulations, I have sought guidance and advice from an Emergency Committee established for this purpose.
On the basis of available evidence, and these expert assessments of the evidence, the scientific criteria for an influenza pandemic have been met.
I have therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6.
The world is now at the start of the 2009 influenza pandemic.
The illustration below will need to be modified for the next edition of my textbook. This week’s pop quiz: What should be the origin of the 8 RNA segments of the 2009 H1N1 pandemic strain? Here is a larger version of the image if you subscribe to the adage that a picture is worth a thousand words.
http://www.nature.com/nature/journal/vnfv/ncurr…
Although the Nature paper revealed several HK swine H1N2 isolates had “very” close relationship with current pandemic H1N1, the closest whole genetic counterpart in pig population still not found worlwide. If this virus is really evovled from the pig population, routine veterianry diagnosis section or even CDC section can detected it before the pandemic. H2N3 has been detected recently (PNAS) as well as human infection with triple reassortant virus. Thus, the real origin of this H1N1 is till elusive, unless the non-reassortant intact virus was found virologically or serologically from unkonwn host (probably pig or human).
PIGS
OK- here’s my attempt based on the diagram in the new Nature paper:
(1) PB1 should be blue (the same as the PB1 from the H3N2 human seasonal on your existing diagram).
(2) H1, N1, NS and NP are all new to your diagram and are from ‘H1 N1 classic swine’. You could perhaps use shades of porky pink for these RNA segments… and I guess you’re going to need to add at least one schematic pig, or perhaps even two schematic pigs because…
(3) The M and N1 come from ‘H1 N1 Eurasian ‘avian-like’ swine’ which its self has origins in an earlier purely avian H1 N1 from which the PB2 and the PA also appear to originate. I’m not sure if any of these (M, N1, PB2 or PA) can be directly equated with any of the avian segments on your existing pandemic diagram.
However, this glosses over the triple reassortant, and to do that justice you’d need a ‘mixing pig’ with avian and human inputs… and then subsequent replacement of the human H3 and N2 with the ‘original’ porcine H1 and N1… and then add a dash of replacement M and N1 from ‘Eurasian avian like swine’ (a different pig input, though ultimately derived from the original avian source that created the triple reassortant in the first place)… and I’m not sure we are even sure the final bit of the mix happened in a pig- could possibly have been in a human?
All I can say is I’m glad I’m not the one having to re-do your diagram.
V, you need a new animal icon to represent a new “species” – swimanavians! Picture an Egyptian like icon: A human torso with the head of a pig and wings like a bird and feet like a duck!!
I think the 1998 reassortant/recombinant(?) virus in pigs changed the paradigm. Even more so, maybe that has been going on for 10,000 years… It was nice and cosy when “swine influenza” was H1N1, but that changed.
No doubt the rapid and ready availability of sequence information has aided in detecting these changes, but, of course they may have always been the rule. Perhaps we need to change the way we think about influenza virus in terms of avian, human, swine, etc., and focus on the dynamics.
Linear thinking about consensus sequences and linear thinking about branched trees based on consensus sequences are all fine and dandy – they generate the models for testing ideas and theories.
But, in reality, we know that viral adaptation and evolution is a “random walk in fitness n-space.” What happened in 1998 in pigs, happened because it could! What happened in 2009 in humans happened because it could! What happens next is a “random walk”.
How to teach that concept? I don't know. But, it needs to be introduced someway and let those young ones figure it out with their creative minds.
Good luck!
You could add a new illustration, one that involves a duck rudely sneezing on a pig which in turn coughs all over a frustrated farmer. Title: Coughs and sneezes spread pandemics
Vincent – your answer with illustration for your textbook can be found here: http://tree.bio.ed.ac.uk/groups/influenza/wiki/…
Vincent – your answer with illustration for your textbook can be found here: http://tree.bio.ed.ac.uk/groups/influenza/wiki/…
Looks like you’ve done your research very well.