Evolutionary theory would not favor the view that swine adapted influenza never existed before then or first reassorted in 1918. This is supported by the observation that influenza B and C viruses do not occur in birds and C viruses are isolated from pigs and dogs, which indicates that these diverged a very long time ago from the primary avian strains. (See: pg 166 on origins.) That indicates that multiple “cycles” of crossover from avians into mammals have occurred in the past, with the crossover viruses adapting to their hosts. It is doubtless the case that most of those crossovers went extinct, thus B and C strains of humans are relics of past events.

So I don't think anyone can say for absolute certain one way or another, only infer from phylogenetic evidence, and negative phylogenetic evidence is weak with influenza because of the high probability that lineages can die out, particularly when there were fewer people and pigs and those populations had poorer interaction networks.

My view is that water birds and other fowl have been infecting pigs with influenza for thousands of years in human communities. The fact that water where waterbirds live can be laden with influenza viruses and that those viruses can remain infectious for long periods in water, dependent on salts, pH and temperature, strongly indicates that the conditions have existed for influenza transmission to pigs anywhere that pigs were kept as livestock in human history. (I believe not keeping pigs as livestock has bearing on the immunological evolution of Native Americans relative to influenza.)

Evolutionary theory would not favor the view that swine adapted influenza never existed before then or first reassorted in 1918. This is supported by the observation that influenza B and C viruses do not occur in birds and C viruses are isolated from pigs and dogs, which indicates that these diverged a very long time ago from the primary avian strains. (See: pg 166 on origins.) That indicates that multiple “cycles” of crossover from avians into mammals have occurred in the past, with the crossover viruses adapting to their hosts. It is doubtless the case that most of those crossovers went extinct, thus B and C strains of humans are relics of past events.

So I don't think anyone can say for absolute certain one way or another, only infer from phylogenetic evidence, and negative phylogenetic evidence is weak with influenza because of the high probability that lineages can die out, particularly when there were fewer people and pigs and those populations had poorer interaction networks.

My view is that water birds and other fowl have been infecting pigs with influenza for thousands of years in human communities. The fact that water where waterbirds live can be laden with influenza viruses and that those viruses can remain infectious for long periods in water, dependent on salts, pH and temperature, strongly indicates that the conditions have existed for influenza transmission to pigs anywhere that pigs were kept as livestock in human history. (I believe not keeping pigs as livestock has bearing on the immunological evolution of Native Americans relative to influenza.)

http://public-healthcare-issues.suite101.com/ar…

Then there's the 10 year study of children with asthma (link above) that showed increased hospitalizations for ILI with asthmatic children who had received seasonal flu shots vs. those who had not. Could development of heterosubtypic immunity be relevant in these cases as well?

Wonder if this will be investigated further…

I'm curious how this might interact with getting the Flumist instead of the inactivated vaccine. On one hand, my CTLs might suppress the infection too fast because it recognizes the similar protein fragments from previous infections. On the other hand, the live virus can give me an effective CTL response for the next time I'm exposed.

http://www.freepatentsonline.com/y2009/0010962….

http://www.youtube.com/watch?v=KmhREAMmfhg&hd=1

This post was mentioned on Twitter by profvrr: Being older is a good defense against 2009 H1N1 influenza virus http://bit.ly/45JNqH at virology blog #h1n1 #swineflu…