Origins of the 1918 Pandemic: Revisiting the Swine ?Mixing Vessel?

[gsgs]

Nelson, Worobey
manuscript

Abstract

How influenza A viruses host-jump from animal reservoir species to humans to initiate global
pandemics is a central question in pathogen evolution. The zoonotic and spatial origins of the
1918 ?Spanish influenza‟ pandemic virus have been debated for decades. Outbreaks of
respiratory disease in US swine occurred concurrently with disease in humans, raising the
possibility that the 1918 virus originated in pigs. Swine also were proposed as ?mixing vessel‟
intermediary hosts between birds and humans during the 1957 ?Asian‟ and 1968 ?Hong Kong‟
pandemics. Swine have presented an attractive explanation for how avian viruses overcome the
substantial evolutionary barriers presented by different cellular environments in humans and
birds. However, key assumptions underpinning the swine ?mixing vessel‟ model of pandemic
emergence have been challenged by new evidence. Increased surveillance in swine reveals
that human-to-swine transmission actually occurs far more frequently than swine-to-human
transmission, and there is no empirical evidence that swine played a role in the emergence of
human influenza in 1918, 1957, or 1968. Swine-to-human transmission occurs periodically and
can trigger pandemics, as in 2009. But swine are not necessary to mediate the establishment of
avian viruses in humans, inviting new perspectives on the evolutionary processes underlying
pandemic emerge


https://academic.oup.com/aje/advance...kwy150/5059949

found with keywords while searching for the Murray paper
not found at FT with those keywords

 

[gsgs]

Nelson, Worobey
manuscript

Abstract

How influenza A viruses host-jump from animal reservoir species to humans to initiate global
pandemics is a central question in pathogen evolution. The zoonotic and spatial origins of the
1918 „Spanish influenza‟ pandemic virus have been debated for decades. Outbreaks of
respiratory disease in US swine occurred concurrently with disease in humans, raising the
possibility that the 1918 virus originated in pigs. Swine also were proposed as „mixing vessel‟
intermediary hosts between birds and humans during the 1957 „Asian‟ and 1968 „Hong Kong‟
pandemics. Swine have presented an attractive explanation for how avian viruses overcome the
substantial evolutionary barriers presented by different cellular environments in humans and
birds. However, key assumptions underpinning the swine „mixing vessel‟ model of pandemic
emergence have been challenged by new evidence. Increased surveillance in swine reveals
that human-to-swine transmission actually occurs far more frequently than swine-to-human
transmission, and there is no empirical evidence that swine played a role in the emergence of
human influenza in 1918, 1957, or 1968. Swine-to-human transmission occurs periodically and
can trigger pandemics, as in 2009. But swine are not necessary to mediate the establishment of
avian viruses in humans, inviting new perspectives on the evolutionary processes underlying
pandemic emerge


https://academic.oup.com/aje/advance...kwy150/5059949

found with keywords while searching for the Murray paper
not found at FT with those keywords
> Overall, the most parsimonious explanation is
> that the genes of the 1918 virus transmitted largely from birds to humans at the start of the
> pandemic, and from humans to swine once the pandemic was widespread in humans, with no
> role played by swine in the origins of the human pandemic (24,29).

24. Worobey M, Han G-Z, Rambaut A. A synchronized global sweep of the internal genes of
modern avian influenza virus. Nature 2014; 508(7495):254-257.
29. Worobey M, Han G-Z, Rambaut A. Genesis and pathogenesis of the 1918 pandemic
H1N1 influenza A virus. Proc. Natl. Acad. Sci. U.S.A. 2014;111(22):8107?8112.
[I remember, those papers were discussed here at FT in 2014]


>An earlier paper positing a
>swine-human reassortant origin of the 1918 virus and decades of mammalian circulation prior to
>the pandemic (8) appears to have been affected by biologically unrealistic sampling times of
>post-1977 human H1N1 strains, which do not account for the missing decades of evolution
>(1957-1977) when the lab escape virus had likely been kept in a freezer (30).

(8) Smith GJD, Bahl J, Vijaykrishna D, et al. Dating the emergence of pandemic influenza
viruses. Proc. Natl. Acad. Sci. U. S. A.2009;106(28):11709?11712.


this, if valid is only a small part of the 2009-Smith paper and doesn't explain
the other findings, which IMO explain the pre-1918 origin of most segments
of the human and swine lineages.
It is petty clear, that the swine H1N1 does not descend from the 1918-human virus,
nor a human virus from >1915


see this thread :
https://flutrackers.com/forum/forum...kroom/77175-re-don-t-blame-birds-for-1918-flu




>> Exceeded the time limit on editing of topic title

ahh, I can no longer edit posts now as before ?!?

 

[sharon sanders]

Gsgs - Add a new post to edit past posts. This way people know there was an edit. Otherwise, people do not know to look at the thread again for updates.

 

[gsgs]

yes, when there is something new. But for correcting typos, rearranging, adding mibor things ,
updating links and such it would just give a mess with all the new posts.
The first post is just a "draft" ... then improved later ?!?