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Influenza
Flu in all Forms, Be Informed...Not Panicked.
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Rescooped by Mel Melendrez-Vallard from Virology News
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Potential for H3N2 influenza pandemic

Potential for H3N2 influenza pandemic | Influenza | Scoop.it

The 2009 swine-origin H1N1 influenza, though antigenically novel to the population at the time, was antigenically similar to the 1918 H1N1 pandemic influenza, and consequently was considered to be [ldquo]archived[rdquo] in the swine species before reemerging in humans. Given that the H3N2 is another subtype that currently circulates in the human population and is high on WHO pandemic preparedness list, we assessed the likelihood of reemergence of H3N2 from a non-human host. Using HA sequence features relevant to immune recognition, receptor binding and transmission we have identified several recent H3 strains in avian and swine that present hallmarks of a reemerging virus. IgG polyclonal raised in rabbit with recent seasonal vaccine H3 fail to recognize these swine H3 strains suggesting that existing vaccines may not be effective in protecting against these strains.

 

Vaccine strategies can mitigate risks associated with a potential H3N2 pandemic in humans.


Via Ed Rybicki
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Ed Rybicki's curator insight, May 13, 2013 10:24 AM

No-one think of H3N2...except, as it happens, these folk - who have shown quite convincingly that circulating strains of H3N2 in birds and pigs would be quite capable of avoiding vaccine-conferred immunity, and potentially of causing a pandemic, if they reassorted with human-infecting viruses.  

 

I can't help but feel that there are several ticking influenza pandemic time bombs out there...H5N1, H7N9, and now H3N2.

Rescooped by Mel Melendrez-Vallard from Virology News
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Antigenic Drift of the Pandemic 2009 A(H1N1) Influenza Virus in a Ferret Model

Antigenic Drift of the Pandemic 2009 A(H1N1) Influenza Virus in a Ferret Model | Influenza | Scoop.it

Infection with influenza virus leads to significant morbidity and mortality. Annual vaccination may prevent subsequent disease by inducing neutralizing antibodies to currently circulating strains in the human population. To escape this antibody response, influenza A viruses undergo continuous genetic variation as they replicate, enabling viruses with advantageous antigenic mutations to spread and cause disease in naïve or previously immune or vaccinated individuals. To date, the 2009 pandemic virus (A(H1N1)pdm09) has not undergone significant antigenic drift, with the result that the vaccine remains well-matched and should provide good protection to A(H1N1)pdm09 circulating viruses. In this study, we induced antigenic drift in an A(H1N1)pdm09 virus in the ferret model. A single amino acid mutation emerged in the dominant surface glycoprotein, hemagglutinin, which had a multifaceted effect, altering both antigenicity and virus receptor specificity. The mutant virus could not be isolated using routine cell culture methods without the virus acquiring additional amino acid changes, yet was fit in vivo. The implications for surveillance of circulating influenza virus are significant as current assays commonly used to assess vaccine mismatch, as well as to produce isolates for vaccine manufacture, are biased against identification of viruses containing only this mutation.

 

Influenza virus graphic by Russell Kightley Media 


Via Ed Rybicki
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Ed Rybicki's curator insight, May 10, 2013 12:19 AM

There is a rather disturbing result in this paper: that is, that the mutation in the H1N1 HA that emerged in serial ferret transfers that was responsible for antigenic drift, resulted in a virus that could NOT be cultured by routine methods despite being quite happy in ferrets.  In fact, adapting the virus to culture meant it accumulated MORE mutations, meaning the thing they got out by "current assays" was NOT the same thing that was causing disease.

 

This is worrying for a number of reasons, not least of which is that informed decisions on probable vaccine efficacy are made as a result of such assays - and the vaccines themselves, in some cases.  And if what these decisions are based on is incorrect...?

 

Time for some better science here, people - like next-gen sequencing rather than isolation as a measure of what is causing disease!