Comments on: Influenza: Our Incompetent Enemy

By: gsgs

gsgs — Sat, 02 Mar 2013 14:54:30 +0000

> it spreads because—surprisingly—its presence causes functional dengue
> viruses to transmit more efficiently

http://newsroom.ucla.edu/portal/ucla/defective-virus-surprisingly-243742.aspx

maybe an interesting followup story to write about …

By: chris

chris — Mon, 28 Jan 2013 00:35:52 +0000

the later experiments using the california/09 and new caledonia/99 strains suggest that the effect is not an artifact of using lab strains, though it remains to be seen what unpassaged natural isolates would look like.
the image shown in figure 5 tries to show that productive and non-productive infections are clearly identifiable by eye, despite the seemingly arbitrary 2 cells vs. 3 cells cut-off.
it will be interesting to see the effect of this on mixing between different strains.

By: Dan Smith

Dan Smith — Wed, 23 Jan 2013 09:07:37 +0000

The tenfold variation in the percentage of non-propagating infections in the paper does rather suggest this might be a lab strain artefact. I am dubious about counting foci and surrounding cells by eye and declaring two adjacent infected cells an example of failure to propagate while three is not. However, it is tempting to think that establishing a latent infection which can be complemented later by different strains might contribute to the comparative ease with which influenza A can jump species barriers.

By: Sharon

Sharon — Tue, 22 Jan 2013 12:04:31 +0000

My grandmother was 23 with 3 small children when she died in 1918. The virology is interesting to me as a non-scientist, but ultimately interesting to me as a person who didn’t have a grandma. We need to also consider the human aspect of it. By the way, it was common to take photographs of people in their coffins in those days. Besides my grandmother’s wedding picture, the only other one I have is her in the coffin with her three small children standing beside it, looking bewildered.

By: Wayne RB Tod

Wayne RB Tod — Wed, 16 Jan 2013 20:21:25 +0000

It’s the simplicity of lifes Questions that we are not prepared to accept! (John F K) The R Ready”
Life iz but a simple Question you ask & you will an. Knew understanding is the only way to make up times lost. Open Knowledge by way of you

By: Donald Kelmers

Donald Kelmers — Wed, 16 Jan 2013 18:17:34 +0000

I remember reading a few years ago that one of the mysteries of the 1918 pandemic was that the new virulent flu appeared almost simultaneously in America, Europe, India and Australia. Travel at that time was by steamship, thus intercontinental spread by infected persons could not explain the near simultaneous appearance of the disease. What are your thoughts on this issue?

By: Elizabeth Mabugay

Elizabeth Mabugay — Wed, 16 Jan 2013 13:21:29 +0000

It’s ‘flu alert’ here in the Philippines and airport officials are closely monitoring arriving passengers for flu and flu-like signs and symptoms. Sweeter it is to see people cooperating to overcome their collective weakness against an unseen enemy.

Ooooppss, seems to me there’s some ‘deletion-mutation’ here: Nobody knows the success rate for this step of influenza infection is ?

By: zmil

zmil — Wed, 16 Jan 2013 03:31:47 +0000

High numbers of apparently defective particles are not found in all viruses, but it is a fairly common phenomenon, especially in RNA viruses- mumps, for example, and, IIRC, many retroviruses.

What’s different here, it appears to me, is that they’ve demonstrated that a large percentage of the particles that would be classified as ‘non-infectious’ by a traditional plaque assay are in fact capable of producing proteins and even particles- it’s just that, since they are missing a protein, without the help of other particles that do have that protein, they will be unable to spread beyond that single, initially infected cell, and thus will not produce a visible plaque.

At high multiplicities of infection, when there are tons of other particles around, this could change the dynamics of the infection significantly- the percentage of infectious particles could increase greatly, because all the defective particles are able to help each other out by genetic complementation.

By: Paul Lund

Paul Lund — Wed, 16 Jan 2013 00:41:14 +0000

the following should read with ‘continuous’…”Rather than being one continue string of genetic material, the flu virus genome…”

By: Hal

Hal — Tue, 15 Jan 2013 14:00:13 +0000

Mike, the thought on the virulence of the 1918 flu was that, yes, it caused cytokine storm. The spread of the disease is credited to wartime travels as well.

There is no real consensus as to what distinguishes strains of the flu that cause cytokine storm in young, but not very young, patients.