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TWiV 148 Letters

Ed writes:

Gentlemen, I think you'll find that Dylan Thomas was Welsh, not Irish. Though you are of course correct on his penchant for writing and


Josh writes:

Dear TWiV Doctors,

I have one question and one comment about your section on the DRACO broad spectrum antiviral:

This might be a stupid question, but: Would not this antiviral interfere with the normal body microbe population by destroying unknown virus activity that we might need to live?

My comment:

Given your comment about the Lincoln Lab at MIT being involved with the Defense Department, wouldn't this be the antiviral compound you would come up with if you wanted to treat the victims of a bioterrorism attack? I mean, the problem of treatment timing doesn't fit a normal clinical situation (because when they came in they'd probably be on the downside of it), but it does fit a situation where you know that large numbers of people are exposed at the same time. If you suspected that you had been attacked that way, this antiviral would fit the bill. Of course, this assumes you would know that you have been/are being attacked this way, but that's a different subject.

What do you think? Am I off in space on this one?

Great show as always,


Alberto writes:

Hi Twivers,

Here's a story from 2 years ago covering the release of mosquitoes in Queensland following on from your recent episode regarding control of Dengue Fever. It contains some great images of the release trial and the mosquito breeding cages.




Lance writes:

You've probably seen this already and I've missed yesterday's TWiV, but the second item (influenza reassortant) is really interesting and it would be good to hear what you think about it.

I've not heard about this happening much or even at all like this - my question is why isn't this more common?

Thanks for all the great work,


Wellcome Trust Clinical Fellow



A ProMED-mail post


Date: Wed 8 Jun 2011

From: Jonathan Gubbay < This email address is being protected from spambots. You need JavaScript enabled to view it. > [edited]

Reassortment following coinfection with seasonal H3N2 and pandemic

(H1N1) 2009 viruses in Ontario, Canada

- ----------------------------------------------------------------------

A 16-month-old infant was admitted to a Greater Toronto Area Hospital on 24 Jan 2011 with respiratory and gastrointestinal symptoms. After 15 hours, he was discharged home and subsequently recovered uneventfully. 2 nasopharyngeal swabs were collected on the day of admission and sent to the Ontario Agency for Health Protection (OAHPP) Public Health Laboratories (PHL) for influenza testing by real-time reverse transcriptase PCR (rRT-PCR). Influenza A [virus] was detected in both specimens by rRT-PCR, and when subtyped were positive for hemagglutinin (H3) gene in a moderately high copy number (cycle thresholds 29 and 31). They were also noted to be positive for the pandemic (H1N1) 2009 (pH1N1) neuraminidase (NA) gene at a very low level (CT values 38 and 39), which was detected using an in-house rRT-PCR (1). Suspecting contamination, primary samples were reextracted and retested; identical results were obtained.

Further sequencing confirmed presence of the following genes in the primary samples:

A. Pandemic H1N1 2009 genes: Matrix, NS, H1, N1 (H1 sequencing was conducted on one primary sample only)

B. Seasonal H3N2 genes: N2 (H3 sequencing was not conducted on either primary sample)

The 1st specimen underwent conventional viral culture in rhesus monkey kidney cells. Whole genome sequence analysis of cultured material showed that the isolate possessed H3 and N2 of seasonal H3N2 in combination with PB2, PB1, PA, NS, NP, and M of pandemic H1N1. Gene sequences obtained in culture and primary specimen were identical. A BLAST [basic local alignment search] was conducted against sequences available in GenBank. The H3 and N2 gene sequences most closely matched the currently circulating A/Perth/16/2009 strain.

The matrix and NS genes amplified from the primary sample were identical to currently circulating pH1N1, most closely matching the A/California/07/2009 strain.

Canada's National Microbiology Laboratory performed plaque forming assays on the primary sample and culture material using Madin-Darby canine kidney cell lines. Sequencing of individual plaque material in both primary sample reconfirmed a reassortant virus as described above, with no evidence of the HA and NA genes of pH1N1. In addition, gene sequences obtained in both plaque assays matched each other, and were also identical to those obtained at OAHPP. The isolate strain type was A/Perth/16/09 (H3N2) by hemagglutination inhibition assay.

Summary and implications


This case represents coinfection with H3N2 and pH1N1, followed by reassortment in the patient (in vivo reassortment). The low level of pandemic H1N1 2009 NA gene in the primary sample indicates that the reassortment occurred in the child and the lab detected a remnant of NA left behind. If it were just coinfection but not reassortment, we would have expected to find evidence of H3N2 viral genes other than H3 and N2 in the primary sample. The subsequent reassortant virus consisted of HA and NA of H3N2 together with the remaining 6 genes (PB2, PB1, PA, NS, NP and M) of pH1N1.

To the best of our knowledge, this is the 1st case of reassortment involving pH1N1 and seasonal H3N2. We could not document any transmission of this reassortant, which arose during a confection involving both subtypes. In a recent study reverse genetics was used to generate a laboratory reassortant of this type -- infection of ferrets with this reassortant resulted in higher levels of virus and more severe respiratory damage when compared to wild-type pH1N1 (2).

This case and the 5 reports of human infection with swine triple reassortant H3N2 in the United States since September 2010 highlight the need for ongoing molecular and phenotypic surveillance for novel influenza strains (3).

- --

[ProMED-mail is indebted to Dr Gubbay and colleagues for drawing the attention of readers to the outcome of an investigation which has established that the coinfection of a child with pandemic H1N1 and seasonal H3N2 influenza viruses in the Toronto area was accompanied by genome reassortment in the patient ( _in vivo_ reassortment). A recombinant (reassortant) virus was recovered from the patient possessing the external protein genes of the H3N2 influenza virus and the internal protein genes of the pandemic H1N1 influenza virus.

During the 2010/2011 influenza epidemic season in North America both the seasonal H3N2 and the pandemic H1N1 viruses have been prevalent and the occurrence of coinfection is not surprising, but this appears to be the 1st demonstration of _in vivo_ reassortment. Fortunately the infected child has recovered and the recombinant (reassortant) virus was not transmitted. It remains to be seen whether this or similar reassortants will appear in subsequent epidemics. - Mod.CP]

Ruth writes:

Dear Vincent & twiv virologists,

I very much enjoy listening to Twiv and find your outlook on topical virology issues both refreshing and extremely interesting. Thank you so much for this!

I am a University teacher in Virology at The University of Glasgow, Scotland. We have recently received MRC funding for a new Virology institute that is currently being built on our Garscube campus and there is a wealth of exciting Virology research going on in Glasgow. I am involved in Virology undergraduate teaching here and my students listen to your podcasts. I am always on the lookout for novel teaching aids for virology and wonder if you can recommend any?

We have your textbooks already, they are excellent!

I appreciate that you are very busy, however I hope that you can recommend something new/fresh to me. Our students receive lectures & tutorials and they read the literature and present virology topics in a number of formats ( projects, dissertations and posters ).

I am looking for some new ideas and have a small budget for this (£600) and am considering developing some good quality teaching software myself, pitched for senior undergraduates .

Please let me know if you can recommend any good teaching resources for virology.

Thanks in advance for your time.

Your sincerely,


Kristina writes:

Hi There,

RNA viruses are the cause of so much human suffering. Most often we are presented with estimations of morbidity and mortality for individual viruses, but I've never seen a figure for RNA viruses (or DNA viruses) as a whole. Do you have an estimate?


Jenny writes:

Hi TWIV-casters!

I've been a listener to TWIV for a while, and I can't tell you how enough how much I enjoy listening to your podcast.  I'm a graduate student working on immune responses to influenza and it is a wonderful addition to my education.  I usually listen to TWIV while working in the hood or doing my runs or doing chores at home, allowing me to use my time wisely.  Anyways, I came upon this review of a book by Carl Zimmer, maybe you could feature it on your picks of the week.  I haven't read it yet, but it looks to be an interesting read.  Here is the link to the book review in PLoS Biology:http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001139.

Thanks so much for all the work you do!  I enjoy the witty banter and the geeky punchlines too.  Who knew listening to a virology podcast can make you laugh out loud?  More power!



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