Robin writes:

Symptoms in tobacco plants:

Tobacco, and other plants and most animals have no symptoms: they cannot communicate in human language.

Chimpanzees using sign language may be an exception.

Hand washing isn’t just for viruses. One of the big ones is Clostridium difficile. Alcohol etc. for hand sanitation doesn’t do diddly-squat to its spores. Foam hand cleaners just move the spores around on the hands.

TWIV 300 topic: Norovirus.

The “CH”-47 is still the cargo helicopter. The only time I got airsick was in BOAC (back of a Chinook). I personally liked the CH-54 Skycrane.

The Huey is retired from the Army. It was the primary chopper in my time, just after Vietnam.

Keith writes:

Dear TWIVadventurers,

Regarding your discussions prompted by the report of a plant virus in honeybees on TWIV #271, there was discussion about viruses switching or jumping between host kingdoms. Although comments toward the end of the episode acknowledged there were examples of viruses infecting both plants and animals, I thought a few additional comments might provide perspective.

Viruses infecting plants and animals (e.g. insects) are not uncommon. In fact they are globally distributed and in some cases relatively common. As recognized for decades (and mentioned toward the end of the episode) there are plant viruses classified as members of the families Reoviridae (currently 13 species) Rhabdoviridae (currently 19 species) and Bunyaviridae (currently 8 species). These are viruses that replicate in both plant hosts and in the insect vectors that facilitate their transmission from plant to plant. In fact, the plant bunyaviruses are one of the two most important groups of emerging plant viral pathogens, causing agricultural problems in plants and replicating in insects all over the world. There are also bunya- and reoviruses that infect mammalian hosts and replicate in insect vectors (e.g. Rift Valley fever virus in mosquitoes, Bluetongue virus in midges). The missing link is that of extant viruses that infect both mammals and plants; I do not believe there are any substantiated examples of this. Nonetheless, insects would seem to be an obvious evolutionary bridge that might have facilitated viruses moving from plants to mammals or from mammals to plants. In contrast to the evolutionary time scales in which such movement between kingdoms might take place, examples wherein the terms host switching or jumping are apropos would seem to be occurring in more recent time frames (years to decades). Should you or listeners know of any examples of kingdom switching on a more recent time scale, please share them.

Regarding the discussion of Tobacco ringspot virus being found in honeybees, an association is not at all surprising given that this virus and other members of the same group (nepoviruses) have been observed within pollen and in some cases reported as transmitted via pollen. Depending on the time of year and location, it might be arguably more surprising not to find this virus associated with honeybees. That said, the idea of any more intimate association of tobacco ringspot virus with bees or an ability of bees to support replication of the virus is quite intriguing. In spite of any limitations you found in the methods and conclusions, this paper was provocative and made for a great TWIV segment.


Keith L. Perry, Associate Professor
Henry and Mildred Uihlein Professor of Plant Pathology
Director, New York State Foundation Seed Potato Program
Department of Plant Pathology and Plant-Microbe Biology
Cornell University

Mark writes:

Hello to the TWiV Team,

I very much enjoyed episode 271 – “To bee, or not to bee, that is the infection.” I’ve been listening since Spring 2009. One of my familiar “friends” on TWiV has been stories about bees and colony collapse syndrome. Your stories have provided fodder for my lunchtime discussion with a colleague and friend who used to harvest bee colonies in Kent, England before moving to Silicon Valley. One thing I learned from him is that when colonies are moved and deposited in neutral area so that the hive can rest that the distance should be over 5 miles from the prior location otherwise the bees can get disoriented based on their “memories” of their hive’s location. Moving the hive less than 5 miles causes bee death due to stress and confusion resulting from disorientation relative to where the hive should be.

Last Sunday afternoon — it was overcast and an a balmy 58F for much of central/northern California — I was listening to TWiV during a weekend get-a-way on California’s Central Coast. I intently listened to the discussion about virus jumping from plant to bee. During my drive, various photo opportunities presented. I took the attached picture on my iPhone out of the window. Feel free to use this in a blog post.

Shortly after hearing D-D-D mentioned that a hive is valued at $5,000, I drove past this, to me, familiar site: a few dozen bee hives placed adjacent to a meadow for winter rest. You can see the hives in a line in the attached photo, with cows & calves in the foreground. The following Monday, I drove by this same area in the early morning to return to Silicon Valley, and to my surprise *all* of the hives had been moved. Is it coincidence, or does the TWiV audience include thieves — dare we call them “bee rustlers” — who learned the value of the hives from listening to your show?

Adieu and adios.


Timo writes: 

Dear Twiv-Team,

Rhanks for the great show! I found this article about a retroviral insert that serves as an enhancer for a human gene involved in CNS development. It really reminds me of the syncytin story! If you haven’t done it so far (I still have to catch up with the more recent Twivs) you could discuss the article in one of the future episodes.

Best wishes

Sandra writes:

Dr. R: I don’t follow Chelsea Clinton on Twitter, but Scientific American retweeted this. I would love to share it with the TWiV and TWiM panel but don’t know how so I am sending it to you:

Chelsea Clinton @ChelseaClinton
Its hard to imagine what we can’t see. If we want more women in science, its vital to provide dynamic female examples.

The link is to Scientific American website, podcast titled “Women Physicists Keep Female Students Psyched”

I have seen quite a few articles over the last few years about women not being treated equally in scientific occupations (academia and private sector.) As a result, it is refreshing to hear women on TWiV and TWiM podcasts, and also to hear the occasional comments made about women in science.

I almost used “Vincent” instead of “Dr. R” at the top of this email. Listening to TWiV and TWiM for months has made me feel almost as if I know you because I feel that I get to “hang out” with you and the other scientists and listen to you talk about science.

I very much appreciate the time and effort all of you put into these podcasts. Here are the things that make them great, for me:

1. While all of you are very knowledgeable and clearly have your own opinions, none of you ever come across as pretentious. The respect you show for the unique backgrounds of everyone on the show (including guests) and willingness to consider alternative explanations is refreshing. You all very clearly delight in learning new things.

2. Along those lines, I appreciate it when you and your guests state the things that aren’t yet known about subjects. Surely this is inspiring for young scientists. For those of us who are not young or scientists, it gives us a better understanding of each subject to learn:
– what is believed to be “known” (subject to new science disproving it)
– various ideas about the things that are uncertain
– the questions still to be answered on a particular subject

3. When someone says something humorous it is usually humorous in a witty or intelligent way (and yes, I even enjoy Alan/Dr. Dove’s humor.)

4. The podcast isn’t cluttered with jarring sound effects. Neil DeGrasse Tyson (spelling?) is a fascinating scientist, but I cannot bear to listen to his podcasts as they are noisy, his sidekick seems (to me) to add no value, and the humor is quite forced/artificial.

5. None of the subjects ever has anything whatsoever to do with what I do for a living or my educational background – which makes every episode fascinating.


Sandra in Dallas

Nicola writes:

Greetings TWIV team,

As a retired botanist who is just now able to indulge my longtime fascination with human virus, I am thrilled to discover TWIV, TWIM, TWIP. Thank you all for these valuable podcasts. I have before me a long, plantless winter, just right for catching up on all the podcasts. Please forgive how basic these questions are but I find a lot of contradiction in the medical sources:

1. Is there a difference between “a cold” and “the flu” besides severity of symptoms, which is so subjective and so variable from one individual to the next? Is a rhinovirus a flu or a cold?

2. Is it possible to become infected with the same strain of a virus more than once? My doctor says, Of course! and yet she wants me to have a flu shot, which strikes me as contradictory. I thought the premise of a flu vax was to have an exposure that would prevent a subsequent exposure (assuming we are talking about the same strain). In reading Dr. Racaniello’s blog it sounds as though reinfection would be a very rare event indeed.

3. As a botanist I have long been aware of the effects of pH in plant growth and plant pathogens and have for more than 30 years been a lonely proponent of immediately using large doses (500mg/hour) of ascorbic acid to diminish upper respiratory symptoms. This claim was a source of much laughter from the family members who are in medical fields . Based on the following studies, is there a chance of my being vindicated in my lifetime?

Framingham, MA (where it is 0 degrees F; –18 C and 28% relative humidity)

Judi writes:

To the assorted twivers…

as usual, thanks for all you do — I learn so much.

Here is a potential listener pick — some great visuals and explanations thanks to Howard Hughes Medical Institute.

now for a quick question…
I want to bring some virology into my advanced science classroom. I think students should learn to love plaque assays like you do.
so – is there a safe virus that plaques that I can use in high school and where could I get it? I thought about SV40 or GT11 – my favorites from my biotech years in the 80s – but I am having trouble finding a reasonably price source. Maybe T4?

I would appreciate your thoughts, your ideas, and any suggestions on protocols.

Again, thanks for being my professional development for high school….

High School Science Teacher and devoted follower

Lance writes:

Dear Vincent, Rich, Kathy, Alan and occasionally Dickson,

Once again many thanks for your excellent efforts across the TWiX series. You introduce me to so many things that are outside my own field and I would not encounter otherwise. This really is the best way I know by far of expanding one’s scientific knowledge – the fact I can do it in the car and make productive use of time which otherwise would be wasted never ceases to delight me!

I have not written in a long time and I have been accruing things to say to you. So many, in fact, that I cannot say them all (and I don’t remember half of them anyway).

I missed a lot of episodes last year, but I now have about 1.5h of commuting in the car every day so I have completely caught up. I have thoroughly enjoyed it – at end of one episode Dickson’s comment “my amygdala thanks you all very much” had me laughing out loud! I am now working my way through TWiM.

Let me start with some comments on TWiV 269. A listener had written in asking about viruses that basically don’t leave a lasting effective adaptive immune response. Like Rich I was also yelling “Norovirus” at the iPod. The listener who wrote in then made some comments about RSV and the formalin inactivated RSV vaccine (FI RSV), and I wanted to weigh in here with some additional information about this. The reason the FI RSV vaccine of the 1960s not only did not work but was harmful appears to be because the formalin treatment abolishes the TLR4 mediated response to one of the viral proteins. TLR4 ligation on B cells is needed for a high avidity antibody response to RSV and in an animal model when you administer FI RSV along with a TLR4 agonist a protective response is restored ( This situation is unphysiological, so is not really a great example of a natural viral infection leaving an adaptive immune imprint which is either harmful or inadequate. There are better examples of adaptive immune mediated pathology caused by prior immune priming – dengue is by far the best but there is evidence for flu as well as you have covered on TWiV some time ago ( Nevertheless, RSV is a good example of a virus not leaving effective adaptive immunity. Geraldine Taylor from the Pirbright labs in the UK gave an excellent talk on RSV at the British Society for Immunology last December; she said she thinks the lack of lasting adaptive immunity following RSV infection might be because it replicates in such a superficial location in the respiratory tract. I don’t know what the evidence for this is, but I wonder how superficially in the gastrointestinal tract Norovirus replicates? (Incidentally – did you know that calves are the best animal model for RSV?)

Another topic I wanted to weigh in on is from much further back – I’m afraid I can’t remember which episode. This bedbugs as disease vectors. I think you had expressed surprise that there aren’t any viruses known to be transmitted by bedbugs. Personally I am not surprised that bedbugs aren’t disease vectors as they are not as mobile as ticks or mosquitoes so it will be more difficult for each bug to bite enough different hosts during its lifespan to transmit efficiently. The relationship between virus, host and reservoir is really an ecological one. For example Japanese encephalitis virus (JEV) will grow happily in Aedes albopictus C6/36 cells in the lab, but this is not the vector in nature. That’s not to say that JEV can’t infect Aedes albopictus, but most JEV is in wild wading birds in Asia which are more likely to be exposed to mosquitoes of the genus Culex which can breed in muddy rice paddy water, where the birds are. An exception would be the recent chikingunya alteration resulting in the ability to be transmitted by Aedes. I don’t think the ecology of bedbugs leads them to be efficient viral vectors.

Next topic: grant writing! I note you are despairing of the current tendency to try to make grants translational. Of course in reality the whole of science is translational – we just don’t always know how up front. I entirely agree we should do basic research just because, but we should also do translational research. There is nothing quite as cool as a really interesting uncovering of a basic mechanism that also has potential application. I offer you the HIV/T cell pyroptosis paper in Nature you did the other week as an example of this. I just hope you are not too prejudiced against investigators who try to make their grants seem translational in the current climate – it’s hard enough to get finding as it is and I’d hate to think that people might disadvantage themselves by shoehorning in translational potential when the guy in the next seat might mark them down for not mentioning this! So many funding agencies ask now for specific goals and outputs that you just have to play the game. I think we just need to grin and bear it, and try to ignore those comments if you don’t like them! Good ideas are still good ideas.

TWiV 213 the Lipkin CFS study: I know many people feel this was a waste of money. Personally I don’t agree. Most of the money was spent recruiting the patients, this cohort now has many other potential applications for CFS research where a breakthrough is very much needed.

A selection of other random things:
I am VERY impressed that Rich’s father in law is the inventor of the Swan Ganz catheter!
Random Polio question: do the three types represent separate introductions into humans or diversification within humans?
Random tech question: can anyone recommend a good RSS feed reader without having to rely on email? Email just gets so full up…
One correction – last time I wrote (Sept 12?) you said I was from the Wellcome Trust – I am funded by the WT not from the WT technically.

I wanted to recommend Ben Goldacre’s book Bad Pharma as a pick of the week – especially to Alan but I can’t remember why now!

Sorry this is so long and rambling and probably very boring… LASTLY but by no means least – the weather in Bangalore (close to Ooti where Dixon was recently) is glorious – 28C by day falling to a balmy 17C at night, hardly a cloud in the sky, no rain now for the four weeks since I arrived. It may not rain here until April now, by which time it will be an inferno!

All the best,

Dr Lance Turtle
NIHR clinical lecturer in infectious diseases
Institute of Infection and Global Health
University of Liverpool

Jacob writes:

I don’t know who made these detailed models of influenza virus and the steps involved in membrane fusion, but they’re great! I came across them while looking for some images for a presentation. Just thought I’d share in case you haven’t seen these before:

RPI, Troy, NY

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