Stephen writes:

Dear TwiV Team,

During TWiV 378 it was suggested that viruses may engage in an evolutionary arms race with the blood-brain barrier. I couldn’t help thinking that this seemed unlikely, because I can’t think of a virus for which neuroinvasion in humans or most other hosts isn’t a dead end with respect to transmission. Instead, it seems more likely to me that properties of the virus selected for in other compartments or other species incidentally lead to the ability to invade the human CNS.

Possibilities could include a requirement to cross endothelial barriers in other contexts such as to established viremia or systemic infection, or the ability to replicate in cells that may periodically enter the CNS for purposes of immune surveillance. I’m sure other pressures exist that might select for viruses capable of neuroinvasion, but I’m handwaving and can’t come up with other examples right now. Thanks for the continued excellent coverage of ZIKV and, as always, great papers covering any and all areas of virology (except plant viruses).



Samuel writes:

Howdy pathogenic partners! Viral varmints! Capsid cowpokes! Sheriffs of small infectious particles that replicate inside the living cells of other organisms!

It’s an abnormally beautiful (though blustery) 11ºC and sunny day in Madison, Wisconsin. I celebrated this freaky February weather/evidence of anthropogenic climate change by saddling up my steel-framed steed, cuing up some back episodes of TWiV on my iPhone earbuds, and pedaling along the Badger State Trail towards the Iowa State Line. I listened to episode #375 (Zika and you will find) while my bike and I battled a ferocious 17 mph headwind blowing from the south. The insightful, comprehensive, and informative commentary (and great perspectives from your guests!) kept me thinking about flaviviruses and torch pathogens as I fought the wicked wind.

Clearly, the popular press has made a mess of their Zika reporting, leaving people (my grandparents, for example) confused, frightened and misinformed. A recent episode of WNYC’s On [The Media] critically analyzed the sensational and sometimes flagrantly inaccurate coverage of the outbreak. ( I thought you might enjoy hearing insiders pick apart media swirl and agenda-setting around the arbovirus du jour.

I appreciated the variety of viewpoints: a NYT reporter who reported on ZIka while he himself came down with the disease, a Brazilian journalist, a communications spokesperson for the WHO, and Nikos Vasilakis of UT Austin. My favorite segment of the episode, though, was the final story which drew parallels between the current debates about abortion going on in Brazil, to the 1964 Rubella outbreak in the United States that paved the way for Roe vs. Wade (

Thank you all for everything that you do! I only recently added TWiV and TWiP to my slate of science podcasts, although I started listening to TWiM (#25 in fact…magnetotactic bacteria!) during my second rotation as a first year PhD student at the University of Washington Seattle. I ended up joining that very lab; episodes of TWiM got me through the innumerable ChIPs and reversion assays that went into my thesis (The consequences of head-on replication-transcription conflicts in Bacillus subtilis).

Now I’m kicking myself for ignoring the rest of the TWiX canon! I was bacterially biased as a grad student (my reasons for resisting were: “who cares about viruses….they’re not even ALIVE” and “parasites? like worms? I don’t want to hear about any cell with a nucleus”). Now that I’ve moved to Madison, Wisconsin in the midst of a horizontal career transition from researcher to science writer, I’ve broadened my worldview (or maybe learned to appreciate smaller things) and I’m eagerly working my way through your back catalogue.

Thanks again. Your podcasts are the pinnacle of science communication. I truly appreciate the insightful questions, charming banter, and deep dedication to inquiry that each of you put into producing top-notch content. The sense of wonder each of you brings to research (listening to Vincent enthusiastically explain gene drives during TWiP100 was the highlight of my week) is an inspiration for an aspiring science communicator like myself.

Miriam writes:

Dear TWiVists,

I have a query about polio eradication. In a recent episode Vincent mentioned the destruction of polio laboratory samples, as a part of coming to the end of the eradication program. I am puzzled by this as you have previously described the problem with ending vaccination – i.e. that the IPV does not give immunity in the gut and that the OPV reverts during passage through the gut, meaning that both vaccine-derived and wild type virus are likely still prevalent, and liable to cause disease again should vaccination be suspended. Has a solution to this problem been found? Or have I misunderstood the issues? I am sure Vincent has views on this and would be very interested to hear them.

On a different topic, in contrast to a recent correspondent of yours, I find the way you work through topics that are not in your own specialism one of the most valuable things about TWiV. Established facts can be easily gleaned from any textbook, but the process of pulling together known facts to produce viable hypothesis is not so easily learnt and I find your discussions fascinating.

Miriam (Undergraduate in the Open University’s Natural Sciences program, UK)

Jelle writes:

Dear Vincent and other TWiVers,

I’m currently preparing a new lecture in which I will lecture about the microbiome and more specifically on the virome. During these classes the students will get a task to listen to one of the TWiV shows (and read the paper discussed in that show), make a presentation about it and present it to their fellow classmates. I have prepared a list of relevant TWiV shows of which most (not all) deal with the virome or viral metagenomics studies:


TWiV312 She sells B cells

TWiV313 With viruses like these, who needs enemas?

TWiV323 A skid loader full of viromes

TWiV342 Public epitope #1

TWiV355 Baby’s first virome

TWiV356 Got viruses?

TWiV362 Gotta catch ’em all

TWiV365 Blood, feuds, and a foodborne disease (Hepegivirus)

TWiV365 Blood, feuds, and a foodborne disease (HAV)

TWiV375 Zika and you will find

TWiV271 To bee, or not to bee, that is the infection (Tobacco Ringspot Virus Honeybee)

TWiV271 To bee, or not to bee, that is the infection (Plant virus to vertebrates)


I’m not a 100% sure, but I do recall a show where you discussed the following paper:

Pathogenic simian immunodeficiency virus infection is associated with expansion of the enteric virome. Handley SA, Thackray LB, Zhao G, Presti R, Miller AD, Droit L, Abbink P, Maxfield LF, Kambal A, Duan E, Stanley K, Kramer J, Macri SC, Permar SR, Schmitz JE, Mansfield K, Brenchley JM, Veazey RS, Stappenbeck TS, Wang D, Barouch DH, Virgin HW. Cell. 2012 Oct 12;151(2):253-66. doi: 10.1016/j.cell.2012.09.024.

However, I could not find the correct TWiV number. Can you help me out?

Would you have any other good suggestions for TWiV shows related to virome/viral metagenomics studies?

Thank you very much in advance,

Jelle (pronounce like “yellow”, but replace the “ow” with “e” as you pronounce it in yellow”)

PS1: I will be organising the “13th International double Stranded RNA Virus Symposium” in the fall of 2018, most likely in Belgium. I would love to have a live TWiV show there. As soon as I have the final dates I will send you an invitation!

PS2: 8°C in Leuven, Belgium, with scattered clouds and a cold 29 km/h wind from the Southeast


Prof. Jelle Matthijnssens

Connie writes:

SW Alberta Canada, 4’C no wind,

I am a retired Animal Health Lab.Tech.

The Camelid “have to have” tidal wave happened some 20+ years ago. In the lab I did blood separation for IgG-lacking Cria, more in Llamas than in Alpacas. We shear fiber animals now and have found through the years that females producing IgG-lacking young would produce this same problem over and over. We also see sour mouth orf (sheep and goat disease) as a chronic disease in Camelids, more in suri alpacas (crossbred ?). I have also seen one whole herd that was dealing with BVD in the herd to the point the herd was sold (?). Really looked like a carrier in the herd as other than the acute animals the rest of the herd was healthy and cattle were not in immediate area. Listening to your Zeca (sp) talk made me throw together all this and think. The camelids came down out of high plains without mosquitos to mosquito-infested areas of South America. With what I have seen as low or no antibody response to so many viruses could this have been a missed link to this virus. In the Lab I saw no virus isolation done on any of the cases we got except the BVD herd. The “that could not be the case” really rings in my mind.


ps newbie to your Twiv podcast and just loving it.

Ken writes:

Hi TWIVsters:

I have a relative who spent the summer of 2001 camping in National Parks in Uganda.

A couple years later he began having tingling feelings in his hands which was suspected to be Guillian-Barre Syndrome (GBS) and eventually diagnosed as Chronic inflammatory demyelinating polyneuropathy (CIDP), the chronic form of GBS.

With the news of Zika and GBS, he asked his neurologist this week if it made sense to test for Zika antibodies. The neurologist said (rightly) that there is no reason to test since it won’t change the diagnosis or treatment at this point.

But my relative is now curious, and thought there may be a study that he could volunteer to participate in based on his history.

Do any of you know of any such work currently being done that needs subjects?



Snohomish, WA

Where the weather = Seattle winter.

Peter writes:

Hi TWiV team

I have a listener pick of the week.

A short (9 minute) programme from BBC World Service on the broken market for antibiotics:

“It is a life and death situation – the world is at its last line of defence against some pretty nasty bacteria and there are no new antibiotics. But it is not the science that’s the big problem, it is the economics. Despite the $40 billion market worldwide there is no money to be made in antibiotics so big pharmaceuticals have all but stopped their research. Why is this and how do we entice them back in? Wesley Stephenson finds out.”



Leave a Reply

Your email address will not be published. Required fields are marked *

2 comments on “TWiV 379 letters