Anthony writes:

If the history of Polio was vertical spread by care givers not practicing hygiene, there’s no reason to expect diarrhea.  In a domestic situation — from camp fire to castle — that would not increase transmission.  For a pathogen that water dispersal is natural (like Cholera) instead of tangential, diarrhea in particular and virulence in general is a suitable strategy.

Just a stray thought.

Matt writes:

Good morning distinguished TWiV hosts!

My name is Matt Nance and I have been a listener and devoted fan since episode 65–Matt’s Bats in January 2010. I cannot thank you enough for all the hard work you do and the educational, entertaining hours you’ve given me on my commutes, bike rides and post Netflix-binge time over the years.

I wanted to add my understanding of matric potential to the mix in response to some confusion I heard in episode 423. Having completed an MS degree in Soil and Water Science at the University of Florida, I was beaten over the head with the concepts multiple times and will attempt to share my knowledge here. I actually rode down the hill to Dr. Condit’s building one day to meet him before he retired–a highlight of my years in Gainesville to be sure!

Matric potential refers to the accumulated forces which hold water to soil surfaces (and lower the availability of water to plants, fungi and microbes). This force is largely a function of capillary effects, but several other forces contribute as well. Essentially, matric potential refers to the force required to “remove” water which is adhered to soil surfaces and pore spaces, and why it is represented by negative values (a “negative pressure” that “holds” water as opposed to positive values which “push” water). This force is variable based upon many factors including soil structure, atmospheric variables such as humidity and rainfall, as well as the mineralogy of the parent material of the soil. It is important to note that some of these factors can change minute-to-minute, while some change on a geological time scale.

A practical example: after a heavy rain when the soil has been saturated, matric potential is effectively zero, as water is readily available and little to no energy is required for acquisition/uptake into organisms, diffusion, osmosis, etc. As the excess water drains, the water which remains is found on soil particle surfaces and in porous spaces within soil, where capillary forces cause it to be retained. Whenever the organisms’ ability to exert partial pressures for water acquisition is exceeded in magnitude by the matric potential of the water/soil system, said organism is no longer able to acquire water until the matric potential is raised sufficiently to allow for acquisition/uptake to resume (again, matric potential is a negative value and saturated systems have a matric potential of zero…I don’t know of a scenario in nature in which matrix potential would be positive).

And so, the curing of fungi using matric potentials is essentially sorting them by ability to acquire water from various systems wherein the matrix retains water with variable force. This would be why the relative amount of germination decreases as matric potential decreases, and also why no germinations occurred at -5 and -6 MPa–the pressure is just too low for the fungi to have access to water for growth.

This is my quick coffee-shop summary and I’m sure I’ve severely dumbed-down the subject, but hopefully this helps somewhat. I’m certain my soil physics professor would love to read this explanation and clarify my simplifications with gusto.

Thank you again for all the learning and laughs,


Ryan writes:

Hello Vincent and Friends,

I’m writing in regards to the email you received in TWIV 423, about HPV purification affecting infectivity; as well as a shameless attempt, to snag some more reading material. Although I don’t have much experience with viruses (minus M13) I do know a thing or two about nanoparticles! When gold nanoparticles are introduced into the blood stream, various proteins adsorb to the surface of the particle to form a protein coat called a protein corona. Depending on what proteins non-specifically adsorb to the surface of the particles, it can affect their distribution within the body. Although gold nanoparticles aren’t exactly viruses, seeing as nature loves to follow murphy’s law, it wouldn’t be surprising for the adsorption of host proteins and other biomolecules to alter how the virus interacts with the body.  As with all things in science, further study of this could yield some interesting results.

Thanks again for a great podcast!  I’m currently a graduate student in Toronto studying Optogenetics (an en-lightening experience) where it is a warm -2 C. Your frequent discussions have kept me company throughout my undergrad and as of a week ago into graduate school as well. Keep up the good work.


Suellen writes:

There was a story on our local news here in Atlanta (where it’s currently 58 degrees F and drizzling), about a woman with a number of chronic illnesses that have apparently been linked back to mono that she contracted when she was 19, and to Epstein Barr Virus (EBV). I’m always skeptical of anything I see on the evening news that shouts “Childhood ‘kissing disease’ linked to chronic illnesses” (you TWIX folks and a BA in Biology have made me this way), so I would like to ask you guys for your educated input on this subject.

Here’s a link to the news story:

The research cited in the story was done by a Dr. HH Balfour, Jr, who — according to PubMed — is at the University of Minnesota Medical School. So I guess he’s reputable. But this quote from him in the article just seems — well — unsupportable, considering that nearly everyone has EBV in their blood and I have not seen any studies that have definitely linked EBV to cancer or MS:

“Epstein Barr Virus is responsible for a number of chronic conditions, especially certain forms of cancer and autoimmune disease and even multiple sclerosis. Everybody with MS essentially has been infected with EBV. Ninety to 95 percent of the world’s population is infected with this virus and so right there, not considering cancers and MS, we would have a huge problem solver. Epstein Barr Virus is definitely involved in multiple sclerosis, in several forms of cancer such as Hodgkins disease and in auto immune diseases other than MS such as lupus, or even rheumatoid arthritis.”

Can you respected virologists shed some light on this? Have there actually been studies definitively linking EBV — to the exclusion of any other possible cause — with MS, cancer, lupus, and/or any other autoimmune diseases? Or is Dr. Balfour’s reach exceeding his grasp of the facts, so to speak?

He is apparently working on an EBV vaccine, so perhaps the proof will come when we are all vaccinated, and no one ever gets MS or cancer again? Just joking, of course, I’m sure it’s not the ONLY contributor, but it bothers me to see a proper scientist speak so rashly — unless he is, indeed, just stating the facts.


PS — Big fan of all the TWIX podcasts. I hope there will be a TWI-IN (This Week in Insects) in 2017.


Harold writes:


Long time listener to TWIV here in Cubeland where the temperature is currently 75.7 degrees F and the day is always bright under the fluorescent lights.

Saw this article (or a well timed advertisement for a book about fat) in Wired about Chickens and the SMAM-I virus, human AD-36 virus and obesity.

This seems to be a claim that probably gets trotted out around diet time this year as click bait,

The article leads to some questions.

  • Could eating chicken infected with the SMAM-1 virus be causing obesity?
  • Could other viruses be causing the other forms of obesity?
  • If SMAM-1 causes obesity shouldn’t all poultry workers be obese because they come into close contact with the animal.
  • Should obese people be avoided because they can give you AD-36 and make you obese?
  • Why aren’t all people who were exposed to AD-36 obese?

Keep up the good work,

Bob writes:

So I was net surfing and ran across this Wired article:

which implies that some cases of obesity are caused by a virus (Ad-36 or SMAM-1.)

Doing Google searches for Ad-36 turns up very few hits which makes me very suspicious of this theory.

What does the panel think?


Yawlhoo writes:

Pakistani city launches new polio campaign after rare strain found

Dr. T writes:

Hello TWIVLords

CAUTION: Please do not try to pronounce my name. Call me Dr.T/ T-Dog

I am material scientist with a PhD in Nanotechnology from SRM University India.

I joined Deepak Shukla’s Lab at University of Illinois at Chicago as a Post Doc and now work on herpes simplex viruses. You might be confused about why I made a drastic change from material science to virology, but you will never know the answer because I am unsure myself. It really felt like a good idea.

I have technically never touched a micropipette earlier in my life, now I can do a 384 well plate within an hour while half asleep or while listening to your wonderful podcast.

I was introduced to your podcast by my colleague Joshua Ames who is a patron of your podcast.

Being a Podcaster myself YTY Show – ( and an avid listener to podcasts, I was suggested by Josh to go listen to your podcasts in order to improve my podcasting skills. (In retrospect I think he was trying to tell me that my podcast sucks… hmmm).

When I started listening to your podcast, I was initially irritated as to why these people were talking about the weather so much. But now 20 episodes later, I like it and enjoy the convo you all have. The day I seriously started loving your podcast is when I was listening to “A Nef is enough” and that afternoon, the Italian professor you were referring to in that paper gave a lecture in our auditorium. This was the first (after 8 months of virologists around me) lecture I understood in full. To me (a material scientist) all the virology lectures were more or less “protein protein protein…. protein is protein… interacts with protein… hence its a bad protein”. Listening to your podcast and then listening to the author himself, I was suddenly able to understand all that he was saying from start to finish.

I love all your podcasts, It now helps me understand a lot of virology I never understood earlier.

P.S. It’s -14 degrees C in Chicago. Sunny blue skies. I love Prof Dickson

My fav podcast is – harry potter and the methods of rationality


Andrew writes:

Dear Twiv team,

I am a veterinary virologist, studying avian viruses. I am a big fan of the show, and appreciate the diversity of viruses you discuss, including those that infect a variety of organisms and species. However, please can you stop referring to them as “the kind that make you sick.” ? Many of these don’t cause disease in people, so I feel the tag-line might need updating.


Ps, it’s been a cool but sunny  6C today here in Surrey in the U.K.

Best wishes,

Andrew Broadbent

Research Fellow

The Pirbright Institute


Mike writes:

I love viruses. My first real introduction to viruses was when I picked up the 2nd edition of Principles of Virology and I went online to to check out the authors. That’s how I found TWIV and subsequent iterations, and I’m always looking forward to new episodes. I’m still hoping to see if there will be an immunology podcast. It looks as though Audiommunity is fading into the sunset.

Hope you all have good 2017.

Mike in Oregon

Broc writes:

Hoping for email #23……So I can “flint-erize” my virology vocab. Thanks for the enjoyable education of TWIV!! I heartily endorse a This Week in Bugs, though pronouncing TWIB will sound like you caught a rhinovirus. Here’s to a long future of TWIV!


Dylan writes:

Dear TWiV Team,

Hello from chilly Minneapolis where the current weather is -5F/-21C (before the windchill). I also assumed I had missed a chance at the textbook last week, but I guess many listeners had the same thought. Thank you for another great year of TWiV and best wishes for 2017.

Jarrett writes:

Hello again!

I’m writing a second time in hopes of securing a copy of Principles of Virology, as Dr R. had mentioned in TWIV 422 that he had only received a few emails in response to this most exciting of giveaways. One of those emails was mine, so I’m sending another to increase my odds, given that is allowed. If not, allow me to report that we are currently having magnificent weather in Austin today, at 21 C and sunny with winds of 11km/h. Happy new year to you all.

-Jarrett H.

Austin, TX

Diane writes:

Hello TWiVsters! I hope I’m not too late in telling you how much I enjoy the podcast and that I love viruses! I listen to both TWiV and TWiM and soon hopefully more from your group of podcasts. I enjoy the banter as well as the information you share every week with us. It is currently a brisk 40 degrees Fahrenheit in Louisburg, NC, which is located about 30 miles northeast of Raleigh, and we are anticipating our first snowfall this weekend. This might give me some time to sample  TWiP and TWiEVO to decide which, or both, to add to my playlist. I look forward to many new and exciting podcasts in 2017; keep up the wonderful work!

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