Paul writes:

To the Twivle Seat:

Sunny, 7 c with rising pressures and 16 km of visibility out my window in Philadelphia, PA

I appreciated your discussion of prion assays in TWIV 424.

It reminded me of several Lewis Thomas essays where he advocated focusing on the unexplained and inconsistent phenomenon as signposts to breakthrough knowledge: he repeatedly focused on the example of the transmissible spongiform encephalopathies– anomalous, and, at the time, unexplained, phenomena.

My question for you and your many guests is what are the anomalous and unexplained phenomena in virology today – the facts and circumstances that defy explanation by the standard model?

David writes:

Dear TWIVaniellos,

First of all: a happy new year to yall.  Just listened to the year overview, and heard that number 23 was not in yet, so I mail in with this one.

After the reference to Ladri di biciclette, my head started filling with memories of glorious  movies of a bygone era – I would particularly recommend Riso Amaro (, 1949.  Then I drifted off to The number 23 where Jim Carrey becomes obsessed with numerical associations – I wonder now whether the number could have been a metaphysical reference to the number of chromosomes as a symbol of humanity, although I probably overthink it.  

Just one more thing: I am hardly a mathematician, but the discussion on orthogonality set me thinking.  Orthogonality refers to angles of 90 degrees in 3 dimensional axis systems, or as wiki puts it:

In mathematics, orthogonality is the relation of two lines at right angles to one another (perpendicularity), and the generalization of this relation into n dimensions; and to a variety of mathematical relations thought of as describing non-overlapping, uncorrelated, or independent objects of some kind.

Orthogonal planes hence meet where they intersect, or in the biological sense, when they are relevant to the object of the study.

Wish you all the best for the new year and look forward to the next 50 episodes!

Kind regards,


Ian writes:

Hello to the twiv team.

Following up on Twiv 337, and the subsequent discussions on transmissible cancers in the clam, the same authors have a second Nature paper I don’t recall hearing discussed on twiv, and searches reveal nothing.

“Widespread transmission of independent cancer lineages within multiple bivalve species” (full text on pubmed)

“These findings show that transmission of cancer cells in the marine environment is common in multiple species, that it has originated many times, and that while most transmissible cancers were found spreading within the species of origin, cross-species transmission of cancer cells can occur.”

The cross-species transmission is indeed between closely related species, but showing multiple occurrences is fascinating.

With the two devil tumors, canine, and steamer, and the several others from this paper, it seems ever more likely that this is not uncommon in nature, especially in those animals with no MHC or similar mechanism to recognise self. (or with deficient MHC due to population bottlenecks)

More benign tumor derived cell-lines infecting species may be very hard to find without sequencing the whole organism.

Traumatic insemination amongst insects comes to mind as one obvious route of transmission, as well as the obvious dissemination through filter feeding.

I wonder when the first beneficial transmissible tumor cell line will be found.

From a cold and dull Scotland, where I don’t want to think too much about the temperature or climate outside.

Jamie writes:

Hi TWiVologists!

You had asked in an earlier episode what other podcasts we the listeners listen to, and for a while I was determined to not stray from the TWiX family ever (call me crazy but it felt like cheating). But eventually I caught up and had nothing new to listen to, so I regrettably started searching for other science shows. It took some searching, but I came across a Podcast called Science..Sort Of, and though not refined like yours, eventually I was hooked. They cover a wide range of “topics that are science, topics that are sort of science, and topics that wish they were science.” Notably episode 244, where they interview Mary Roach for her new book, Grunt; and episode 245, all about the science of Game of Thrones (spoilers included).

This podcast led to other interesting Podcasts, including:

History of English- a chronological history of the English language

Generation Anthropocene- stories about planetary change

In Defense of Plants- all about plants

And they are constantly mentioning new podcasts that sound interesting too, but there is only so much time in the day, and then only after I’m all caught up with the latest TWi’s 🙂

Andrea writes:

Since I am of the non-scientists/non-medical listeners of your podcasts (I listen to TWIM and TWIP too) this book is probably more of my speed, although I am learning a lot from your podcasts. I have learned to be afraid of mangoes (TWIP), there’s some kind of microbe in the soil up here in the state of Washington that can kill me (TWIM), but I’m not afraid of vaccines (TWIV)!

As always, thanks for all of your work!


Seattle 40F and rain (as if it would be anything else🌧)

Jim writes:

Hi Y’all,

I’m crossing my fingers that I am lucky number 17. Like another listener I stumbled upon TWIV while looking for a good virology textbook last year and have been listening intermittently ever since. I’m sad that I missed the contest for a free copy for Principles of Virology 4th Ed since I am taking virology this semester and have to buy a copy. I’m writing from Bangor Maine where it is currently sunny and -12C.

Justin writes:

For Rich:

Personally I had no idea cats (domestic but more likely peridomestic?) could serve as a potential vector. Are the titers high enough for transmission, most likely through saliva? I know cats constantly groom themselves so perhaps it could be possible to have some virus on their claws and if they scratch or bite maybe transmission can occur? Either way this is news to me.

Nele writes:

Dear all,

In TWIV 423 you shortly discussed a potential Norovirus toxin and someone mentioned the minor capsid protein as candidate. Even though I have also heard speculations about a norovirus encoded toxin, I was (so far) not successful in finding any literature to back this up. As far as I know the minor capsid protein (of which only a few copies are found inside the virion) is thought to be involved in particle assembly and possibly virion stabilisation, however, for the putative toxic effect non-structural proteins are being discussed.

The weather in Rotterdam is very dutch, which means wet and grey.

Best regards

Nele (PhD at Erasmus Medical Centre)

Sam writes:

Dear TWIV team,

I hope that I am the 17th respondent so that I may win the book. Other podcasts I listen to regularly include Audiommunity, Wait Wait Don’t Tell Me from NPR (yes it’s a radio show but I listen to it exclusively as a podcast), and The Weekly Planet, a humorous Australian take on comic book and movie news.

Since I wrote you last, I have succeeded in getting my parents, neither of whom have any background in science, into TWIV.

Thank you for you wonderful podcast.


The weather is 4C and rainy in Toronto, Ontario, Canada.

Jessica writes:

Hello twivers!

My name is Jessica and I am a research tech in the University of Pennsylvania’s Gene Therapy Program. I’ve been listening to TWIV for just about a year and very quickly discovered the rest of the Twix podcasts! I am thoroughly addicted and your conversations help pass the time on my commute every day. I would love to be the 17th email to receive the new book! I wish you all the best, and I would love to hear podcasts from you for many years to come!

Thank you,


Chris writes:

Hello once again,

It has been a weather roller coaster in Central Ohio over this past week: we had a high for the week of around 66°F yesterday, but it had cooled below freezing overnight and is currently around 30°F as I write this e-mail.

I tried to hold off on sending this e-mail after I was a whole episode too early for being lucky e-mail 23 in the previous contest.  The use of prime numbers as the lucky number makes me quite happy, although there does not seem to be a discernible mechanism as to why prime numbers are more pleasing than composite numbers.  Perhaps it is their indivisibility into smaller integers that makes them feel more wholesome, but that is pure speculation.

This past week’s weather has made me curious whether you all have had the following long-term observations about the weather: it seems that over the past 5 years, the extremes temperatures of the year have become much more divergent than when I started to read the weather section in the newspaper around 15 years ago.  Between when I started reading the weather section and when I left for college, I do not remember having any days in the summer with a high over 100°F or winter days that went below 0°F, and even single-digit winter days were pretty rare (though highs in the 90s were common during the summer months).  However, over the past 5 or so years, it seems that there’s consistently been at least one day with a high over 100 and another with a low below 0.  Does this match your observations?  When discussing this with my family, we seem to have the consensus that, at least in the Midwest, climate change is causing shorter and colder winters.

— Chris

P.S. What apps, newspapers, or websites do you all prefer to get your forecasts from?  I have far too many weather apps on my phone because I never ended up finding one that was clearly better to all the others, since each one has a feature that I like that the others do not have.  This made my day interesting yesterday when they were competing to give me notifications that the National Weather Service had issued a Severe Thunderstorm Warning.

Suellen writes:

Maybe this has been picked before, but a friend who’s a nurse practitioner sent me the link, and it was so good I thought I’d pass it on:

For all the anti-vaccine people on there, here’s a little science for yah

It probably won’t change the mind of any anti-vaxxers out there, but it does explain a lot of the “scary” things about vaccines in an easy to understand way.

Best to you all, my TWIV family!


from Roswell, Georgia, where it was 65 degrees and cloudy today. Right now it’s 58 and dark.

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