Carol writes:

Vince, Cathy, Allen et al.,
I just saw Emily and the Oats great Dengue virus on the podcast. What’s really funny is that I also figured out how to knit a virus this past year. What are the odds? In my case, I went for picornavirus, and I made an icosahedron frame out of Styrofoam.

I’m including the link to my Ravelry site where I have the free pattern for any other like-minded knitters.

Love the podcast! I recommend it to my students all the time.


Dept of Biology
Hofstra University

Geoffrey writes:

Illustrious Doctors:

There has been an idea floating around in my head since I read about rodents and bats (in particular) acting as reservoirs for numerous viruses. Perhaps their particular ecological niches put them in a genetic space where they are inundated with viruses and have had to evolve in that direction but that could be said of many other genera which are not particularly noted as being reservoirs. This might be more common in these genera because, as with viruses, hyper-adaptability is favored in species where reproductive rates allow for large numbers of throw-away (mal-adapted) individuals.

But I keep wondering if all of this adaptability and reservoir capacity might not also have evolved as a survival advantage in the form of defensive biological warfare. Isolated communities of a species adapt to the local virome and act as reservoirs for a number of viruses. Since the process of adaptation is somewhat random, each community and species develops unique reservoir capacities that even members of the same species “over the next ridge” won’t match. As such, interactions with other species will always carry viral consequences.

In the case of members of similar species entering a new community, they bring their own viral reservoir with them but, in a kind of reverse of herd immunity, their reservoir has less chance of overwhelming the native community than of the native community’s reservoir overwhelming the intruder. Viral warfare defending territory and, potentially, leading to species isolation and divergence.

In the case of, for instance, predator species, they generally have a lower reproductive rate and, so are not as adaptable as their prey. Every time they consume a viral reservoir, they are at increased risk from that viral reservoir. In this case, the viral reservoir acts as a group defense reducing predatory pressure.

I strongly suspect that this sort of activity of viral reservoirs in rodents, bats, and the like exists on a statistical level but, the nagging idea in my head is that one or more groups might have evolved a genetic mechanism to enhance the defensive aspects of viral reservoirs. My questions for you experts are: “Is there any evidence that viral reservoir defense exceeds simple statistical effects?” and “How might you start to gather the data that you need to perform such an analysis and how might you start to look for the genetic ‘regulators’ of such a system?”.

As always, thanks for the extra insights into the workings of this world,


Dave writes:

Hello Mr. Racaniello,

I would like to introduce you to a podcast I listened to recently through CFR. Here is the link,

Here is a copy/paste from the CFR site,

CFR Senior Fellow Laurie Garrett discusses pandemic preparedness on a global scale with professors and students, as part of CFR’s Academic Conference Call series.

It should raise your blood pressure.

Robert writes:

Dear TWIV hosts,

I just wanted to say thank you for all of the fantastic TWIV episodes all of you have done in 2013. I can’t tell you how much my wife and I look forward to each new posting. I met my wife in my postdoc mentor’s lab where she was a research associate. That was 38 years ago and we are still academics at heart. TWIV feels very much like the lunch time discussions we had with other students, postdocs and faculty when we were at UCLA. We both look forward to another fantastic year of TWIV.

The weather here in Orange County, CA has been very mild. We did have a cold spell for a week or so where the day time temps were never much above 60 F (15.5 C) the past week brought temps as high as 80 F (26.7 C). I have been surfing and skiing since I was a boy and I still enjoy both sports. Yesterday along with some of my friends we spent the morning at San Onofre surfing in 2-3 ft swells and relatively warm water 60 F. We quit surfing around 11 AM and after driving home, rinsing out the wet suits and eating great meal prepared for us by our wives, we loaded up two cars with our skis and drove to Big Bear in the San Bernardino Mts. We skied from 5 to 9 PM, enjoyed another great meal ( mexican food) we drove home. Southern California is a great place to live! Weather today here in Orange was 60 F (15.5C) humidity 70%, Dew Point 49 F, Pressure 30.22 in.

I have a book that I’d like to recommend. “RNA Life’s Indispensable Molecule“, James Darnell, Cold Spring Harbor Laboratory Press, 2011. This book is a fantastic review that is accessible to anyone with an interest in the history of the rise of molecular biology and in particular the part that RNA has played. The author has spent 50 years studying RNA and he has provided a wonderful, well referenced, readable story of those years. I also would like to recommend the book “Biochemical Pathways: An Atlas of Biochemistry and Molecular Biology, 2nd Ed., Gerhard Michal and Dietmar Schomburg, Wiley 2012. Anyone who has ever been in a biochemistry laboratory will be familiar with the wall chart showing the Biochemical Pathways which is currently in its 4th Ed (Roche Diagnostics, Mannheim). This book presents the pathways, networks, and systems that have been elucidated with the advent of omics. The second edition has been enlarged and contains by the authors’ estimate at least one half more material than the first edition. It is available in a Kindle Edition.

Once again I hope that you all have a wonderful holiday season and that the New Year is filled with successful grant applications, accepted papers, happy and productive graduate and postdoc students, and TWIV episodes.

Yours truly,


David writes:


Dear Vincent Racaniello,

I am an MSc graduate of virology and currently working as research assistant at Urmia University of medical science, West Azerbaijan, Iran. I want to thank you and twiv for all these great podcasts but sadly, I should tell you that we did not know about the twiv and its podcasts until recently, and since then I recommend it to all of my friends in the field of virology in our country. I have searched among all episodes but did not find any twiv about the Human Cytomegalovirus and its reactivation and latency. If it is possible, please make an episode about it in future. Thanks in advance.

Best regards

Robin writes:

Pleo & Poly

Pleo: a continuum of variation.

Poly: multiple but discrete.

Victor writes:

Thought you might appreciate this

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One comment on “TWiV 267 letters

  1. I have heard about the discussion concerning whether or not a virus is alive. We know cells are alive, and they carry out the needs of the multicellular organism it is part of as well as it’s own molecular housekeeping. A virus does none of this. It does not live, it does not metabolize, create or destroy proteins, o9r do any of the things that are the hallmarks of life. It is a mechanism or program in stasis and as soon as it encounters the correct cellular attachment it delivers it’s program to the cell along with assorted ‘hacking’ molecules that make sure the cell runs the viruss’ program – which it does and in time the cell emits the newly created virus particles, via budding, lysis or ??

    So since a virus does not metabolize on it’s own, when it is alone it is not alive. Even when in a cell, you might say the cell lives and has been diverted from it’s original task into a virus factory – so has become a living slave, as long as it lasts.