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TWiV 145 Letters

David writes:

Hi Twiv folks

I am developing a class on how infections can alter the behaviour of their hosts. There are some fantastic examples of this in parasitology where the parasite alters the behaviour of the host to increase its chances of transmission. The reason I decided to develop this class is that I find it fascinating that rabies induces aggression, causing the infected animal to bite and transmit the disease, but I dont know anything about how it actually does it. I’m developing the class with a physiological psychologist who does animal behaviour research and we are already having too much fun learning about zombie ants and other strange infections.

My question is, other than rabies are there other viruses that alter host behaviour, especially with the effect of increasing transmission?

It seems like there must be a sexually transmitted disease that increases sexual desire or promiscuity, but havent found one. Do you know of any?

Also, do you have any thoughts on the origins of the mythology of zombies and vampires as possibly based on behaviour mediating infections? Certainly many zombie movies portray zombieism as an infectious disease, could these ideas have started with historical cases of altered behavior due to infections?


David Esteban

Biology Department

Vassar College



Wendy writes:

I was recently listening to your 100th podcast where you featured David Baltimore. One aspect of virological history that was discussed, but is frequently overlooked, is the work by several investigators at NIH in the late 1970s to determine if indeed cloning was safe. These investigators took time from their own studies to identify dangers of cloning and whether such studies could safely be performed. The studies were very important in the history of molecular biology as well as virology and I believe that the details of these studies would be of interest to the community at large. Those individuals who did this work are getting older and that history will be lost once they are gone since there seems to be few details of this work published (as far as I can tell). How about getting some of those scientists on your program to talk about the events?


University of Iowa

Joe writes:

Dear TWIVcats.

I would like to wade in to the viruses are they/aren’t they alive debate with a thought experiment.

Like every person on the planet, I am related to every other terrestrial organism via a common ancestor, for a Chimpanzee our shared relative lived relatively recently (geologically speaking), whereas for an E.coli it was probably billions years ago. However, we share grandparents and are all very distant cousins. So, with this in mind, am I also related to Poliovirus, is Ebola my tear-away cousin 10 to the power 30 times removed? And if we are related to viruses, does this have implications for their alive/not-alive/undead status.

Just a thought.

Love the show.


Joe (London, UK)

Joe writes (re Agave viruses, Kevin’s letter on TWiV 137):

As a long time listener to TWIV I was dismayed that the crew was not familiar with the groundbreaking work of Prof. Jose Cuervo regarding the agave life cycle. He identified the T-Kwillia virus as its primary infective agent and showed how it was transmitted by the common Bar Fly. It is one of few agents that also causes diseases in humans, the dreaded Morning After Sickness with the classic symptoms of headache, dry mouth, blurry vision and tremors.

Love the shows


PS. Allan can probably come up with a better virus name, feel free to edit.


EH&S Manager

Jeffrey writes:

Hello – In TWIV 139, after describing the loss of the fiber genes from the mimvirus genome upon passage, one of you asked if other viruses lose their fibers as well and someone mentioned adenoviruses. I am now a community college assistant professor, but in my former life I was a researcher and did my dissertation on the persistence of adenoviruses in human lymphocytes. Bringing up adenovirus was interesting for a couple of reasons.

First, if you compare the genomes of the animal adenvoiruses, the conserved genes are in the middle of the genome and its the ends that are the most different (see http://vir.sgmjournals.org/content/84/11/2895.long).

Second, its the fiber genes that are in the middle (not at the ends) and appear to be pretty well conserved.

Anyhow – love the show; thanks for keeping me current on research now that I have to spend my time grading.


Assistant Professor of Biology

Georgia Perimeter College

Geoffrey writes:


I feel that I must rebut a point made by Alan Dove in episode 130:

“We’re not looking at a world where we have a choice between these genetically-modified pest-resistant plant and some beautiful organically-grown, no-pesticide, no-evil chemical, no-nothing types of food. In fact, with more than six billion people on the planet, what we have is a choice between these pest[icide – delete?]-resistant, genetically-modified plants or plants that are grown with petrochemical pesticides.”

First, ask Dr. DesPommier to describe permaculture to you. It is proving to be an increasingly more viable method of growing food while improving the environment. Farmers like Mark Shepard in Wisconsin (Here is a little information on Shepard and his farm:http://www.forestag.com/bio.html. Here is an article by him:http://www.nfs.unl.edu/documents/specialtyforest/shepard.pdf) are showing that permaculture can be a financially viableand product ton/acre efficient way to produce food without pesticides. Second, there is at least one other alternative to grow enough food to feed our planet – grow your crops within a semi-customized eco-system (rather than in isolation) and direct natural biological controls towards keeping your crops happy as your first line of defense. Use pesticides as a highly selective and time-limited second line.

This is not to protest against genetic engineering. I strongly believe that it has a valuable place in the future of our culture but it should be used in a manner that promotes rather than degrades the health of the planet.

Yes, this type of agriculture requires a complete re-structuring of our current agricultural system but, then, what do we think will happen to the system when gasoline (and related petrochemicals) reach $5… $10 a gallon?

Thanks for the excellent show,

Geoffrey Tolle


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