Arnau writes:

Dear Professor Racaniello,

First of all, thank you for your amazing podcasts. On last TWiV (#555) you talked on RNA viral populations (27:00), and you sustained that quasispecies was a dated and not very appropriate term. I find it surprising, as lots of current articles on viral populations use “quasispecies”. Even if quasispecies applied to RNA viruses has been controversial (e.g. Esteban Domingo vs Eddie Holmes), I am not aware of any decisive proof against the existence of viral quasispecies. Would you mind to clarify your position? 

Kind Regards,


Caitlin writes:

Dear Autonomous CollecTWiVe,

After a two-year TWiX bender, I have finally caught up, and am writing in to mark the sad and joyful day. I do not exaggerate when I say that your voices have been a constant in my life, and have frequently helped me get through difficult times. Your podcast is truly a gift to the world.

Unfortunately, I have absolutely nothing useful to add to the virological discourse, so instead I list some facetious suggestions for special episodes that have occurred to me over the past couple of years. They may not be suitable for Episode 600, but perhaps for Episode 666.

  • Firstly, an exercise in masochism. The TWiV team plays some anti-vaxxer or other fake science podcast and debunks it. Appropriate pauses for horrified screaming, furious rants, and loud expletives.
  • TWiV after dark! The TWiV team tells their most shocking, terrifying, and unbelievable laboratory tales. Turn it into a contest: which host will win, in the categories of scariest incident, strangest coworker, weirdest experiment, dumbest mistake, and favourite lab memory?
  • Drunk TWiV. This should be fairly self-explanatory. For extra fun, it could be done through a drinking game. Dig out the old TWiV Bingo Card and have every host do a shot every time someone drops one of the bingo phrases.
  • The TWiV team attempts to decipher a paper that none of them have seen before, which is in a foreign language. They may use only their knowledge and Google Translate. Bonus points if it’s in Italian, for obvious reasons.
  • Special guest: Andrew Wakefield (rubs hands together gleefully). Better yet: Rich bursts into his “clinic” unannounced, avec mike, and takes him to task on the spot.

I doubt any of these TWiV episodes will ever exist outside of my imagination, but the thoughts made me giggle.

Finally, and I want you to take this very seriously: f**k the haters. If you get even one more letter whining about the weather segment, please forward it to me, and I will swiftly track down the ungrateful hooligan and insert a pineapple into their backside. TWiV is perfect the way it is.

Caitlin, in Seattle (where the weather is not nearly as rainy as I was led to believe).

Chris writes:

Dear TWiV Team,

In my opinion, if Zika virus infection causes microcephaly in humans then it is very likely to cause other, far less obvious, outcomes in the foetus. The question is, How do we prove the association? The recent article published by Nielsen-Saines et al. in Nature Medicine,  is a very interesting paper, certainly adding to our knowledge, but unfortunately not able to tell us much more about cause and effect. The lack of a control group does not help, but even if controls were available, it would only tell us so much. The paper describes a cohort of children born to mothers who had symptomatic, PCR-proven, ZIKV-infection while pregnant. What we do not know however, is whether ZIKV was transferred to the foetus in these cases. If only these children had been tested for the presence of anti-ZIKA IgM, or tested by PCR, shortly after birth. Antibody tests have had issues with cross-reactivity with related viruses and therefore the results of antibody tests may not be as clear-cut as we would like, however PCR tests should have been conclusive and would have indicated that the foetus had indeed been infected in utero. If one could have tested the newborns for evidence of infection with ZIKV, it would also be worth testing for evidence of other intra-uterine infections (such as cytomegalovirus, Toxoplasma, and rubella) as well. However, even if infection of the foetus could have been be demonstrated, it doesn’t necessarily indicate that any damage results from the infection, although I believe it would be strongly suggestive. When a vaccine becomes available, the link between infection and pathology should become much clearer. And what about subclinical ZIKV infections? Can they result in delayed childhood neurodevelopment and neurosensory alterations? I believe that the harder we look, the more we are likely to identify associations between ZIKV infection and pathology in newborns, children and possibly adults, further justifying the need for an effective vaccine.

Thanks for a wonderfully informative and entertaining podcast.



Christopher Ring MSc PhD FIBMS FHEA

Senior Lecturer in Microbiology.

First Year Tutor for BSc Biomedical Science.

Programme Leader for MSc Biomedical Science (Medical Microbiology), BSc Biomedical Science (Sandwich) and the BSc Applied Biomedical Science programmes. Module Leader for specialist postgraduate Medical Microbiology and postgraduate Biomedical Science Research Project modules.

Department of Natural Sciences,

Faculty of Science & Technology,

Middlesex University

Eric Delwart writes:

Dear Vincent and TWIVsters

i’d like to recommend a New York Times podcast by Dr Robert Grant about pre-exposure prophylactics (PrEP) for control of HIV transmission. 

He asks the question: If we could stop the HIV epidemic would we? 

Dr Grant was first to demonstrate the efficacy of PrEP in preventing HIV transmission. He knows his stuff. 

He argues we now have a drug that effectively works like an HIV vaccine when consistently taken before HIV exposures. 

He clearly spells out the role of big pharma (in this case Gilead) in limiting access by charging $20K a year in the US.

A powerful and touching testimony about a major problem translating scientific progress into actual public health benefits. 


Eric Delwart

About the Truvada patent