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TWiV 191 Letters

Russ writes:

Hi Vince and the TWiV crew

I love the podcast. It keeps me in touch with lots of basic research in virology which I would otherwise miss.

I do pediatric infectious diseases and you can imagine how much time we spend dealing with viruses. In my spare time, I do hospital infection control. I wanted to comment on your questions about this statement in the Fouchier paper: “The pandemic and epidemic influenza viruses that have circulated in humans throughout the past century were all transmitted via the airborne route, in contrast to many other respiratory viruses that are exclusively transmitted via contact. “

In hospital infection control, we institute isolation precautions based on the usual route of transmission of the organism of concern. These are in addition to Standard or Universal Precautions which apply to all patients to prevent exposure to blood and body fluids. The guidelines come from the CDC and are for the most part evidence based. They are:

Airborne: These are organisms that can spread by small airborne droplet nuclei for distances of greater than 3-6 feet. The list is pretty short and includes tuberculosis (not a virus!), varicella-zoster virus, measles, smallpox, SARS, and avian influenza. It was also applied to the 2009 H1N1 influenza but probably wasn’t necessary. It is known that VZV can go under the door and infect someone down the hall.

Droplet: these are spread by large droplet particles that spread no more than 3-4 feet after a cough or sneeze. Lots of organisms here but the principal respiratory viruses that fall under this are seasonal influenza, rhinoviruses, and adenovirus. Also includes other infections such as mumps, diphtheria, rubella, pertussis, Mycoplasma pneumonia, Parvovirus B19, plague, group A Streptococcus, and patients with meningitis caused by Haemophilus influenzae type b and Neisseria meningitidis, where respiratory carriage is expected.

Contact: spread by hands and other forms of direct contact (stethoscopes). The main respiratory viruses here are respiratory syncytial virus, human metapneumovirus, and parainfluenza viruses. RSV (not Rous Sarcoma virus) is a huge problem in children and also in the elderly and immunosuppressed. No vaccine yet, and there is a huge need. I have attached a quite old but instructive clinical study showing that RSV is spread by contact and not through the air – at least not as far as 6 feet. The set-up is not dissimilar from the model for showing airborne transmission in the ferrets! In case you are wondering, folks with lice also get contact precautions....

So flu gets droplet precautions and RSV contact precautions. Go figure...

Keep up with the great podcast

Russell Van Dyke M.D.

Section of Infectious Diseases

Department of Pediatrics

Tulane University Health Sciences Center

Natasa writes:

I read your blog and look forward to all new posts. I was wondering if you were going to cover the news story on poultry vaccine strains deadly recombinant?

If so I would appreciate if you could address the following questions in your blog, as none of the articles so far seems to be covering this issue.

Question 1: how many genomes of viruses carried by people who have died or have suffered long-term effects following vaccinations have been fully sequenced?

Question 2: following on above (assuming the numerical answer is low/close to zero) how can we rule out with absolute certainty the possibility that some of the severe or prolonged negative reactions to vaccines are NOT due to recombinant or mutant viral strains (including possibility of vaccine+wild strain recombinants)? Are there any large scale study in the pipeline meant to address this question?

Larissa writes:

Dear TWiV Panel,

I have been looking for a list of papers reviewed by the three podcasts recently and I can't seem to find one. Is there a list on your website of papers reviewed or should I just listen to TWiV(P)(M) with a pen and paper at hand always?

Thanks for all the great dissemination of scientific literature, it helps fill what would otherwise be many unscientific hours.

Warm Regards,


Oren writes:

Dear lords of the Twiv.

It is a pleasure writing to you after being a long time fan (the weather in Tel Aviv is extremely hot and humid from April to October).

The show is great and keep me up to date in aspects of virology not in my direct field.

Well, I probably got the Twiv bump (Twiv 115 - color me infected) as now I am starting my own lab in the medical school at Tel Aviv University.

We are currently trying to upgrade the virology lab for the medical students and make it more appealing.

We have low budget wet lab that complement the medical students virology course.

If you or your listeners have any idea for an interesting way to attract medical students it will be highly appreciated.

Keep on the good work and Thank you,


Dr. Oren Kobiler

Clinical Microbiology and Immunology

Sackler School of Medicine

Tel Aviv University

Marcin writes:

Hello Viro-cides!

Can you please provide your comments to the attached editorial? It seems rather depressing that there are investigators out there that believe that if scientists don't work 24/7 then they are not doing a good job. It seems that it is especially true at Johns Hopkins (see another recent article at:

Thanks a lot, and keep up the good work with the delightful and engagin podcast! I just suggested to my summer mentee to listen to you and I believe he'll get virally "hooked" as well!



Clarissa writes:

Hi Vince and Rich,

great discussion!

Just to explain why we grow Cotia virus at 34oC. It grows better when we infect cells at 50% confluence. Actually, if we started plaque assay with 80% confluence at 37oC as we usually do for vaccinia, we'd get no plaques at all after 11 days of infection. Monolayers must be infected at 50% confluence or even less than that, and we set the growing temperature to 33oC-34oC in order to keep cells growing slowly. So I believe the virus grows better under these conditions not because of the temperature, but because it doesn't like old, confluent cells. The adjustments in growing conditions in order to plaque purify Cotia virus took us over 6 months of work...

And yes, I agree with you that this paper has a lot of classical virology. I'm glad we stuck with this despite the opinion of most referees to remove these data and just leave the genomic stuff and phylogenetic analysis! And I'm glad that there are still several virologists who appreciate this kind of assays and pass this to their students.

Gopal writes:

Dear TWiV-ers

Since TWiV has, from time to time, gone beyond virology to discuss how science ought (or ought not) to be done, I thought I would bring this article that appeared in TheScientist to your notice.


Gopal N. Raj

Science Correspondent, The Hindu newspaper.

Kerala state, India.

Luis writes:

Dear TWiVessors,

A few months ago, I read in Nature a few notes by Prof. Robin Weiss about recent books on AIDS. One of them, "The origins of AIDS" by Dr. Jacques Pepin, attracted my curiosity and decided to read it. I have just finished it and I must say that it has been an excellent read. The author who worked in Africa many years, describes the likely events that probably started around 1920s with the transmission of HIV from a chimpanzee to a human and ended up in a world-wide pandemic.

In the middle, many societal changes: from the colonial rule in central Africa, establishing new cities in the banks of the river Congo; with mostly male migrants and a thriving sex market. Then, a surge in the use medical injections with non-sterile syringes to treat different diseases (trypanosomiasis, yaws, syphilis, malaria), and also political instability after the independence of different countries that weaken their medical systems and produce a dramatic loss of doctors and health professionals, apart from teachers, engineers, etc... Highly-qualified workers were brought from other countries, and in this context, the infection was exported to Haiti and beyond. Furthermore, uncontrol blood trade in the 70s may have contributed to amplify the infection.

The book is a wonderful combination of contemporary history and epidemiology and health science.

The link for the commentary on Nature is:

For the book:

Thank you very much again for your wonderful podcast and efforts to promote science in general and virology in particular… and long life to TWiV!


Centro de Biologia Molecular Severo Ochoa (CSIC-UAM)

Madrid, Spain


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