Jason writes:

Dear Twiv, 

I think I can add a tiny bit more on why the Department of Energy might be releasing a report on SARS CoV-2 origins. 

Rich was spot on, but here’s a tiny bit more background. The Joint Genome Institute (https://jgi.doe.gov/), the organization that coordinated the publicly funded wing of the human genome project, is operated by the Lawrence Berkeley National Labs (LBL), which in turn is funded by the Department of Energy.  It exists now as a user facility for advanced genomic research and continues to house a considerable deal of expertise across a wide range of biology. LBL also houses the innovative genomics institute whose staff and faculty include Nobel Laureate Jennifer Doudna.  

It seems entirely reasonable that from a scientific standpoint, the JGI would be a wing of the government weighing in analysis of SARS-CoV-2 origins. Without an actual report with data, none of us can tell if this is a genuine, scientifically plausible report from experts qualified to weigh in or if it’s merely  more speculation using the JGI as a cover to provide the report with an aura of science (or some third option). However, DoE via the JGI would be a perfectly reasonable place to generate a scientific analysis, and until we see the report, there’s certainly no call to question the appropriateness of DoE to weigh in.


Berkeley CA 

Please forgive typos. I’m writing from a phone while walking my dog in the hills of Berkeley, directly above the institute and this doesn’t lend to the best proofing.

Volker writes:

Dear Vincent, Alan, dear Polio Experts,

I have been following your coverage on the active poliovirus found in US sewage water, and I have a question that I hope you can help me with. Despite the constant inflow of people from regions where OPV is used and the majority of people in the US being immunized by IPV, why is there only a small amount of poliovirus found in sewage water, which in several cases can even be traced to one spreader? My assumption is that vaccine-derived poliovirus should be everywhere, as almost everybody’s guts can be infected. I would like to understand this better.

Thank you for your time and expertise.

Best regards from Bavaria,


John writes:

Drs TWiV:

It would not surprise me if Paul Berg’s classic Protein Synthesis video “in the dance idiom” had already been a Pick, but if not, it should be. You of course know the video.  But even better, someone has recently dug into the history of it, which is here along with an embedded link to the video, and Paul Berg even lived just long enough to comment on it.  Roger Hendrix was at Stanford at the time, but when I asked him once if he knew any of the background about it, he didn’t.  So here it is now: https://stanmed.stanford.edu/protein-synthesis-an-epic-on-the-cellular-level/

Otherwise, the wind woke me up a couple times last night here in Greater Braddock but by afternoon it had become a relatively civilized and sunny 7C.  

Best regards,


Patrick writes:

Dear TWIV,

Just listened to the latest podcast and just wanted to say that as an idiot lay person, I am so appreciative that you define the terms and explain the acronyms. I know it must be a pain for you to do that but for someone like me, it makes all the difference in the world. I would be totally lost if you didn’t take the extra time to explain the basics. I learn so much from listening to TWIV. For example, I was also wondering if they “Pool” plasma to get more diversification or just use a single patient source and you answered that for me and so many other great questions.

Thank you so much,


Bill writes:

Hi TWIV Team!

There is disagreement on the origins of SARS-CoV-2. So what? Let the experts pull their hair out trying to figure out what actually happened. The next spillover is coming.  The magnitude of the next spillover depends on our actions. Here are some suggestions to cover our butts-regardless if it was a lab or wild spillover. You are welcome to add your own suggestions.

  1. The study of existing pathogens and novel potential pathogens, along with their reservoirs and vectors, to gain an understanding of how they could possibly spillover into human populations.
  2. International agreements to provide unbiased teams to study potential spillover links to help prevent future spillovers.
  3. The study of novel antibiotics and antivirals to the stage where safe and effective versions can be quickly manufactured and released when needed.
  4. Changes in antiviral, antibiotic, and vaccine design and production so they may reach all human populations without delay.

Shouldn’t our representatives be working on tangible solutions rather than pointing fingers?

All the best!


Bo writes:

Hello TWiV team,

I just listened to epitope 987. Very informative as always, but it seems there’s a little confusion between plasma and serum. Basically like Dr. Casadevall said, plasma is the liquid portion of your blood. Serum is the liquid portion without the coagulation factors, so it is collected after coagulation has happened. If you spin the blood right after collection, you’ll get plasma. If you let it sit for a while, coagulation will happen (for most people), and you will get mainly serum after spinning. Or if you let it sit for a while, even without centrifugation, you will see a layer of somewhat clear liquid, depending on how much lipoproteins and whatnot are suspended in there, that would be serum too. In practice, blood is drawn into different types of tubes. If the tube is made of glass or has a silica coating, which will enhance coagulation, after 1 hour you can spin and get serum. If the tube is coated with anticoagulants, for example, heparin, citrate, or EDTA (these two are chelators that can take out calcium which is important for the coagulation cascade.), coagulation factors will remain soluble and you will get plasma after spinning. Plasma donation uses a mechanism that separates plasma and pumps back your red blood cells right away. Anticoagulants are also involved, I think some form of heparin. Because of silica in serum collection, it wouldn’t be a good idea to use sera to treat patients. Coagulation also activates the complement system like crazy.

The first time I wrote I was a research scientist in academia, now I work in a local health department’s public health lab. We do wastewater SARS-CoV-2 testing, so I got curious how  RNA levels could be so high in wastewater and consulted a former colleague. (They developed a feline COVID model and I am a cat person 😢.) I was told that it’s not uncommon for viremia to happen with COVID, and the virus in the bloodstream can infect epithelial cells in the intestines (high ACE-2 expression), and people can shed intact virions. I did find a few studies on finding coronavirus-like particles in the blood and culturable virus in fecal samples.

Coronavirus-like particle in plasma: https://pubmed.ncbi.nlm.nih.gov/34374761/ 

Viable virus in fecal samples: https://www.sciencedirect.com/science/article/pii/S1198743X20304274 

Second time writing, first time donating. Became a sustaining member just now. I’d also like to advocate for careers in public health. Graduates, please check out your local health department for jobs in labs, clinics, or epidemiology departments!



Rohit writes:

Hi guys,

This is Rohit, I’m an immunology student at Caltech. 

I’m curious if you could talk a bit about whether there are heuristics to decide “a priori” if animal testing is a good indicator of human prediction, and what you do if it isn’t? I was reading about how certain aspects of autoimmunity don’t replicate in other species, and it seems like a very tough problem.

Best regards,


Chris writes:

Dear TWiV,

Hello, I’m an undergraduate at Caltech currently taking immunology (Bi 114). I wanted to thank you for putting on your show. I often find it difficult to really know which immunology papers are groundbreaking considering how much background is often required to understand them. Your podcast makes it a lot easier to understand and digest the findings in these papers!

I wanted to ask if there may be a way to induce specific memory B cells against certain antigens in a vaccine immune response. As was discussed, the intention of Scott’s work is in part to create a vaccine that forms the basis of future immune responses to vaccines when given in the future. I’m curious about what other cofactors, if any, might be necessary to ensure that the future vaccine-caused responses are strong enough against an injected antigen to ensure that memory B cells are activated and undergo proliferation?

I look forward to hearing more about this topic!


Chris Pukszta ‘24