Marc Johnson Profile picture
Jun 4, 2023 15 tweets 4 min read Read on X
Ohio cryptic lineage update.

We’ve made no progress identifying the individual, but we have learned a few things.
1/ Image
First, the signal is almost always present in the Columbus Southerly sewershed, but not always at Washington Court House. I assume this means the person lives in Columbus and travels to WCH, presumably for work.
2/ Image
Second, the signal is increasing with time. Washington Court House had its highest SARS-CoV-2 wastewater levels ever in May, and the most recent sequencing indicates that this is entirely the cryptic lineage.
3/ Image
Third, I’ve tried to calculate how much viral material this person is shedding. (Multiply the cryptic concentration by the total volume). I’ve done this several times and gotten pretty consistent results.
They are shedding a few trillion (10^12) genomes/day.
4/
What does this tell us? How much tissue is infected? It’s impossible to know for sure. Chronically infected cells probably don't release much, but acutely infected cells produce a lot more. I gather a typical output in the lab is around 1,000 virus per infected cell.
5/
If we assume we are getting 1,000 viral particles per infected cell, that would mean there are at least a billion infected cells. The density of monolayer epithelial cells is around 300k cells/sq cm. A billion cells would represent around 3.5 square feet of epithelial tissue!
6/
Don’t get me wrong. The intestines have a huge surface are and 3 square feet is a tiny fraction of the total.
But it’s still a massive infection, no matter how you slice it.
7/
I do not know of any persistent infections that shed this much virus without killing the patient. (Correct me if I’m wrong). The closest would probably be HCV, an infection that often ends in liver cancer.
8/
My point is that this patient is not well, even if they don’t know it, but they could probably be helped if they were identified.
9/
How do you figure out if you have a COVID GI infection. Most rapid antigen test are not explicitly for stool. However, I know of at least one that is. The instructions from that test say to mix a ‘matchhead’ worth of feces with the buffer.
10/

dyonmedical.com/en/corona-ag-a… Image
I can tell you that with very positive wastewater samples we got a positive by just sticking the swab into the wastewater before adding it to the buffer. Either way, it is essential to use the buffer provided or the test doesn’t work.
11/
If you do get a positive reading, I would suggest having someone else try with the same kind of test with their feces to be sure it isn’t a false positive. Weird shit happens.
12/
If you are the individual, let me know. There is a lab in the US that can do 'official' tests for COVID in stool, and there are doctors that I can put you in contact with that would like to try to help you.
13/
What's more, if we can figure out how these infections occur, and how to treat them, it could potentially help out a whole lot of people.
14/ Image
Two comments I should have made in my thread.

Washington Court House is a town of 15k (not an actual courthouse).

I haven't invaded anyone's privacy. Approximately 1600 people commute between Columbus and WCH. That isn't enough information to pinpoint the source.

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More from @SolidEvidence

Nov 23
What should we expect this flu season?

Here’s a forecast from a wastewater perspective (because sh*t don’t lie)

1/
Background. The 4 main kinds of influenza circulating among humans (in order of severity) are:
FluA H3N2
FluA H1N1
FluB
FluC (many don’t know this one)

2/
Last season, there was a pretty even split between H1N1 and H3N2, with a little bit of FluB late in the season. At least according to CDC patient data.
3/ Image
Read 13 tweets
Nov 21
This is wild.

Remember the NJ crytic lineage?

I posted 18 months ago that the Spike was too divergent to predict ACE2 binding, and asked if someone else could figure it out.

Some colleagues took me up on it.

Guess what they found?
1/
This preprint just came out. @wchnicholas and team reconstructed and tested the NJ Spike and found that it has the tightest ACE2 binding of any SC2 Spike ever measured.
2/
medrxiv.org/content/10.110…
We first found the NJ variant in 2023 because this sewershed from NJ with 1.5 million people because it regularly had a sequence that was a reversion to the bat sarbeco sequence, which is common in cryptics.
3/

Read 9 tweets
Oct 31
Can you take a quarter cup of composite sewage, simply ask ‘what’s in there?’, and find out all of the pathogens circulating in that community?

That is the question we asked in our latest pre-print.

Turns out you can.
1/
medrxiv.org/content/10.110…
We are not the first group to do unbiased sequencing of wastewater to monitor circulating viruses, but I think we are the first to ever do it at this scale.

Weekly wastewater samples for 18 months, totaling over 85 Billion sequence reads.

2/ Image
Among the ‘known’ viruses, there was a fairly even split between bacteria viruses (phages) and eukaryotic viruses.
This was just raw reads though, if you look at diversity there was considerably more species of phages.
3/ Image
Read 23 tweets
Oct 24
Help me out, I’ve got another wastewater virus mystery.

This one really blows my mind.
1/
Starting in the late 2023, + @securebio have been doing ultra-deep metagenomic sequencing of the virome from Columbia, MO wastewater.

We’ve collected and sequenced sample for over 90 consecutive weeks.
2/Lung.fish
We sequence about a billion reads per sample. That’s generated about 16TB of data from this site so far.

To put this in perspective for people my age, it would take a stack of 3.5 in floppy disks 200 miles high to store this data.
3/
Read 12 tweets
Oct 17
It looks like Coeur d’Alene, ID cryptic is gone for now, but it has still managed to answer a lot of lingering questions for me about SARS-CoV-2 evolution, and what to expect next.

Here's a whole genome summary and interpretation.
1/ Image
For a long time cryptic lineages were all from pre-Omicron lineages.

I started wondering:

Will there be Omicron cryptics?

If so, will they have the same evolutionary trajectories as the pre-Omicron cryptics?

ID shows that the answer to both questions is yes.
2/
We don’t do a lot of whole genome sequencing, so I sent 3 samples to @dho lab, who got fantastic sequences for all 3.
These samples were virtually 100% cryptic, so we have nearly complete coverage of the genome for a change.
3/ Image
Read 12 tweets
Sep 10
This really pisses me off.

I obviously knew there was some manipulation of post metrics on social media, but I really didn’t realize just how hard this platform slams the breaks on posts it doesn’t like.

Here’s my experiment.
1/
This weekend I posted 3 threads.

1. on a cryptic lineage
2. on H5N1
3. on seasonal respiratory viruses

Each time I posted the threads on X and bsky at the same time.
2/
The three threads each got roughly the same attention on bsky.
However, on X the first 2 each had hundreds of RTs and over 1k likes.
The 3rd was practically invisible. It had only 5 RTs and 28 likes after 2 days. Over 40-times fewer views.

3/
Read 7 tweets

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