Marc Johnson Profile picture
Jun 4 15 tweets 4 min read Twitter logo Read on Twitter
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

May 24
I've got another cryptic lineage mystery and this one is really specific (read to the end).

It's a lineage from the Bronx that have been appearing in Biobot's sequences off and on since last August. Image
The phylogenetic tree makes it look like the lineage is an XBB derivative, but I think that is misleading.

In the 5' end through Spike it appears to be an Omicron derived (something BA.2 or XBB-like), but the genes at the 3' end all appear to be B.1.1 derived.
Specifically the sequences lack the deletion in N gene that is in all Omicrons, but it contains the B.1.1 changes at positions 203-204.

Further, they lack the 3' s2m deletion, but contains the s2m 'correction' that I've talked about before.

Read 7 tweets
May 19
Our updated manuscript with @dho about a SARS-CoV-2 cryptic lineage from Wisconsin is now online.
1/
medrxiv.org/content/10.110…
A cryptic lineage is a SARS-CoV-2 sequence detected from wastewater that is distinct from anything that has been seen before and is of unknown origin.

At the start of this investigation I thought these lineages probably came from an animal reservoir.

I was wrong.
2/
The WI lineage was continually detected from Jan 2022 until Jan 2023. It was probably present earlier, but that is when we first detected it.

The sequence was diverse (mixed), evolutionarily advanced, and looked nothing like circulation lineages.
3/ Image
Read 11 tweets
Apr 29
I’ve started doing a deeper dive looking at the genome of the latest cryptic lineage from Ohio.

Warning – I’m going deep into the weeds.

Lay summary: cryptic lineages have a lot of convergent mutations, and for the most part we don’t what they mean.
1/
Image
I repeated the screen of ALL of the wastewater samples to specifically look for this lineage. Still only from Ohio, but I found 2 more positive samples from Columbus. These two were from the sewershed on the North side of town. Both were from December.
There have been 20+ samples that contained the cryptic lineage so far. I took the top 15 and compared what mutations were present.

Theses samples had about 200 different mutations (not all were consensus changes) that are extremely rare in circulating lineages.
Read 15 tweets
Apr 24
Help me solve a COVID cryptic lineage mystery.

Cryptic lineages are distinct SARS-CoV-2 lineages that we detect in wastewater, but do not know their source. We believe they are from patients with very long COVID infections.

Here is more backstory.



1/
We recently discovered a cryptic lineage in Ohio. It appears to be derived from a person that was infected over 2 years ago. It is a B.1.1 derivative, but is highly divergent.

We first detected this lineage in a sample from last summer, and as recently as last month.

2/ Image
The one thing we know for sure it that this person is shedding a ton of viral material. I suspect that they have a SARS-CoV-2 GI infection and may think they have something like IBD or chronic diarrhea.

3/
Read 6 tweets
Mar 25
What's next for COVID?

I projected a few weeks ago that XBB.1.9* would be the next dominant lineage in the US.

This lineage was a little over 4% of US sequences over the last 2 weeks, and the numbers are doubling roughly every 8 days.

It's in almost every state.

1/
The competition.

XBB.1.16 remains the fastest growing lineage. Worldwide it is doubling about every 5 days. (world data shown)

However, it is less than 1% of US sequences in the last 2 weeks, and only seen in 13 states so far (including Missouri).
2/
If trends hold, XBB.1.9 will still become the dominant lineage in the US in late April, but it won't hold the position for long.
3/
Read 6 tweets
Mar 21
Update on Polio.

After the detection of Polio in NY last year, there was some pressure to do wastewater testing in Missouri.

So we developed a few polio wastewater assays. One generic enterovirus screen, and 2 polio-specific (targeting the 5’UTR and the Capsid)
1/14
None of the Missouri samples had any sign of Polio, so we decided to throw the net a little bit wider and looked at other samples.

Don’t ask me where they were from. Most of them were de-identified so I couldn’t tell you if I wanted to, but they were from all over.
2/14
We only had one surprise, which was from Utah. I’m revealing the location only because it was recently reported in the press. (It was NOT a false positive, by the way.) Polio was about 2% of the sequence in our generic enterovirus screen.
3/14
deseret.com/utah/2023/3/20…
Read 14 tweets

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