Thread by @1goodtern

Ok folks.

You've maybe heard the word methylation recently, and while people are talking about it as if it's a big deal, you don't have the faintest idea what it means.

Let's change that.

A quick thread about the vital process by which your body decides which *genes* to silence, how that system works, and what happens when it goes wrong.

(Especially after *infection*)

*DNA methylation* is part of the process by which each cell of your body governs which parts of your DNA to use and not use.

Because each expression of your DNA has all your DNA, but each cell only needs to use the parts of your DNA *relevant to that cell*.

A skin cell doesn't need to do liver things.

A liver cell doesn't need to do eye things.

Imagine your DNA is like a piano keyboard.
Methylation is like putting sticky notes on certain keys telling a cell "don't play this note".

Or like the cells of your body are different members of an orchestra.

And they all have a copy of the same big sheet of music...

But the sticky notes tell them which bits to play and which to ignore.

Methylation doesn’t *change* your DNA, it just tells the different parts of your body which bits of your DNA to use.

It helps keep the right genes active and the wrong ones quiet.

It works by enzymes called "DNA methyltransferases" adding tiny chemical tags (methyl groups) to specific parts of your DNA, usually near a gene’s on switch.

This *blocks the machinery that would normally turn the gene on*.

So how does the body know where to put these tags?

Partly by inherited (Epigenetic) memory, partly learned as they go.

As cells mature and their identity is established, they methylate unneeded genes as they go.

But there's a problem.
Methylation also responds to the environment:
stress, nutrition, infection, toxins.

Sadly, that’s where things get tricky.

When the body is under intense stress, say during infection with a virus like covid, it can mess up the delicate balance that keeps methylation working as it should.

During a covid infection, and for months after, genes that should stay quiet get activated. Others that should be in use get inappropriately silenced.

In a recent covid study, researchers found reduced methylation at cancer-linked genes like ZFP64p1 and CBR3-AS1.
polybio.org/polybio-suppor…

Less methylation = more gene activity.
These genes are usually kept in check.
Now, after a covid infection, they’re more switched on.

ZFP64p1 boosts expression of tumour-promoting genes.
CBR3-AS1 is linked to inflammation and immune disruption.
These aren’t genes you want overactive for months after infection.

Methylation is part of how your body keeps your genetics in order.

Covid infection is dysregulating methylation.

Those sticky notes?

Covid infection is *removing* the "do not play" ones from the piano keys.

And the tune they play is a dark one.

Covid isn't the only virus proven to do this.
Epstein-Barr virus (EBV), Human papillomavirus (HPV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human immunodeficiency virus (HIV), Helicobacter pylori (not a virus) all do it.

But covid is probably the only one that people are catching as if it's candy thrown out by a benevolent uncle.

A bit of an expander on how Covid actually messes with the methylation...

In your cells you have control mechanisms that regulate which genes get used, when, and how much, based on the stage of development of the cell and of you, on the environment, and on stress signals.

Three of the basic ones are:

DNA methylation enzymes (that stick "off" tags on genes),

Histone modifiers (that loosen or tighten the DNA packaging, for using or not using it),

And non-coding RNAs (that help fine-tune gene activity).

Covid produces proteins (like NSP5, ORF8, and others) that interact with the host cells regulators above.

These proteins can *hijack* the cell's machinery.

Some of the viral proteins can block or redirect DNA methyltransferases (DNMTs)—the enzymes responsible for adding methyl groups (the sticky notes).

Other viral proteins can mess with histone modifiers, which work alongside methylation to control gene expression and usage.

Think of the virus as reprogramming the cell to favour its own survival and replication, *at the expense of silencing tumour suppressors or activating dangerous genes*.

Covid infection often triggers prolonged systemic inflammation (more than just superficial swelling, *swelling within tissue and organs and all the disruption that comes with it*) and...

... and oxidative stress (when your body has too many unstable molecules (called free radicals) and not enough defences to neutralise them, which can damage cells and DNA.), especially in Long Covid cases.

Chronic inflammation alters the activity of DNMTs and other methylation-related enzymes that place the 'do not use' stickies...

... and 'reactive oxygen species" (ROS) which are unstable molecules your body makes under stress, can damage DNA and mess up the system that controls which genes get turned on or off...

Basically, the cell is in panic mode, and its usual genetic discipline slips.

Cells under duress (e.g., from viral infection or cytokine storms of inflammation) may enter a state where they try to adapt to the stress, changing the way they do methylation to try to survive.

And in the process, genes involved in metabolism, immune regulation, and even cancer pathways are getting turned up or down inappropriately.

Plus... Covid may reactivate latent viruses like Epstein-Barr virus (EBV), which is already known to mess with methylation.

So some of the changes may be *secondary*, driven by covid suddenly waking up dangerous co-infections.

You may be thinking to yourself that probably all viruses do this, and that we shouldn't be singling out covid as a danger.

Wrong.

Viruses like flu are usually short-lived in your body.
Two weeks, and it's *gone*.

And while flu causes inflammation, the body typically resets after recovery.

Some epigenetic changes can happen (especially in severe cases), but they’re not as deep or lasting as those seen after Covid infection.

There is *no strong evidence* that flu reprograms methylation in cancer-linked genes or drives long-term immune exhaustion like Covid does.

And you may be saying "yeah, but this was only in the first wave, right? This study was probably done five years ago and before vaccination, right?"

Wrong.

This study is brand new, using data from late 2024.

It was published as a preprint in April 2025, and the participants had *recent infections*, not ones from the first wave.

This study shows epigenetic damage and immune disruption are happening *now*.

Vaccines aren't stopping it from happening.

Prior infections aren't stopping it from happening.

Basically, if those two red lines are lighting up, the virus is *replicating throughout your body*, and your body is at risk of these processes happening.

And if you're thinking "well, I've already had it once, there's no point trying to avoid it now" or "nothing happened when I caught it and I'm fine"...

Then you don't understand that this effect will almost certainly be cumulative.

Racking up covid infections won't undo it.

That'll make it worse.

What's going to be the long term effect of all this?

I have no idea.

Even if it only increases the amount of cancer by 5% that's a 5% increase we don't need.

But the cumulative effect?

I don't want to find out.

I want us to stop spreading this flipping virus.

Hmm.

If you've got this far, you may be thinking to yourself, "why the heck does the body have these genes like ZFP64p1 and CBR3-AS1 that can do weird cancer stuff".

Well, the truth is that your DNA is packed full of stuff that is useful if it's used at the right moment in the right amount, but is hugely dangerous if used at the wrong moment in the wrong amount.

Your body is immensely hugely spectacularly mind-blowingly complicated.

All of this wellness shit, just pretending that if you think positive thoughts and drink guava juice you're going to experience physical health nirvana is just bullshit.

The organs and systems of your body are in a constant chaotic whirl of trade, battle, growth, recycling, policing, replication, waste removal, monitoring, nutrient exchange, espionage, rest.

And, yes, a healthy lifestyle and good diet are going to help smooth things along the way...

... but your body's biggest enemies are time, pathogens, poisons, pollutants, damage, and your own body itself.

And when you get a combination of those:
Like a pathogen that poisons, pollute, and damages your body at the very cellular level...?

Well...

Your government decided you should be infected with one endlessly, so... good luck.

As for me... I'm masking, thanks.

With an ffp2+/n95+ mask that fits well.

And I'm trying to reduce my exposure to covid by doing as much outdoors as possible, and by ventilating and filtering indoor air, and reducing the number of unnecessary in-person meetings...

... and by remembering that covid isn't stopped by positive thoughts or wishful thinking or ignorance.