(Replying to PARENT post)

If you (or others) would humor a newbie question - assuming that host cells start expressing the spike protein, and the immune system learns to react to it, what are the chances that it will also learn to react to other proteins expressed by those cells, which are not related to the virus, and basically learn to attack its own cells?

In other words, is there a worry of MRNA causing auto-immune reaction/disease due to those proteins getting expressed by host's own healthy cells?

👤throw9678🕑5y🔼0🗨️0

(Replying to PARENT post)

there is a self recognition system, the body indexes its components and will end process when the protien is recognized as self. foriegn molecules are not indexed and if large enough [as in protiens, not water or salt] they will trigger immune response a wanted poster and a bunch of antibodies are produced that tag the invader.

the mRNA of concern will not modify your DNA sequence, the expression of the S protien occurs untill the mRNA is destroyed by the cell, or the cell itself is destroyed taken apart and compared to self antigens, the foriegn antigen is expressed by MHC cells and PresenteD in a context of this is a hostile thing [a wanted poster]

this all occurs in a system of interdependent cell types and thier interactions.

your question addresses the crux of immunology, and needs a lot more attention than would be constructive here.

put on your reading cap and check this out:

https://en.wikipedia.org/wiki/Immunology

https://en.wikipedia.org/wiki/Autoimmune_disease

👤rolph🕑5y🔼0🗨️0

(Replying to PARENT post)

My understanding is that normal viral infections cause proteins to be expressed by cells in the same way — in fact, uninfected cells also continually display a "status report" of protein fragments. Your immune system monitors this to detect cells that have gone haywire, whether by mutation or infection.

https://en.wikipedia.org/wiki/MHC_class_I#Effect_of_viruses

I don't honestly understand how the immune system decides which protein fragments are okay to develop a response to, but the point is that that is already part of the normal immune response pathway that learns new antigens every day; after the protein fragment shows up on the cell surface, the rest of the process is similar to the response to an attenuated-virus vaccine or a natural infection.

👤wiml🕑5y🔼0🗨️0

(Replying to PARENT post)

If one gets infected with COVID19, the cells containg the virus will too produce the spike protein among other virus constituents as specified by the virus RNA.

I'm no expert either, but I don't see a difference here between virus infected cells and mRNA "infected" cells. So cells primed with mRNA simply produce less virus parts than those with the real virus?

👤jcynix🕑5y🔼0🗨️0

(Replying to PARENT post)

> assuming that host cells start expressing the spike protein, and the immune system learns to react to it,

Firstly they only express it as long as the mRNA remains intact. mRNA are degraded naturally so there is a finite time window as the mRNA is not reverse transcribed into DNA and reintegrated into the genome.

> what are the chances that it will also learn to react to other proteins expressed by those cells,

T (and B cells? I can't remember) cells undergo a selection process in the thymus that select against cells with receptors that bind to self proteins, that is proteins made normally by the body. Sometimes this fails and you get autoimmune disorders. Chances are very slim and no more than any other antiviral vaccine.

👤nicwilson🕑5y🔼0🗨️0