> With mRNA vaccines we get the cells to produce the protein. Does this imply that synthesis of the spike protein is difficult, or is it that administration is?
It's that the mechanism of production of spike (inside infected cells) parallels the mechanism of production of spike protein in a natural infection. This stimulates the immune response against spike without need for additional adjuvants.
> This then begs the question, could mRNA injections be used in place of traditional medication?
Not my specialty, but as you say targeting may be difficult. There are various lipid carriers that I believe can target certain cell types or tissues, but I don't know how well these work, and of course actually distributing them so that they will reach lung tissue is also a matter. And then how well would they work in already infected lung tissue versus just spraying the lungs with the protein?
As for the second segment. I only have more questions now. Could it be that requesting that the cells produce additional proteins of a particular kind "overloads" them or simply "asks too much" in a fashion similar to a virus?
That seems unlikely unless the administered medication is simply "too much". I wonder, is there a saturation point? ie a point where additional mRNA medication does not result in more cells producing the target protein? Seems likely.
Which then raises the question, if such a saturation point exists, then what is causing cells to explode due to virus replication? Is it that the viral particles can not escape the cell and thus they "use" pressure? If so, have we encountered a virus that "opens up" a cell without damaging it and eventually becomes parasitic to the host?
It's probably the case that when cells die prematurely, they leave traces for our immune system to trigger an issue, so not destroying the cell seems like a beneficial evolutionary advantage. Otoh, the additional code required for this is likely very "expensive".
I hope a virologist drops by and clarifies on this.
I'm not a virologist, and this is taxing to my memory, so it will be a bit more basic than you might prefer, and won't be as accurate.
> Could it be that requesting that the cells produce additional proteins of a particular kind "overloads" them or simply "asks too much" in a fashion similar to a virus?
It could be. I believe that most of the cells that express from the mRNA vaccine do indeed die (from the immune response against them). I'm not positive about this though. In general if a cell is preferentially producing protein from a particular mRNA it doesn't have to resources left to do what is expected of it (including cellular maintenance).
> then what is causing cells to explode due to virus replication?
https://bio.libretexts.org/Bookshelves/Introductory_and_Gene...
"During release, the newly-created viruses are released from the host cell, either by causing the cell to break apart, waiting for the cell to die, or by budding off through the cell membrane."
According to the video below it can be caused by crowding. I think it can also be caused by virus proteins, or an apoptotic response - programmed cell death done to hinder the viruses ability to replicate more infectious particles. Often enough the cell does not burst, but simply buds off new virus. This is still very detrimental because the cell isn't doing what it is supposed to do, instead having been hijacked to create new viruses.
> If so, have we encountered a virus that "opens up" a cell without damaging it and eventually becomes parasitic to the host?
What I'm going to say won't directly answer your question, but it will answer the question you would have had if you knew a bit more. You want to look up lytic versus lysogenic viral replication. A basic overview: https://www.khanacademy.org/science/high-school-biology/hs-h...
It's that the mechanism of production of spike (inside infected cells) parallels the mechanism of production of spike protein in a natural infection. This stimulates the immune response against spike without need for additional adjuvants.
> This then begs the question, could mRNA injections be used in place of traditional medication?
Not my specialty, but as you say targeting may be difficult. There are various lipid carriers that I believe can target certain cell types or tissues, but I don't know how well these work, and of course actually distributing them so that they will reach lung tissue is also a matter. And then how well would they work in already infected lung tissue versus just spraying the lungs with the protein?