Sciencemadness Discussion Board

Questions about mRNA vaccine for Coronavirus

wg48temp9 - 18-5-2020 at 05:17

So they synthesis a mRNA corresponding to part of the protein outer envelop of a virus. The mRNA is then encapsulated in a vector and injected in to a person. The mRNA enters cells of the person and causes the cell to synthesise the protein that is part of the viruses envelope which triggers the immune system of the animal to make antibodies against that part of the virus.

Apparently the vector can be a virus or even a just an emulsion containing the mRNA. Is it that easy to get mRNA into a cell and get the cell to manufacture the protein and get the cell to export the protein out ?

Presumable the cells continue to make the protein until the mRNA stops working ?

Also presumable the cell will have some of the protein in its envelope and may be attacked by the immune system?

I assume/hope the vaccine will be well tested.

Metacelsus - 18-5-2020 at 05:22

Quote: Originally posted by wg48temp9  
So they synthesis a mRNA corresponding to part of the protein outer envelop of a virus. The mRNA is then encapsulated in a vector and injected in to a person. The mRNA enters cells of the person and causes the cell to synthesise the protein that is part of the viruses envelope which triggers the immune system of the animal to make antibodies against that part of the virus.

Apparently the vector can be a virus or even a just an emulsion containing the mRNA. Is it that easy to get mRNA into a cell and get the cell to manufacture the protein and get the cell to export the protein out ?


Getting mRNA into a cell isn't very efficient, but once it's inside the mRNA will be translated just like any other. And the spike protein naturally displays itself on the cell surface.
Quote:

Presumable the cells continue to make the protein until the mRNA stops working ?


Yes. mRNA half-life (in the absence of degradation signals) is on the order of ~10 hours. Presumably the vaccine designers will use some tricks (there are many) to make it more stable.
Quote:

Also presumable the cell will have some of the protein in its envelope and may be attacked by the immune system?


Yes, that's the idea.
Quote:

I assume/hope the vaccine will be well tested.


Yes, this is what clinical trials are for.

wg48temp9 - 18-5-2020 at 06:06

Its amazing how much we know about the biochemistry of cells and how we can use that knowledge. PCR tests for example or how our immune system manages to make such a variety of antibodies.

I don't like the idea of having my cells tricked in to making foreign proteins.
However I don't want to get killed by virus so I will be one of the first to line up for the vaccine.

DrRadium - 2-8-2022 at 05:22

Quote: Originally posted by wg48temp9  
So they synthesis a mRNA corresponding to part of the protein outer envelop of a virus. The mRNA is then encapsulated in a vector and injected in to a person. The mRNA enters cells of the person and causes the cell to synthesise the protein that is part of the viruses envelope which triggers the immune system of the animal to make antibodies against that part of the virus.
[snip]


Even today I think there are two things most people don't know about the mRNA vaccines. First, was how the speed of production helped provide time for testing. The mRNA component was designed in about a day, and the first of the experimental vaccine itself was ready in a few weeks. And from then to when they were given emergency approval was all preclinical and clinical testing.

Second, I doubt most people were aware how well developed the basic technology behind the mRNA vaccines was going into the pandemic. I had worked with a 2nd or 3rd generation lipid (from a kit no less) coating nucleic acids, and injecting the liposomes into brain to induce transient expression of two proteins (a serotonin receptor and a GFP marker protein) I was using DNA not RNA but it was the same basic idea as the mRNA vaccines. That was in 1998. The technology was already well developed enough that there were plug and play kits for using it.

Granted I ended up using a viral-based gene transfer vector, the efficiency of liposome mediated expression being at least an order of magnitude lower than the viral system, which itself wasn't spectacular but it was good enough and persisted longer. The lipids for in vivo lipofection have been improved greatly, and mRNA vaccines are an almost ideal use for them. As a rule the big problems with trying to induce expression of a transgene via a gene transfer vector of any kind is the low number of cells affected and brief duration of expression. With a vaccine, you don't have to affect very many cells to get a good immune response and you want only a brief expression.


[Edited on 2-8-2022 by DrRadium]