sometimeslight
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hey,

i've never managed to find an answer to this even though it seems like a fairly obvious question about vaccines.

Instead of administering mRNA to produce antigens e.g. COVID-19
s-protein or administering a virus whether inactivated or weakened that would produce the antigen, why not just isolate and administer pure antigen (spike protein)? Wouldn't that expose the body to APCs and produce B Plasma cells, activate T Cells and create an immune response? Is it too difficult to isolate an antigen? Expensive? Does the antigen lose it's function when in our blood? Do we need so much antigen that it wouldn't be possible to administer that in a vaccine and we would need actual genetic material to be injected so that antigen can be made within cells? I tried to look this all up but couldn't really find the answer i was looking for cos im dumb lol

There's obviously a very clear reason and I'm sorry for being the uneducated peasant I am but I feel like they should make a point of this in A-level bio lol
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HarisMalik98
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There are vaccines that use this methodology, they're called sub-unit vaccines (i.e. only a certain fragment, antigen, of the pathogen is presented to the immune system). This makes the vaccine safer as there's no chance of reversion to virulence as is seen in live-attenuated vaccines. Like the mRNA vaccines, though, they require adjuvants and booster doses since the generated immune response is weaker. There probably is labs working on subunit COVID-19 vaccines; and a subunit vaccine would still likely work perfectly well. However, there are a couple of logistical reasons why RNA vaccines have emerged as the most promising candidates.

So they seem similar, but the reason for choosing an mRNA vaccine model was most likely due to easier manufacturing process. When the pandemic hit, as you would expect, there were many groups working on sequencing the genome of SARS-CoV-2. This meant the full sequenced genome was readily available very quickly. If you have the genome, then it's actually relatively quick and inexpensive to generate RNA vaccines. Subunit vaccines involve growing the pathogen (or expressing the protein/antigen of interest in another system) and then isolating the antigen you're interested in - which definitely requires more time, effort and money. They're actually looking at potentially using RNA vaccine technology in flu vaccines. As you may know, flu vaccines are synthesised using forecasted (predicted) strains - which isn't always accurate. Current flu vaccines take about 5/6 months to develop so there's very little that can be done if a more virulent strain does emerge. RNA vaccines can be synthesised much quicker (~2/3 months), meaning they could be produced in response to emerging strains.

Since we are in a pretty wretched situation right now, the faster and cheaper the better!
Last edited by HarisMalik98; 3 months ago
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sometimeslight
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(Original post by HarisMalik98)
There are vaccines that use this methodology, they're called sub-unit vaccines (i.e. only a certain fragment, antigen, of the pathogen is presented to the immune system). This makes the vaccine safer as there's no chance of reversion to virulence as is seen in live-attenuated vaccines. Like the mRNA vaccines, though, they require adjuvants and booster doses since the generated immune response is weaker. There probably is labs working on subunit COVID-19 vaccines; and a subunit vaccine would still likely work perfectly well. However, there are a couple of logistical reasons why RNA vaccines have emerged as the most promising candidates.

So they seem similar, but the reason for choosing an mRNA vaccine model was most likely due to easier manufacturing process. When the pandemic hit, as you would expect, there were many groups working on sequencing the genome of SARS-CoV-2. This meant the full sequenced genome was readily available very quickly. If you have the genome, then it's actually relatively quick and inexpensive to generate RNA vaccines. Subunit vaccines involve growing the pathogen (or expressing the protein/antigen of interest in another system) and then isolating the antigen you're interested in - which definitely requires more time, effort and money. They're actually looking at potentially using RNA vaccine technology in flu vaccines. As you may know, flu vaccines are synthesised using forecasted (predicted) strains - which isn't always accurate. Current flu vaccines take about 5/6 months to develop so there's very little that can be done if a more virulent strain does emerge. RNA vaccines can be synthesised much quicker (~2/3 months), meaning they could be produced in response to emerging strains.

Since we are in a pretty wretched situation right now, the faster and cheaper the better!
this is exactly all I needed. Thank you so much!
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Anonymous_medic
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(Original post by sometimeslight)
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this is exactly all I needed. Thank you so much!
Most of the content and explenation was well covered above. Just to give an example of a subunit vaccine that has been developed now during the pandemic: Novavax. They recently proved efficacy in their UK trial involving 15000 people (95.6% efficacious against wildtype SARS-CoV-2 and 86% against B. 1. 1. 7 [UK varient]). https://ir.novavax.com/news-releases...acy-uk-phase-3
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