> I should have been more clear here, I meant specifically trials of what I presume could have been attempted if the vaccine was expressed as protein instead of mRNA.
Yes, and one vaccine approach is getting a bacterium or other virus to make a lot of a protein you're interested in, and then purifying the stuff you're interested in and forming it into a vaccine product. These are recombinant approaches. E.g. https://en.wikipedia.org/wiki/AIDSVAX is exactly what you describe: a viral protein vaccine developed using recombinant approaches from e.g. Chinese hamster ovary cells https://pubmed.ncbi.nlm.nih.gov/8142140/
The first was a hepatitis B vaccine developed in the 1970s where yeast cells were modified to make hepatitis B proteins. Then the HPV vaccine used the same approach, choosing proteins that would spontaneously assemble into a virus-like particle that triggers a strong immune response.
Complicated proteins have to come from a living thing, in practice. So if you're going to administer a viral protein, it has to come from purifying virus that you've grown or from a recombinant approach of some kind (and growing HIV is problematic for multiple reasons).
Yes, and one vaccine approach is getting a bacterium or other virus to make a lot of a protein you're interested in, and then purifying the stuff you're interested in and forming it into a vaccine product. These are recombinant approaches. E.g. https://en.wikipedia.org/wiki/AIDSVAX is exactly what you describe: a viral protein vaccine developed using recombinant approaches from e.g. Chinese hamster ovary cells https://pubmed.ncbi.nlm.nih.gov/8142140/
The first was a hepatitis B vaccine developed in the 1970s where yeast cells were modified to make hepatitis B proteins. Then the HPV vaccine used the same approach, choosing proteins that would spontaneously assemble into a virus-like particle that triggers a strong immune response.
Complicated proteins have to come from a living thing, in practice. So if you're going to administer a viral protein, it has to come from purifying virus that you've grown or from a recombinant approach of some kind (and growing HIV is problematic for multiple reasons).