NIH launches Zika vaccine trial

>>64564
Sounds pretty neat, but there's a caveat-- we're not using the same infectious material that originally causes the disease in the first place, but we're building something entirely new that kind of looks like the infectious agent.

Plasmids aren't inert matter. They're actual self-replicating stubs of DNA. Bacteria pass around plasmids to share whatever traits they code for without having to rewrite their core genetic structure. They aren't even necessarily restricted to one species or another, we've observed bacteria like to fead on the dead bodies of other bacteria, vacuuming up their genetic material and making it a part of themselves.

You can think of plasmids as a bacteria's religion-- it's not a part of them, but it changes their observable traits.

Now, I don't know about how mammals interact with plasmids. I'd think eukaryotic cells would be too specialized, too closed-off, and protected by an extremely effective immune system to have much use for--or much opportunity to encounter-- these plasmids. That mammal cells can use them at all is a surprise.

So, our cells that start manufacturing these proteins, do they get destroyed by our immune system since they're now "compromised"? What happens if one of these plasmids turn out to be very adept at reproducing itself, and produces enough to penetrate every cell in a person's body? Could be a huge autoimmune disaster. What happens if a bacterium gets ahold of a protein that we thought did nothing in a virus, but actually had a huge impact on the virus' ability to harm our immune system? We could be creating the next super bug.

So yeah. Just some things to think about.

>>64567

>we're not using the same infectious material that originally causes the disease in the first place, but we're building something entirely new that kind of looks like the infectious agent.

This isn't entirely accurate. Second generation subunit vaccines use viral antigen proteins manufactured in vitro, whereas these third generation DNA vaccines use mammalian cells to manufacture the same proteins. In both cases the proteins don't come from live viruses.

>That mammal cells can use them at all is a surprise

Transfection of mammalian cells with bacterial plasmids in a laboratory setting is actually very routine. Depending on the delivery method plasmids can be either integrated into the host cell genome, or transiently expressed by transcription machinery in the nucleus for 48-96 hours.

>do they get destroyed by our immune system since they're now "compromised"?

Generally speaking, natural killer cells of the innate immune system only destroy cells that lack the major histocompatibility complex 1 (MHC I), whereas foreign proteins (antigens) synthesised inside cells are presented to T lymphocytes at the cell surface by MHC I and II. Activated lymphocytes travel to lymph nodes and initiate the immune response to those antigens.

>What happens if one of these plasmids turn out to be very adept at reproducing itself, and produces enough to penetrate every cell in a person's body?

This is a fairly remote possibility. Most plasmids do not encode genes necessary to encase the genetic material for transfer to a new host, and those will be the ones used for vaccines. Although mutation is always a possibility, mammalian DNA proof-reading machinery is much less error-prone than in bacteria, and so the mutation risk is far lower.

With regards to general safety, extensive clinical trials are required before approval of vaccines, and DNA vaccines have already been approved for use in veterinary medicine based on such testing.

This is the first time I've actually learned something on /news/