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  • This episode was filmed on May 29th, 2020.

  • If we have more recent episodes on the COVID-19 pandemic,

  • we'll include them in the description.

  • [♪ INTRO]

  • Researchers have been working on vaccine candidates for COVID-19

  • for months now.

  • Some of their work looks like traditional vaccine development,

  • albeit on a super sped up timeline.

  • But other research groups are trying some more creative approaches

  • to therapy... including ones that involve directly editing our genes.

  • This is known as gene therapy, and it's not as outlandish

  • as you might be thinking.

  • The outlandish part is that viruses are one of our primary tools

  • for gene therapy -- meaning we might be able to solve

  • our current virus problemwith a virus.

  • However, this approach comes with some uncertainty

  • and a significant price tag, so it's hardly a sure thing.

  • Here's how it might work.

  • The goal of a vaccine is to safely expose your immune system

  • to antigens derived from an infectious agent like a virus.

  • After vaccination, our bodies recognize this antigen

  • and know how to defend against it for a period of time.

  • That might mean exposing our bodies to a weakened

  • or inactivated form of a virus or bacterium so that our immune systems

  • can produce antibodies against it.

  • But there are plenty of other ways we can end up with immunity.

  • For example, some doctors are already using convalescent plasma

  • from recovered patients to transfer their antibodies to patients

  • who are critically ill.

  • But that's still in the testing stages.

  • Some of the vaccine candidates making swift progress

  • in clinical trials are based on the nucleic acids DNA and RNA.

  • The idea is to teach our cells to make viral antigens and to show them

  • to our immune system -- rather than bundling

  • the antigens themselves in a shot.

  • One hurdle to this idea is getting that genetic code into cells.

  • RNA, in particular, can get broken down pretty quickly in our bodies.

  • But the concept is solid: teach cells to make a specific part

  • of the virus -- like the spike protein, which SARS-CoV-2

  • uses to invade our cells.

  • So rather than inject patients with just the code,

  • another approach is more akin to fighting fire with fire.

  • Or a virus with a virus.

  • After all, viruses are really efficient at injecting genetic material

  • into host cells.

  • It's what they do -- they're really just little nucleic acid

  • delivery packets, with instructions for making more packets.

  • And we can reprogram those instructions.

  • So they're actually perfect if we want to introduce

  • genetic instructions into a cell.

  • But we need a virus that won't also make us sick, which is why

  • adeno-associated viruses, or AAVs, are the DNA vehicle of choice.

  • AAVs are little viruses that don't cause disease,

  • further genetically engineered to deliver their payload

  • without making more of themselves.

  • They've already been used in the past in efforts

  • against other coronaviruses.

  • Different AAVs tend to infiltrate different tissues,

  • and since COVID-19 affects the lungs, we'd need to find an AAV

  • that can get to our airway.

  • Some of the AAVs scientists have tested were able to get

  • into human respiratory cells in culture, but they haven't been tested

  • in actual humans yet.

  • And since an AAV is just a tiny DNA delivery unit, we could swap out

  • different sequences and test them all very quickly.

  • AAV-based gene therapy for other diseases has already been approved

  • by the US Food and Drug Administration, which could speed

  • implementation of a version of this therapy for COVID,

  • at least according to some.

  • The potential downside is that this style of gene therapy

  • permanently edits cells.

  • Not as permanently as you might be thinking.

  • It wouldn't target our germ cells, meaning we wouldn't pass

  • this DNA down to our kids.

  • We don't yet know all of the cell types we would need to target,

  • but the changes probably wouldn't stay with us for a lifetime.

  • Which means any kind of AAV-based therapy we develop for SARS-CoV-2

  • would only be a temporary fix.

  • But it might offer us some level of protection while we're

  • waiting on a more permanent vaccine.

  • But we can't rule out other long-term side effects

  • from directly tinkering with our DNA, even if it seems like

  • it should be safe based on what we know.

  • On top of all that, there's the cost.

  • Since the currently approved AAV-based drugs treat extremely rare

  • genetic diseases, they come with an inflated price tag.

  • But since an AAV for COVID-19 would be a much larger market,

  • the cost would hopefully be lower.

  • Now, will gene therapy for the novel coronavirus ever actually be a thing?

  • We have some good news on that front.

  • Researchers in Massachusetts recently announced plans

  • for a COVID vaccine clinical trial using AAVs.

  • They're in the preclinical trials right now, and if all goes well,

  • they'll move into human trials later this year.

  • Which means if we do ever see AAV therapy, it will still be a while.

  • But it's definitely one of the more creative efforts out there

  • -- and we need to try everything we've got.

  • Thanks for watching this episode of SciShow, and thanks as always

  • to our amazing patrons.

  • Patrons not only make it possible for us to make free videos

  • for everyone -- they also have access to cool behind-the-scenes perks!

  • If you want to get involved, check out patreon.com/scishow.

  • [♪ OUTRO]

This episode was filmed on May 29th, 2020.

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How to Fight COVID-19... with a Virus

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    ally.chang posted on 2020/06/15
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