New Oral Polio Vaccine Candidate Could Signal Strategy to Fight COVID-19 - Contagionlive.com

New Oral Polio Vaccine Candidate Could Signal Strategy to Fight COVID-19 - Contagionlive.com

New Oral Polio Vaccine Candidate Could Signal Strategy to Fight COVID-19 - Contagionlive.com

Posted: 04 May 2020 12:00 AM PDT

Raul Andino, PhD

Raul Andino, PhD

In much of the world, polio is thought of as a bygone disease—a threat that seems to belong in the history books. However, the virus itself has continued to evolve in dangerous ways, and the polio vaccine itself is actually part of the problem.

In a recently published study, investigators explained how the attenuated virus in the Sabin oral polio vaccine changed—and how they developed a new vaccine that limits the risk of such evolution. The results could have implications for the final push to eradicate polio, and might also affect how vaccine developers create vaccines for conditions like coronavirus disease 2019 (COVID-19).

Writing in the journal Cell Host & Microbe, Raul Andino, PhD, of the University of San Francisco, and Andrew Macadam, PhD, of the National Institute for Biological Standards and Control in the UK, report on the phase 1 results of a study of their new oral vaccine: the first new oral polio vaccine in 50 years.

The vaccine was designed to solve an emerging problem: in some parts of the world with low vaccination rates, weakened virus from the vaccine has been able to evolve and spread from vaccinated people to other individuals.

The effort came as a result of research by Andino and colleagues back in 2017, which found the vaccine virus had made 3 evolutionary changes that had enabled it to spread outside of its host. In response, Andino, Macadam, and colleagues decided to redesign the vaccine to stabilize the part of its viral genome that facilitates evolution.

They hope these changes will disable any ability of the virus to adapt in a way that could be harmful to humans.

"To my knowledge, this is the first effort to rationally design a live attenuated virus based on detailed understanding of its biology, as opposed to the standard approach of blindly passaging the virus in animal cells to eliminate human virulence through poorly understood mechanisms," Andino said in a statement.

In the study, the investigators recruited 15 patients who had previously been vaccinated against polio and performed a test. The team exposed mice to viral samples from the stools of vaccinated humans to see whether or not the samples shed by humans could harm the mice. In earlier research, patients who were given the standard Sabin oral polio vaccine shed viral samples that caused paralysis in as many as 90% of mice.

In the new study, when the previously vaccinated volunteers were given the new oral vaccine, their viral samples proved unable to infect or cause paralysis in the mice.

Investigators are currently conducting a phase 2 trial, and the World Health Organization (WHO) is planning a phase 3 trial.

Andino hopes this research will also have an impact on newer vaccines. Most pressingly, while he notes that the race to develop a COVID-19 vaccine will likely rest on older vaccine-development technologies, he believes a longer-term solution might require the kinds of tailored vaccine-design technology demonstrated in this new research.

"Given how little we know about this new coronavirus," he said, "I'm betting we'll need all the weapons we can muster."

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A Polio Vaccine That Hasn’t Been Used in the U.S. for Two Decades Might Protect Against Coronavirus [Video] - SciTechDaily

Posted: 08 May 2020 12:00 AM PDT

The COVID-19 pandemic has scientists considering a few less-conventional options while vaccines against SARS-CoV-2 are being developed. One option might be the oral polio vaccine. We chatted with one of the researchers proposing the idea — Robert Gallo, M.D. — to understand why  vaccine that hasn't been used in the U.S. for two decades might provide short-term protection against this new coronavirus:

Video Transcript:

Could a polio vaccine help us fight COVID-19?

When I first heard that idea I thought there's no way, polio has nothing to do with coronaviruses. Turns out it's not as crazy an idea as I first thought.

I called up one of the researchers who's proposing it, Dr. Robert Gallo. Dr. Gallo was one of the co-discoverers of HIV and he is a huge name in biomedical research.

[DR. GALLO] This has a chance. A moment like this is for a decisive action and we think it has a real chance of stopping the epidemic.

[SAM] So how could a vaccine for polio keep you from contracting a totally unrelated disease? Generally speaking, it comes down to what the oral polio vaccine does to your immune system. More specifically, how it interacts with your innate immune system, versus your adaptive immune system.

[DR. OZOG] Think of your favorite spy movie, you know like when the spy is invading the compound, like James Bond's trying to get in to sneak into the the base of the bad guy the innate immune system is kind of more like the guard dog that's you know walking around. It's, it's not specifically looking for a James Bond but it knows that anybody who comes over the wall wearing a ski mask it needs to get bit.

[SAM] Your innate immune system is the guard dog. It's not looking for anything specific it just attacks anything that looks dangerous.

[DR. OZOG] I would say the adaptive response is more like a Special Forces sniper. It has the picture of James Bond it, knows what James Bond looks like, and it knows exactly who they're targeting.

[SAM] When you give someone any form of a vaccine you're training the sniper. You're giving your adaptive immune system a picture of the virus and saying, next time you see this kill it.

The oral polio vaccine doesn't just train the sniper. It also startles the guard dog. That's because it's what's called a live, attenuated vaccine. A live, attenuated vaccine contains a complete virus or bacteria that's been weakened in the lab.

It wakes up the guard dog and that guard dog is angry. Or, to use actual scientific terms here, it activates your innate immune response.

Unlike the oral polio vaccine the polio vaccine you have injected is not live and attenuated, it's what's called an inactivated vaccine. Inactivated vaccines don't use complete live virus and bacteria. They're made using a physical process like heat, or chemicals like formaldehyde to inactivate little pieces of bacteria or viruses.

Those pieces, great at building adaptive immunity, but they don't really
spook the guard dog. So the idea here is that the oral polio vaccine would amp up
your innate immune response which would release that guard dog on SARS-CoV-2.

Now you might be wondering why your innate immune system isn't just doing that on its own. Why would it need help from a live attenuated vaccine to stop COVID?

So it turns out that SARS-CoV-2 can make your innate immune system act kind of erratically and even block it from responding. That causes lung inflammation and fluid buildup that you would see in severe COVID cases.

Taking the oral polio vaccine might help keep that from happening.

[DR. OZOG] You could fight off the virus early before it really establishes a good infection, and then later on hopefully that's enough to prevent this inflammatory lung destruction that happens in the in the later process of SARS-CoV-2 infection.

[SAM] So the big question is will the live attenuated oral polio vaccine wake up your innate immune system's guard dog enough to prevent you from getting COVID-19?

[DR. GALLO] This has a chance, if it works. Am I a hundred percent sure? No, I'm a hundred percent sure of almost nothing, so you know, not a hundred percent sure, but we think it has a real chance of stopping the epidemic.

[DR. NIZET] So I think we're looking at interventions that might buy us a little bit of time before a bonafide SARS-CoV-2 vaccine emerges in 2021, hopefully.

[SAM] I also want to mention that the oral polio vaccine is not the only live, attenuated vaccine that's being considered. Vaccines for tuberculosis and measles are also in the mix, and the idea is that they would also boost your innate immune response.

Even in the best case scenario these options are really only going to protect you in the short term, so maybe for a few months at a time. That means that you would have to take them every few months until there's a vaccine for SARS-CoV-2 available.

[DR. GALLO] And when you develop a very good coronavirus vaccine, which is specific, which is long lasting, that would be great. But the truth of the matter is, it's certainly not in time for this epidemic, and further truth of the matter is you never can give a date for a vaccine. I mean, I hear a lot of suggestions for about the months will take to get it, but reality is, you have a vaccine when you have a vaccine.

[SAM] So at the end of the day these are really just buying as time. You can buy us even more time by staying home, washing your hands, avoiding large gatherings, keeping your distance from other people, and wearing a mask. Maybe just sit on your couch and binge your favorite American Chemical Society YouTube series.

Stay safe, everyone.

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