Inside the Delta Variant: A conversation with Western’s virologist, Gerry Prody
The Delta variant now is responsible for most new cases of infection in Washington state, and a week of public health reversals from the Centers of Disease Control and Prevention is sure to raise fresh health concerns.
To find some answers, Western Today chatted with Western’s own virologist, Associate Professor of Chemistry Gerry Prody, about the Delta variant, how it works, and what makes it so dangerous.
WT: The Delta variant has caused a fifth wave in COVID cases mostly among the unvaccinated. Do vaccines offer a good protection against the Delta variant?
GP: “Yes, the vaccines offer a great protection against the variants, though we do hear about breakthrough cases. But if you compare the number of people that get sick, that aren't vaccinated, with the number of people that get sick who are vaccinated, it's overwhelmingly those who aren't vaccinated. Vaccination is still our best hope for controlling this situation and the vaccines are about 90% effective or better.
We don't have a lot of data against the Delta variant yet, but we do know that the vaccinated people who are getting sick are not getting seriously sick for the most part.
And so, like I said, vaccination is what we need to do. The Western community is doing a really good job of getting the word out that we all need to be vaccinated so that we can get back to normal.”
WT: Can fully vaccinated people transmit the delta variant to others?
“Yes, it seems so. Even asymptomatic people can transmit the virus, so it seems to be especially important now that we all mask up when we're out in public, particularly indoors.
But it does appear that vaccinated people can transmit the virus, and so again the mask mandate is going to be important to enforce.”
WT: How do viruses mutate?
“There are a couple of different categories of viruses. The simplest way to think about a virus is that it is instructions for replicating, which are contained in nucleic acids. The nucleic acids are either DNA, deoxyribonucleic acid, or RNA, ribonucleic acid. Viruses that are DNA based, like smallpox, tend to mutate relatively slowly, whereas viruses that are RNA based, like HIV or Coronaviruses, tend to mutate fast. This is because the enzymes that replicate these viruses are more error prone.
We're lucky in the case of the SARS-CoV-2 because this replicase has an editing function that notices when mistakes are made. So, even though the variants that are showing up are very scary, there aren't as many as we might expect. If you compared to HIV, which is also an RNA virus, there are hundreds if not thousands of HIV variants running around.
Of course, HIV has been around a lot longer. Even within a single individual there are hundreds of HIV variants, whereas this SARS-CoV-2 is mutating at a much slower rate, so the mutations happen as the replication takes place.
In the case of RNA viruses, the wrong RNA base gets substituted, and it doesn't get corrected. So that just carries on and sometimes that change is deleterious.
The whole process of a mutant taking over depends on infecting people. And in in this case, it's non vaccinated people that are now spreading this mutant and allowing it to take over.
In the U.S., you probably know that the Delta variant is accounting for the vast majority of new infections, and it's being spread because some people decided not to protect the community. So, they made this decision for themselves, but it's affecting the whole community.
Of course, the stress is on the health care system.”
WT: What kind of properties change when the virus mutates?
“Well, it depends on where the mutation is. The genome for COVID codes for 25 or 26 different proteins and some of them are more important than others. The ones that we hear about so much are the ones that code for this spike protein. The spike protein is the protein that binds to the ACE2 receptor, which is the protein that we have in our respiratory tract that attracts the virus.
The spike protein, like the name implies - I mean you've seen pictures of the virus - It's got this surface protein that sticks out. There's this receptor on our cells that the spike protein sticks into. If that protein gets a mutation that makes the key fit better in the lock, then that's good for the virus.
One of the mutations that the Delta variant has just makes more copies of the spike protein on the surface of the virus. This just gives it more of an opportunity to find its ‘keyhole,’ if you will.”
WT: Is it possible to prevent the virus from mutating?
“Mutation is a natural process, and all our cells, when they replicate, undergo mutation at some low rate. I would say it's not possible to prevent mutation.
What we try to do is prevent the virus from replicating. You do that by throwing in drugs that jam up the replication events.
What biochemists and pharmacologists and all these people around the world are trying to do is to look at all the places in the virus life cycle where it's possible to put up a roadblock, then design a drug that will effectively prevent the continuation of that virus life cycle.
And so far, nothing is working very well. But everybody is continuing to charge ahead. That's a great question, and if we could figure out a way to effectively prevent the virus from mutating, if we could prevent it from replicating, we'd have solved the problem.”
WT: What makes Delta such a threat?
“The big news here is that it is a lot more contagious than some of the other mutants because its incubation period is a lot shorter than the other variants. Most of their incubation periods are around six days. This one is only four days, so people are getting sick a lot sooner.
I mean, they named it ‘D’ because it's so different. It's gone on a detour.
It has one mutation, which, as I already told you, increases the number of spike proteins on the surface of the virus, that makes it easier for the virus to enter cells.
It has another mutation that the Alpha mutant has that makes people have about 1,000 times more virus particles in their respiratory tract. What that means is every time these people sneeze or cough or laugh, they're going to spread a lot more virus. That single mutation seems to be why this virus is so much more effective.”
WT: Earlier in the pandemic, the CDC said that once exposed to someone with COVID, symptoms can take up to 14 days to appear. Are symptoms for Delta appearing earlier than that?
“Yes, and that's because of the shorter incubation period. The shorter incubation period I would guess, is just due to the higher virus titer. And by that, I mean that more virus particles are produced in a shorter period of time. Remember, there are about 1,000 times more virus particles in the respiratory tract of infected individuals.
Just please everybody go get your shots. They don't hurt. I know that there are a lot of people out there who are reluctant to have a vaccine with this new messenger RNA technology. I would just like to stress that there is a third option, and that's the Johnson & Johnson vaccine, which is based on the same old technology that has been used in vaccinations for decades.
It's a great alternative if you're worried about the new technology.
I'll add one more thing and that is other people have been questioning how these vaccines were rolled out so fast. ‘How could they possibly have done this in nine months?’ Well, they didn't do it in nine months - These vaccines were already basically ready to be rolled out against SARS and based on previous research done on MERS. This was 15+ years ago. This technology was basically ready to go … it just needed to be tweaked for COVID.
Note added after the interview: And we now have the new Lambda variant on the scene. It’s the dominant variant in Peru. What we know so far is that our US type of vaccines seem to be effective against it, but it’s more important than ever that folks get vaccinated.
Gerry Prody has taught at Western since 1984. She received her doctorate in biochemistry from the University of California at Davis in 1981. To read our last Q&A with Prody about myths surrounding the Coronavirus vaccine, click here.