Wednesday Nite at the Lab. I'm Tom Zinnen.
I work here at the UW Madison Biotechnology Center.
I also work for UW Extension Cooperative Extension, and on
behalf of those folks and our other partners, Wisconsin Public
Television, the Wisconsin Alumni Association, and the Science
Alliance, thanks for coming to Wednesday Nite at the Lab.
We do every Wednesday night, 50 times a year.
It's not always this gorgeous out, however, so I really
appreciate you coming tonight. Tonight I'm delighted to be able
to introduce to you Holly Basta. She's currently a fourth year
PhD candidate in the cell and molecular biology program here
at UW Madison. She's a research assistant in
Ann Palmenberg's lab, and in that lab they study
picornaviruses, pico standing for small and rna standing for
RNA. These are the small RNA viruses
that you'll get to hear more about during Holly's talk.
Holly was born in Great Falls, Montana.
If you've never been to Great Falls, I highly recommend it.
It's got a great Lewis and Clark museum, and the Great Falls are
still pretty great. She completed her undergraduate
degree at Montana State University in Bozeman in 2008.
She just told me that she graduated, she got married, and
got in a car and moved here to Madison.
So it's all been on continuous, enjoyable series of research.
Tonight, she's going to talk about Antiviral Drugs and
Vaccines: Insights From the Model Structure in the
Rhinovirus C. Please join me in welcoming
Holly to Wednesday Nite at the Lab.
[APPLAUSE]
Can everyone hear me okay? Alright.
Thank you all for coming to see my talk today.
I'm going to put in a plug for vaccines because of a lot of
things that have been going on in the news lately, and then
I'll get into my research. I'm excited to talk to you
today. So the central dogma of
molecular biology is that DNA is made into RNA that's made into
protein. So if you leave with anything
from this talk, you will know the central dogma of molecular
biology. So DNA goes to RNA through a
process called transcription, and then RNA leave the nucleus
of the cell and is then made into protein by a process called
translation. So most of the things I'll be
talking about today are either RNAs or proteins.
So to get you, to introduce you to the jargon I'm going to be
using today, so when we're talking about the host, which in
the case of rhinovirus is humans, the DNA is called the
genome, the host genome. RNA is typically messenger RNA,
and then that's translated into protein.
When I'm talking about my rhinoviruses, their genetic
information is actually stored in RNA that completely skip the
DNA step, and that puts them a step ahead of the host.
So when I talk about their genomes, I'm talking about RNA,
and then when I talk about the capsid, that is a protein that's
made by their RNA. So what is a virus?
Like I said, a virus can have either RNA or DNA, and that's
where all of their genetic material is stored.
And then they have to have something to carry around their
genetic material in, and that's called the capsid, and that's
just this shell of protein. What I'm showing you here is the
capsid cut in half. So it's basically a hollow globe
full of their genetic material. And throughout the talk I'm
going to introduce these misconceptions in hopes that you
guys come away with better understanding of what viruses
are. So the first misconception I've
run into is that viruses are a type of bacteria, and that is
absolutely not true. Viruses are a completely
different thing. Bacteria are actually much more
complex, but viruses are just this: a protein shell and RNA or
DNA. So another misconception that
people have is that viruses are nearly as big as human cells.
What I'm showing you here is a scale of size.
So here's a human, a small human, about one meter.
Down here are things that you can see.
Thickness of human hair. Then visible light is here, and
viruses are actually smaller than that.
And that's what make them so difficult to study because you
can't actually look at them underneath the light microscope.
And they're pretty much only bigger than pieces of cells, and
then atoms are down here. So I'm going to show you a cool
little schematic here. We got closed down.
Let's try this way.
We're actually going to skip that one because it's being
difficult. Alright.
So, this is a video. >> So let's say that this guys
has the flu. >> And I'm just going to let
them go. >> And here's a droplet from his
sneeze containing, if we move in and take a really close look you
see each one of those little purple things is a virus, and
there are a lot of viruses floating through the air, some
of which go inevitably up this unfortunate man's nose.
How did that guy feel you ripped off half of his face?
It was interesting because we did it while he was sleeping.
[LAUGHTER] >> Okay.
I am talking with medical illustrator David Bolinsky who
designed this video for a research company.
So here comes the virus, and it's going to land on one of
this guy's throat cells. So notice it's covered with
little yellow knobby things. You all these key.
Those are the keys. >> This is a key.
This is a key. This is a key.
Okay, if the keys on this virus happen to fit the locks, which
are the little purply stick-uppy things on the surface of the
cell, if there is a match, the cell, watch this, welcomes the
virus in. And what's this?
This is the welcoming committee.
They all interlock with each other, and they pull this
membrane down into the cell. >> And down it goes deeper and
deeper, and that welcoming structure disperses and the
virus capsule bursts and out comes the secret recipe for how
to make more viruses, those little noodly things.
So this unsuspecting cell has been tricked into guiding these
virus recipes right into its own command center, the nucleus.
So in they go. >> And they are immediately
recognized by this big pink molecule which his a mini
factory. >> What is it doing?
It threads the nuclear material, the instruction code
of the virus, through one hole, and out another hole comes a
brand new instruction set. >> So it's a copying machine
making copy after copy after copy of virus recipes which then
go out of the nucleus. The little chefs, those blue
peanutty things, they cook up proteins that go back into the
nucleus where they are reassembled into baby viruses,
and then out they go. They get covered up and head to
the surface where they get new keys and then boom.
Here they come. This is an eruption of virus
after virus after virus after only virus entered this cell,
but how many came out? Well, millions.
Millions. So if one virus can produce a
million babies and do it again and again and again, how come
this guy doesn't just drop dead? [LAUGHTER]
Well, because you have about a hundred trillion
cells. >> So a million viruses is just
a drop in the bucket when you have a hundred trillion cells.
Remember, you do have your own immune system which when it sees
a virus usually... [LAUGHTER]
So while the virus does multiply fast, with any
luck your immune system will work just a little faster.
So yes viruses, all viruses, want to spread.
That's what they do. But most of the time we do keep
them in check. Most of the time.
Alright, so here's the thing I was going to show you before
this. So this is actually a really
cool website. It's called
learn.genetics.Utah.edu, and this has a little scrolling bar,
our movie is still making noises.
So there's a little scrolling bar.
Now I restarted. I'm sorry.
Alright, so there's a little scrolling bar, and as you scroll
it gets smaller and smaller. So here's a coffee bean and a
grain of rice. Sesame seed.
Grain of salt. And as you go in, now we're
getting to the microscopic things.
Amoebas, paramecium, there's a human egg and sperm.
A photoreceptor in your eye. Red blood cell.
Baker's yeast. X chromosome.
E.coli. Mitochondria.
Now we're starting to see the viruses.
There's measles. There's HIV.
There's influenza. And all the way down here is
rhinovirus. So it's really, really small,
and it's even small for a virus. And there's a ribosome, which
they showed you in the movie was making the proteins, and then as
you get smaller and smaller there's an antibody all the way
down to a single amino acid and then a carbon atom.
So that should give you some indication of how tiny viruses
are and how amazing they are to cause so many problems.
Alright, so we watched that. So there are two ways that we
treat viruses. Either antiviral drugs or
vaccines. Both treatments are good in
their own ways. Drugs you're only given once
you're sick, and they're specific to the specific virus
that you have. The picture here is for Tamiflu,
which is for the influenza virus.
They usually inhibit viral development, and they're
typically small molecules. So just little chains of
carbons, usually, and they help only you versus vaccines which
help you and help others in that you're not infecting other
people. So vaccines are given before
you're sick, as you know. They're specific to a certain
virus, and how they work is they tip off the immune system.
They say this is what this virus is going to look like.
When you see it, kill it. And so vaccines are typically
made from pieces or whole viruses.
So there's many different types of vaccines, and they range in
their safeness and effectivity. So not all vaccines are just
dead versions of viruses. So these attenuated and
inactivated viruses are, yes, dead versions of viruses.
Attenuation, they take out a piece of the virus that it needs
to be a full replicating virus. And the vaccines that you may
have had that are attenuated viruses are the MMR, chicken
pox, or the nasal flu spray. Inactivated viruses, typically
what they do is they shoot them with UV or they put them in a
really highly acidic condition, and then the virus is dead or
inactivated. One of the polio vaccines was
made this way, and the flu shot is made this way.
Fractionation, they essentially just chop up a virus, and then
you see little bits of the virus but it never forms into a fully
infectious virus. The newer methods in making
vaccine are actually much safer because they take a piece of the
virus and then they put it into a bacteria's DNA, and the
bacteria actually makes the viral proteins, and then you
purify them out, and in that way there's never a full virus ever
in contact with the vaccine that you get.
So one of the vaccines you may have heard of that are made like
this are hepatitis B vaccine and the HPV vaccine.
So the problems with these kinds of vaccines is that you never
know what the best part of the virus for your immune system to
recognize is. So HPV requires three boosters
because it's not a really potent vaccine.
So here's the vaccine schedule that the CDC recommends.
It's been a while since a lot of us probably got vaccines, but
these are the ones that you get up until you're six years old.
So a major misconception is that most vaccines are new, and
therefore untested, and what I'm showing you here is that most of
these vaccines were around when I was a kid.
A lot of them were around when you were kids.
So influenza started in 1945. The Varicella is from 1974.
So a lot of these vaccines have been around for a long, long
time, and there's really strong data about how safe they are.
So I don't know if any of you heard of any of the news about
vaccines. Can anyone call out something
they've heard about a vaccine? [INAUDIBLE]
Autism. Autism is a big.
So I'm going to show you the actual data about vaccines and
autism, and then you can make an educated decision about vaccines
and autism. So some of the other things that
people have concerns about are that vaccines contain mercury,
and that actually was true but none of the current vaccines
contain mercury. In the past, vaccines had trace
amounts of mercury, and there were never any negative effects
noticed from them. But currently no vaccines have
mercury in them. Other ones that I have heard are
that doctors get paid to vaccinate.
That's false. Unless you know some dirty
doctors that I don't know. I don't think there's any
biotech plots to get people vaccinated.
So let's talk about vaccines and autism.
So how they determine if something causes something else
is, essentially, you divide the people who got, in this case
autism, who had the vaccine by the people who got autism that
didn't have the vaccine. And this is how you calculate
relative risk. Now relative risk of one means
there's no difference between the two groups.
So the same amount of people who got the vaccine got autism as
the people who didn't get the vaccines.
So when they tested the MMR vaccine, which is the one that
was said to be associated with autism, actually slightly more
people who didn't have the vaccine got autism, and then
within 24 months it was pretty much equal.
And to put this into context, the relative risk of lung cancer
in smokers is over 20. So this says pretty much vaccine
or no, you have even chances of getting autism.
What about five years or ten years later?
So the association, he asked what about five or ten years
later. The association was said to be
within weeks or months after the shot happened because many times
you get the vaccine at age two or three, I believe, and that's
when autism symptoms cropped up. And that's what made them
originally go after this vaccine for that reason.
So it just happened to be a coincidence that kids would
start developing autism around the same time they would get the
vaccine. So, by later ages, typically
kids have shown to be autistic or not.
So then other myths are there's no risk to not getting
vaccinated and that vaccines can wait.
So is it okay to not get vaccinated?
So here are the MMR and DTaP vaccines, and here's the risk of
getting them. So one in a million people can
get encephalitis or have a severe allergic reaction versus
these are the three diseases that you are immunized against.
Measles, one in 300 people die. Mumps, one in 300 get
encephalitis. And rubella, one in four can get
congenital rubella syndrome. And the numbers are pretty
similar for the DTaP. There's been no proven deaths
from it, but one in 20 people die from diphtheria.
And it's easy to forget that these diseases were a big deal,
but actually now because a lot of people are opting not to
vaccinate, a lot of these illnesses are making a comeback.
So these are pretty recent news articles.
This one says there's been 640 cases of whooping cough as of
March 31st compared to 94 during the same time period last year.
And this one is an outbreak of a meningococcal disease, and in a
single school district there were five cases and two students
actually died. And last year the CDC reported
that the measles cases were at a 15-year high despite vaccines
being available. >> Can you speak to the whooping
cough epidemic at the moment going on?
So, yes, there is a whooping cough epidemic going on at the
moment. There is a combination of issues
between children get vaccinated very young for whooping cough
and sometimes the vaccines wear off, but that's also being
perpetuated by not being vaccinated.
So I'm just going to talk about herd immunity right now.
You lead me right into it. So there's certain number of
people that need to be immunized to actually protect a population
from having a disease, and it's different for different viruses.
So, essentially, if 83% of people in a population are
immunized to small pox, small pox won't be able to spread.
And so the problem right now is that these numbers are dipping
below, number of immunized people are dipping below these
numbers, and we're losing our herd immunity.
And then another misconception, since we're talking about polio,
is a lot of people think polio is eradicated and there's no
need to be vaccinated anymore, but that's not true.
In a lot of places it's impossible to get the polio
vaccine. It requires a cold chain.
So the vaccine always has to stay cool, and there's places in
the world that you just can't bring something cool to them.
So there's actually polio still cropping up in many places.
So we still need a vaccine. >> What about small pox?
Small is eradicated Small pox hasn't cropped up again.
So the only thing they're worried about small pox is if
it's in somebody's freezer somewhere because small pox, we
were lucky in that it doesn't have an animal host so there's
nowhere for it to come from except for other people and
nobody has it anymore. So, yes, small pox is officially
eradicated. >> But if it should come back,
they have not been giving small pox vaccines for quite a while.
That's correct. We haven't been vaccinated for
small pox in many years. So why aren't there vaccines for
everything? I just told you that vaccines
were awesome and everybody should get them.
So there's big problem with safety, and particularly with
the rhinovirus, which I'll talk about later, it definitely can't
have side effects that are worse than the virus.
So the common cold isn't so bad in the spectrum of viruses, so
it has to have very, very minimal side effects to be
considered. So to get a safe vaccine, you
have to make sure that it actually does what it's supposed
to and that it alerts your immune system to a virus.
It has to be biologically stable, like I was talking about
with the polio vaccine. It has to be able to be
delivered to people in Third World countries and have a
practical delivery system. So an impractical delivery
system would be 10 shots over three months.
Nobody is going to go in for 10 booster shots.
And the public must see more benefit than risk, which has
actually become the biggest issue in recent years because
when I said vaccines, you guys said autism and we all saw the
news story linking vaccines and autism but I don't know that
anybody saw that data that refuted it.
And there's also been a lot of issues with the HPV vaccine
because people have moral issues with it.
That's all I'm going to say. And then to kind of lighten the
mood, I have heard that people believe there's a zombie virus,
and actually there isn't just so you know.
Not yet. [LAUGHTER]
So major challenges in making vaccines.
Viruses have a very high mutation rate.
So, to put into context, you and I may have a couple kids over
our lifetime and they may be slightly genetically different
from us, but a virus, like you saw on the video, can have
billions of offspring, and each of them can have different
mutations, and they replicate within hours, and in that way
they're evolutionary time is much shorter than ours.
DNA viruses can integrate and associated with the host genome,
and so rhinoviruses don't do this but some DNA viruses can
actually shove themselves into your DNA so your host machinery
makes the virus right along with your own proteins.
Which ones are those? >> Retroviruses do that, like
HIV. So viruses can also infect
immune privileged regions of the host, and what I mean by that is
your nervous system and your brain don't have hardly any
immune response whatsoever. Places like you airway and your
intestinal tract have great immune responses because things
from the outside come in and you need to be protected from that.
But many times viruses can find their way to your nervous system
which have not a very good immune system at all.
And then viruses have ways to get around the immune system by
directly shutting down parts of your immune system or sneaking
around it. This is a major issue.
With rhinoviruses there's multiple serotypes, and the same
thing with influenza. So the reason you have to get an
influenza vaccine every year is it's a cocktail of many
different serotypes of influenza.
And then it's very expensive and time consuming to develop
vaccines. Years and years and millions and
millions of dollars. So now we're going to talk about
my research. Rhinoviruses are the main cause
of the common cold. There's over a hundred unique
serotypes, and they're divided into three species.
They're really small, simple viruses like I showed you.
They're much smaller than HIV or small pox.
So why don't we have a vaccine for rhinoviruses?
We all get them. People are studying them.
So rhinoviruses actually have a lot issues with developing the
vaccines that I told you about. They have a very high mutation
rate, and that's because they have the RNA genome that allows
them to be really fast and mutate quickly.
They target the immune system, there's a lot of serotypes, and
the cost and time involved in developing the vaccines becomes
an issue because there's not a lot of people that die from
rhinoviruses. So the money goes into things
like HIV which a lot of people die of.
So here's the schematic of the rhinovirus genome.
And remember your central dogma. This is the RNA.
It gets translated and these are proteins.
And then the proteins get chopped up into smaller
proteins, and then they form into a capsid.
So here's a picture of a rhinovirus capsid, and we kind
of look at this like a 3-D map of the virus, and there's
specific landmarks that we know about.
So here's, this triangle right here is blown up into a cartoon
here. So all rhinoviruses have a
canyon. So kind of a dip.
And then there's actually a hole in them, and most of the
antiviral drugs are targeted to go into this hole.
And how they work is they essentially stick that hole
closed and then the virus is trapped in its own capsid.
So when it gets into the cell, it's just stuck in the capsid.
It can't release its genetic material, and it can never make
more viruses. So then this is that same
triangle thing but these are what the proteins actually look
like. So the capsid is composed of a
VP1 which stands for viral protein 1, 2, and 3 and then the
VP4 is inside the capsid. So these are all color coded.
This blue is this blue over here.
So they have a five-fold, three-fold, two-fold, and
another three-fold axis. So this triangle is essentially
repeated around into this capsid.
Because they only have four proteins that make up the
capsid, it's repetitive. So that's how they make their
capsid. So what this is is a
phylogenetic tree, and we use these a lot to tell how closely
things are related to each other.
So these are all the known serotypes of rhinoviruses.
So these ones right here are rhinovirus As.
These right here are Cs, and these here are Bs.
So these, the As, Bs, and Cs are all very different from each
other and make it a real challenge to make a single
vaccine or a single antiviral drug that will work on all of
them. And all of these strains are
circulating right now. Most of these were actually
isolated at the hospital here. So the rhinovirus C species is
the one I'm interested in, and the reason for that is it was
just recently discovered in 2007, but they found it
associated with almost half of rhinovirus infections in young
children. The reason they didn't find it
before is it can't be propagated in cell culture, and how they
grow it now is they have to get primary cells from patients.
So if you have an operation on your nose, they can take a
snippet of those cells and then put rhinovirus on there and grow
it, but it's a really inefficient way to do it because
you have to count on people having surgeries and signing off
on their cells being used for things.
And then, oftentimes, those people are already infected with
a rhinovirus so it convolutes the results.
And then to grow these are any length, you need an air liquid
interface system. So the reason for that is these
rhinoviruses grow in your airway and those cells like to be
partly in air and partly in your mucus, essentially.
So they're very difficult to grow.
So what we normally use for cell culture are HeLa cells, and
here's what they look like. And we grow them in little
dishes like this in serum. And then how you tell if the
virus has infected them is you cover them with this overlay and
dead cells will appear as holes. So these are cells that have
been killed by the virus. So this is how we normally study
viruses, but because rhinoviruses can't infect these
cells, we weren't able to study them.
So the rhinovirus Cs are really interesting because they
actually have a higher propensity to cause more severe
illnesses. So these are actually patients
from UW Hospital, and they ranked how severe illness was
with which rhinovirus different patients had, and they found
that rhinovirus C in red and rhinovirus A in black usually
caused more severe illnesses than the ones in green, which
are rhinovirus Bs. And this separate group found
that when they studied 128 children with asthma, they found
that rhinovirus C really exacerbated the children's
asthma much more than other rhinoviruses.
So these viruses are very, very medically relevant, but we can't
grow them so it's very difficult to study them.
So why won't they grow? So in the video we saw, remember
they had the lock and the key? So the lock they were talking
about are actually host cell receptors, and how these work is
your cell essentially says I need something from the
environment, I'm going to put out bait for it.
And then when it picks up whatever it gets, it brings it
into the cell, into those balls that you saw in the movie, but
the viruses pretend like they're something else, and the cell
says, oh, I have what I'm fishing for, and they pull it in
thinking they have what they want, and it's actually a virus.
But we don't know what bait the rhinovirus Cs take, and we know
it's not present in any of the common cell culture lines we
use. It's in your airway.
We don't know what it is. So there's no way to get enough
virus to figure out this actual 3-D structure of what the Cs
look like. So what I did was using
computational methods, and we knew the 3-D structures of other
rhinoviruses and a lot of other proteins, I made the hypothesis
that I could use the known structures and computational
methods to predict the structure of rhinovirus Cs.
And the method I used for that is called 3-D protein threading.
And so how that works is you take the protein sequence of
whatever protein you want and you force it into different
confirmations. These are different
confirmations of protein. And then with equations you find
out which is the lowest energy structure that sequence could
fit into. So I did that with the
rhinovirus Cs, and then when I overlaid it with the real
structures of Bs and As, it overlapped pretty well.
The only differences were in this region right here which is
the five-fold axis. And so here's the full
structures when I made them into a capsid.
So here's real experimentally solved structures from A and B,
and here's the model I made. So they're pretty similar
looking. But when we went in and looked
closer, so right here, these are the five-fold axis and you can
tell because that has five little points, when we zoom in
on that and cut it in half, we see that the rhinovirus Cs have
a very short five-fold axis. And then when I make these road
map projections, so how these work is it's just like a
topographical map. So red would be a mountain, and
blue would be a valley. So here's the As, here's the Bs,
and here's the Cs. So right here at this five-fold
axis where there's normally a hill, there's actually no hill
in the Cs. And that's very interesting that
they're so drastically different from these other types of
rhinoviruses. And this is very interesting
when you take into account that they don't use the same receptor
as the As and Bs. So this is the five-fold axis
and this is the five-fold axis. Both different types of
receptors that rhinoviruses use involve the five-fold axis.
And the rhinovirus Cs just don't have it.
So they must be interacting with their receptor at somewhere else
on their capsid. So can we make a vaccine for the
rhinovirus Cs? So how you test for potential
vaccines is that you find the regions that are most likely to
confirm mutant protection after vaccination or natural
infection. And these have been mapped for
the rhinoviruses. I don't think you can see it
very well here. So here's these road mapped
projections. And these are the regions that
your body sees the rhinovirus. So right here, a lot of them are
at the five-fold axis. There's other regions that your
body sees, but the major one is at the five-fold axis, and the
Cs are just missing those. And how the virus deals with
this is it makes loops of variable regions.
So it says, oh, you're looking at me here?
Well this is going to be the region where I vary the most and
where I mutate the most. But the rhinovirus Cs just don't
have this spot to mutate. So there might be a possibility
that a vaccine would work better because they actually lack this
evolutionary space. So major focus of my work was to
see if current antiviral drugs would work on the rhinovirus Cs.
So, like I told you before, drugs are typically designed for
this region here. It's called the hydrophobic
pocket. It has an open pore and a closed
toe. And normally in nature there are
pocket factors, so just pretty much long carbon chains that sit
in there, and they don't bind very tightly and allow the virus
to open up and release their genetic information.
But drugs mimic these but bind much more tightly and glue the
capsid together. So here's the five-fold axis,
and here's it zoomed in, and here is the antiviral drug
sitting in the pocket. So that's where they hang out is
pretty much right up in here. So there are two antiviral drugs
that have come out of research that look promising.
So there's pleconaril, and it was actually evaluated in two
large phase three clinical trials, and it was found to
work. It shortened the duration of
common cold virus and the window that you spread the virus.
It wasn't ultimately approved by the FDA, and I heard that it
somehow interfered with birth control, and that's why it was
canned. But the next one that's coming
down the pike is called BTA. It inhibits 56 rhinovirus
strains, and an analog to this drug right here is actually in
clinical trials here at the hospital.
So there were two drugs I was interested in because they have
been the most effective so far on rhinoviruses.
So we know which amino acids line the inside of the
hydrophobic pocket, and this is a representation of those amino
acids. So all of the rhinoviruses
besides the Cs fall into one drug group or another.
One group of drugs works on one group of rhinoviruses and one
group of drugs work on another. So I wanted to know which group
the rhinovirus Cs fit into. So these are representation of
their sequences, and at lots of places they're the same.
So they all have the same amino acid here, but at some places it
differs a lot. So this amino acid is in these
two drug groups and it's not in these ones.
So I then asked, well, which of these is actually important?
All of these amino acids are in the hydrophobic pocket, which
ones are most important for the drug binding?
So I analyzed all 27 of the structures that have been solved
for different rhinoviruses and found that in all these cases
most, the drug was within four angstroms of this residue.
So what that means is these particular amino acids were
close to where the drugs was suggesting they were interacting
with the drug. And then the ones in gray are
the ones that have been found experimentally to bind
pleconaril. So in this way I weighted which
amino acids were important for drug binding.
So then I modeled in pleconaril into the different rhinoviruses,
and what I found was pleconaril fit just fine into the
rhinovirus Cs making me think that it would probably work on
them. So then through a collaboration
with a group at the hospital, they went and tested pleconaril
and this BTA 188, and they found that neither of these drugs
significantly decreased rhinovirus C, which was
interesting to us because my modeling had suggested that
these drugs would work. So then I went and looked a
little closer and found that the hole to the drug binding pocket
is actually smaller in the Cs than it is in the As or Bs.
So this is the As and this is the Bs, and they all have an
alanine which is a very small amino acid.
All of the rhinovirus Cs, however, have an isoleucine or a
similarly large amino acid. So when I simulated the alanine
being mutated to an isoleucine, you can see that it makes the
pore smaller. So what that made me think was
that yes maybe the drugs could fit once you forced them in, but
they probably couldn't get in in the first place.
And this particular amino acid at the pore residue is very
interesting because it's conserved within groups of
enteroviruses. So rhinovirus is a part of a
bigger group of viruses called enteroviruses, and all the
different groups either have the small alanine or something
bigger and it's conserved by the group.
So all bovine viruses don't have an alanine, but all human
enterovirus Cs have an alanine. So I thought that that was an
indication of how biologically relevant this particular residue
was. So what does this all mean for
rhinovirus C treatment? Maybe a vaccine is possible.
Probably not. They are only that one
immunogenic site so probably they would still be able to
mutate away from vaccines. But we now know a lot more about
what type of drugs would fit into the rhinovirus Cs, and it
might be that we need to develop drugs specifically for the
rhinovirus Cs. None of the drugs that work on
the As or Bs will work for the Cs.
So the good news is that we now have an idea what the rhinovirus
Cs look like, and we didn't have to grow them in anybody's
primary cells. And we can steer the antiviral
testing and we can also suggest receptors, and we've done that a
lot with the collaboration at the hospital.
Oh, we missed misconception. You can catch computer viruses.
[LAUGHTER] I looked online and
some people think you can catch computer viruses.
So if you learn nothing else from this talk, you can't give
your computer a virus and it can't give you a virus.
So you should feel safe. So I'd like to acknowledge the
people that helped me with this work.
My lab is the Palmenberg lab, and we collaborated with -- for
the computational stuff and the Jim Gern lab at the hospital
helped us with testing the drugs.
And I'm funded by the NIH, and thank you all for listening.
[APPLAUSE]