Learn about the evolving Ebola epidemic and its various aspects including disease prevention, management and treatment, response to the epidemic, ethical considerations, and the post-Ebola global health landscape.
Exploring The Immune Response to Ebola: Implications for Future Therapeutics and Vaccines
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From the course by Emory University
Ebola Virus Disease: An Evolving Epidemic
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From the lesson
Laboratory Issues
Upon completion of this module, learners will be able to: Discuss clinical laboratory considerations for Ebola Virus Disease.Differentiate between persons under investigation and persons with confirmed EVD. Identify where and how EVD laboratory testing is performed. Recognize the safety concerns surrounding the disposal of specimens and human remains. Explore the immune response to EVD and discuss the implications for future therapeutics and vaccines.
Meet the Instructors
Dabney P. Evans, PhD, MPHAssistant Professor
Hubert Department of Global Health. Rollins School of Public Health. Director, Center for Humanitarian Emergencies.
Carlos del Rio, MDChair
Department of Global Health at the Rollins School of Public Health
I'm Rafi Ahmed.
I'm an Immunologist by training and
I head the Emory Vaccine Center at the Emory University School of Medicine.
And I'm here with my colleague Anita McElroy.
Anita is a physician scientist and
is a Pediatrician but and, but also has extensive training.
In, in Biology, modern infections and
has training in working, at high containment levels.
And, when the four patients who were infected with Ebola virus were admitted to
Emory University there was a extraordinary opportunity that presented, itself to us.
Until now there had been no studies looking at what happens to the immune
response in the infected patient.
How does the patient respond to this viral infection.
And this had not been done because of the, of many for, for a variety of reasons.
But one of the biggest reasons for this was the.
Lack of, appropriate facilities to do high containment work,
where these, patients were.
Which typically was in, in rural parts of Africa.
but the four patients being at Emory, University Hospital,
in close proximity to the Centers for Disease Control.
Allowed us this opportunity to take, the very first look.
At how these patients are responding to the Ebola virus infection.
And this is was a collaboration between the Emory Vaccine Center.
Scientists there.
Between the Centers for Disease Control and
the clinicians who are treating patients at Emory University Hospital.
And I will now ask and in addition to Anita, there was a,
this was a cross collaboration with the Special Pathogens Branch
at the Centers for Disease control that is headed by.
And I will now ask Anita to, to tell me about how it was.
How was it like working when these patients were infected?
In the hospital I Know that there was continuous monitoring of these patients
for their clinical conditions and
also in terms of the level of virus they had in the blood.
>> Mm-hm. >> And
then you were very brave in doing all this work with this with these samples.
So can you just share your experiences of what was happening on a day to day basis?
And how this analysis was being done.
>> Sure. So, we actually had
patient specimens on a daily, to sometimes every other day, or every third day.
And all of the patient samples were handled inside the BSL4 laboratory at CDC,
which is absolutely required for safety.
And it turns out that working in the BSL4 lab is really strenuous work.
So, the folks who do the work have to wear encapsulated, positive pressure suits.
And these, you may have heard these in the past refered to as spacesuits.
They're really heavy, thick plastic material.
They're rather cumbersome to wear and there are very thick gloves attached.
And this makes dexterity quite difficult when you're working in containment.
So these suits also have special air filters in them and in order for
the investigator working in the suit to, to, to walk around the lab they have to
connect to an air hose to have breathing air so
that they don't get exposed to the air that's in the laboratory itself.
Now when an investigator needs to go from one area of the lab to another they have
to unhook their air supply and then reattach it in the next room.
And when they're finished with their work for the day they leave the lab going
through a chemical decontamination shower and then a regular shower.
So you can imagine that this takes a lot of time to do this type of work inside
containment and essentially everything that's done inside the BSL4 takes
about twice as long as it would take you outside of a BSL4 laboratory.
>> So Anita how is mobility in there?
I mean, does it get uncomfortable?
For how long can you work?
>> Sure. It's very limited.
Most investigators try not to work for more than four hours at a time and,
of course, you can't eat or drink while you're in the containment space.
Neither can you use the restroom so those things require you to come out of the.
Thus containment space out of the decontamination shower.
And there's like a small area in between the decontamination shower and
the regular shower for rest, if that's necessary.
But it does require coming out sometimes just to take a break.
>> Yeah.
And you are going into this almost every day, or
were you going in there even twice a day sometimes.
>> Yeah ev-,
certainly every day during the most critical phases of the patient care.
And then sometimes every other day when the patients were in their
convalescent phase or starting to improve clinically.
>> And for how long did you analyze their immune response
while they were in the hospital?
How many time points were taken?
>> Sure. There were multiple time points for
every patient.
Some patients were cared for in the hospital for up to 40 days.
So as many as 20 to 30 particular specimens per patient.
Other patients were in the hospital for only a month or
potentially one was actually very short, only in the hospital for two weeks.
So that was a much shorter course.
>> So as Anita has said this was a remarkable opportunity
to see how the patients are responding to the Ebola virus infection.
During this acute phase of disease.
So Anita can you tell me what you learned from this this really in depth,
detailed analysis immune response during this period.
>> Sure, so up until this point, there really as Dr.
Ahmad had mentioned, very few studies of the human immune response to Ebola.
But this really gave us an opportunity to look in much more depth because of the.
The type of, immunologic assays we were able to do.
So, in the past, because these studies have been done in the field,
the immunologic assays that were done were very rudimentary.
And those very limited samples demonstrated that humans
often succumb to disease before they develop even in the antibody response.
And so this had led to an over-arching assumption that individuals who were
infected with Ebola.
Were having suppressed immune responses.
This also was supported by the fact that the virus is able to encode some proteins
that are inhibitory to certain aspects of the immune response.
And there's also a group of proteins that are present in the bloodstream of
folks know-, known as Cytokines.
And these proteins help guide immune cells when they respond to infection.
And it had been noted that individuals who were infected with Ebola virus,
have disregulation of these important signaling molecules.
So, collectively, all of these little tidbits of information that we had,
led to this presumption that the immune response was just ineffective
during Ebola virus infection in fil-, in humans.
However, when we studied these four patients that we had over at Emory.
We were quite surprised to see that all four patients in the study
had evidence of activation,
not suppression, of their immune response in both their T and B cells.
Now B cells are immune cells that make Antibodies.
And these Antibodies are proteins that bind to and can inactivate viruses.
T cells on the other hand are immune cells that attack and
clear virus infected cells.
Now in our patients both the B and T cells were activated and
it turns out that the degree of activation that we saw
correlated with the severity of their disease.
And not only were the cells activated, but
we were able to demonstrate that they were functional and specific for Ebola virus.
And at in least a couple of the patients, we saw that these activated responses
were prolonged, so they had prolonged activation of B and T cell responses.
But overall we saw the opposite of what we expected.
Instead of suppressed short lived immune responses, all four of the patients had
very robust immune activation in response to their Ebola virus infections.
>> So Anita, do you think that it's possible that the immune
system was involved in controlling their infection?
>> Most certainly because as you're familiar with, Dr. Ahmed, we saw.
A decrease in the levels of their viral loads.
So that body seemed to be able to control the virus
as the levels of immune activation were increasing.
>> Right, so it looks like there's a race between the immune response and
how fast the virus is replicating.
As opposed to the previous assumption
that actually we did not generate an immune response.
>> Yeah, and in fact.
In one patient who was very severely ill
we were able to demonstrate that that patient, as they started to get better,
really clearly had elevated immune system responses as their viral loads improved.
And in fact, it was likely the supportive care that they received and were
provided here at Emory University Hospital that allowed them to get to that point.
>> [INAUDIBLE] I think these are really important findings.
And what Anita has just told you will bring about really a, a, a big change in
thinking about how Ebola virus interacts with the with immune system.
So these results have told us that immune system does respond, but
basically the virus is running faster than the immune system is.
And it take, and that's for some of one of the reasons for
the increased disease during this period, and
also the mortality deaths observed in many of the infected patients.
But the immune system is activated and
is trying to catch up and eliminate the virus.
And this has huge implications and very promising implications.
For the development of a vaccine.
There are currently several groups,
which are developing, candidate vaccines against Ebola virus.
And, the reason that these results are encouraging for, vaccine development and
the potential usefulness for
vaccine is that basically what the vaccine will do is it will.
Already primed the immune system to react faster or
respond faster when the person is exposed to Ebola virus in a natural setting.
And because the immune system is able to respond even without being primed,
having been primed, it will come up much faster.
So I think there is these results suggest that.
Since Ebola virus by itself is not suppressing the immune response,
any previous priming of the immune system results in a faster response and
that will change the balance between the kinetics or
the race will be more in favor of the immune system.
So I think that the current vaccines that are.
In, in a clinical trials, and we learn from the studies that are ongoing,
how good they are in terms of priming the system and
that is actually going to be interesting to study and also we'll.
But hopefully, result in a vaccine that will prevent,
certainly will prevent disease if not prevent infection [INAUDIBLE].
Yeah.
I'll now tell you a few things about additional studies that Anita,
CDC and our group is involved.
In, in studying from these patients.
So there are two important questions that we are asking now.
The patients have been extremely cooperative.
They have agreed to give us
access to their blood samples over a three year period.
So we'll now be able to understand how the immune system evolves
after the infection is dissolved.
We'll understand how long.
They maintain T and B cell memory responses to Ebola virus,
again something that has not been studied in detail.
We will also learn about the kind of
antibody responses that these individuals are making.
This information will be very useful when we compare.
Response to the, the vaccine is generating.
So one of the important goals
of our studies in collaboration with the people doing the vaccine development
will be to see what kind of immune response the vaccine induces.
And what kind of immune responses are induced during natural infection.
And that would again provide additional guide,
guiding in the design of of the vaccine.
And, and improving it.
And one additional aspect that we're looking at
is the development of therapeutics.
As Anita pointed out to you these patients made a good B cell response.
Against Ebola virus.
B cells secrete a molecule called Antibodies.
And Antibodies can actually can will bind to the virus and will neutralize it.
That is it will inactivate the virus.
This is the immune system's most efficient way of preventing infection.
The antibody binding to the.
To the viral particle and inactivating it.
And so what we are doing is we are generating
clones of Antibodies from the patients.
So we will take the patient's Antibodies and produce large amounts of it.
And essentially, these could be used as therapeutics for
the treatment of, of infected people.
It could also be used Prophylactically.
In, if somebody was going into a area of high containment.
Of, of high exposure.
At that time, they could be given Antibodies before,
they go into an area where there's a, there's an Ebola infection.
For example, if there were.
Some healthcare workers going into an endemic area where there's infection.
They could be given an infusion of a monoclonal antibody that will
be able to protect them from getting infected.
So these patients B cells will be isolated in our in our laboratories.
And then the vaccine center.
And then we will generate therapeutic Antibodies that will be made available to
to to, to potential people who, who would need these.
The studies that we're doing are are funded by DARPA, which is a U.S.
army, it's a defense research organization that's funding our studies.
With these patients.
Our collaborative team also involved investigators from
several other universities.
We also working closely with the CDC and the U.S.
Ambre which is a, which is an Army hospital in, Washington DC.
Anita, are there any additional things you would like to point out in terms of what
we've learned from these studies?
>> Yeah, in fact,
I think the most remarkable thing about this study is that we were able to do it.
And that was only possible because of close collaborations between
the Emory Vaccine Center and our colleagues at CDC and
the Viral Special Pathogens branch.
It's been really an amazing journey and we still have a lot to learn.
>> And we would like to thank, thank all of you for, for listening to us and
it's been as Anita pointed out, it's been quite a, opportunity for us.
And we, we are both looking forward to continuing these studies and
we'll keep all of you posted as we learn more,
as we learn more about the immune response against Ebola by studying these patients.
Thank you very much.
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