Viruses Evade the Immune Response - Video Tutorials & Practice Problems
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Intro to How Viruses Evade the Immune Response
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2m
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in this video we're going to begin our lesson on how some viruses are able to evade the immune response. And so once again in order to successfully replicate inside of a host. Some viruses must evade host defense mechanisms. Now moving forward in our course, we're going to talk about three different ways by which some viruses can evade host defenses. And so which you'll notice is that down below we're going to mention each of these three different ways. But moving forward in their own separate videos will get to talk more details about each of these three different ways. And so the first way that some viruses can evade host defenses is by preventing the effects of anti viral proteins or a VPs. And so that could involve the use of viral proteins to protect viral M. RNA from rig like pr Rs pattern recognition receptors. And again we'll talk more details about this process. Moving forward. Another way by which some viruses can evade host defenses is by viruses interfering with the antigen presentation process. And so what you'll notice is that here is a virus and the virus is interfering with the antigen presentation process so that it will not be recognized by other immune cells. And again we'll talk more details about this process moving forward. And then last but not least. The third way by which some viruses can evade host defenses is by some viruses avoiding the effects of bound antibodies. And so once again we'll get to talk more about that later and talk about how some viruses are able to mutate to change their surface proteins to avoid being detected by antibodies. Uh, and so this year concludes our brief introduction to how some viruses can evade the immune response. And we'll get to talk more about each of these three different ways as we move forward in our course. So I'll see you all in our next video.
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concept
1) Viruses Prevent Antiviral Effects of AVPs
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4m
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in this video we're going to talk more details about how some viruses are able to avoid the immune response by preventing antiviral effects of antiviral proteins or a VPs. And so first we need to recall from some of our previous lesson videos what interference are and what they do. And so recall from those older videos that interference our side all kinds that are produced by virally infected cells. And when those virally infected cells produce the interference those interference can alert neighboring cells that have not yet been infected and allow those neighboring cells to produce antiviral proteins or a V. P. S. Now the infected cell is initially going to be able to identify the viral RNA. A via pattern recognition receptors or PR Rs inside of the cytoplasm for example a rig like receptor or a rig like PR R. Is an example of a pattern recognition receptor that can detect viral RNA. And so some viruses are able to coat their RNA with a viral protein that basically hides or protects the viral RNA from the cell cytoplasmic P. R. R. S. And so if we take a look at our image down below, we can get a better understanding of this idea and which will notice is that we're showing you how some viruses can protect their RNA and blocking apoptosis in cells. And so notice here what we're showing you is a virus that is coming into a host sell this big blue thing represents our host cell and we have a virus that is infecting the host cell and it encodes and releases its new its nuclear acid. It can be transcribed to form viral M. RNA. And which will notice is that in some cases viral proteins are able to bind and protect the viral RNA. And so here we have viral protein you can see the viral RNA is really the thread and the viral proteins are these little purple circles that are all over it. And so those viral proteins can protect the viral RNA and prevent RIG like receptors or RL RS, which are really just pattern recognition receptors that belonged to the host and prevent them from binding to the host to the viral RNA. And so notice that this big red X here represents the fact that the RIG like receptor is not able to to bind to uh the viral RNA. And so that means that the viral RNA is able to be translated to create viral proteins. And in addition, once these viral proteins have been made, many of these viral proteins may inhibit or block the process of apoptosis. And so which will notice is the viral proteins are in orange and the hosts apoptosis proteins are in green and the viral proteins can bind to the host uh apoptosis proteins and prevent apoptosis from occurring. And so what we need to recall is that from some of our previous lesson videos once again is that antiviral proteins can cause a virally infected cell to immediately go into apoptosis and apoptosis is preventing viral replication. And so it's in the viruses best interest to prevent apoptosis. And so some viruses are able to inhibit the expression of certain genes in the host cell that will prevent apoptosis so that the virus is able to replicate. And so once again, that's what we're seeing down below. Over here on this side, we're showing you how viral proteins can inhibit host apoptosis proteins from triggering apoptosis. So that way the virus blocks apoptosis, apoptosis does not occur and that allows the virus to be able to replicate. And so this here concludes our brief lesson on how some viruses are able to avoid the immune system by preventing antiviral effects. By again using proteins to prevent recognition uh through PR Rs and also using viral proteins to prevent and blocking apoptosis. And so we'll be able to get some practice applying these concepts and learn more as we move forward. So I'll see you all in our next video
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Problem
Problem
Host cells that are infected with a virus should undergo apoptosis. However, some viruses can prevent host cells from undergoing apoptosis and thus allowing the virus to continue to replicate within the infected cell. All of the following are ways viruses prevent host cell apoptosis except which of these answers?
A
Covering viral RNA with viral proteins so host cell RIG-Like PRRs do not bind to the viral RNA.
B
Inhibiting the expression of host cell genes which trigger apoptosis during an infection.
C
Evolving antigenic variation to avoid detection by host antibodies and immune cells.
D
Preventing the expression of host antiviral proteins which trigger apoptosis.
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concept
2) Viruses Interfere with Antigen Presentation in Infected Cells
Video duration:
3m
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Problem
Problem
A virus that causes the infected host cell to express and present 'fake' MHC I molecules on its surface is evading detection from which host immune cells?
A
TH cells & NK cells.
B
TC cells & NK cells.
C
TREG cells & TC cells.
D
NK cells & macrophages.
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concept
3) Viruses Avoid the Effects of Antibodies
Video duration:
3m
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Problem
Problem
Some viruses want to be engulfed by phagocytic immune cells. These viruses use some of the same survival mechanisms that bacterial pathogens use to survive and replicate within a phagocyte. Those mechanisms include all of the following except which of these answers?
A
Escaping the phagosome after being engulfed by the phagocyte.
B
Having defenses against the digestive and hydrolytic enzymes of the phagolysosome.
C
Preventing the phagosome and lysosome from fusing to create the phagolysosome.
D
Preventing antibodies from binding the virus and triggering the process of phagocytosis.
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Problem
Problem
Which of the following statements about viruses is false?
A
They can enter the host cell via endocytosis.
B
They are known to colonize the surface of the skin.
C
They have the ability of preventing apoptosis of infected host cells.
D
They may enter host cells by fusing their viral envelopes with the host cell membrane.
E
They may suppress the expression of MHC I molecules on host cells.
