Unit 3 Viral Pathogenesis Flashcards Preview

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Flashcards in Unit 3 Viral Pathogenesis Deck (66):

For viruses, infection simply means entry of a virus into a host cell

This type of infection has new infectious particles produced inside the host cell

For this type, few, if any new viral particles are produced inside the host cell. Not good for the virus.

Productive Infections

Abortive Infections


Abortive infection is sometimes due to 2 things:

Mutation (of the virus)
Protective mechanisms of the host


This type of infection is of short duration, signs/symptoms observed, and then infection is cleared (immunity results)

Prime example is the

Acute infections
(rapid in rapid done)


This type of infection is not completely eliminated after primary infection

What is the example of this

Latent Infections

Herpesviruses (there are 8)


This herpes virus is primarily responsible for cold sores but it could also be

Genital ulcers are usually this herpes virus but can also be

HHV-1 is primarily responsible, can also be HHV2 (genital ulcers is a symptom too)

HHV-2 is primarily responsible, HHV-1 can cause them as well


Chickenpox and shingles are this herpes virus

HHV-3 (varicella zoster)


This term means virus is in the blood, and applies to chickenpox before rashes emerges. Explains why rashes appear all over body



This is the reactivated form of chickenpox and is more localized, can be activated by stress. A vaccine is out there to keep our immune system in check for it.



This herpes virus causes mononucleosis (sick and tired all the time) and Burkitt lymphoma, a reactivated version of it, especially common in HIV positive individuals

It likes to reproduce inside of ____ cells


B cells


This herpes virus is associated with Kaposi Sarcomi, also associated with HIV positive status. Causes an overgrowth of blood vessels underneath the skin.



Latency is maintained inside ___ cells, by maintaining a circular ___ during latency

These help maintain latency

Nerve cells
Circular Episome

Latency associated transcripts (LATs)


Stress, UV light, hormonal changes, and getting over other sicknesses may cause reactivationcc



This is the term for chronic infections, where new viral particles are continuously produced. The host doesn't clear the virus even though signs and symptoms may cease

Persistent Infections


Persistent infections may be a result of a targeted weakening of the immune system or mutational changes in the virus and/or changes in the virus and/or changes in host target cells



Examples of persistent infection include

Do these illnesses always become persistent in individuals?

HIV, hepatitis B and C

No, but they can in some individuals and do.


Viruses must be able to leave one host and enter another. What are the 4 basic types of transmission

Horizontal Transmission
Vertical Transmission
Zoonotic Transmission
Vector Transmission


This type of transmission is due to an animal passing it onto a human

This is more specific, is flea or blood sucking animal

Zoonotic Transmission

Vector Transmission


Which type of viral transmission passes between friends, or from individual from individual within the same species. Includes respitory, fecal oral, and sexual transmission

Which can be passed through mother to offspring in unborn children

Horizontal Transmission

Vertical Transmission


Rhinovirus, influenza, poliovirus, hepatitis A, HIV and HPV are what type of transmission?

Horizontal Transmission


This type of transmission occurs within the same species but from mother to fetus or newborn. Can be transmitted through the ____ or during birth via blood.

The virus can also be transmitted by bodily secretions like

A few viruses can even be transmitted via these type of cells, spermatocytes/oocytes infected with mouse mammary tumor virus

Vertical Transmission, placenta (rubella aka German measles, Hep B and C, HIV)

Breastmilk (HIV)

Germ line cells (reproductive cells)


Facilitated transfer of virus from host to host via another vector, like yellow fever or the myxoma virus

How is it different from zoonotic?

Vector Transmission

Animal isn't affected by pathogen, it's more specific (blood sucking insect passes it from one organism to another)


What are the two ways a virus can kill a body cell

What is the other way body cells can die?

Necrosis and Apoptosis

The immune system (kills infected body cells)


This type of viral induced cell death causes the cell to burst

Is this usually naked or enveloped virion?

What are three mechanisms that cause the cell to burst?


Naked (only way to get out, no spike protein)

Overfilling cell with new viruses
Viral impairment of normal cell function
Additionally, the virus produces particles that weaken the membrane (some)


What symptom is necrosis associated with?

What is inflammation caused by?


Tissue damage that releases chemicals that trigger immune response (chemicals inside cells, like via process of necrosis)


This is the more subtle death of cells that is safer for surrounding cells. The cell commits suicide, sometimes as ordered by the immune system to safely kill virally infected cells.



During apoptosis, internal events occur that degrade DNA into small fragments, bits of cell are released as ______

Does this induce inflammation?


No, not rupturing/leaking the cell contents out


Some viruses can fuse host cells together, forming ___ that often kill the cells

What virus is well known for doing this?




By doing syncytia, what does the virus avoid? Intracellular or extracellular immune responses

Extracellular Immune responses


In HIV, syncytia occurs via spike proteins injected into a CD4 cell membrane, where they can bind to the other CD4 cell because the spike proteins have gp120. The newly infected CD4 cells can't function.



Can a virus move between different cells when synctia occurs?

How is this benefecial

Yes it can move between the cells that are involved in a synctia

Avoid extracellular immune responses


Other viruses may form clumps of virus or proteins inside host cells that often kill cells by interfering with cell function, these clumps are called

Inclusion bodies


What are inclusion bodies helpful for?


Viral identification

Niger bodies in detection of rabies


The signs and symptoms of viral infection may be a result of our own immune responses

What causes the symptoms in the common cold this way?

Inflammatory cytokines (chemicals involved in communication, stimulates other immune cells)
-causes tired/aching/fever/mucous production etc


What does the mucous do in the common cold?

Prevents virus particles from attaching to host tissues (too much cold medicine can be bad)


Another example of inflammatory cytokines in viruses, cold sores/red blisters

Decline in CD4 cells leading to opportunistic pathogens taking over part of your body is




The impact of the hepatitis B virus on liver function is a result of immune responses killing off infected _______, aka liver cells

What type of infection is can hep B be??


Acute (not bad) Chronic/persistent infection (bad)


Chronic hep B can cause liver disease, which is _______________ mediated

Liver disease can lead to _____ when coupled with Hep D infection

It can also cause kidney disease, which is ___ mediated (humoral/autoimmune response), they attack our tissues causing damage

reCytotoxic lymphocyte mediated

Liver Cancer



The signs/symptoms of autoimmune diseases may be a result of our own immune response against viruses. If molecular ____ occurs, an antiviral response accidentally views self structures as foreign

Molecular Mimicry (cross re-activity of antibodies)


It's not the same surface chemical on the host cell as the virus that activates white blood cells but they look close enough in molecular mimicry. Killer Ts make the mistake this way (ex: multiple sclerosis)



In autoimmune disease ____ cells attack healthy body cells that have similar proteins that are on pathogens

Killer T cells (CD8)

In MS, it targets dendritic cells that make myelin sheath


MS is marked by a rapid deterioration in


Also uncoordinated movement

Also pins and needles


Do all people with MS die?

No, some have one episode, some it progresses quickly, some progress slowly


Tranformation events produce changes in a cell that make it cancer like

Some viruses possess _____, genetic material capable of inducing tranformation events in host cells



In cancer, oncogenes go what?

Turn off tumor suppressor genes


This may result from a viral protein inducing a normally quiescent (or not dividing, in a G0 phase) cell to enter the cell cycle


leads to warts, etc.


This disease is associated with warts, especially genital , does give rise to others.

Are the warts always visible?

Does every strain have oncogenes?

If you do have the oncogenes, you have an increased chance of

HPV (Papillomaviridae family)



Cancer developing (penile/scrotal or cervical)


HPV has a vaccine for both men and women.



This disease is associated with the herpesviridae virus family and it transforms endothelial blood vessel cells, a defining cancer of people with HIV/AIDS

Kaposi Sarcoma


This disease is associated with herpesviridae and causes infectious mononucleosis more commonly

Burkitt Lymphoma


Why is it beneficial for viruses to up the cell cycle?

It gives them more hosts to infect (leads to warts)


The virus cells, like the dead epithelial cells, are at the surface and can infect other people when they shed

! Scary.


There are events at the genomic level that can occur as viruses reproduce that can alter there virulence. What are the 3 things?



This type of event produces changes in the genome directly

Viral Mutation


Eukaryotic/prokaryotic cells have many ways of preventing mutations. The proofreading activity of ____ is one. It lowers the amount in this type of virus

Some viruses lack these capabilities, like viruses that have _____

DNA polymerase used by DNA polymerase

RNA polymerase used by RNA viruses (including reverse transciptase!)


So which produce more viral mutations, DNA or RNA viruses?

RNA viruses, they don't have proofreading capability (reverse transciptase or RNA polmerase


Viral mutations can lead to issues with treatments, and can change which cells are infected in a persistent infection



In one strain of HIV, the CD4 surface receptor and the _____ surface co-receptor on monocytes can be infected

In another strain, the helper T cells have CD4 and the _______ coreceptor, when this occurs in HIV its more dangerous.




In many HIV cases, especially if it was contracted sexually, most people get exposed to which strain of HIV, CCR5 or CXCR4?

Over time what occurs?

CCR5. So the first wave of cells infected are the monocytes/macrophages.

Mutations, causing different strains to emerge like the strain that affects helper T cells (the generals of the immune system)


This type of event occurs during Prophase I, fusions of pieces of two separate viral genomes creates a new hybrid genome, can result in entirely new properties rapidly. Not always good for the virus.

Virus Recombination


As an example of virus recombination, this virus has two strains, the polymerase can create 4 different viruses

Coronavirus (2 strains, 4 possibilities)

1 all strain 1, 1 all strain 2, 2 recombinant viruses


This type of process can lead to antigenetic shift, multiple viruses with segmented genomes infect the same cell and can swap segments in a newly formed virus. This can lead to new or modified virulence traits

Viral Reassortment


A slight mutation giving a little change in a surface protein so the immune system doesn't recognize it is defined as

Antigenetic Drift


This is a big change, the genome is re-assorted and a different strain occurs. Very low herd immunity results.

Antigenetic Shift


Viral reassortment occurs between these viruses

Swine flu , Avian Flu, Human flu


In order for something to be a pandemic flu, it everybody has t be susceptible, in other words, the virus must be



Note: antigenetic shift may occur but it isn't very transmissible. What is an example of this?

Bird flu, spreads rapidly between birds but doesn't spread between humans well. But it could become the next pandemic flu with a shift/drift

Additionally, H1N1