Unit 3 Viral Pathogenesis

Question 1

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.

Answer 1

Productive Infections

Abortive Infections

Question 2

Abortive infection is sometimes due to 2 things:

Answer 2

Mutation (of the virus)

Protective mechanisms of the host

Question 3

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

Prime example is the

Answer 3

Acute infections
(rapid in rapid done)
Rhinovirus

Question 4

This type of infection is not completely eliminated after primary infection

What is the example of this

Answer 4

Latent Infections

Herpesviruses (there are 8)

Question 5

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

Answer 5

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

Question 6

Chickenpox and shingles are this herpes virus

Answer 6

HHV-3 (varicella zoster)

Question 7

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

Answer 7

Viremia

Question 8

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.

Answer 8

Shingles

Question 9

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

Answer 9

HHV-4

B cells

Question 10

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

Answer 10

HHV-8

Question 11

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

These help maintain latency

Answer 11

Nerve cells
Circular Episome

Latency associated transcripts (LATs)

Question 12

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

Answer 12

!

Question 13

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

Answer 13

Persistent Infections

Question 14

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

Answer 14

!

Question 15

Examples of persistent infection include

Do these illnesses always become persistent in individuals?

Answer 15

HIV, hepatitis B and C

No, but they can in some individuals and do.

Question 16

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

Answer 16

Horizontal Transmission
Vertical Transmission
Zoonotic Transmission
Vector Transmission

Question 17

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

This is more specific, is flea or blood sucking animal

Answer 17

Zoonotic Transmission

Vector Transmission

Question 18

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

Answer 18

Horizontal Transmission

Vertical Transmission

Question 19

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

Answer 19

Horizontal Transmission

Question 20

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

Answer 20

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

Breastmilk (HIV)

Germ line cells (reproductive cells)

Question 21

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

How is it different from zoonotic?

Answer 21

Vector Transmission

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

Question 22

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

What is the other way body cells can die?

Answer 22

Necrosis and Apoptosis

The immune system (kills infected body cells)

Question 23

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?

Answer 23

Necrosis

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)

Question 24

What symptom is necrosis associated with?

What is inflammation caused by?

Answer 24

Inflammation

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

Question 25

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.

Answer 25

Apoptosis

Question 26

During apoptosis, internal events occur that degrade DNA into small fragments, bits of cell are released as ______ Does this induce inflammation?

Answer 26

Blebs No, not rupturing/leaking the cell contents out

Question 27

Some viruses can fuse host cells together, forming ___ that often kill the cells What virus is well known for doing this?

Answer 27

Synctia HIV

Question 28

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

Answer 28

Extracellular Immune responses

Question 29

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.

Answer 29

!

Question 30

Can a virus move between different cells when synctia occurs? How is this benefecial

Answer 30

Yes it can move between the cells that are involved in a synctia Avoid extracellular immune responses

Question 31

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

Answer 31

Inclusion bodies

Question 32

What are inclusion bodies helpful for? Example?

Answer 32

Viral identification Niger bodies in detection of rabies

Question 33

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?

Answer 33

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

Question 34

What does the mucous do in the common cold?

Answer 34

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

Question 35

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

Answer 35

Herpes HIV

Question 36

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??

Answer 36

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

Question 37

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

Answer 37

reCytotoxic lymphocyte mediated Liver Cancer Antibody-mediated

Question 38

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

Answer 38

Molecular Mimicry (cross re-activity of antibodies)

Question 39

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)

Answer 39

!

Question 40

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

Answer 40

Killer T cells (CD8) In MS, it targets dendritic cells that make myelin sheath

Question 41

MS is marked by a rapid deterioration in

Answer 41

Vision Also uncoordinated movement Also pins and needles

Question 42

Do all people with MS die?

Answer 42

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

Question 43

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

Answer 43

Oncogenes

Question 44

In cancer, oncogenes go what?

Answer 44

Turn off tumor suppressor genes

Question 45

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

Answer 45

Tumorigenesis leads to warts, etc.

Question 46

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

Answer 46

HPV (Papillomaviridae family) No. No. Cancer developing (penile/scrotal or cervical)

Question 47

HPV has a vaccine for both men and women.

Answer 47

!

Question 48

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

Answer 48

Kaposi Sarcoma

Question 49

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

Answer 49

Burkitt Lymphoma

Question 50

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

Answer 50

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

Question 51

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

Answer 51

! Scary.

Question 52

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

Answer 52

Mutations Recombinations Reassortments

Question 53

This type of event produces changes in the genome directly

Answer 53

Viral Mutation

Question 54

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 _____

Answer 54

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

Question 55

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

Answer 55

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

Question 56

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

Answer 56

!

Question 57

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.

Answer 57

CCR5 CXCR4

Question 58

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?

Answer 58

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)

Question 59

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.

Answer 59

Virus Recombination

Question 60

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

Answer 60

Coronavirus (2 strains, 4 possibilities) 1 all strain 1, 1 all strain 2, 2 recombinant viruses

Question 61

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

Answer 61

Viral Reassortment

Question 62

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

Answer 62

Antigenetic Drift

Question 63

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

Answer 63

Antigenetic Shift

Question 64

Viral reassortment occurs between these viruses

Answer 64

Swine flu , Avian Flu, Human flu

Question 65

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

Answer 65

Transmissible

Question 66

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

Answer 66

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