Viral Dz Overview

Question 1

What are the parts of a virus?

Answer 1

Nucleic Acid Core
Capsid
+/- Envelope

Question 2

What is the Nucleic Acid Core?

Answer 2

DNA, RNA, or dsRNA

Question 3

What is a capsid?

Answer 3

an arrangement of protein subunits that surround the nucleic acid core

Question 4

What is the envelope?

Answer 4

a lipoprotein coating that is usually gained from the host cell;
surrounds the capsid

Question 5

Infectivity vs Virulence

Answer 5

The ability of different viruses and their strains to…
Infectivity –> infect a host
Virulence –> produce Dz

Question 6

List the 4 steps needed for a virus to infect a host

Answer 6

1. Adsorption
2. Uncoating
3. Replication
4. Viral Assembly

Question 7

What happens during adsorption?

Answer 7

the virus binds and enters the host cell;

the virus has adapted to be able to bind to a receptor present on the surface of the host cell

Question 8

What happens during uncoating?

Answer 8

Now inside the host cell, the virus capsid breaks down, releasing nucleic acid into the host cell’s cytoplasm.

Question 9

What happens during replication?

Answer 9

the virus inhibits the host cell’s ability to make its own DNA/RNA/proteins;
now the virus can use that same equipment to reproduce its viral genome

Question 10

What happens during viral assembly?

Answer 10

after the viral proteins and nucleic info has been made inside the host cell, a new virion is formed; many virions can be made within a host cell, which can result in 3 different outcomes for the host cell.

Question 11

What are the 3 consequences for a host cell infected by a virus?

Answer 11

1. Little to no damage if the virus leaves via exocytosis (results in enveloped viruses)
2. Lysis (results in non-enveloped viruses)
3. Malignant transformation into a tumor (if virus damages host DNA during viral replication process)

Question 12

Define acquired immunity

Answer 12

the ability of the body to recognize previous invaders when they attempt to re-invade and and to respond even more quickly with more assertiveness and efficacy

Question 13

Name and describe the 2 types of acquired immune responses

Answer 13

1. Humoral- targets extracellular invaders; uses antibodies

2. Cell Mediated- targets intracellular invaders; uses cytotoxic cells

Question 14

How is acquired immunity related to vaccination?

Answer 14

Vaccines introduce an antigen (ie a killed or modified live virus) into the body to stimulate the humoral immune response. Lymphocytes begin to make antibodies against the antigen, which creates a template for if the actual virus enters the body.

Question 15

What is the “memory response”?

Answer 15

The response that occurs at exposures after the first initial exposure.

Question 16

What does the memory response indicate?

Answer 16

the immune system’s ability to remember the first exposure and respond accordingly

Question 17

Why does the memory response occur?

Answer 17

Because memory T-lymphocytes have been made that last longer and retain their ability to recognize the specific antigen and immediately initiate a response to the antigen

Question 18

How do vaccines work?

Answer 18

The patient is exposed to the selected antigen via injection/instillation –>
the body takes appx 1 wk to produce detectable antibody levels in the blood –>
after peek response occurs, antibodies decrease and disappear –>
the patient is exposed a second time to that same antigen –>
the body responds faster and with longer lasting antibody responses

Question 19

What is the point of booster shots?

Answer 19

they get the body to respond faster then before with a longer lasting antibody response

Question 20

Is there a maximum antibody response that can be reached?

Answer 20

Yes

Question 21

How do neonates get maternal antibodies?

Answer 21

• in the womb

- via colostrum

Question 22

Why are maternal antibodies a problem with vaccines?

Answer 22

They can bind to the vaccine antigens before the body is able to recognize the antigen is even there. This means antibodies won’t be made to target that antigen.

Question 23

How long do maternal antibodies hang around? What does this mean for puppy/kitten vaccination schedules?

Answer 23

They decreased naturally as time goes on, but how quickly they decrease really varies by individual. By vaccinating them every 3-4 weeks until appx. 16 weeks of age, we are most likely able to get an effective first and second exposure.

Question 24

Why do we still recommend that puppies/kittens don’t have access to unvax’ed animals/areas where the virus may exist until after their vaccine series is completed?

Answer 24

There will likely still be a window of time where maternal antibody levels are high enough to block vaccine antigens but not high enough to protect against exposure to the virus.