Virology Overview

Question 1

What is virology?

Answer 1

The study of viruses and viral diseases

Question 2

What is a virologist?

Answer 2

Someone who studies viruses

Question 3

What is veterinary virology and why is it important?

Answer 3

the study of viruses in non-human animals

-Viruses cause high rates of mortality

• financial losses to the livestock and poultry industries, hampering the economic
  development of a country

-Some of the viruses are zoonotic

Question 4

What is a zoonotic disease?

Answer 4

Diseases that can be transferred from animals to people.

Question 5

Are viruses living or non-living?

Answer 5

Non-living

Question 6

Describe the structure of a virus.

Answer 6

• Contains nucleic acid genome (DNA or RNA) surrounded by a protein capsule and can sometimes a lipid envelope
• They do not contain organelles
• Cannot make energy themselves, rely on host
• Viruses are obligate intracellular parasites
• They do not have the genetic capability to multiply by division

Question 7

What is a capsid?

Answer 7

a protein shell of a virus that encases/envelopes the viral nucleic acid or genome

Question 8

What is a lipid envelope?

Answer 8

The lipid bilayer envelope that covers the capsid. Only some viruses have this and it derived from the host cell.

Glycoproteins are present on the surface of the envelope, and often appear as spikes.

Question 9

Define intracellular parasites in regards to viruses.

Answer 9

Viruses are inert or dormant particles outside of the cell. Inside the cell, the virus hijacks and utilizes the host cell machinery to produce its proteins and nucleic acid for the next generation of virus

Question 10

Describe how a virus replicates.

Answer 10

Viruses do not have the genetic capability to multiply by division. The process of virus reproduction resembles an assembly line in which various parts of the virus come together from different parts of the host cell to form new virus particles.

Question 11

What is a capsid made of?

Answer 11

Capsomeres held together by non-covalent bonds

Question 12

What is a nucleocapsid?

Answer 12

Capsid + virus nucleic acid (DNA or RNA)/ Genome

Question 13

What are the spikes on virus and to what layer are they attached?

Answer 13

Glycoproteins, the lipid envelope

Question 14

What is the lipid envelope derived from?

Answer 14

The host cell

Question 15

What is a naked virus?

Answer 15

A non-enveloped virus that has only a protein capsid enclosing nucleic acid

Question 16

What is an enveloped virus?

Answer 16

A virus with a lipid envelop enclosing the protein capsid enclosing the nucleic acid

Question 17

Define pleomorphism

Answer 17

The ability of some viruses to alter their shape or size

Question 18

Do viruses contain DNA or RNA? Single stranded or double stranded?

Answer 18

All of the above! Can be RNA or DNA, can be single or double stranded.

Question 19

What are the stages of virus replication?

Answer 19

attachment (to the cell), penetration (of host cell membrane), uncoating, synthesis of viral nucleic acid and protein (using host cell machinery), assembly and maturation, release in large numbers

Question 20

What are the impacts of virus replication in the host cell?

Answer 20

Cell death (lysis, alteration of cell membrane, apoptosis), no apparent changes (persistent or chronic infections), transformation of cell into a malignant one, fusion of cells (multinucleated)

Question 21

Who is responsible for the classification of viruses and what are they responsible for?

Answer 21

The International Committee on Taxonomy of Viruses (ICTV) Classification System is followed by virologists worldwide.

The ICTV is charged with the task of developing, refining, and maintaining a universal virus taxonomy by the International Union of Microbiological Societies.

Question 22

How are viruses spread? (7 ways)

Answer 22

Direct-contact transmission
indirect-contact transmission
common-vehicle transmission (fecal/viral contamination of food or water)
Airborne transmission
Vector-borne transmission (arthropods)
Zoonotic transmission
Vertical transmission (infection transferred from mother to embryo/fetus/newborn shortly before parturition)

Question 23

How are viruses diagnosed? (5 ways)

Answer 23

By gross evaluation (clinical signs/ necropsy) and histopathology.

By cultivation/ isolation of viruses in cells/tissue culture and inoculation of eggs.

Electron Microscopy

Serology- detection of viral antigen or host antibody against virus

Detection of viral nucleic acids

Question 24

What 3 serology techniques are used in the detection of viruses?

Answer 24

ELISA (Enzyme-linked ImmunoSorbent Assay)
Fluorescent antibody staining
Immunohistochemical staining

Question 25

What 3 techniques are used in the detection of viral nucleic acids?

Answer 25

RT-PCR/ PCR
Quantitative PCR
Virus Genome Sequencing (reading virus genes)

Question 26

How are viruses treated? (3 ways)

Answer 26

Antiviral drugs
Immune system stimulation
Synthesize antibodies or administration of natural antiserum (antobodies)

Question 27

How are viruses prevented?

Answer 27

Vaccination
Proper hygiene and sanitation
Eliminating arthropod vectors
Quarantine and Culling

Question 28

What types of vaccinations are used to prevent viruses?

Answer 28

Live-attenuated virus vaccines
Non-replication virus vaccines
Vaccines produced by Recombinant DNA and related technologies

Question 29

How are viruses prevented by using proper hygiene and sanitation?

Answer 29

Use of disinfectants
“All in, all out” management system
Hand washing and decontamination of contaminated equipment
Proper waste management in farms

Question 30

Describe the “all in, all out” management system.

Answer 30

Animal houses are emptied, cleaned, and disinfected between batches of animals. No contact between batches of animals.

Question 31

How can arthropod vectors be eliminated?

Answer 31

Biological control (use of natural enemies, such as predatory fish that feed on mosquito larvae)

Chemical control (use of insecticides)

Question 32

What is involved in quarantine and culling?

Answer 32

Separating and restricting the movement of animals, culling (killing of animals), and proper disposition of culled animals.