Virology Introduction

Question 1

What is an envelope in the context of viruses?

Answer 1

A lipid-containing membrane that surrounds some virus particles, acquired during viral maturation by a budding process through a cellular membrane.

Virus-encoded glycoproteins are exposed on the surface of the envelope, with projections called peplomers.

Question 2

What are peplomers?

Answer 2

Projections on the surface of the viral envelope that are virus-encoded glycoproteins.

They play a role in the virus’s ability to infect host cells.

Question 3

Define nucleocapsid.

Answer 3

The protein-nucleic acid complex representing the packaged form of the viral genome.

The term is commonly used when the nucleocapsid is a substructure of a more complex virus particle.

Question 4

True or False: The nucleocapsid is always the outermost structure of a virus.

Answer 4

False.

The nucleocapsid can be a substructure of a more complex virus particle.

Question 5

Fill in the blank: The envelope is acquired during viral maturation by a _______.

Answer 5

budding process through a cellular membrane.

Question 6

What is genetic shift?

Answer 6

A major change in the nucleic acid of a virus.

Question 7

True or False: Antigenic shift refers to minor changes in virus antigens.

Answer 7

False

Question 8

What type of virus change does antigenic shift involve?

Answer 8

Major changes that result in new antigenic properties.

Question 9

Fill in the blank: Genetic shift is primarily associated with __________.

Answer 9

RNA viruses

Question 10

What is the primary consequence of antigenic shift in viruses?

Answer 10

It can lead to pandemics due to changes in the virus that the immune system does not recognize.

Question 11

Which viruses are most commonly associated with antigenic shift?

Answer 11

Influenza viruses.

Question 12

What is the difference between antigenic drift and antigenic shift?

Answer 12

Antigenic drift involves minor mutations, while antigenic shift involves major changes.

Question 13

Multiple choice: Which of the following is a result of antigenic shift? A) Seasonal flu B) Pandemic flu C) Cold virus

Answer 13

B) Pandemic flu

Question 14

True or False: Antigenic shift can occur through reassortment of viral genes.

Answer 14

True

Question 15

What is reassortment in the context of viral genetics?

Answer 15

The process by which two different strains of a virus exchange genetic material.

Question 16

Fill in the blank: Antigenic shift can create __________ viruses that the population has little or no immunity against.

Answer 16

Novel

Question 17

How often does antigenic shift occur in influenza viruses?

Answer 17

Irregularly, typically during pandemics.

Question 18

What is the role of host species in antigenic shift?

Answer 18

Different host species can serve as reservoirs for genetic material exchange.

Question 19

True or False: Antigenic shift is a gradual process.

Answer 19

False

Question 20

Short answer: Why is monitoring antigenic shift important in public health?

Answer 20

To predict and prepare for potential outbreaks or pandemics.

Question 21

What is a potential source of genetic material for antigenic shift in influenza?

Answer 21

Coinfection of a host with multiple strains of the virus.

Question 22

Multiple choice: Which factor can influence antigenic shift? A) Temperature B) Humidity C) Viral reassortment

Answer 22

C) Viral reassortment

Question 23

What are the implications of antigenic shift for vaccine development?

Answer 23

Vaccines may need to be updated frequently to match the new virus strains.

Question 24

Fill in the blank: Antigenic shift can result in a __________ of previously circulating viruses.

Answer 24

Re-emergence

Question 25

True or False: Antigenic shift is a common occurrence in all viruses.

Answer 25

False

Question 26

Short answer: What is the significance of genetic shift in the evolution of viruses?

Answer 26

It allows viruses to adapt rapidly and evade the immune system.

Question 27

What is the relationship between genetic shift and zoonotic diseases?

Answer 27

Genetic shift can facilitate the jump of viruses from animals to humans.

Question 28

Multiple choice: Which of the following best describes antigenic shift? A) Minor mutations B) Gene reassortment C) Spontaneous mutations

Answer 28

B) Gene reassortment

Question 29

What is a key challenge in managing diseases caused by viruses that undergo antigenic shift?

Answer 29

Rapid changes in virulence and transmissibility.

Question 30

Fill in the blank: The study of genetic shift is crucial for understanding __________ in viral pathogens.

Answer 30

Epidemiology

Question 31

True or False: Antigenic shift can lead to increased pathogenicity.

Answer 31

True

Question 32

What is a virus?

Answer 32

An obligate intracellular parasite that is among the smallest of all infectious agents capable of infecting an animal, insect, plant, or bacterial cell. ## Footnote Viruses cannot replicate without a living host cell.

Question 33

Define pandemic.

Answer 33

The emergence of a new viral disease across a very large geographic region (worldwide) with prolonged human-to-human transmission. ## Footnote Most recorded pandemics have been caused by an influenza virus.

Question 34

True or False: A virus can replicate independently of a host cell.

Answer 34

False ## Footnote Viruses are incapable of replication without a living host cell.

Question 35

What type of cells can viruses infect?

Answer 35

Animal, insect, plant, or bacterial cells. ## Footnote This highlights the diverse nature of viral infections.

Question 36

What are structural units in the context of viruses?

Answer 36

The basic protein building blocks of the coat, usually a collection of more than one nonidentical protein subunit ## Footnote The structural unit is often referred to as a protomer.

Question 37

Define subunit in viral structure.

Answer 37

A single folded viral polypeptide chain

Question 38

What is a virion?

Answer 38

The complete virus particle

Question 39

What is one theory of viral origin?

Answer 39

Viruses may be derived from DNA or RNA nucleic acid components of host cells that became able to replicate autonomously and evolve independently ## Footnote This theory suggests that viruses resemble genes that acquired the ability to exist outside of the cell.

Question 40

What do some viral sequences resemble?

Answer 40

Portions of cellular genes encoding protein functional domains ## Footnote This indicates a potential evolutionary link between viruses and cellular life.

Question 41

What is the second theory of viral origin?

Answer 41

Viruses may be degenerate forms of intracellular parasites ## Footnote This theory posits that viruses evolved from more complex intracellular organisms.

Question 42

Is there evidence that viruses evolved from bacteria?

Answer 42

No, there is no evidence that viruses evolved from bacteria ## Footnote However, other obligately intracellular organisms like rickettsiae and chlamydiae presumably evolved from bacteria.

Question 43

What is unique about poxviruses regarding their evolutionary origin?

Answer 43

Poxviruses are large and complex, possibly representing evolutionary products of some cellular ancestor ## Footnote Their complexity distinguishes them from simpler viruses.

Question 44

Fill in the blank: Viruses may resemble _______ that have acquired the capacity to exist independently of the cell.

Answer 44

[genes]