TOPIC 9 - VIROLOGY PART 2

Question 1

A fully assembled infective virus

Answer 1

Virion

Question 2

What is the fundamental component of virion that has the ability to infect host cells and replicate in them; thus ensuring continued survival ?

Answer 2

Nucleoprotein core

Question 3

Shell of proteins that encloses the genome of vertebrate viruses

Answer 3

Capsid

Question 4

Used to describe the packaged form
of the genome in the capsid

Answer 4

Nucleocapsid

Question 5

What are the 2 types of capsid symmetry?

Answer 5

1. Icosahedral
2. Helical

Question 6

In many types of viruses the nucleocapsid is covered by an envelope composed of a lipid bilayer and
associated glycoproteins. True or False?

Answer 6

True

Question 7

The _____ are associated with binding to receptors on host cells, membrane fusion, uncoating of the virion and destruction of receptors on host cells.

Answer 7

Glycoproteins

Question 8

______ on envelope glycoproteins are often important for inducing protective immune responses
in infected animals.

Answer 8

Epitopes

Question 9

Used to describe features such as protrusions seen on the surface of
virus particles in electron micrographs

Answer 9

Capsomere

Question 10

Give the viral families of the following classification:

Double-stranded DNA and enveloped

Answer 10

• Herpesviridae
• Asfarviridae
• Hepadnaviridae
• Poxviridae

Question 11

Give the viral families of the following classification:

Double-stranded DNA and non-enveloped

Answer 11

• Iridoviridae
• Papillomaviridae
• Adenoviridae

Question 12

Give the viral families of the following classification:

Single strand DNA and non-enveloped

Answer 12

• Parvoviridae
• Circoviridae

Question 13

Give the viral families of the following classification:

Single strand RNA and enveloped

Answer 13

• Coronaviridae
• Orthomyxoviridae
• Paramyxoviridae
• Bunyaviridae
• Retroviridae
• Rhabdoviridae
• Togaviridae
• Flaviviridae
• Arteriviridae
• Arenaviridae
• Filoviriae

Question 14

Give the viral families of the following classification:

Single strand RNA and non-enveloped

Answer 14

• Picornaviridae
• Caliciviridae

Question 15

Give the viral families of the following classification:

Double-stranded RNA and non-enveloped

Answer 15

• Reoviridae
• Birnaviridae

Question 16

This viral classification is based on the nature of the genome and pathways of mRNA synthesis.

Answer 16

Baltimore classifications

Question 17

Give the 5 virus replication stages.

Answer 17

1. Attachment to a surface receptor on a susceptible
   host cell
2. Entry into the cell
3. Uncoating of viral nucleic acid
4. Replication of viral nucleic acid and synthesis of virus-encoded proteins
5. Assembly of newly-formed virus particles and
   release from host cell

Question 18

Initial virus-cell interaction is a random event which
related to the number of _____ ____ present and the availability of appropriate _____ ____.

Answer 18

virus particles; receptor molecules

Question 19

Virus-cell interaction determines both ___ ___ and ____ ____ of viral species.

Answer 19

host range; tissue tropism

Question 20

In orthomyxoviruses and paramyxoviruses, the
detachment is mediated by _____ _____, a receptor-destroying enzyme.

Answer 20

viral neuraminidase

Question 21

Entry into the cell of virus is processed in 3 aspects. What are these?

Answer 21

(1) Receptor-mediated endocytosis
(2) Clathrin
(3) Fusion of viral envelope with the plasma membrane

Question 22

The process whereby the viral genome is released in a form suitable for transcription.

Answer 22

Uncoating

Question 23

Synthesis of viral proteins requires the production of ?

Answer 23

viral mRNA

Question 24

For DNA viruses, which replicate in the nucleus, it can avail of host cell _____ to synthesize viral mRNA.

Answer 24

transcriptases

Question 25

Most viral proteins undergo post-translational modification including ?

Answer 25

1. Proteolytic cleavage 2. Phosphorylation 3. Glycosylation

Question 26

In _____, sugar side-chains are added to viral proteins in a programmed manner as the proteins are being transferred from the RER to Golgi apparatus in preparation to final assembly and release from the cell.

Answer 26

glycolysation

Question 27

Non-enveloped viruses of animals have _____ structure.

Answer 27

icosahedral

Question 28

Give some examples of viruses that assembles in cytoplasm of the cell.

Answer 28

1. Picornaviruses 2. Reoviruses

Question 29

Give some examples of viruses that assembles in the nucleus.

Answer 29

1. Parvoviruses 2. Adenoviruses 3. Papovaviruses

Question 30

What is the final step in the process of virion assembly?

Answer 30

Involves acquisition of an envelope by budding from cell membranes

Question 31

These enveloped viruses are cytolytic.

Answer 31

1. Togaviruses 2. Paramyxoviruses 3. Rhabdoviruses

Question 32

These viruses acquire their envelopes inside cells by budding through the membranes of the RER or the Golgi apparatus and then transported in vesicles to the cell surface where the vesicle fuses with the plasma membrane releasing the virion by exocytosis.

Answer 32

1. Flaviviruses 2. Coronaviruses 3. Arteriviruses 4. Bunyaviruses

Question 33

This virus is unique as it replicates in the nucleus and bud through the inner lamella of the nuclear membrane and accumulate in the space between inner and outer lamellae, in the cisternae of the ER and in cytoplasmic vesicles.

Answer 33

Herpesvirus

Question 34

This virus assembly and release are a complex process taking several hours.

Answer 34

Poxviruses

Question 35

Give this method of detection of virus, viral antigens or nucleic acid: * This method can be used to recognize mixed viral infections and detect viruses which cannot be grown in vitro * Has limitations (e.g. large numbers of viral particles must be present in clinical samples)

Answer 35

Electron microscopy

Question 36

Give this method of detection of virus, viral antigens or nucleic acid: * Antiviral antibodies labelled with fluorochromes can be used to detect viral antigens in clinical specimens * Can be used to demonstrate virus or viral antigen in specimens

Answer 36

Immunofluorescence and Immunohistochemistry

Question 37

Give this method of detection of virus, viral antigens or nucleic acid: * Carried out in agar * Placing a fluid sample containing the virus under test in a well in the agar opposite a well containing antiserum * Fluids diffuse out of the wells, a line of precipitate forms if the sample under test contains viral antigen

Answer 37

Immunodiffusion

Question 38

Give this method of detection of virus, viral antigens or nucleic acid: * Viruses such as Orthomyxoviridae, paramyxoviridae, adenoviridae and parvoviridae and togaviridae can interact with erythrocytes of many animal species causing hemagglutination * Hemadsorption is used to describe binding of erythrocytes to cells infected with hemagglutinating viruses

Answer 38

Hemagglutination and hemadsorption

Question 39

Give this method of detection of virus, viral antigens or nucleic acid: * In vitro method is based on the amplification of a particular nucleic acid sequence using a thermostable DNA polymerase and primers

Answer 39

Polymerase chain reaction (PCR)

Question 40

Give this method of detection of virus, viral antigens or nucleic acid: *Enzyme-linked immunosorbent assay *Serum neutralization test * Hemagglutination inhibition test * Complement fixation tests *Western Blotting

Answer 40

Diagnostic serology