Lesson 1

Question 1

infectious extracellular virus particle consists of nucleic acid that is covered by a protein coat called capsid

Answer 1

Virion

Question 2

A shell of subunits of proteins called capsomere that encloses the
genome of vertebrate viruses

Answer 2

Capsid

Question 3

3 capsid functions are ;

Answer 3

1. offers protection for the nucleic acid against adverse
   conditions,
2. it facilitates attachment and entry of the virus into host cell,
3. it
   possesses antigens used for virus identification in serological tests and it
   determines the symmetry of the virus

Question 4

the two types of capsid symmetry are

Answer 4

Icosahedral and helical symmetries

Question 5

term used to refer to the combined nucleic acid and capsid
which can either be naked or covered with a membrane termed an envelope

Answer 5

Nucleocapsid

Question 6

A proteins that make up the subunit of capsid,

Answer 6

Structural proteins

Question 7

generally assembled in the host cell prior to
incorporation of the viral nucleic acid.

Answer 7

Icosahedral capsids

Question 8

formed by the insertion of protein units between each turn of
the nucleic acid helix, incorporating the RNA in the tubular package

Answer 8

Helical capsids

Question 9

a lipid bilayer and associated glycoproteins that cover a nucleocapsid

Answer 9

Envelope

Question 10

usually susceptible to detergent and are rendered noninfectious following damage to the envelope

Answer 10

Enveloped viruses

Question 11

the proteins encoded by viral nucleic acid for binding to
receptors on host cells, membrane fusion, uncoating of the virion and destruction
of receptors on host cells

Answer 11

Glycoproteins

Question 12

are knob-like projections from the envelope formed from
the oligomers of glycoproteins.
and used to bind to cell receptors or may have enzymatic
activity

Answer 12

Peplomers or spikes

Question 13

a layer of protein present between the nucleocapsid and the
envelope in some enveloped viruses that provides additional rigidity to the virion

Answer 13

Matrix protein

Question 14

The 3 primary considerations for virus taxonomy are

Answer 14

1. the type and nature of the
   genome,
2. the mode and site of replication ;and
3. the structure and morphology of
   the virion.

Question 15

It developed and expanded the universal scheme in which characteristics of
virions are used to assign them to five hierarchical levels (order, family,
subfamily, genus and species).

Answer 15

The International Committee on Taxonomy of Viruses (ICTV)

Question 16

Mononegavirale is made up the families

Answer 16

Paramyxoviridae,
Rhabdoviridae,
Bornaviridae and
Filoviridae.

Question 17

Herpesvirales comprising the families

Answer 17

Herpesviridae,
Alloherpesviridae and Malacoherpesviridae

Question 18

Picornavirales comprising the families

Answer 18

Picornaviridae,
Iflaviridae,
Dicistroviridae,
Marnaviridae and
Secoviridae;

Question 19

Nidovirales comprising the families

Answer 19

Coronaviridae,
Arteriviridae and
Roniviridae

Question 20

are infectious particles, which can transmit a disease without any detectable nucleic acid

Answer 20

Prions

Question 21

chemical disinfectants

Answer 21

phenol

Question 22

Active virucidal agents

Answer 22

formaldehyde and
betapropiolactone

Question 23

most active antiviral disinfectants.

Answer 23

hydrogen peroxide,
potassium permanganate,
hypochlorite;and
organic
iodine compounds

Question 24

The viruses usually remain viable in a pH is

Answer 24

pH range of 5–9,

Question 25

the viruses are readily inactivated by:

Answer 25

sunlight, ultraviolet (UV) radiations; and ionizing radiations

Question 26

active against enveloped viruses

Answer 26

chloroform, and detergents

Question 27

An eclipse is what ?

Answer 27

the initial stage of virus replication whereby the infecting virus loses its physical identity and most or all of its infectivity.

Question 28

After this eclipse phase, it is followed by?

Answer 28

productive stage as new viral particles are formed and released from the cell wherein the number of viral particles increases exponentially.

Question 29

Abnormal replicative cycles may occur in 4 ways

Answer 29

Incomplete viruses Pseudovirions Abortive infections Defective viruses

Question 30

some of the daughter virions that are produced may not be infective.

Answer 30

Incomplete viruses

Question 31

are the viruses that occasionally enclose host cell nucleic acid instead of viral nucleic acid, therefore, are non infective and lack the capability to replicate.

Answer 31

Pseudovirions

Question 32

Are the virus components may be synthesized but the maturation is defective maybe due to infection of the wrong host cells by the virus.

Answer 32

Abortive infections

Question 33

are viruses that produce fully mature virions only in the presence of helper viruses

Answer 33

Defective viruses

Question 34

2 principal methods of virus

Answer 34

Mutation Recombination

Question 35

Spontaneous and random errors in the copying of viral nucleic acid,, can occur during the replication of viruses. Termed as what ?

Answer 35

Mutation

Question 36

Is the resulting from single nucleotide substitutions, are the most common type of mutation

Answer 36

Point mutations,

Question 37

Less common types of mutation result from

Answer 37

deletion or insertion of one or more nucleotides.

Question 38

the exchange or transfer of genetic material between different but closely related viruses infecting the same cell simultaneously

Answer 38

Recombination

Question 39

Is widely used for virus propagation

Answer 39

Tissue culture

Question 40

Is required for the isolation and identification of viruses involved in disease, for the titration of viruses for vaccine production and for the provision of stocks for research purposes.

Answer 40

Propagation

Question 41

a tissue fragment is used to isolate viruses from animals with persistent infection.

Answer 41

Explant cultures

Question 42

a tissue fragment is used to isolate viruses from animals with persistent infection.

Answer 42

Explant cultures

Question 43

the tissues are digested into individual cells by mechanical cutting followed by digestion with enzymes such as trypsin.

Answer 43

Cell culture

Question 44

Three types of cell culture:

Answer 44

Primary cell culture Semi continuous Continuous cell cell culture

Question 45

It is derived directly from tissues and contain many cell types such as epithelial cells, fibroblasts, keratinocytes, melanocytes, endothelial cells, muscle cells, hematopoietic cells, mesenchymal stem cells

Answer 45

Primary cell culture

Question 46

or diploid cell lines retain their characteristic diploid chromosomal constitution and can support the growth of a wide range of viruses

Answer 46

Semi-continuous

Question 47

or immortal cell lines are derived from either normal or neoplastic tissue and can be passaged indefinitely

Answer 47

Continuous cell cell culture