Basic Virology

Question 1

What 2 bacteria require living cells to survive?

Answer 1

Chlamydia and Rickesttsiae

Question 2

Do viruses need living cells to survive?

Answer 2

Yes, they are obligate intracellular parasites

Question 3

Viruses consists of

Answer 3

NA (DNA or RNA, not both) and proteins, some possess an envelope

Question 4

Viruses are simple replicons, yet

Answer 4

they can take over the host cells machinery and use hots enzymes for replication

Question 5

Size of viruses

Answer 5

15-300nm, must use ELECTRON microscopy

Question 6

Virion

Answer 6

complete viral particle, able to infect host and replicate

Question 7

Genetic material

Answer 7

dsDNA, ssDNA, (+)ssRNA, (-)ssRNA, dsRNA with identical or complementary strands, linear or circular, usually condensed with histones

Question 8

Each infectious virion possess the same

Answer 8

NA

Question 9

Protomer

Answer 9

protein subunit of the capsid (viral protein envelope)

Question 10

Protomers can be arranged 2 ways:

Answer 10

icosahedral or helical

Question 11

Capsomers

Answer 11

arrangement of protomers that form a capsid with icosahedral symmetry

Question 12

capsid

Answer 12

protein shell that self-assembles from protomers and encloses a core of NA

Question 13

There are 3 architectural structures of a capsid

Answer 13

complex symmetry, cubic/icosahedral symmetry, helical symmetry

Question 14

Complex symmetry

Answer 14

viruses with unresolved arrangements (not solved yet)

Question 15

cubic/icosahedral symmetry

Answer 15

20 faces, each is an equilateral triangle, protomers arranged into capsomers

Question 16

helical symmetry

Answer 16

enveloped or non-enveloped nucleocapsid formed by a single repeating protomer and ssRNA

Question 17

nucleocapsid:

Answer 17

protomers assembled in a helical structure around the nucleic acid genome of the virus (capsid + NA + associated proteins)

Question 18

Nucleocapsids can be enveloped or not, non-enveloped nucleocapsids are

Answer 18

stable, resistant to desiccation, acids, and detergents

Question 19

Nucleocapsids may have an envelope that is derived from

Answer 19

host NM, CM, or organelle membrane

Question 20

Peplomer

Answer 20

protein on surface of enveloped nucleocapsids (spikes) that play a role in attachment to cell receptor

Question 21

Tegument and Matrix protein

Answer 21

layer between envelope and nucleocapsid that has complex function and maintains shape

Question 22

Nucleocapsids can be enveloped or not, enveloped nucleocapsids are

Answer 22

fragile, easily disrupted/denatured, sensitive to desiccation and detergents

Question 23

If an enveloped virus is disrupted

Answer 23

the virus becomes inactive

Question 24

Nearly ALL enveloped viruses are transmitted via

Answer 24

arthropods in respiratory droplets or bodily fluids

Question 25

Viruses are classified by 4 categories:

Answer 25

type and polarity of NA, type of capsid symmetry, presence of envelope, quantitative measure of capsid architecture

Question 26

5 Orders of Viruses

Answer 26

Caudovirales, herpesvirales, mononegavirales, nidovirales, picornavirales

Question 27

Viral clade

Answer 27

all descendants from a common ancestor as determined by sequence similarity w/in clade and sequence variation among population

Question 28

Virus serotypes

Answer 28

based on antigenic diversity

Question 29

Examples of clades (Hepatitis C)

Answer 29

6 major clades with genotypes differing by 30-50%

Question 30

Quasisepsis

Answer 30

chronic viral infection that spontaneously generates a population of virions with significant diverse genomics

Question 31

Medical significance of clades:

Answer 31

immune evasion