virology 3

Question 1

Attachment

Answer 1

virus recognition of the target cell
binding virus attachment proteins (VAPs) on the surface of virion on the receptors on the target cell

Question 2

Non-enveloped VAPs

Answer 2

part of the capsid or a protein extending from the capsid

Question 3

Enveloped VAPs

Answer 3

spike/peplomer glycoprotein on the envelope

Question 4

Receptor

Answer 4

protein, carbohydrates on glycoproteins or glycolipids on the cell surface
receptors on the host cell determine host range, tissue tropism

Question 5

Penetration

Answer 5

3 types
entry into the cell
energy dependent, rapid

Question 6

fusion

Answer 6

envelope
fuse with cell membrane

Question 7

endocytosis

Answer 7

enveloped

Question 8

translocation

Answer 8

non-enveloped virions
bind attach and simple pass through

Question 9

uncoating

Answer 9

protective protein shell
nucleocapsid is disintegrated
genome freed in cytoplasm
protein disintegrate in cytoplasm
following uncoating synthesis of viral proteins by cellular metabolism

Question 10

translation

Answer 10

viral RNA/protein utilize cellular machinery
viral mRNA translation to viral protein is essentially the same as cellular mRNA
posttranslational modifications

Question 11

macromolecular synthesis

Answer 11

transcription, translation, posttranslational modification and viral genome replication

Question 12

DNA viruses

Answer 12

replication in nucleus
most use host cell’s DNA-dependent RNA polymerase II and other enzymes to transcribe viral mRNA

Question 13

RNA virus

Answer 13

replicate in cytoplasm: must encode or carry necessary enzymes for transcription and replication in their genomes

Question 14

assembly

Answer 14

viral matrix protein brings viral nucleocapsid to the cell membrane

Question 15

maturation

Answer 15

budding virion
no cellular protein on the membrane
all viral protein

Question 16

Release

Answer 16

take portion of cell membrane
completely replace cell protein with viral protein
free infectious virion

Question 17

Steps:

Answer 17

attachment
penetration
uncoating
macromolecular synthesis
transcription and translation
replication
assembly (maturation)
release

Question 18

Cytopathic Effect (CPE)

Answer 18

morphological changes of infected cells such as rounding, lysis, detachment, syncytia, inclusion bodies

Question 19

causes of CPE formation

Answer 19

direct pathological injury of the infected cells
side effect (altered metabolism due to virus replication)

Question 20

site of replication

Answer 20

dna virus in nucleus
rna virus in cytoplasm

Question 21

effect of viruses on cell metabolism

Answer 21

inhibit everything because they need those machinery to translate viral protein

Question 22

Entry of virus into the host

Answer 22

respiratory tract
GI tract
conjunctiva
genitourinary tract
skin

Question 23

skin

Answer 23

natural barrier-outer layer contains keratinized dead cells of stratum corneum

Question 24

respiratory tract

Answer 24

barriers
mucus, mucociliary movement, neutrophils, macrophages
IgA, CMI
droplet size, air current, humidity, temperature

Question 25

Gastrointestinal tract

Answer 25

barriers
low pH
proteases
bile salts
mucus
IgA, CMI
enzymatic enhancement

Question 26

Genitourinary tract

Answer 26

barriers: mucus, IgA, CMI

Question 27

Conjunctiva

Answer 27

Barriers: tear, IgA and IgG

Question 28

Hematogenous spread-Viremia

Answer 28

vascular system: major pathway, systemic spread
entry site:limited replication
primary viremia-spread to distant organs (major replication site)
secondary viremia: major clinical signs
high viremia=virulence

Question 29

lymphatic spread

Answer 29

lymphatic spread-less important than viremia
primary replication-epithelial cells, vascular system
spread-lymphatic vessels to other tissues

Question 30

neural spread

Answer 30

factor influencing the spread via CNS
primary replication site
viremia (titer and length)
duration of nerve tissue exposure
transport speed: 2-16 mm/day along nerve axon