Lecture 8

Question 1

human virome

Answer 1

including acute and chronic infections, endogenous viral elements, and bacteriophages

Question 2

classification criteria

Answer 2

1. type of structure of viral nucleic acid (DNA or RNA, single or double strand, linear or circular)
2. Shape/symmetry of capsid (helical or icosahedral)
3. Presence of lipid envelope

Question 3

virus structure

Answer 3

• genome and capsid
• enveloped or non-enveloped

Question 4

Non-enveloped

Answer 4

• more virulent - more aggressive
• cause host cell lysis
• more resistant
• norovirus, enterovirus, rhinovirus

Question 5

Enveloped

Answer 5

• less virulent - harder to transmit person-person
• no cell lysis
• escape immune system
• more sensitive
• more severe symptoms
• influenza, HIV, RSV, COVID

Question 6

Non-enveloped uptake

Answer 6

• endocytosis (brought in w/ nutrients, etc)
• do not fuse to host membrane

Question 7

Enveloped uptake

Answer 7

• fuse their viral envelope directly
• HIV bind to CD4 and chemokine receptors
• some use endocytosis and form vesicles (dengue, influenza)

Question 8

Attachment structures

Answer 8

• surface glycoproteins: enveloped viruses
• capsid proteins
• use cell surface molecules
• canonical match between virus and host cell

Question 9

Genome replication

Answer 9

• positive sense: genome serves directly as mRNA
• negative sense: undergo duplication first
• double stranded: segmented genomes
• retrovirus: reverse transcribed into DNA

Question 10

pathogenesis

Answer 10

• local replication
• transmission by ingestion
• hematogenous spread (bloodstream)

Question 11

Persistence

Answer 11

• antigenic variation - mutating
• secretion of immune modulatory proteins
• immune-privileged sites

Question 12

Cancer

Answer 12

• direct transformation: interfere with normal cell regulation
• indirect: chronic inflammation/infection increase risk of genetic damage

Question 13

host response

Answer 13

• cell mediated immunity is more important than innate in resolving acute infections
• antibodies protect from subsequent infections

Question 14

antivirals

Answer 14

target virus replication steps
- entry
- polymerase
- integrase strand
- protease - prevent maturation (antiretrovirals HIV)
- release (prevention and treatment of influenza)
- interferon-a - induces antiviral state

Question 15

Hep B vaccine

Answer 15

• routine testing of all pregnant women
• prophylaxis for infants
• universal vaccination for infants at birth