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lolmyi > Viral Pathogens > Flashcards

Viral Pathogens Flashcards

1
Q

What are the different viral structures?

A

→helical
→icosahedral
→complex virus
→enveloped virus

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2
Q

What are the 4 structures of viral genome?

A

→Single-stranded RNA (ssRNA) →Double-stranded RNA (dsRNA) →Single-stranded DNA (ssDNA)
→Double-stranded RNA (dsDNA)

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3
Q

In what sense, can viral genomes be encoded?

A

→both 5’3’ and 3’5’

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4
Q

What is the Baltimore classification?

A

→classification system that places viruses into one of seven groups depending on a combination of their nucleic acid (DNA or RNA), strandedness (single-stranded or double-stranded), Sense, and method of replication

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5
Q

What is group 1 of the BCS?

A

→dsDNA

→+and -

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6
Q

What is group 2 of the BCS?

A

→ssDNA viruses (+)sense DNA

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7
Q

What is group 3 of the BCS?

A

→dsRNA viruses

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8
Q

What is group 4 of the BCS?

A

→(+)ssRNA viruses (+)sense RNA

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9
Q

What is group 5 of the BCS?

A

→(−)ssRNA viruses (−)sense RNA

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10
Q

What is group 6 of BCS?

A

→ssRNA-RT viruses (+)sense RNA with DNA intermediate in life-cycle

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11
Q

What is group 7 of BCS?

A

→dsDNA-RT viruses

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12
Q

What does the outer envelope of HIV consist of?

A

→lipid bilayer with protruding Env spikes (heterotrimers of SU3TM3)

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13
Q

What lies in the envelope of HIV?

A

→Gag proteins

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14
Q

What coats the RNA genome?

A

→nucleocapsid

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15
Q

What does the core of the HIV virus contain?

A

→two genomic RNA strands (plus strand),

→tRNALys3,
→~50 copies of each viral enzyme: protease, integrase and reverse transcriptase

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16
Q

What are the three polyproteins retroviruses synthesise?

A

→Gag
→Pol
→Env

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17
Q

What are Gag polyproteins?

A

→group specific antigen

→viral core proteins

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18
Q

What are Pol polyproteins?

A

→viral enzymes

→RT, IN,PR

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19
Q

What are Env polyproteins?

A

→envelope glycoprotein

20
Q

What are the HIV-1 regulatory accessory proteins?

A

→Tat - potent activator of viral transcription
→Rev - mediates unspliced RNA nuclear export
→Vif - critical regulator of virus infectivity
→Nef - immune modulator, T-cell activation, virus spread (?)
→Vpu - immune modulator, virus release
→Vpr - cell cycle, virus nuclear impor

21
Q

What are the components of HIV RNA?

A 
→Trans-activation response element
→Rev responsive element  
→5 and 3 UTR
→Repeat
→Long Terminal repeat
22
Q

What does the Env polyprotein in HIV-1 consist of?

A

→a trimer of gp41 and gp120 peptide subunits

→covered with glycans

23
Q

What are glycans?

A

→post translational modification eg carbohydrates

24
Q

What does HIV-1 entry require?

A

→CD4

→a chemokine receptor (CCR5/CXCR4)

25
Q

What is HIV-1 tropic for?

A

→for CD4 expressing cells such as helper T cells and macrophages

26
Q

What does loss of CD4 result in?

A

→immunodeficiency (AIDS).

27
Q

Why does HIV-1 replicate in the nucleus?

A

→nucleic acid present

28
Q

How does HIV-1 gain entry into the nucleus after fusion?

A

→uses microtubule network

29
Q

What allows the core to be deposited into the nucleus?

A

→Viral core has capsid modifications

30
Q

What are the components of RT?

A

→heterodimer of p66 and p51 subunits

31
Q

What are the roles of p66 and p51?

A

→Catalytic properties are in p66 subunit,

→p51 serves structural role
→lacks RNAse H domain

32
Q

What are the three enzymatic activities of RT?

A

→RNA-dependent DNA polymerase
→RNAse H (cleaves RNA from RNA/DNA hybrid)
→DNA-dependent DNA polymerase

33
Q

How does the viral genome integrate into host genome?

A

→integrase enzymes
→recognise flanking sequences
→bends host DNA
→brings together host and viral DNA

34
Q

What is the function of LEDGF/P57 in viral integration?

A

→binds HIV-1 integrase and facilitates targeting to chromatin

35
Q

How doe ensure we get preferential transcription?

A

→Viral Tat protein- binds specifically to viral RNA and enhance RNA pol II

36
Q

What produces different mRNAs for viral proteins?

A

→HIV-1provirus

37
Q

What protein mediates nuclear export of unspliced RNA?

A

→ HIV-1 Rev
→binds to RRE region
Promotes viral export over cellular RNA export
→has specificity

38
Q

What does HIV-1 Rev protein interact with?

A

→Crm1 and the RRE RNA

39
Q

What is the purpose of unspliced HIV-1 mRNA?

A

→for Gag and Gag-Pol proteins

40
Q

Why does unspliced viral RNA dimerise?

A

→allows packing of two genomes

→kissing loop complex

41
Q

What is Gag-pol protein generated by?

A

→1 ribosomal frameshifting induced by a ‘slippery’ sequence

→an RNA hairpin structure

42
Q

What allows viral genome to be associated with the plasma membrane?

A

→Myristoylation of Glycines in the MA domain of Gag

43
Q

What is required for virus budding?

A

→HIV-1 PT(S)AP motif

44
Q

What is abscission?

A

→organisation of all the proteins that pushes viral protein into cytoplasm

45
Q

What allows abscission of viral release?

A

→The ESCRT machinery is hijacked by HIV

46
Q

What are the components of the ESCRT machinery?

A

→Gag
→Tsg101
→Alix
→ESCRT-II CHMP4A

47
Q

What causes the release of proteins from Gag and Gag-Pol polyproteins?

A

→Protease

→viral proteins are cut up into individual proteins allowing them to reorganise

lolmyi (31 decks)

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