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Virology > Virus genomes and proteins > Flashcards

Virus genomes and proteins Flashcards

1
Q

Do RNA viruses have a big or small genome?

A

Small generally

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1
Q

What is a virus?

A

Nucleic acid enclosed in a protein coat

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2
Q

Do eukaryotes contain RNA dependent RNA polymerase?

A

No

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3
Q

How error prone are viral RdRps?

A

Very

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4
Q

Do viral RdRps contain error correction and what does this mean for the virus?

A

No, more mutations leading to quick evolution

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5
Q

How do RNA viruse prevent too many errors amounting?

A

By having a small genome

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6
Q

Are coronavirus genomes big or small?

A

Big

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7
Q

How do coronaviruses correct genome mistakes?

A

Their RdRps have proofreading

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8
Q

What sense virus carried RdRp on the end of its strand?

A

Negative sense

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9
Q

What is the IRES?

A

Internal ribosome entry sites

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10
Q

Function of the IRES

A

Virus genome folds up, the RNA molecule folds up and can interact with eachother forming H bonds. THese interact with host machinery to initiate transaltion.

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11
Q

Examples of Flaviviruses (+)

A

Dengue fever virus
Yellow fever
West nile virus
Tick borne encephalitis

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12
Q

Flavivirus genome

A

Single ORF encoded polyprotein which is cleaved into indicidual polypeptides.

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13
Q

How is Hep C different from Flaviviruses?

A

Instead of a cap it has an IRES which initiates transalation

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14
Q

Picornavirus examples (+)

A

Poliovirus, rhinovirus, Hep A virus.

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15
Q

Alpha virus examples

A

Eastern equine encephalitis virus

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16
Q

Structure of alphavirus (+)

A

M7G cap, poly A tract, mimicing mRNA. Two ORFs encode two polyproteins.

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17
Q

Coronavirus examples (+)

A

SARS, SARS-Cov2, MERS

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18
Q

Structure of coronavirus genome

A

Multiple ORFs. A m7G cap and poly(A) tail. There is negative-strand production and then transcription of sub-genomic RNAs which are then translated into the virus proteins.

19
Q

Retrovirus examples

A

Mo-MLV, HTLV and HIV

20
Q

Are retrovirus postive or negative sense?

A

Positive

21
Q

How many copies of genome are encapsulated in a retrovirus?

A

Two

22
Q

Example of negative sense non segmented viruses?

A

Rhabdoviruses

23
Q

Examples of rhabdoviruses (-)

A

Rabies virus and vescular stomatisis virus (VSV).

24
Q

Structure of rhabodoviruses (-)

A

Poly U tract, terminator and promotor sequence. Monoscitronic RNA mimics cellular mRNA, freq of mRNA declines.

25
Q

Examples of filoviruses? (-)

A

Ebola and Marburg

26
Q

Genome structure of filoviruses?

A

Genes defined by hihgly conserved transcriptional start signals at theri 3’ and termination signals at their 5’ ends.

27
Q

Example of orthomyxoviruses?

A

Infleuenza, negative sense and 8 segments.

28
Q

Examples of linear DNA viruses

A

Adenovirus, Herpesvirus, Poxvirus

29
Q

Examples of circular DNA viruses

A

Papoviruses
Hepadnaviruses
Parvoviruses

30
Q

Example of ssDNA virus

A

Parvovirus

31
Q

Features of human DNA viruses

A

All have origins of DNA replication. Most use host DNApol. Most replicate in cytoplasm.

32
Q

Features of adenoviruses

A

Inverted terminal repeats (ITR) contain origin of DNA replication. Terminal protein (TP) is linked to 5’ ends.

33
Q

Herpesvirus features

A

Long and short regions flanked by inverted repeats. 3 origins of DNA replication seperated through genome.

34
Q

Papillovirus features

A

Early and late expressed genes
Overlapping reading frames

35
Q

What virus is the leading cause of cervical carcinoma?

A

Human papillomaviruses

36
Q

What charge do capsid proteins usually have?

A

Highly positive

37
Q

What residues are capsid proteins rich in

A

Arg and Lys

38
Q

Two forms of capsid protein structure

A

Helical, or icosahedral

39
Q

Picornavirus capsid protein structure

A

Four protein form basic unit, 60 form icocasehrdal head. Negative charge of RNA is counteracted by Na+ and K+ ions

40
Q

When are matrix proteins present?

A

In enveloped viruses

41
Q

What is the matrix protein in herpesviruses called?

A

Tegument

42
Q

What protein makes up the retroviral matrix?

A

Matrix aantigen (MA/p17)

43
Q

Role of viral glycoproteins?

A

Mediate fusion between viral and cellular membranes, regulated fusogenic activity.

44
Q

how does the gp160 HIV-1 glycoprotein mature?

A

Proteolytic cleavage –> gp120 and gp41

45
Q
A

Virology (6 decks)

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