Viral Structure, Replication and Pathogensis Flashcards Preview

CMBM exam 3 > Viral Structure, Replication and Pathogensis > Flashcards

Flashcards in Viral Structure, Replication and Pathogensis Deck (65):
1

What are the classifications of viruses?

Polio
Rota
Human papillo
Adeno
Semliki
Influenza
Paramyxo
Smallpox

2

What is virology?

Scientific study of viruses and disease they cause

3

What is a virus?

Infective agent typically consisting of a of a nucleic acid in a a protein coat
Obligate intracellular parasite that depends on the host for reproduction

4

How are viruses similar to living organisms?

Proteins and glycoproteins
Nucleic acid

5

How are viruses different from living organism?

No polysaccharides, small molecules or ions
If they are lipid they are only enveloped
No ribosomes

6

Do antibiotics work against viruses?

No

7

Does a virus contain DNA and RNA?

No they can only have DNA or RNA, never both

8

What are possible structures for DNA viruses?

Single or double strand
Linear or circular
Open or closed
Continuous or nicked

9

What are some possible structure for RNA viruses?

Single or double strand
Linear
Possible segmentation
Single strand may be plus or minus sense

10

What are the steps to name a virus?

1. Structure: size morphology and nucleic acid
2. Biochemical characteristics: structure and mode of replication
3. Disease
4. Means of transmission:
5. Cell, tissue or organ
6. Host cell range

11

What a virion?

Structurally complete infective virus particle

12

What is a capsid and what are capsomeres?

A protein shell that encloses the nucleic acid
Capsomeres are units on the surface in clusters

13

What is a nucleocapsid?

Capsid along with the inside nucleic acid

14

What is the tegument of a virus?

Proteinaceous material between envelope and capsid

15

If a virus is said to have an icosahedral shape, what does it look like?

Rigid and uniform structure
ex. Multiside hexagon

16

If a virus is said to have a helical shape, what does it look like?

Swirly squiggly

17

A naked virus...

Protects viral genes from inactivation by adverse environments
Packaged, protect and deliver genome
Mediate attachment (VAP)
Release by cell lysis

18

An enveloped virus...

Has a lipid bilayer with embed proteins
More susceptible to chemical agents
Determines host cell specificity and penetration
Facilitates attachment
Released by budding

19

A virus is icosahedral naked. What types of genome does it have?

dsDNA, ssDNA, dsRNA, ssRNA

20

A virus with an icosahedral shape and is enveloped has what types of genome?

dsDNA, dsRNA, ssRNA

21

A virus has a helical shape and is naked. What are its genomes?

dsDNA, ssDNA, ssRNA

22

An enveloped helical virus is found. What genome will it have?

ssRNA

23

What are the 2 types of exceptions to viral symmetry?

Complex viruses: poxvirus and bacteriophages

24

What is tropism?

Factors that affect host range

25

What are some factors that allow viruses to enter cells?

Can use more than one receptor or many viruses use the same receptor

26

What are the most common routes of entry for a virus?

Blood and bodily fluids
Insect bites
Respiratory
GI
Direct contact

27

What are some viruses that enter through blood or fluid?

CMV, EBV, HBV, HCV, HIV

28

If an insect bites you, what viruses could it transmit?

Dengue, EEEV, WEEV, West Nile

29

Oh no! You touched a surface covered in viruses! What could viruses could you get?

HSV, smallpox, VZV

30

Viruses that can be inhaled are:

Small droplets: influenza, measles, smallpox, VZV
Large droplets: adenovirus, parainfluensa, parvovirus, smallpox
Direct to secretions: RSV, rhinovirus

31

What viruses can be transmitted through the GI tract (facal-oral)?

Enteric adenovirus, HAV, norwalk virus, polio, rotavirus

32

What the main routes for viral spread?

Hematogenous spread
Neural spread
Muliple pathways

33

In hematogenous spread, what does it mean when primary replication proceeds initial viremia?

There are asymptomatic for prodromal symptoms (Enteric or respiratory viruses)
Dissemination to other tissues leads to amped up secondary viremia

34

In hematogenous spread, what viruses travel freely or with other cells?

Enteroviruses, HBV, tagoviruses (free)
Rift valley fever, Colorado tick fever (RBCs)
CMV, EBV, HIV (lymph or monocytes)

35

In the neural spread of viruses, where can entry happen?

Near the CNS and then spreads
It can be near synaptic endings, motor neurons, sensory neuronsm infection of schwann cells and olfactory rods
(HSV, rabies, VZV)

36

What are the basic steps of entry of an enveloped virus?

Attachment to cell receptors
Penetration of host cell by fusion protein
Merging of viral envelope and cell membrane

37

What are the full steps to viral mutliplication?

Attachment/ absorption
Penetration/ entry
Uncoating/ release of nucleic acid
Relication
Assembly
Release

38

When is the viral titer stable?

During the period of attachment

39

When is the viral titer unstable?

Eclipse phase: diassembly, transcription, translation, and genome replication

40

When does the titer increase?

As the viral progeny are assembled and are infectious

41

Which types of viruses make use of their own viral RNA polymerase for replication?

ssRNA+, ssRNA-, all dsRNA

42

Which types of viruses use viral host RNA polymerase?

Hepadnavirus
Retrovirus (also needs viral reverse transcriptase)

43

What viruses use viral RNA polymerase for protein synthesis?

ssRNA- and dsRNA

44

What viruses use host RNA polymerase for protein synth?

Hepadnavirus, ssDNA, dsDNA

45

Which viruses use host DNA polymerase for replication?

ssDNA
dsDNA (can also use viral DNA pol)

46

During early transcription of DNA viruses what is necessary?

Regulatory proteins

47

What is needed during late transcription of DNA viruses?

Structural proteins

48

What type of cycle is an acute viral infection and how does it cause infection?

Lytic cycle
Multiple rounds of replication resulting in cell death
Many progency viruses produced and released
(ex. polio or influenza)

49

What type of cycle is a chronic viral infection and how does it cause infection?

Non-lytic, productive
Undergoes replication and shedding that continues even after acute illness ends
+/- symptoms and cell injury
Continue infecting
Can be localized (warts) or systemic (HIV)

50

What is a latent viral infection?

No replication until signaled
Limited to macromolecules
Genetic material: incorporates into cell or host genome
DNA virus or retrovirus

51

How does a latent infection transform into an active one?

Malignancy of host cell
Invasive growth
Benign or cancerous growth

52

In the prodrome phase of an actue viral infection what cytokine is active?

IFNgamma

53

In the classical sign phase of an acute infection what immunoglobulin is active?

IgM (if primary infection)

54

In the recovery phase of an acute infection what immune cells and immunoglobulin are active?

CD4+, CD8+, IgG

55

What is a nonenveloped single stranded linear DNA virus?

Parvovirus

56

What is a nonenveloped double strand linear DNA virus?

Adenovirus

57

What are nonenveloped double strand circular DNA viruses?

Papillomavirus
Polymavirus

58

What are enveloped double stranded linear DNA viruses?

Herpesviruses
Poxvirus

59

What is an enveloped double stranded circular DNA virus?

Hepadnaviruses

60

What are nonenveloped single stranded positive sense RNA viruses?

Astroviruses
Caliciviruses
Picornaviruses

61

What are nonenveloped double strand RNA viruses?

Reoviruses
Rota viruses

62

What are enveloped single strand positive sense RNA viruses?

Togavirus
Flavivirus
Coronavirus

63

What are enveloped single strand negative sense linear RNA viruses?

Rhabdovirus
Paramyxovirus

64

What are enveloped single strand negative sense segmented RNA viruses?

Arenavirus
Bunyavirus
Orthomyxovirus

65

What are enveloped retroviruses (RNA)?

Lentivirus
Oncovirus