DD- VIRUS STRUCTURE ANDFX Flashcards Preview

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Flashcards in DD- VIRUS STRUCTURE ANDFX Deck (31):
1

Koch's postulates viral pitfall

The agent must be isolated from the host and grown in vitro- viruses cannot always do this

2

The agent must be present in every case of the disease

The agent must be isolated from the host and grown in vitro.

The disease must be reproduced when a pure culture of the agent is inoculated into a healthy susceptible host.

The same agent must be recovered once again from the experimentally infected host.

Koch's postulates

3

A virus is a submicroscopic, infectious,______ intracellular parasite

obligate

4

The genetic material of a virus enters a host cell and directs the production of the:


building blocks of new virus particles

5

The genetic material of a virus is either _____ and is encased in a protein shell

DNA or RNA

6

New virions are produced from self-assembly of______ components within the host cell

newly synthesized

7

The new virions produced in a host cell ______ to another host cell or organism to carry out another round of infection

transport the viral genetic material

8

Viruses house their DNA or RNA genomes in:

small proteinaceous particles (capsids).

9

The viral genome contains all the information to______an infectious cycle.

initiate and complete

10

Viruses establish a relationship that ranges from ____ in a population of hosts

benign to lethal

11

2 Classification of viruses

The classical system: Linnaean/biological categorization of viruses governed by the ICTV

The Baltimore classification scheme

12

The classical system:
Viruses grouped according to their shared physical properties (4)

a) Nature of the genetic material in the virion (DNA or RNA)

b) Symmetry of the capsid (helical or icosahedral)

c) Naked or enveloped

d) Dimensions of the virion and capsid

13

dsDNA
Gapped circular DNA
ssDNA
dsRNA
ss(+)RNA
ss(+)RNA with DNA intermediate
ss(-)RNA

Seven Classes of Viral Genomes

14

The Baltimore classification scheme

Based on the Central Dogma:

DNA --> RNA -->protein

15

a) Nature of the genetic material in the virion (DNA or RNA)

b) Symmetry of the capsid (helical or icosahedral)

c) Naked or enveloped

d) Dimensions of the virion and capsid

The classical system: Linnaean/biological categorization of viruses governed by the ICTV

16

Seven Classes of Viral Genomes

dsDNA
Gapped circular DNA
ssDNA
dsRNA
ss(+)RNA
ss(+)RNA with DNA intermediate
ss(-)RNA

17

_____protect the genome and serve as a specific genome delivery device

Capsids

18

Nucleocapsid

Nucleic acid-protein complex in a virion when this is a substructure of a complex particle

19

Envelope

Host cell-derived lipid bilayer

20

Capsids assemble from components ______made during infection

(capsid proteins)

21

Spike

Virus derived membrane-bound glycoproteins

22

Viruses have evolved two general forms for packaging their genomes

Helical Capsids
Icosahedral Capsids

Both kinds can be surrounded by a lipid envelope

23

Virion

Infectious virus particle

24

virally encoded glycoproteins (spikes) function in

- entry and host range determinants

- assembly and egress

- evasion from the vertebrate immune system

25

During the eclipse to latent period there is a lot going on inside of the cell (5)

Entry

Viral gene expression

Translation of viral proteins

Virus genome replication

Assembly of new viruses and release of virus from the cell

26

A______ cell has a functional receptor for a given virus--the cell may or may not be able to complete the replication cycle

susceptible

27

A _______cell has no receptor--it may or may not be competent otherwise to replicate the virus.

resistant

28

A_______ cell has the capacity to replicate virus--it may or may not be susceptible

permissive

29

A _________ cell is the only cell that can take up virus and replicate it

susceptible AND permissive

30

Virus attachment to the cell surface

At least two steps are involved:

1. Non-specific, electrostatic binding places viruses in close proximity to cell surface.

2. Proteins on the virus particle must interact with proteins on the cell membrane to initiate the entry process.

31

gain access into different tissue types

entry of virus into a single cell: co-receptors.

combination of carbohydrate and protein receptor molecules

these are examples of:

viruses use more than one receptor