virus classification

Question 1

what can viruses be classified upon>

Answer 1

genome structure and core
capsid structure
Type of mRNA produced during the replicative cycle of the virus (Baltimore Classification

Question 2

what is the influenza viruses made up of

Answer 2

RNA polymerase
neuramindidase
hemaggluttin
ion channel
matrix protein
lipid bi layer
nucleo capsid

8 ssRNA strands

Question 3

what type of virus has a naked helical capsid structure?

Answer 3

TMV

Question 4

what type of virus has a complex virus capsid structure/

Answer 4

herepsvirus, small pox

Question 5

what is the Baltimore classification?

Answer 5

System of virus classification

Question 6

Baltimore classification further detail?

Answer 6

viruses are grouped according to how the mRNA is produced during the replicative cycle of the virus

Question 7

what are some Viral hosts - Ecological niche

Answer 7

Animal viruses
Plant viruses
Bacteriophages

Question 8

Zoonoses definion?

Answer 8

are infectious diseases of different species that can be transmitted to humans

Question 9

E.coli virus?

Answer 9

T4 bacteriophage

Question 11

Listeria monocytogenes virus?

Answer 11

Caudovirales

Question 12

The International Committee on Taxonomy of Viruses decide on what>

Answer 12

decide on the classification and nomenclature (naming) of viruses

Question 13

what are viruses dependant on?

Answer 13

Viruses are dependent on their host’s enzymes and cellular machinery to produce new virions

Question 14

what happens when the the virus infects a cell?

Answer 14

once infected, the host is forced to replicate viral genetic material

• and translate new proteins, including viral capsomeres and viral enzymes

Question 15

what are the 6 steps for a virus to infect a cell?

Answer 15

1)attachment
2)penetration
3)uncoating
4)expression-
4)replication -
(assembly)
5)maturation
6)releease

Question 16

what happens in the attachment/ docking?

Answer 16

The virus first attaches itself to a specific host cell

the T4 phage uses the tail fibres to attach itself to the host cell

The virus attaches to ‘receptors’ - specific proteins, glycoproteins or glycolipids on the host cell

Question 17

what is direct penetration?

Answer 17

The virus bind to specific receptors(proteins)on the surface of the host cell
This is followed by the injection of genetic material into the host cell

Question 18

what is membrane fusion?

Answer 18

The virus binds to specific receptors on the host cell
The envelop of the virus then fuses with the host cell membrane
The viral capsid enters the host cell
This is then followed by the ‘uncoating’ of the viral capsid

Question 19

endocytosis?

Answer 19

The viral envelop binds to specific receptors on the surface of the host cells
The host cell then internalises/engulfs the whole virus
Degradation of the lipid envelop and ‘uncoating’ follows that results in the release of viral genome into the host

Question 20

what does uncoating involve?

Answer 20

involves the separation of the nucleic acid of the virus from its protein coat

Question 21

how does uncoating occur?

Answer 21

degradation by host lysozymes - the host lysozymes degrade the capsid protein

• the action of the viral enzyme

Question 22

how are the new assmenled virons released?

Answer 22

the release of virions is by ‘budding’ resulting in a lipid envelope around the capsid
the release of virion is by membrane rupture (Lysis)

Question 23

There are two main cycles of viral infection :

Answer 23

The lytic cycle

The lysogenic cycle

Question 24

summarise the lytic features?

Answer 24

The virus enters the host cell

The genetic material is replicated and transcribed by the host enzymes

The viral components are assembled to form intact virions

The virions leave the cell by lysis

Enveloped viruses leave the cell by the process of budding

Question 25

Lysogenic Cycle - General Features

Answer 25

The virus enters the host cell
- the viral genetic material is inserted into the genetic material of the host
when the host genome is replicated, the viral genome is
replicated as well
- the virus can live undetected in the host cells for long periods of time
- it can enter the lytic cycle upon activation and result in the formation of numerous virions

Question 26

how does lysis occur?

Answer 26

After assembly of the new virus particles, an enzyme is produced that breaks down the bacteriacell wall

allows fluid to enter

the cell is eventually filled with viruses which results in lysis of the cell

The new viruses are free to infect other cells and start the process again

Question 27

what are virulent viruses?

Answer 27

Viruses that reproduce via the lytic cycle are called virulent viruses

Question 28

how can lysogenic viruses enter the lytic cycle?

Answer 28

when initiated by UV light or certain chemicals

Question 29

Examples of Lytic viruses

Answer 29

Influenza, Rabies, Tobacco mosaic virus, SARS

Question 30

Examples of Lysogenic viruses

Answer 30

• Herpes I and II,HIV, Hepatitis B, Varicella-Zoster