Microbio Chapter 13- Viruses

Question 1

What is a virus?

Answer 1

Obligate parasites

Question 2

What is a virion?

Answer 2

Fully developed, infective form of a virus outside a host cell

Question 3

A virion contains?

Answer 3

A genome
A capsid
An envelope
Spikes

Question 4

How can virus parasites be transmitted?

Answer 4

Birds, bats, humans, swine
-They act as mixing vessels for genes

Question 5

What genome does a virion have?

Answer 5

DNA or RNA

Question 6

What is a capsid?

Answer 6

A protein coat
Made from subunits called Capsomeres

Question 7

What are the functions of a capsid?

Answer 7

1. Used for identification (Gives cell a unique shape)
2. Used for transmission to the hosts
3. Used for attachment + protection

Question 8

What covers the capsid?

Answer 8

The envelop

Question 9

Do all viruses have an envelop?

Answer 9

No some can be non-enveloped

Question 10

What is the envelop made of?

Answer 10

A phospholipid bilayer, proteins and crabohydrates

Question 11

What is the envelop’s function?

Answer 11

Protection

Question 12

What are a viruses spikes made from?

Answer 12

Protein and carbohydrates

Question 13

What are the types of spikes?

Answer 13

Hemagglutination spike (HA)
Neuraminidase spike (NA)

Question 14

What shape is a Hemagglutination spike?

Answer 14

Cone (triangular)

Question 15

What shape is a Neuraminidase spike?

Answer 15

Bulb (circular)

Question 16

What is the function of HA spikes?

Answer 16

Kills blood cells and penetrate the cell
-Can also be used to recognise the virus

Question 17

What is the function of NA spikes?

Answer 17

Separate the virion from the host cell after infection

Question 18

What part of the virus do some vaccines target?

Answer 18

The spike protein
e.g; Covid-19 mRNA vaccine

Question 19

What do the letters and numbers in H1N1 mean?

Answer 19

H- Hemagglutionation
N- Neuraminidase
The numbers represent how many mutations each protein spike has undergone

Question 20

What happens to a virus the more it mutates?

Answer 20

It gets more infectious

Question 21

What does HIV stand for?

Answer 21

Human Immunodeficiency Virus

Question 22

What does HIV target?

Answer 22

T- helper cells and CD4 receptors

Question 23

What genome does an HIV virion have?

Answer 23

RNA
-Single stranded

Question 24

What does an HIV virion have?

Answer 24

Genome
Capsid
Envelope
Glycoprotein spike

Question 25

What kind of virus is HIV?

Answer 25

Retrovirus

Question 26

What is a retrovirus?

Answer 26

A virus with Enzyme Reverse Transcriptase

Question 27

What does enzyme reverse transcriptase do?

Answer 27

Typically during transcription DNA is copied to RNA, this enzyme reverses this process and converts RNA to single stranded DNA. SS DNA is recopied using the enzyme to become DS DNA and becomes a parasite

Question 28

What is the viral double stranded DNA called? | (That is inserted into the huam DNA)

Answer 28

Provirus stage of infection

Question 29

What is a provirus capable of producing?

Answer 29

New viral particles | (Virions)

Question 30

What is the name of the provirus stage when it is in hiding?

Answer 30

Latent stage -When it emerges the cycle continues

Question 31

What is the end stage of HIV?

Answer 31

AIDS

Question 32

What is Kaposi's sarcoma?

Answer 32

Cancerous tumours caused by T-helper cells turned into cancer cells by HIV/AIDS

Question 33

What are the stages of AIDS created by CDC?

Answer 33

Stage A Stage B Stage C

Question 34

What is Stage A?

Answer 34

-T-helper cell count falls to 500/mm3 -leads to Lymphademopathy (swollen lymph nodes)

Question 35

What is the normal T helper cell count in a healthy person?

Answer 35

1500-3000/mm3 -1000 or higher

Question 36

What is Stage B?

Answer 36

T-helper cell count is 200-499/mm3

Question 37

What is Stage C?

Answer 37

Less than 200 t-helper cells

Question 38

What does Stage C signify?

Answer 38

Clinical AIDS

Question 39

How is AIDS transmitted?

Answer 39

mostly Blood and semen also vaginal secretions, breast milk and Saliva

Question 40

How many AIDS virions are transmitted through blood?

Answer 40

1000-10000 virions IP/mm3

Question 41

How many AIDS virions are transmitted through semen?

Answer 41

10-1000 virions IP/mL

Question 42

How many AIDS virions are transmitted through saliva?

Answer 42

1 IP/mL -Very rare source

Question 43

What therapy treats AIDS?

Answer 43

Highly Anti Retroviral Therapy

Question 44

What are examples of Antiretroviral drugs (NRTI's) used to treat AIDS?

Answer 44

1. Zidovudine® (AZT) 2. Lamivudine ® (3-TC)

Question 45

Why is it difficult to develop a vaccine for AIDS/HIV?

Answer 45

It is highly mutated and most patients have multiple strains when infected

Question 46

What are Cytopathic effects?

Answer 46

Consequences of viral infections

Question 47

What are 4 main types of Cytopathic effects?

Answer 47

1. Lytic/Acute infection 2. Persistent infection 3. Latent infection 4. Cancer

Question 48

What is a Lytic/Acute infection?

Answer 48

Causes lysis of cells e.g Cold virus, Influenza

Question 49

What is a persistent infection?

Answer 49

Infection for months-years until death -No virus cell death, it remains in host e.g, Measles, SSPE (neurological degeneration --> death)

Question 50

What is a Latent infection?

Answer 50

Virus hides in cells and then emerges - happens over years or months e.g Herpes-1 aka Cold sores Herpes-3 aka Shingles Herpes-4 aka Mono

Question 51

Example of a virus turning a host cell to cancer?

Answer 51

EB virus (Herpes-4) converts cells in jaw into a tumour called Burkitt's lymphoma -Targets B cells -Leads to nasopharyngeal cancer