L08: Intorduction Of Viruses

Question 1

What scheme is used to classify viruses

Answer 1

Baltimore scheme

Question 2

What does the baltimore scheme classify viruses depending on

Answer 2

Rna or dna
Double strand or single strand
Is there a reverse transcriptase
Sense (like mRNA) or antisense

Question 3

How many groups are there in the Baltimore scheme

Answer 3

7

Question 4

What is group 1

Answer 4

Double stranded DNA

Question 5

What is group 2

Answer 5

Single stranded DNA

Question 6

What is group 3

Answer 6

Double stranded rna

Question 7

What is group 4

Answer 7

Sense RNA

Question 8

What is group 5

Answer 8

Antisense RNA

Question 9

What is group 6

Answer 9

RNA reverse transcribing

Question 10

What is group 7

Answer 10

DNA reverse transcribing

Question 11

Describe the viral life cycle

Answer 11

1) virus glycoproteins interact with the cells surface receptor
2) this enables receptor mediated endocytoses so virus enters cytoplasm
3) virus capsid with genetic material is transported to the cells nucleus
4) nucleic acids become, transcribed, transplanted, replication.
5) envelopment of genome
5) new protein/virus becomes assembled and released out of the cell.

Question 12

Why is it important to know every stage of virus replication

Answer 12

So we can target it by drugs against them

Question 13

What are drug target for viruses

Answer 13

Virion uncoating 
DNA polymerase
Reverse transcriptase
Viral protease
Viral neuraminidase
Inositol monophospahte dehydrogenase

Question 14

What are the most clinically important viruses

Answer 14

Influenza virus
Hepatitis b and c
HIV
Herpes virus

Question 15

What are the features of influenza

Answer 15

Enveloped
With glycoproteins of haemaglutinin and neuraminidase
Single RNA genome

Question 16

What are the 3 types of influenza that infect humans

Answer 16

Influenza a: cause pandemic
Influenza b: cause seasonal epidemics
Influenza c: cause mild respiratory illness

Question 17

What is influenza virus divided into subtypes depending on

Answer 17

Haemoglutinin or neuraminidase

Question 18

What receptor does the haemagglutinin interact with in the airway epithelium

Answer 18

Alpha 2,6 Sialic acid

Question 19

Why does influenza of haemaglutinin give repeated infections

Answer 19

Neutralising antibodies that stop haemooglutinin from binding to alpha 2,6 sialic acid stops working due to antigenic variation

Question 20

What are the 2 types of antigenic variations

Answer 20

Antigenic shift

Antigenic drift

Question 21

What is an antigenic drift

Answer 21

1) Small changes in the genes of influenza that happen continuously
2) the viruses accumulate overtime and generate proteins that have haemolgutinin mutated so neutralising antibodies do not recognise it
3) influenza therefore enters cells.

Question 22

Why do mutations of virus genes occurs

Answer 22

Rna viruses have to replicate its RNA genome by RNA polymerase which lacks proofreading compared to DNA polymerase so they have greater mutations.

Question 23

What is antigenic shift

Answer 23

This is not about mutation
A cell with 2 different viruses have there virus segments completely swapped
This results in a new virus.

Question 24

How can antigenic shifts occur

Answer 24

Virus from birds get into pigs

Human influenza gets into pigs

Question 25

What does antigenic shift cause

Answer 25

Pandemic

Question 26

Which type influenza has antigenic shift occurs

Answer 26

Only in influenza a

Question 27

What are the features of hepatitis b

Answer 27

Enveloped DNA Glycoproteins E antigen expressed when the virus is replicating itself

Question 28

How can hep b be transmitted

Answer 28

``` Perinatal transfusion Blood to blood Needle stick injury Sexual Medical instruments ```

Question 29

Is hep b acute or chronic infections

Answer 29

Can start as acute but develop into chronic

Question 30

How would you test for hep b

Answer 30

Test for antibodies

Question 31

What will you see in an acute hep b infection in a test

Answer 31

HBe antigen during first exposure of virus | IgM antibodies after hep b exposure

Question 32

What will you detect in chronic hep b infection

Answer 32

DNA | Hep b antigen hbe antigen

Question 33

What is the features of hepatitis c

Answer 33

Enveloped Single stranded RNA Glycoproteins 1 and 2

Question 34

How is hepatitis c transmitted

Answer 34

Blood borne e.g sharing injection equipment

Question 35

Is hepatitis c infection acute or chronic

Answer 35

Starts as acute then can become chronic

Question 36

How would you test for hepatitis c

Answer 36

Antibody testing to see if you have the infection before | If antibody test is positive you carry out viral nuclei acid test to tell you if you have a current infection

Question 37

What does the test results show if you have had hep c but no current infection

Answer 37

Antibody positive | Rna negative

Question 38

What would show if there is an acute infection

Answer 38

Antibody postive | Rna postive

Question 39

Why do we get point mutation occuring for hepatitis c

Answer 39

Hepatitis c is a RNA virus so rna polymerase does not proofread which leads to point mutations

Question 40

What does treatment to chronic hepatitis c depend on

Answer 40

Treatment depepends on genotype of hepatitis b

Question 41

What is the structure of HIV

Answer 41

Enveloped Rna single stranded Glycoproteins : GP41 and GP120

Question 42

Which immunity cells does HIV infect

Answer 42

CD4+ T cells | Macrophages

Question 43

What are the subtypes of HIV

Answer 43

HIV-1 | HIV-2

Question 44

Does HIV involve acute or chronic infection

Answer 44

Chronic infection

Question 45

Why do people with HIV get chronically infected

Answer 45

HIV replicated of low levels for decades | Virus loads increase as CD4+ T cell count drops

Question 46

What happens when the person with HIV has a CD4+ T cell count below 200cell per mom

Answer 46

Person is diagnosed with AIDS

Question 47

What is the maximal survival with someone with aids

Answer 47

3 years

Question 48

Why is the maximum survival really low for AIDS

Answer 48

The person does not have immunity so they a prone to infections

Question 49

Which infections are opportunistic in AIDS

Answer 49

``` Cryptococcal meningitis Toxoplasmosis Pneumocystis pneumonia Oesophageal candidiasis Certain cancers ```

Question 50

How doe we test for HIV in the lab

Answer 50

HIV antibody test If postive for antibody: nucliec acid test (measures virus load) Antigen/antibody test: measures P24 antigen which is a marker of active virus replication

Question 51

If HIV is an RNA virus what does this mean in terms of mutations

Answer 51

It is prone to mutations due to RNA polymerase not proofreading

Question 52

What is the structure of herpes virus

Answer 52

Enveloped Linear double stranded DNA Glycoproteins Has proteins inside which activate innate immunity

Question 53

What are the 2 subtypes of herpes virus

Answer 53

HSV-1 | HSV-2

Question 54

What can HSV-1 cause

Answer 54

Stomatitis

Question 55

What is stomatitis

Answer 55

Inflammation of mouth and lips

Question 56

Why do you get stomatitis in HSV-1

Answer 56

Replication occurs in the mucoepithelial cells

Question 57

What type of infection does herpes present with during later on in life

Answer 57

Latent infection

Question 58

How does latency occur in herpes virus

Answer 58

Virus turns off its genes so the infected cells become immunologically silent Reactivation of the virus can occur Hsv1-/2 invade sensory neurones and establish latency in ganglia

Question 59

If the virus invades the CNS what can this result in

Answer 59

Meningitis

Question 60

What does varicella zoster virus cause

Answer 60

Chicken pox and shingles

Question 61

Who gets chickenpox

Answer 61

Children

Question 62

Who gets shingles

Answer 62

Elderly

Question 63

What type of infection is shingles

Answer 63

Latent infection