Lecture 3 - Viral Pathogenesis Flashcards Preview

MIIM20002 - Microbes, Infections, Responses > Lecture 3 - Viral Pathogenesis > Flashcards

Flashcards in Lecture 3 - Viral Pathogenesis Deck (33):
1

What are some important features of viruses?

- non living
- rely on a host cell to replicate
- non-motile
- no metabolism
- obligate parasites

2

Which two technologies allow us to visualise viruses?

X ray
Electron microscope

3

What are the two forms of capsid symmetry?

Helical symmetry
Icosahedral

4

Which viruses types have envelopes?

Helically symmetrical viruses

Some icosahedral viruses

5

What are the subunits of the capsid called?

Capsomeres

6

What is the symmetry of influenza virus?

Helical

7

What is the symmetry of adenoviruses?

Icosahedral

8

What is the symmetry of mumps?

Helical

9

What is the symmetry of herpes virus?

Icosahedral

10

What is the symmetry of papillomavirus?

Icosahedral

11

What is the symmetry of poxviruses?

Complex symmetry

12

All helically symmetrical viruses have a ... genome

RNA

13

Describe how viruses gain access to cells

1. Molecules (RECEPTOR BINDING PROTEIN) on the surface of the virus binds to the host's receptor
2. RME or / fusion of envelope with host cell

14

What determines the tropisms of viruses for cells, tissues, species etc.

1. Receptor Binding Proteins
2. Enzymes released by host cells (think Tryptase clara)
3. Temperature
4. Ability to get 'free ride' by replicating inside certain cells

15

What happens once the virus has penetrated the host cell?

Uncoating of the capsid to reveal the genome

16

What are the ways that a virus can leave the host cell?

1/ LYSIS: Non-enveloped: build up, lyse the cell

2/ EXOCYTOSIS: enveloped viruses, from plasma membrane / golgi

17

Which is the most common route of entry into the human body for viruses?

Mucosal epithelium

18

What are the defence mechanisms of the respiratory tracts?

Mucous
Ciliated elevator in the trachea
Tears
Alveolar macrophages
Surfactant

19

Which viruses infect the respiratory tract and remain localised?

Rhinovirus
RSV
Influenza

20

Which viruses invade via the respiratory tract and then invade further?

Measles
Mumps
Rubella

21

How does Herpes invade?
To where does it then spread?

Via the oro-pharynx
It remains localised

22

How does Rotavirus invade?
To where does it then spread?

Invades via the oro-pharynx
Then goes further --> enteritis

23

How does HIV invade?

Rectal route

24

What are the defences of the alimentary tract?

Mucous
Acid and Bile

25

Describe the pathogenesis of mumps

1. Entry via respiratory tract
2. Primary colonisation of cells of the URT
3. Systemic infection of many organs (Sialic acid receptor)
4. Mild meningitis (common)
5. Encephalitis (uncommon)
6. Salivary gland involvement

26

What is the receptor that mumps virus uses to spread to many organs all over the body?

Sialic acid

27

What does optimal temperature of replication affect?

The spread of the virus

eg. Rhinovirus needs a slightly cooler temperature, thus it remains localised in the nose

28

How do viruses usually access the blood?

Via lymph nodes

29

Why is the blood hostile for viruses?

- Inhibitors
- Antibodies
- Phagocytes

30

What is it called when there is virus in the blood?

Viremia

31

What is the difference between primary and secondary viremia?

Primary: low numbers, before amplification in the liver and spleen

Secondary: high numbers, after replication

32

What are some examples of viruses that spread round the body via the nervous system?

Rabies

Poliovirus:
- not part of its normal pathogenesis, however

Varicella zoster

33

Describe the pathogenesis of varicella zoster

1. Infection of conjuntiva
2. Primary virema
3. Amplification
4. Secondary viremia
5. Infection of skin, vesicular rash
6. Migration of the virus up the regional dorsal root ganglion
7. Latency period
8. Immuno-suppression --> Shingles