Principles of Infection II

Question 1

What is the cell structure of the herpes simplex virus?

Answer 1

• virus has an envelope
• 120 to 300 nm
• nucleocapsid inside evenloped structure
• tegument between nucleocapsid + envelope
• virus has DNA

Question 2

What is the name of the family of DNA viruses responsible for herpes infections?

Answer 2

Herpesviridae

Question 3

How is herpes simplex virus type 1 transmitted?

Answer 3

Contact transmittion - from person to person, by sharing objects or even oral sex.

Question 4

How is herpes simplex virus type 2 transmitted?

Answer 4

Transmitted by skin contact - usually sexually transmitted

Question 5

What does more sexual partners suggest?

Answer 5

More likely to have antibodies to HSV2, but having a single sexual partner doesn’t mean you will not be infected.

Question 6

When infected, do you ever clear the virus - what happens?

Answer 6

No, you have periods of latency - virus replication stops and then reactivation - release of latent virus.

Question 7

What is the common figure for reccurences of the herpes virus?

Answer 7

1-5 per annum, some never have them, some have them frequently

Question 8

Which virus causes chickenpox?

Answer 8

Varicella Zoster virus

Question 9

Which virus causes glandular fever and how is it transmitted?

Answer 9

Epstein Barr virus - transmitted via saliva (kissing disease!)

Question 10

What is the cellular structure of adenovirus, it’s transmission and impact?

Answer 10

• no envelope - dna virus
• transmitted via contact
• has different ‘serotypes’ -> causes eye/resp/GI infection

Question 11

What is the cellular structure of papillomavirus, it’s transmission and impact?

Answer 11

• no envelope - DNA genome
• horizontal (human to human) - sex involved
• causes warts + cervical cancer

Question 12

What is the structure of HIV?

Answer 12

• enveloped
• RNA virus

Question 13

What is the structure of rotavirus and its cause?

Answer 13

• non enveloped
• small
• causes diarrhoea

Question 14

Which viruses are transmitted horizontally (human to human)?

Answer 14

• measles
• mumps
• adenovirus
• influenza
• ebola

Question 15

What are some early symptoms of ebola infection?

Answer 15

• take 2-21 days to show
• fever
• headache
• diarrhoea
• vomiting, stomach/muscle pain
• unexplained bleeding + bruising

Question 16

What is the structure of ebola virus?

Answer 16

• RNA virus
• enveloped

Question 17

What is the pathophysiology of ebola (how it enters/impacts) and how is it transmitted?

Answer 17

• enters through mucuous membranes, breaks in skin, parenterally
• infects many cell types
• migrates from initial site to lymph nodes -> liver, spleen, adrenal
• tissue necrosis + organ failure
• inflammation
• transmitted by direct contact with body fluids + contaminated objects (person to person)

Question 18

How is rubella transmitted?

Answer 18

vertical (mother to foetus) mainly

Question 19

Which diseases can be transmitted by insect bites and animal bites?

Answer 19

Insect bites: haemorrhagic fevers, yellow fever

animal bites: rabies

Question 20

What are some clinical factors of diagnosing infection?

Answer 20

• patient symptoms
• duration of symptoms
• have there been contacts with sources of infection
• what is circulating in the population
• location
• lifestyle
• other risk factors

Question 21

What antibodies are looked for in an immunoassay?

Answer 21

IgM - recent infection

IgG - past infection

Question 22

Describe the method of culturing virus in cells

Answer 22

Human viruses need human cells to grow - takes 2-3 days, use light microscopy for cytopathic effect.

Question 23

What is a quicker alternative with culturing virus in cells?

Answer 23

Look for viral proteins in cell cultures:
- use immunofluorescence labelling method

• use antibody directed against viral proteins
• label antibody with immunofluorescence tag
• you can see viral proteins

Question 24

Describe the method of looking for RNA/DNA in the blood and how it can be amplified

Answer 24

• difficult to detect RNA/DNA as not enough in sample
• use PCR to amplify nucleic acid
• run it on a gel and see amplified product as a band