Viral & Prion Proteins

Question 1

What are herpes viruses?

Answer 1

Double stranded enveloped DNA viruses (herpes simplex 1 &2, varicella, Epstein Barr, CMV, Human Herpes 6A & B and 7 and 8.
- characterised by ability to establish latency and reactivate.

Question 2

What do HSV-1 and HSV-2 cause?

Answer 2

HSV- 1 ‘cold sores’ and 2 ‘genital herpes’.
via direct skin, genital or eye contact tw/ vesicle fluid from HSV lesions can cause..
1. ulcers (both)
2. encephalitis (HSV-1)
3. Meningitis (HSV-2)
4. Neonatal herpes - vertical transmission via mother’s genital tract

Question 3

What does herpes virus - Varicella Zoster Virus cause?

Answer 3

Primary infection - chicken pox, reactivation = herpes zoster/shingles

Question 4

How does varicella virus spread?

Answer 4

Respiratory droplets of vesicle fluid from infected person, after primary infection latency established in dorsal root ganglion.

Question 5

What is chicken pox?

Answer 5

febrile illness with widespread vesicular rash. Usually uncomplicated but sometimes can cause pneumonitis (esp adults), encephalitis, acute cerebellar ataxia

Question 6

What are shingles/herpes zoster?

Answer 6

reactivation causing unialteral vesicles in a dermatomal dsitribution.

Question 7

What is Epstein Barr/Glandular Fever/ Infectious Mononucleosis?

Answer 7

Virus spread by saliva and genital secretions. Causes - sore throat, fever, lymphadenopathy, hepatosplenomegaly.
Atypical lymphocytes in blood film - look like monocytes therefore mononucleosis.

Question 8

What is cytomegalovirus?

Answer 8

CMV spread via saliva/gential secretions or donated organs. Causes infective mononucleosis primarily.

• Congenital infection = in mothers with virus babies can have retinitis, deafness, microcephaly.
• In immunosuppressed transplant patients
• In patients with HIV/AIDS reactivation of latent CMV can cause retinitis or colitis.

Question 9

What is rhinovirus?

Answer 9

‘common cold’ - aerosolised respiratory secretions.

Question 10

What is influenza?

Answer 10

Resp virus - can spread b/w species. A, B and C.

• Influenza A mutates regularly.
• viral surface proteins H & N have multiple variants.

Question 11

What S and S in primary influenza illness?

Answer 11

fever, myalgia, headache, cough, nasal discharge, sore throat.

Question 12

What S & S in Post-influenza secondary bacterial lung infection?

Answer 12

with S. pneumonia, H. influenzae, S. aureus.

Question 13

What respiratory syncytial virus?

Answer 13

RSV occurs in winter, aerolised transmission of rest secretions.

• commonest in young children.
• can cause BRONCHIOLITIS in children under 2yrs. -> Inflammation of bronchioles cause cough, wheeze, hypoxia, fever.

Question 14

When does AIDS results from HIV?

Answer 14

When virus load increases and T lymphocyte (CD4) cells fall. AIDS defining illnesses = TB, pneumocystis, pneumonia

Question 15

How are hepatitis A and E spread and what are symptoms?

Answer 15

faeco-orally & nausea, myalgia, arthralgia, fevers, juandice, URQ pain

Question 16

How are hepatitis B and C spread?

Answer 16

blood-borne. (Hep D = defective virus & can only survive with B).

Question 17

What is the epidemiology of hepatitis A?

Answer 17

developing world (Europe), mostly children, lower socioeconomic groups

Question 18

What is epidemiology of Hepatitis E?

Answer 18

Asia, Africa- associated with contaminated water. In developed countries w/ pigs & undercooked meat. Fulminant hepatitis in pregnant women.

Question 19

How is Hep B transmitted?

Answer 19

vertically, sexually, parenterally. Most asymoptomatic but can become chronic and develop -> cirrhosis -> hepatocellular carcinoma.

Question 20

How is Hep C transmitted?

Answer 20

IVDU, transfusion (sexually less common). 85% chrohic and then -> c -> hc c

Question 21

What is Norwalk/norovirus?

Answer 21

ssRNA virus - common w/ short-lived immunity, esp. in point-source outbreaks e.g. hospitals.

• caused by ingestion/inhalation of vomit particles.
• vomiting dominant feature

Question 22

What is Rotavirus?

Answer 22

dsRNA virus esp in childhood. Seasonal (winter).

• faced-orally spread, via contaminated food, aerosolised faeces.
• Symptoms = fever, vomiting and watery diarrhoea.

Question 23

What are enteroviruses?

Answer 23

Polio, Coxsackie A and B, enterovirus and echovirus.
Epi = mostly in summer, most under 15Y
Spread & Path- faec-orally, don’t cause GI symptoms -> LN -> viraemia
Syndromes to all = fever-rash in children, meningitis, encephalitis, severe disseminated diseases in neonate
Specific syndromes = Herpangina (mouth blisters) => Coxsackie A. Pericarditis => Coxsackie B.

Question 24

What is parvovirus?

Answer 24

‘slapped cheek syndrome’
- respiratory droplet transmission
- infects erythrocyte progenitor cells causing transient anaemia
Clinical Syndromes Associated:
1. Erythema Infectious = fever, fiery rash on cheeks.
2. Transient aplastic crisis = (affects those w/ high RBC turnover) e.g. sickle cell causes dyspnoea, confusion, cardiac failure,
3. Infection in pregnancy - fetal loss can occur, can develop hydrous fetalis - severe foetal anaemia, oedema, ascites, heart failure.

Question 25

What is a prion?

Answer 25

small infectious pathogen containing protein but no nucleic acid.

• resistant to protease if gene mutation leads to misfolding
• accumulate in cell and can cause spongiform change
• inherited or consumed
  e. g. Sporadic Creutzfeld-Jackob disease = rare, gene mutation, progressive ataxia & depression then death
  e. g. nvCJD linked to BSE (bovine, spongiform encephalopathy) same structure as prion.