Exacerbation of Asthma

Question 1

What is the main aetiology of asthma exacerbations and what is the most common species?

Answer 1

Viral infection

Rhinovirus (62%) Edwards et al 2012

Question 2

Rhinovirus causes _____ _____ and _____. It is a _____ stranded, _____-sense Picornavirus (~6-7kB). Rhinovirus is a key exacerbator of asthma

Answer 2

Rhinovirus causes common colds and wheeze. It is a single stranded, positive-sense Picornavirus (~6-7kB). Rhinovirus is a key exacerbator of asthma

Question 4

Briefly outline the mechanism by which diversity is achieved in Rhinovirus

Answer 4

1. Mutations
   
   1. Polymerase is inaccurate
2. Genetic Recombination

Question 6

How can rhinovirus be divided into subgroups

Answer 6

1. By receptor
   
   1. Major = ICAM-1
   2. Minor = LDL receptor
2. By RNA sequence
   
   1. RV-A
   2. RV-B
   3. RV-C -> thought to be more pathogenic

Question 8

Corne et al Lancet 2002 Observed spouse pairs (one atopic and one non-atopic asthmatics). They performed regular nasal sampling (every 2 wks for over 3 mths and daily diary cards) and PCR for rhinoviruses. They found:

1. ↔incidence of infection between A and NA
2. LRT symptoms and falls in PEF more severe and prolonged in A

Describe some reasons as to why A suffered more.

Answer 8

1. IFN-β and IFN-λ deficiency in A tissues (~20 studies)
2. A have ↑Rhinovirus replication
3. A have ↓infected-cell apoptosis

Studies have shown the above and that the pro-inflammatory cytokines are being produced normally.