Peak expiratory flow changes during experimental rhinovirus infection.

Area of Science:

• Respiratory Medicine
• Virology
• Immunology

Background:

• Rhinovirus (RV) infections are known triggers for asthma exacerbations.
• Experimental RV infections are used to study these mechanisms.
• A direct temporal link between experimental RV infection and reduced lung function (PEF) has not been established.

Purpose of the Study:

• To demonstrate a temporal association between experimental rhinovirus infection and decreases in peak expiratory flow (PEF).
• To investigate respiratory morbidity following experimental RV infection in normal, atopic, and atopic asthmatic subjects.
• To validate experimental RV infection as a model for studying RV-associated airway symptoms and asthma.

Main Methods:

• 22 volunteers (normal, atopic, atopic asthmatic) were inoculated with RV serotype 16.
• Peak expiratory flow (PEF) was measured twice daily for 2 weeks pre-infection and 6 weeks post-infection.
• Respiratory morbidity was defined by validated criteria based on PEF changes; viral load and immune response (seroconversion) were also assessed.

Main Results:

• Six significant PEF reductions temporally correlated with RV infection occurred 4-9 days post-inoculation (p=0.1).
• Subjects with PEF reduction showed lower mean PEF (87.8% predicted) and higher symptom scores on day 6 (p=0.01 and p=0.03, respectively).
• Higher RV seroconversion was observed in subjects with reduced PEF (p=0.02), suggesting a link to the host response.

Conclusions:

• Experimental rhinovirus infection can induce temporal respiratory morbidity, evidenced by PEF reduction, in a subset of normal and asthmatic individuals.
• The study supports the use of experimental RV colds as a valid model for investigating rhinovirus-associated airway symptoms and asthma exacerbations.
• Individual variability in response highlights the complexity of rhinovirus-induced respiratory illness.