A model of viral wheeze in nonasthmatic adults: symptoms and physiology

Episodic wheezing associated with viral infections of the upper respiratory tract (URT) is a common problem in young children but also occurs in adult s. It is hypothesized that an experimental infection with human coronavirus (HCoV), the second most prevalent common cold virus, would cause lower res piratory tract (LRT) changes in adults with a history of viral wheeze. Twenty-four viral wheezers (15 atopic) and 19 controls (seven atopic) were inoculated with HCoV 229E and monitored for the development of symptoms, ch anges in airway physiology and provocative concentration of methacholine ca using a 20% fall in forced expiratory volume in one second (FEV1) (PC20). A t baseline, viral wheezers were similar to controls in PC20 (mean +/- SD lo g(2)PC20: 5.1 +/-1.9 and 5.8 +/-1.4 g.L-1, respectively) but had a lower FE V1 than controls (mean +/- SD 85.8 +/- 11.4 and 95.6 +/- 13.2% predicted, r espectively p < 0.05). Nineteen viral wheezers and I I controls developed c olds. Viral wheezers with colds reported significantly more URT symptoms th an controls (median scores (interquartile range): 24 (10-37) and 6 (4-15), respectively p = 0.014). Sixteen viral wheezers, and no controls reported L RT symptoms (wheeze, chest tightness and shortness of breath). The viral wh eezers; with colds had small (3-4%) reductions in FEV1 and peak expiratory flow on days with LRT symptoms (days 3 - 6), but a progressive reduction in PC20 from baseline on days 2, 4 and 17 after inoculation (by 0.82, 1.35 an d 1.82 doubling concentrations, respectively). The fall in PC20 affected bo th atopic and nonatopic subjects equally. There were no changes in FEV1 or PC20 in controls. An adult model of viral wheeze that is independent of atopy and therefore, of classical atopic asthma was established.