Comparison of viral load in individuals with and without asthma during infections with rhinovirus

Abstract

Rationale: Most virus-induced attacks of asthma are caused by rhinoviruses (RVs).

Objectives: To determine whether people with asthma are susceptible to an increased viral load during RV infection.

Methods: Seventy-four children (4-18 yr old) were enrolled; 28 with wheezing, 32 with acute rhinitis, and 14 without respiratory tract symptoms. Nasal washes were evaluated using quantitative polymerase chain reaction for RV to judge viral load along with gene sequencing to identify strains of RV. Soluble intercellular adhesion molecule-1, IFN-λ1, and eosinophil cationic protein in nasal washes, along with blood eosinophil counts and total and allergen-specific IgE in sera, were also evaluated. Similar assessments were done in 24 young adults (16 with asthma, 8 without) who participated in an experimental challenge with RV (serotype 16).

Measurements and main results: Fifty-seven percent of wheezing children and 56% with acute rhinitis had nasal washes testing positive for RV. The geometric mean of viral loads by quantitative polymerase chain reaction in washes from wheezing children was 2.8-fold lower, but did not differ significantly from children with rhinitis (7,718 and 21,612 copies of viral RNA per microliter nasal wash, respectively; P = 0.48). The odds for wheezing were increased if children who tested positive for RV were sensitized to one or more allergens (odds ratio, 3.9; P = 0.02). Similarly, neither peak nor cumulative viral loads differed significantly in washes from adults with asthma compared with those without asthma during the experimental RV challenge.

Conclusions: During acute symptoms, children infected with RV enrolled for wheezing or acute rhinitis had similar viral loads in their nasal washes, as did adults with and without asthma infected with RV-16 experimentally.

Figure 1.

Quantitative polymerase chain reaction (qPCR) for rhinovirus (RV) in nasal washes from children with wheezing and acute rhinitis. Geometric mean values and 95% confidence intervals for viral load expressed as copies of viral RNA per microliter of nasal wash were 7,718 (95% confidence interval, 870–68,485) in washes from wheezing children and 21,612 (95% confidence interval, 2,915–160,250) in washes from children with rhinitis. P = 0.48. HEV = human enterovirus; HRVA, HRVB, and HRVC = human rhinovirus types A, B, and C.

Figure 2.

Nasal wash levels of soluble intercellular adhesion molecule-1 (sICAM-1) in children with wheezing and acute rhinitis. sICAM-1 values are shown as solid circles for wheezing children, open circles for children with rhinitis, and solid triangles for children without respiratory tract symptoms. Geometric mean values are noted to the right of the horizontal lines for each group. NEG = negative; POS = positive; RT-PCR = reverse transcriptase polymerase chain reaction.

Figure 3.

Quantitative polymerase chain reaction for rhinovirus in nasal washes from subjects with asthma and control subjects without asthma after inoculation with rhinovirus-16. The geometric mean of quantitative polymerase chain reaction values are indicated by symbols and standard error bars for each day that nasal washes were collected. The number of washes testing positive for virus at each time point for each group is shown beneath the figure.