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Abstract Rationale Aeroallergen sensitization and virus-induced wheezing are risk factors for asthma development during early childhood, but the temporal developmental sequence between them is incompletely understood. Objective To define the developmental relationship between aeroallergen sensitization and virus-induced wheezing. Methods A total of 285 children at high risk for allergic disease and asthma were followed prospectively from birth. The timing and etiology of viral respiratory wheezing illnesses were determined, and aeroallergen sensitization was assessed annually for the first 6 years of life. The relationships between these events were assessed using a longitudinal multistate Markov model. Measurements and Main Results Children who were sensitized to aeroallergens had greater risk of developing viral wheeze than nonsensitized children (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.2–3.1). Allergic sensitization led to an increased risk of wheezing illnesses caused by human rhinovirus (HRV) but not respiratory syncytial virus. The absolute risk of sensitized children developing viral wheeze was greatest at 1 year of age; however, the relative risk was consistently increased at every age assessed. In contrast, viral wheeze did not lead to increased risk of subsequent allergic sensitization (HR, 0.76; 95% CI, 0.50–1.1). Conclusions Prospective, repeated characterization of a birth cohort demonstrated that allergic sensitization precedes HRV wheezing and that the converse is not true. This sequential relationship and the plausible mechanisms by which allergic sensitization can lead to more severe HRV-induced lower respiratory illnesses support a causal role for allergic sensitization in this developmental pathway. Therefore, therapeutics aimed at preventing allergic sensitization may modify virus-induced wheezing and the development of asthma.

Abstract Rationale Virus-induced wheezing episodes in infancy often precede the development of asthma. Whether infections with specific viral pathogens confer differential future asthma risk is incompletely understood. Objectives To define the relationship between specific viral illnesses and early childhood asthma development. Methods A total of 259 children were followed prospectively from birth to 6 years of age. The etiology and timing of specific viral wheezing respiratory illnesses during early childhood were assessed using nasal lavage, culture, and multiplex reverse transcriptase–polymerase chain reaction. The relationships of these virus-specific wheezing illnesses and other risk factors to the development of asthma were analyzed. Measurements and Main Results Viral etiologies were identified in 90% of wheezing illnesses. From birth to age 3 years, wheezing with respiratory syncytial virus (RSV) (odds ratio [OR], 2.6), rhinovirus (RV) (OR, 9.8), or both RV and RSV (OR, 10) was associated with increased asthma risk at age 6 years. In Year 1, both RV wheezing (OR, 2.8) and aeroallergen sensitization (OR, 3.6) independently increased asthma risk at age 6 years. By age 3 years, wheezing with RV (OR, 25.6) was more strongly associated with asthma at age 6 years than aeroallergen sensitization (OR, 3.4). Nearly 90% (26 of 30) of children who wheezed with RV in Year 3 had asthma at 6 years of age. Conclusions Among outpatient viral wheezing illnesses in infancy and early childhood, those caused by RV infections are the most significant predictors of the subsequent development of asthma at age 6 years in a high-risk birth cohort.

Abstract Daycare attendance and siblings are associated with viral-induced wheezing in children. Preexisting immunologic factors may influence the expression of viral infections in infancy, and in turn, recurrent infections may influence the development of immune responses. A total of 285 children were enrolled in the Childhood Origins of Asthma Project at birth and followed for at least 1 year. Cord blood and 1-year mononuclear cells were stimulated with phytohemagglutinin, and cytokine-response profiles were measured by enzyme-linked immunosorbent assay. Nasal lavage was performed for moderate to severe respiratory illnesses. Daycare attendance and/or siblings significantly increased the likelihood of contracting respiratory syncytial virus (1.5–1.6-fold increase) and rhinovirus (1.8–2.1-fold increase), and increased the risk of rhinovirus-induced wheezing (14–18% vs. 2%, p = 0.011). Cord blood IFN-γ responses were inversely related to the frequency of viral respiratory infections (rs = −0.11, p = 0.05), and more significant for subjects with high exposure to other children (rs = −0.27, p = 0.028). The interval change in infantile IFN-γ responses correlated positively with the frequency of viral infections in infancy (rs = 0.12, p = 0.047). These data suggest that neonatal IFN-γ responses may influence antiviral activity, or may represent a marker of antiviral immunity maturation. Conversely, the frequency of viral infections in infancy can influence IFN-γ responses.

Understanding place-based contributors to health requires geographically and culturally diverse study populations, but sharing location data is a significant challenge to multisite studies. Here, we describe a standardized and reproducible method to perform geospatial analyses for multisite studies. Using census tract-level information, we created software for geocoding and geospatial data linkage that was distributed to a consortium of birth cohorts located throughout the USA. Individual sites performed geospatial linkages and returned tract-level information for 8810 children to a central site for analyses. Our generalizable approach demonstrates the feasibility of geospatial analyses across study sites to promote collaborative translational research.