Molecular and Microbiome/Metagenome Correlates of Recurrent Wheeze in RSV Infected Infants

Respiratory syncytial virus (RSV) causes yearly epidemics of respiratory infection with a significant burden of disease in those at the extremes of age. Infants with RSV infection develop a range of illness from mild or in apparent upper respiratory infections to severe lower respiratory disease with wheezing and/or pneumonia. RSV infection is the most common cause of hospitalization in infants in the US.

The great majority (85%) of hospitalized infants are diagnosed with bronchiolitis and 78% are noted to have wheezing. RSV infection leads to even greater outpatient utilization of medical care including Emergency Department visits (39-69 per 1000 under 6 months and 45-68 per 1000 from 6-11 months) and visits to pediatricians (108-157/1000 under 6 months and 160-194 per 1000 from 6-11 months).

Following primary RSV infection several epidemiological observations have identified an increased frequency of recurrent wheezing in 34 to 56% of infants.

The objectives of this study include:

Primary Objective: To test whether clinical factors, airway gene expression and microbiome/metagenome patterns in the nasal epithelium at the time of primary RSV infection can predict/classify infants with recurrent wheezing.

Secondary Objective 1: To identify airway gene expression and microbiome/metagenome correlates of primary RSV infection that may inform pathogenic mechanisms associated with recurrent wheeze.

Hypotheses

Primary Hypothesis: Infants with recurrent wheeze following primary RSV infection will have a defined set of clinical, airway gene expression and/or airway microbiome/metagenome characteristics associated with a post bronchial wheezing phenotype.

Secondary Hypothesis 1: Respiratory epithelial innate immune responses to primary RSV infection, and their interaction with microbiome composition and functional processes, will identify biological mechanisms contributing to post bronchial wheeze.

This is a single center, prospective, case-control observational study. Full term (>36 and 0/7 gestation) infants born after the prior RSV season of the prior year with primary RSV infection and no prior episodes of wheezing will be enrolled during their first RSV season from both outpatient and inpatient locations in Rochester New York. During the subsequent seasons of enrollment infants will meet the above eligibility requirements and also be tested and negative for acute infection with Severe Acute Respiratory Syndrome-Coronavirus-2.100 infants total with RSV infection will be enrolled with approximately 50 from the hospital and 50 from the Emergency Department (ED) or outpatient clinic in order to enroll infants with a range of severity, but with a focus on those presenting for medical care due to symptoms. Active surveillance for subsequent wheezing episodes will be conducted by phone/text/email follow-up every two weeks over the subsequent year, including a second full winter season for all subjects, beginning six weeks after the index illness. At the first report of subsequent wheezing a research clinic or home visit will be conducted to confirm the presence of wheezing by a trained staff member. Recurrent wheeze will be defined by two separate episodes of wheezing separated by at least 14 days with the first episode confirmed by study staff. In addition to this active surveillance, caregiver's will be asked to sign a medical records release for their child at the first visit that will cover the period of participation in the study. At the end of the study we will review each subject's medical records to determine if the child has had wheezing documented by a medical provider and not reported by the family. Once recurrent wheeze has been confirmed the subject will have reached an endpoint. At the end of the follow-up period the clinical and biological characteristics of participants with recurrent wheeze and those without recurrent wheeze will be compared.