Single-cell immune profiling reveals markers of emergency myelopoiesis that distinguish severe from mild respiratory syncytial virus (RSV) disease in infants

While the majority of infants infected with respiratory syncytial virus (RSV) exhibit mild or no symptoms, approximately 3 million children under the age of five are hospitalized every year due to complications from RSV. This research sought to explore the biological processes and related biomarkers responsible for the varied manifestations of RSV disease in young infants. The goal is to pave the way for a more precise categorization of RSV-infected infants based on their medical requirements. Whole blood samples are collected from infant case-control cohort study, the RESCEU case-control cohort is a multinational, multicenter, observational study (clinical trial registration number: NCT03756766). Infants < 12 months old with RSV disease were recruited from the University Medical Center Utrecht (UMCU) in The Netherlands, Hospital Clínico Universitario de Santiago (SERGAS) in Spain, Imperial College (IMPERIAL) National Health Service Trust (NHS) and Oxford University Hospital NHS Trust (OXFORD) in the United Kingdom during the RSV seasons 2017-2018, 2018-2019, and 2019-2020. Healthy controls without underlying comorbidities were recruited outside of the RSV season. Eligibility criteria included hospitalization for less than 48 hours at enrolment or within 96 hours of disease onset, no previous receipt of medications to treat RSV infection, no prior exposure to an investigational RSV vaccine or medication, no previous receipt of immunoglobulins or monoclonal antibodies, and had not used montelukast or oral steroids within seven days before enrolment. Infants with co-morbidities were not evaluated in the manuscript. RSV was detected using RSV point-of-care test (POCT) by either a rapid antigen detection test (Alere I) (Alere Inc, Waltham, Massachusetts) or rapid RSV polymerase chain reaction (PCR) test at the hospital setting, or a RSV PCR test at the laboratory. Convalescence samples were collected 7 ±1 weeks after a positive RSV diagnostic test result. We used microarray to assist us to identify biomarkers for severe RSV disease. Healthy infants and infants with mild (RSV-infected, non-hospitalized), moderate (RSV-infected, hospitalized without mechanical ventilation), and severe (RSV-infected, hospitalized with mechanical ventilation) RSV disease were recruited during the acute RSV infection and at convalescence. Whole blood samples were analysed using Clariom GOScreen human assay in 384 well plate format. Infants with comorbidities excluded from the downstream comparative analyses. The clinical data necessary for batch correction (site of sample collection) is accessible by request only from the submitting party.