Respiratory syncytial virus (RSV) is the major cause of hospitalization for bronchiolitis during infancy. RSV infection manifests with a wide clinical spectrum ranging from asymptomatic to severe respiratory illness. Severe RSV infections have been also associated with wheezing-asthma later in life. Thus, understanding the factors predisposing to severe RSV infection are goals of outstanding importance.
RSV typically occurs in specific season and birth cohort studies have shown that the incidence of bronchiolitis varies with age, showing an incidence peak at 3-5 months and relatively low infections at 1-2 months. Currently a clear explanation for this age-related incidence pattern is lacking.
The hypothesis underlying this project is that prenatal exposure to RSV in a specific time window may induce an RSV-specific immune response in the fetus that can confer protection to postnatal RSV severe disease in infants. Accordingly, prenatally exposed (through the mother) newborn babies may show an RSV specific response that differs from newborns not exposed to RSV.
Our main aims will be: 1) to assess maternal RSV infection; 2) to investigate RSV specific response in cord blood mononuclear cells (CBMCs).
Women will be enrolled in the II-III trimesters of pregnancy and tested twice (before and after RSV season) for circulating anti-RSV antibodies (an increase would be indicative of RSV infection) and, in case of respiratory symptoms, for viral infection by PCR on nasopharyngeal swabs. Infants from enrolled women will be classified according to prenatal exposure; their CBMCs will be tested in order to explore infant innate and adaptive immune response to RSV, and to differentiate these responses in relation to prenatal RSV exposure.
The demonstration that a first RSV contact can happen during prenatal life and that this may confer a protective immunity in postnatal life would improve the understanding of RSV severe disease and contribute to prevention strategies.
