Respiratory Syncytial Virus (RSV)-Specific Antibodies in Pregnant Women and Subsequent Risk of RSV Hospitalization in Young Infants

Background The fusion (F) glycoprotein of respiratory syncytial virus (RSV) represents the major neutralizing antigen, and antibodies against the pre-F conformation have the most potent neutralizing activity. This study aimed to assess the correlation between maternal antibody titers against the pre-F, post-F, and G glycoproteins and the child's risk of developing severe RSV bronchiolitis early in infancy. Methods We identified previously healthy term infants <3 months of age hospitalized with RSV bronchiolitis from December 2015 to March 2016. We measured IgG antibody titers to pre-F, post-F, and G proteins in maternal sera obtained at 9-12 weeks of pregnancy of these hospitalized infants' mothers (n = 94) and compared them with serum antibody titers of control pregnant mothers (n = 130) whose children were not hospitalized. Results All maternal samples (n = 224) had detectable pre-F antibodies. Pre-F antibody titers were significantly lower in mothers whose infants were hospitalized with RSV bronchiolitis compared with those mothers whose infants were not hospitalized (23.9 [range (or antibody titer range), 1.4-273.7] mu g/L vs 30.6 [XXX, 3.4-220.0] mu g/L; P = .0026). There were no significant differences in maternal post-F and G antibody titers between hospitalized and nonhospitalized infants. Conclusions Our findings indicate that maternal pre-F antibodies are fundamental for providing immune protection to the infant. Maternal serum immunoglobulin antibody titers directed to respiratory syncytial virus (RSV) pre-F glycoprotein were lower in infants less than 3 months of age hospitalized with RSV bronchiolitis than in maternal serum samples of age-matched control infants who were not hospitalized.