Abstract 997 Poster Session IV, Tuesday, 5/4 (poster 84)

Healthy infants enrolled soon after birth and their mothers were followed for up to three RSV seasons. Data on their first RSV season is presented. Blood specimens and nasal secretions were collected prior to and after the RSV season. Primary RSV infection occurred in 50 (58.8%) of 86 infants. The percent of infants and their mothers with high serum RSV/A neutralizing antibody (NtAb) titers (≥ 0log2) at preseason were 10% and 42.4% (p < .001) and at postseason 6.2% and 39% (p < .001). The % of children and their mothers with IgA anti-fusion antibody in nasal secretions at preseason were 6.8% and 85.9% (p < .001) and at postseason 15.7% and 91.6% (p < .001). At postseason, serum RSV/A NtAb titer (log2) and IgA anti-fusion antibody in nasal secretions in mothers, RSV culture positive infants, RSV infected infants based on significant NtAb rise and uninfected infants are presented in the table below. (Table)

Table 1 No caption
Full size table

Thus infants' reduced immune responses to RSV compared to mothers may contribute to increase susceptibility to RSV reinfection.

Funded by the Acute Viral Respiratory Disease Unit, contract NO1-AI-15103 and SmithKline Beecham Pharmaceuticals