[Fetal and neonatal transmission of type-b anti-haemophilus influenzae antibodies protecting the newborn rat].

Haemophilus influenzae type b is the most common cause of bacterial meningitis in children. Intranasal or intraperitoneal inoculation of infant rats with Haemophilus influenzae type b results in bacteremia and meningitis and has been proved to be a reproductible model of the human disease. For these reasons, it was of interest to use rats as experimental model for the study of anti-Haemophilus influenzae type b vaccine. Immune serum against Haemophilus influenzae type b cell surface extracts was prepared on rabbit. In a first experiment, pregnant rats were passively immunized with either immune rabbit serum or normal rabbit serum or saline. In a second experiment, suckling rat mothers were passively immunized with either immune rabbit serum or normal rabbit serum or saline. All infant rats were inoculated intraperitoneally at 6 days of age with Haemophilus influenzae type b. Bacteremia was determined in all infected rats 24 h after challenge. Only infant rats from immune serum-treated mothers were protected. This protection may be transferred from mother to young rat either before of after the birth.