Oral inoculation of the human group A rotavirus MO strain (G serotype 3) into 5-day-old BALB/c mice causes
gastroenteritis characterized by
diarrhea. Using this small animal model, passive protection of suckling mice against human
rotavirus infection was achieved with the use of
immunoglobulin (
IgY) from the yolks of eggs of rotavirus-immunized hens. When
IgY against the rotavirus strain homotypic with the challenge virus (MO strain) was administered to mice, complete protection was achieved. After immunizing 8-month old pregnant Holstein cows with human rotavirus MO strain, colostrum containing
neutralizing antibody to four different G serotypes of human rotavirus, designated Rota colostrum, was obtained. Rota colostrum completely protected suckling mice against
rotavirus infection, and purified
IgG obtained from Rota colostrum protected against
infection with the homologous virus. After randomly grouping 20 infants from a baby care center, 10 infants received 20 ml of Rota colostrum for 2 weeks and 10 control infants received none. Rotavirus-associated
diarrhea developed in 7 of the 10 infants in the control group. None of the three infants in the group daily receiving the Rota colostrum had such symptoms, and one of three infants in the group receiving treatment, every other day developed rotavirus-induced
diarrhea.
Oral administration of Rota colostrum seems to be an effective and safe means of preventing
diarrhea caused by human
rotavirus infection. Recently, the immunized cows were boosted by reinjection of 4 serotypes of human rotavirus into a superficial cervical lymph node two weeks after delivery, resulting in mass production of cow's milk containing a high-titered antibody to human rotavirus. Therefore, the hyperimmune cow's milk is a candidate for a "physiologically functional food" in Japan.