Vaccine Fortifies Milk to Build Immunity

BOZEMAN, MONTANA--Antibodies in mother's milk help protect newborn mammals against many infectious diseases in the critical first few weeks of life. Now scientists report their first success in boosting these protective powers in large animals: The first milk of cows vaccinated while pregnant temporarily immunizes calves against bovine rotavirus, a serious threat to young farm animals. The approach, described here this week at the annual meeting of the American Society for Virology, might be adaptable for protecting human babies in the early months of life.

Humans, cows, pigs, and other mammals are born with antibodies from their mothers that provide early protection before the young animals' immune system begins to recognize pathogens. Antibodies in milk provide a small supplemental boost. But these maternal passive antibodies are insufficient to protect against some early diseases like rotavirus diarrhea. Moreover, because maternal antibodies interfere with childhood vaccinations, children are generally not given vaccines to kick their own immune systems into action until they are at least 2 months old. This leaves them especially vulnerable in those early weeks.

At the Ohio State Agricultural Research and Development Center in Wooster, immunologist Douglas Hodgins inoculated cows with a recombinant synthetic rotavirus vaccine a week before their expected calving date. The first milk secreted after birth, called colostrum, was collected and pooled, then fed to calves for a week. The calves were infected orally with bovine rotavirus about a day after birth. None of the 10 calves fed colostrum from inoculated cows developed diarrhea, while all the calves fed colostrum from uninoculated cows became sick.

In the future, Hodgins says, human mothers might be vaccinated to supplement the antibodies in their breast milk. "In specific instances, this could be a practical approach," says virologist Albert Kapikian of the National Institute of Allergy and Infectious Diseases. For instance, infants sometimes contract rotavirus in the hospital.