The deficiency of vitamin A -- the cause of nictalopia, or night-blindness -- has now been linked to the transmission of the AIDS virus from pregnant women to their babies (Science, Vol 265 No 5170). The study could spur foetal protection. Conducted by Richard Semba and his colleagues at the Johns Hopkins School of Hygiene and Public Health in the US, the study shows that mothers who transmitted the virus had low levels of vitamin A, while infected mothers who did not had higher levels of vitamin A in their serum.