Presence of an acid-labile alpha-interferon in sera from fetuses and children with congenital rubella.

In congenital rubella an acid-labile alpha-interferon was present in sera collected from fetuses between weeks 21 and 29 of gestation and from children with active congenital rubella. This interferon was different from the interferon detected in normal amniotic fluid and was not found in sera from uninfected fetuses or from children with postnatally acquired rubella. The fetal interferon is of interest as a complementary marker to confirm the virus contamination of the fetuses during maternal rubella. The role of the prolonged synthesis of this interferon in congenital rubella disease and its immune defects are discussed.