Rubella Interferon and Factors Influencing the Indirect Neutralization Test for Rubella Antibody

Abstract

Resistance of primary human amnion cultures to Sindbis virus was found to correlate well with the presence of specific rubella cytopathic effects. Certain exceptions to this relationship were noted. Sindbis virus interfering activity present in rubella infected cultures was related to interferon on the basis of chemical, physical and biologic properties. With the indirect interference neutralization test for rubella, using amnion cultures and challenge with Sindbis virus, rubella cytopathology was found to be a useful criterion for determining the optimum time for Sindbis virus challenge. The incorporation of normal rabbit serum enhanced neutralization of rubella virus. Important factors contributing to reliability of indirect neutralization results include the use of 10 or more TCID₅₀ of rubella virus, and the use of more than two cultures per serum dilution tested. It is concluded that the results of interference neutralization tests may reflect a variety of factors in addition to the specific neutralization of rubella virus.