The effect of animal sera on duck hepatitis virus

The incorporation of various types of mammalian sera into the plaque assay for duck hepatitis virus (DHV) produced plaques which were dramatically reduced in diameter and number relative to those produced using avian sera. The virus neutralising substances (VNS) present in the sera appeared to act directly on the virus rather than preventing entry into the cells by blocking receptor sites. Preliminary investigations have shown that the non-specific inhibitory factors in foetal calf serum (FCS) are found in the albumin fraction.