Enhancement of haemolysis by Newcastle disease virus (NDV) after pre-treatment with heterophile antibody and complement.

Pre-treatment of Newcastle disease virus (NDV) with fresh human plasma enhances its haemolytic (HL) capacity by several factors. The effect is due to complement activation by the heterophile anti-chick antibody present in human plasma. All the adult human plasmas tested were effective, also 91/100 human cord blood sera. The antibody was mainly of the IgM class. The enhanced HL was due to integration and transference of the complement 'holed' virus envelope membrane and subsequent leakage of haemoglobin. High concentration of activated complement destroys the integrity of the virus enevelope. Treatment of chick erythrocytes and fibroblasts with human plasma also produced lysis of the cells.