Induction of lymphocyte agglutination and lysis by Newcastle disease virus.

Five strains of Newcastle disease virus (NDV) were tested for their ability to agglutinate and lyse chicken lymphocytes. All 5 strains agglutinated lymphocytes, and the agglutination was inhibited by anti-NDV sera. All 5 strains also caused a different degree of direct virus-induced lysis of 51Cr-labeled chicken lymphocytes. This direct lymphocyte cytotoxicity was lost after heating at 56 degrees C for 30 min, or after treatment with a high concentration of formalin (1:100 dilution). Neither a low concentration of formalin (1:5000) nor trypsin treatment had any effect on cytotoxicity.