HEMAGGLUTINATING AND FUSOGENIC ACTIVITIES OF NEWCASTLE-DISEASE VIRUS - STUDIES ON RECEPTOR-BINDING SPECIFICITY AND PH-INDUCED CONFORMATIONAL-CHANGES

Vaccinal and wild strains of Newcastle Disease virus (NDV) were analyz ed for cell receptor binding and fusogenic biological properties assoc iated with their HN (hemagglutinin-neuraminidase) and F (fusion protei n) surface structures respectively. The evaluation of the biological a ctivities of HN and F was carried out respectively by determination of hemagglutinating titers and hemolysis percentages, using erythrocytes from various animal origins at different pH values. Significant diffe rences in hemagglutination titers for some strains of NDV were detecte d, when interacting with goose, sheep, and guinea-pig and human ''O'' group erythrocytes at neutral pH. Diversity of hemolysis percentages w as observed between different NDV strains at acid pH. These analysis w ere developed to evaluate particular aspects of the actual influence o f the receptor specificity and pH on the receptor binding and fusogeni c processes of Newcastle Disease viruses.