title: Virus content and effectiveness of foot-and-mouth disease vaccines.
abstract: (I) The amount of 22 nm particles in 26 batches of cattle tongue epithelium extract used for the preparation of C-type vaccine was determined with an improved 50% haemolytic and point complement fixation test after fluorocarbon precipitation of non-immunizing 7 nm particles. The total amount of 22 nm and 7 nm particles (alpha GN value) varied considerably from batch to batch, 22 nm components (alpha GF value) showing a maximum 5-fold difference. (ii) Effectiveness of vaccines with known virus content was tested in adult mice challenged with an adapted virus strain. In commercial C-type vaccines the complement-fixing activitiy of 22 nm particles and the potency of the vaccine showed a logarithmic regression (mouse index = -1.43 + 2.27 1g alpha GF).
mesh_terms: D000818:Animals; D000956:Antigens, Viral; D005537:Aphthovirus / Q000276:immunology* / Q000302:isolation & purification; D002417:Cattle; D003168:Complement Fixation Tests; D004848:Epithelium; D005069:Evaluation Studies as Topic; D051379:Mice; D012044:Regression Analysis; D012190:Retroviridae / Q000276:immunology* / Q000302:isolation & purification; D014020:Tissue Extracts; D014059:Tongue; D014765:Viral Vaccines
chemical_list: D000956:Antigens, Viral; D014020:Tissue Extracts; D014765:Viral Vaccines