Neutralizing Antibody Response in Bovine Serum and Nasal and Salivary Secretions After Immunization with Live

Local immunity seems to play a major role in the resistance to infection by rhinoviruses (10). Since foot-and-mouth disease virus (FMDV) shows many of the features of a rhinovirus (8), local immunity in cattle could provide resistance against the disease (7), and it would be possible to appraise it by searching for neutralizing antibodies in nasal secretions. The present work is an investigation of neutralizing antibodies in serum and in nasal and salivary secretions of calves that had been inoculated either with inactive or active type 0, FMDV. The calves selected for this study came from a virus-free farm, and were born from dams vaccinated with commercial, inactive FMDV polyvalent vaccine. The animals had a negative history for FMDV, were negative for intestinal parasites, and had normal hemograms. The calves were isolated when they received live virus. They were examined daily, and the desired specimens were collected at selected intervals after inoculation. The virus, type 01, maintained as a prototype at the Instituto Bacteriolegico de Chile, was kindly provided by Aldo Gaggero. For over 2 years we have grown and assayed the virus in primary cultures of fetal calf kidney cells or in BHK-21 cell cultures, or both. Vaccine was prepared by inactivation of a viral suspension (106 plaque-forming units [PFU]/ml) with 0.05% Formalin at 32 C for 44