Clinicopathological and Immunological Studies on Foot- and- Mouth Disease Vaccine

Abstract

Study of the pathogcnccity of foot- and- mouth disease virus as well as the cvaluation of cell mediated immune responsc and its correlation with the humoral rcsponsc in both FMD vaccinated micc and cattle were thc aim of this work. Adult inbred BALB/C micc (138) as well as suckling outbred CDI mice (30) were uscd in the first experiment of this work while 21native breed calves (6-8months) were used in the second experiment. Results obtaincd through lymphoproliferative and phagocytic assays conducted on adult mice as well as erythrocytes- rosette % in calves revealed a role of the cell-mediated immune response in thc protection of vaccinated animals against viral challenge. These results correlated wcll with serologcal findings (humoral immunity) which revealed significant rise in antibody titre in all animals post vaccination. Significant leukocytosis with lymphocytosis were detected in both vaccinated mice and calves while leukopenia due to lymphopenia (mice) or due to neutropenia (calves) was observed in infected animals. FMD virus could be isolatcd from plasma of infected adult BALB/C mice at 48 and 72- hrs post infection. Fluorescent antibody reaction was also seen in some organs particularly liver from infected adult mice. Different histopathological altcrations were seen in both infected adult and suckling mice. The latter animals showed 100% mortalities due to severe and diffuse myocarditis and myositis.