Determination of proper antigen concentration of foot and mouth disease virus for immunization of Egyptian sheep

ABSTRACT

Twenty-four sheep of local breeds were used in order to determine the proper FMD virus concentration in vaccinal dose. Four batches of vaccines with different concentration of virus particles [10, 20, 30, and 40 million infective particles per each dose] were prepared and used for sheep vaccination. All sheep challenged by FMD virus [10 4 ID50] gave protection at 21-day post vaccination. Meanwhile, the study of immune response by means of serum neutralizing and complement fixing antibody titers revealed that high titer within protective level [0.9 - 1.2 TCID 50/ml] when sheep vaccinated by dose of 10 million virus particles per dose protected sheep for 5 weeks while when vaccinated by 20 million/dose protection level continues up to 12 weeks, in the same time, sheep vaccinated with dose of 30 and 40 million virus particles per dose gave immunity in protection level up to 24 weeks. The most proper antigenic dose was 30 million virus particles per dose