USING OF GUINEA PIGS AS ANIMAL MODEL TO DETERMINE THE PD50 OF LOCAL OIL BIVALENT FMD VACCINE

An inactivated bivalent oil foot and mouth disease (FMD) vaccine was prepared using
the local isolated types of the caused virus (FMDV type O/Egypt/93 and A/1/Egypt/2006).
This vaccine was subjected to the quality control tests which revealed that it is free from
foreign contaminants, safe and potent for Guinea pigs which were used as a model animal for
determination of the vaccine PD50. The obtained results showed that vaccinated Guinea pigs
exhibited good levels of homologous FMD antibodies; as shown by serum neutralization test
and ELISA; by the 3rd week post vaccination enabling them to withstand the challenge
viruses with protection ratios of 100%; 75% against type O for undiluted and 1/4 diluted
vaccine respectively while 100% protection was detected against type A with the 2 vaccine
dilutions. Higher vaccine dilutions were found to be non-protective showing low protection
ratios (25-0%) It was found that Guinea pig 50% protective dose (GPPD50) was 7.94 for
FMD virus type O and 11.06 for type A. Such permissible values of vaccine potency and
PD50 confirm the possibility of the use of Guinea pigs to determine the PD50 of FMD vaccine
as a model animal instead of cattle saving effort and cost.