he object of the present study was to find out a correlation between the potency of the locally produced PPRV vaccine, as estimated in vero cells and in susceptible sheep. In this respect, studying five batches of the vaccine produced as 1ml lyophilized product/vial/100 doses revealed that :
1. Infectivity titres per 1 ml/vial/ 100 sheep doses were found to be not less than 6 log 10 TCID 50 on Vero cells, as estimated for the 5 batches of the PPRV vaccine.
2. Five serial ten fold dilutions (10-3 – 10-7) of batch 1 were used to inoculate (S/C), 5 susceptible sheep groups of 5 heads. Three weeks post inoculation, serum samples were VNT-positive as of 100%, 100%, 60%, 20% and 0% for the 5 respective groups. Corresponding geometric mean neutralizing antibody titres were 80.6, 80.6. 50.8 and 0.
3. Five susceptible sheep groups of 3 heads were used to test the defficacy of inoculating a dose of 2 log 10 TCID 50 per head, corresponding to the 5 batches / 5 groups. Twenty one days post inoculation, serum samples were VNT-positive for each individual animal. Geometric mean antibody titres were 32, 80.6, 80.6, 80.6 and 50.8 for the respective 5 groups.
It was concluded that : 1 vero TCID 50 is equal to 1 sheep ID 50. Potency testing of the PPRV vaccine in vero cells is quite satisfactory and dependable to qualify the efficacy of the product. Such a procedure would be considered as a contribution in saving time, effort and money, through carrying out qualification of the PPRV vaccine