EFFECT OF ATTENUATED MP12 RIFT VALLEY FEVER VACCINE ON IMMUNE RESPONSE OF SHEEP

This work aimed to study the clinical aspects and immune response of pregnant and non-pregnant ewes vaccinated with attenuated MP12 RVF vaccine. Non-pregnant ewes showed slight elevation of body temperature lasted for one day post-vaccination. There were no detectable clinical signs of RVF disease. Pregnant ewes showed no elevation in body temperature, no abortion and delivered healthy lambs (without abnormalities). RVF virus was detected on the 2nd day post-vaccination in 15 out of 18 serum samples using RT- PCR. IgM antibodies were detected on 7 days post-vaccination (DPV) and persisted up to 150 DPV with a titer ranged from 100 – 800. IgG antibodies were detected on 7 DPV reaching the peak on 60 DPV and persisted up to 360 DPV with a titer ranged from 100 – 800. Maternal immunity appeared in newly born lambs after ingestion of colosrum and lasted up to 4 months. It is concluded that MP12 RVF vaccine is safe and potent for vaccination of sheep.