Abstract
Bovine ephemeral fever has major economic significant losses due to drop in milk production in dairy herds and reduction in conditions of prime animals or disruption of stock movements and markets. This study was conducted for evaluation of immune response to a commercial bovine ephemeral fever vaccine in vaccinated calves using the Neutralizing Peroxidase Linked Antibody assay (NPLA) in comparison with micro neutralization test (MNT). The antibody titers were estimated weekly for the first 3 weeks after primary vaccination then monthly after booster vaccination by NPLA and MNT. The geometric mean of antibodies titers for the first 3 weeks by NPLA were 5.2, 12.8, and 24.8 respectively. While MNT for the first 3 weeks were 5.6, 10.8 and 21.6 respectively. After booster vaccination the geometric mean of antibodies titers were monitored monthly for 11 months. The monthly geometric mean of antibody titers by NPLA were 364.8, 396.8, 384, 332.8, 332.8, 345.6, 153.6, 153.6, 89.6, 76.8 and 76.8 respectively. Using MNT were 300.8, 345.6, 332.8, 307.2, 281.6, 256, 160.0, 179.2, 89.6, 57.6 and 76.8 respectively. In conclusion, although there is no significant difference between the NPLA and MNT; The NPLA is an accurate, sensitive and specific method for detection and titration of the neutralizing antibodies to BEF virus induced by the commercially available BEF vaccine. Moreover the NPLA is not affected by the non- specific cytopathogenic effect in cell culture. The level of immunity in the vaccinated calves was found to be protective for 6 months and further studies are needed.