Manan AAA , Kheir MAS, Ballal A, Nour TAM, Wegdan H. Ali , Fatima AT
Using 1-2 and La-Sota strains two inactivated Newcastle Disease (ND) vaccines were produced. The vaccine viruses were inactivated by treatment with 0.05% laboratory-grade formaldehyde, then each inactivated vaccine was preparedas water in oil (W/O) emulsion. For each emulsion, the aqueous phase ratio was (2.4:1) (allantoic fluid: tween 80) respectively. While the oil phase contains (9:1) (paraffin oil: Manidmonoleate (span 80)) as an oil emulsifier. The prepared vaccines were subjected to physical tests including stability, viscosity, and quality of emulsification completeness. The two vaccines were confirmed to be sterile, stable for 30 days at 37?C, and for 6 months at 4 co. the viscosity was 4 ml/8 second. Tests for safety, immunogenicity, and efficacy (challenge test) as well as cross-protection evidence for the two vaccines was performed in -one day- old broiler chicks. For phase I clinical trial both vaccines were found to be safe, immunogenic, and effective with 80% and 40% protection level for oil emulsion vaccines derived from ND I-2 and ND La-Sota strains respectively. Because of the relatively higher efficacy(80%) obtained from the I-2 strain in the phase I trial, this result validates further investigation for the I-2 strain in the phase II clinical trial. In phase II clinical trial, the protection reached 93% in a group vaccinated only with inactivated ND I-2 vaccine, compared with 100% protection against very virulent ND virus for the group vaccinated simultaneously with life and inactivated ND I-2 vaccines. Independent sample t.test was used to compare the GMT Abs titer for the post-vaccination sera with a statistically insignificant outcome (P>0.05). The results obtained in this study confirmed that the killed ND I-2 vaccine produced locally was safe and efficient, and could be used with high efficiency against the very virulent ND strains, and has the potential to replace the imported ND oil vaccines.