Observations On Production, Laboratory Testing And Field Application Of 1-2 Thermo Stable Newcastle Disease Vaccine In The Sudan

Abstract

In the present study, a working seed of the Newcastle disease (ND) thermostable vaccine (I-2) vaccine (supplied by ACIAR, Australia) was prepared in Sudan (CVRL, Khartoum). Experimental trials were conducted to determine safety, potency and the effect of age of chickens, route of administration and dose on the immunogenicity of the vaccine. Vaccination of chicks at 2 and 3 weeks old yielded better immune response and higher protection rates as compared to 1 day and 1 week. Boostering of chicks resulted in a relatively better (p< 0.05) immune response in all age groups as compared to those vaccinated once. With regard to dose, total protection against challenge infection was attained when chicks were vaccinated with double the recommended dose of the vaccine via the intraocular route (I/O). The I/O route was found to be superior to the intranasal (I/N) which was confirmed to be better than the drinking water (D/W) route as observed from antibody titers and percent protection after challenge. Comparison of the doses involved using half, recommended, dquble and four times the dose of the 1-2 vaccine, proved that even half the dose resulted in a reasonable immune response and protection. Moreover, using double or even four times the dose gave 100% protection without resulting in any adverse post vaccinal reactions. Field vaccination trials of village chickens (Baladi) by the D/W, I/O and I/N routes using 1-2 vaccine showed better immune response for 1/0 route as compared to other routes. The immune response was superior when the 1-2 vaccine was used as compared to Komarov vaccine. Use of the thermostable vaccine of ND (112) was proved-from results of this work- very reliable, as it was safe, highly immunogenic and protective. Experiences in distribution of the vaccine and vaccination of village chickens are discussed