engleski

Newly hatched chickens given lentogenic strains of NDV by nebulisation are fully protected

Objectives: Immunogenicity of three lentogenic vaccine strains of Newcastle disease virus given by nebulisation was investigated. Material and methods: A number of 606 newly hatched commercial chickens were divided into five groups: A (103 chicks), B (105 chicks), C (103 chicks), D (105 chicks) and K (190 chicks). Groups A, B and C received respectively water suspensions of NDV strains: IRELAND-ULSTER-1968 (A), NJ LASOTA (B), and AUSTRALIA-QUEENSLAND-V4-1966 (C): while group D received a mixture of equal parts of the three viruses. Control group (K) was not treated. All the remedies were applied by the ultrasonic nebulizer SONOVAC 095&reg ; ; ; ; that produces particles ranging 2 to 5 microns in diameter during an exposition of 60 seconds. Maternal immunity and immune response to the vaccines were tested on collected sera every seven days by immunoenzym tests. During the experiment, challenge was performed on 15 chicks from A, B, C and D groups, as well as on 30 chickens from E group by oculonasal administration of 106 EID50 Herts 33 strain of vNDV at weekly intervals starting on 7th until 49th day. Results: The vaccines didn't cause clinically noticeable reactions in chickens regardless the applied strains. Maternal immunity didn’ t interfere with active immunity. Immune response to each vaccine was significantly higher than in the control group. Chickens that were vaccinated with the mixture of three strains of NDV developed weaker immune response than those that were vaccinated with a solitary strain did. During the virulent challenge infection, 88% of the chickens survived in group A, as well as 98% in group B, 88% in group C, and 75% in group D. In control group (E) 47% of the chickens survived. Discussion: Applied strains didn’ t cause any adverse clinical reaction, nor did maternal antibodies interfere with immunization. Nebulization of three different strains produced highly effective and long lasting (at least 42 days) immunity and protected chickens against virulent challenge infection.

chicken; NDV; nebulisation

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