The Preparation And Evaluation Of Inactivated Vaccine Of Recombinant Newcastle Disease Virus RGM-?m

Newcastle disease,caused by Newcastle disease virus(NDV),is a n acute,septic and contagious avian diseases which can infect chickens,quails,pigeons,t urkeys and other poultries,and lead to damage of central nervous,respiratory and digestive system.ND was listed as one of the priority of the prevention and control of major animal epidemics in the “long-term national animal disease prevention and control planning(2012-2020)”.To date,vaccination campaign was the main method to control the disease.Inactivated oil emulsion ND vaccine was prepared based on recombined GM strain of genotype ?d with water-in-oil method.To evaluate the immune effect of the vaccine,several experiments were processed.Firstly,SPF chickens were inoculated with the recombined vaccine and commercial inactivated vaccine LaSota separately;both GM and LaSota were used as antigens to detect the HI titer after immunization.Besides,four strains of virulent NDV of different resources and genotypes were used to challenge the chickens,the virus shedding rate and survival rate were measured.Secondly,to study the applicability of the recombined vaccine,both SPF chicken and broiler were injected with the recombined vaccine to measure the dynamic change of the HI titer level.Thirdly,the vaccine immune duration test was determined by monitor the HI level of inoculated SPF chicken.Fourthly,SPF chickens were injected with differe nt doses of recombined vaccine to ensured minimum dose.Finally,SPF chickens with different HI levels were grouped and challenged to determine the protective threshold of the recombined vaccine.In this study,both GM and LaSota were used as diagnost ic antigens to detect the HI titers post immunization of two vaccines,results showed the average HI titer of genotype matched antigen was higher than that of different genotype.SPF chicken inoculated with rGM-?m inactive vaccine got 100% protection from NDV challenge,while the protection rate of LaSota was 90%.These results indicated that the immune response,ascending velocity and average level of HI antibodies of recombined vaccine were better than LaSota;the recombined vaccine rGM-?m constantly stimulate high level antibodies to gain complete protection.In the minimum dosage experiment,the 20 ?L vaccine fully protected chickens against virulent NDV challenging.The protective threshold was 5 log2,above which chicken could be fully protected.We also measured the HI titer change of both SPF chicken and broiler chicken,an immunization program was made based on the growth and decline rule of HI titer— for 10-day-old chicken,each bird vaccinated intramuscularly with 0.2 mL oil emulsion inactivated r GM-?m vaccine afford 4 months full protection.Above all,this study had evaluated the antigenecity,the efficiency,the duration,the minimum dosage and the protective threshold of the inactive vaccine rGM-?m,results showed that rGM-?m vaccine is superior to the traditional LaSota vaccine in each aspect,indicating a promising application value.