Immunogenicity of Vaccine Candidate Strains for Avibacterium paragallinarum Serotype A,B,and C
In order to study the immunogenicity of vaccine candidate strains for three serotypes of Avibacterium paragallinarum(Apg),this study prepared monovalent inactivated vaccines with antigen concentrations of candidate strains LY(Serotype A),HB(Serotype B),and KM(Serotype C)at 4.0×108,5.0×108,and 8.0×108 CFU/mL,respectively.SPF chickens aged 4 to 6 weeks were immunized,and after 28 days of immunization,the corresponding serotype strains were used to challenge the experimental chickens to determine the minimum immunizing dose based on the challenge results and evaluate their immunogenicity.The results showed that after 28 days of immunization and challenge,the immune protection rates for each immunization group in the LY strain test were 8/10,9/10,and 10/10,respectively;in the HB strain test,the immune protection rates were 6/10,8/10,and 8/10,respectively;in the KM strain test,the immune protection rates were 2/10,5/10,and 8/10,respectively.The morbidity rates in the challenge control groups for the three serotypes were 9/10,10/10,and 10/10,respectively,all meeting the morbidity standard(≥8/10),confirming the validity of the challenge test.The protection rates for the LY strain with antigen concentrations of 4.0×108,5.0×108,and 8.0×108 CFU/mL,the HB strain at 5.0×108 and 8.0×108 CFU/mL,and the KM strain at 8.0×108 CFU/mL all reached 8/10 or higher,meeting the immunization protection standard(≥8/10).The minimum immunizing doses for the LY,HB,and KM strains were determined to be 2.0×108,2.5×108,and 4.0×108 CFU per bird,respectively,providing a standard for testing the immunogenicity of vaccine candidate strains and serving as a reference for the subsequent development of a trivalent inactivated vaccine for infectious coryza in chickens.
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维普
