Development of A Method for Determination of Immunogenicity of H5N1 Avian Influenza Vaccine for Human Use

Objective To develop a method for determination of immunogenicity of avian influenza vaccine for human use.Methods Prepare vaccine with avian influenza virus strain R1203.Immunize rabbits with the prepared vaccine at various dosages and determine the HI and neutralizing antibodies in sera.Perform cross HI test,cross single immunodiffusion test and cross neutralization test on antisera against human and avian influenza viruses.Results Both neutralizing and HI antibody titers of rabbits were low 14 d after the 1st dose,but increased significantly 14 d after the 2nd dose.The increase of HI antibody titer was dose-independent,while that of neutralizing antibody was significantly dose-dependent.Cross HI test showed cross reaction of different types,and the HI titers of most of samples were not less than 1∶40.Cross single immunodiffusion test showed no cross reaction of antisera of different types.The antisera induced by avian influenza virus could not neutralize human influenza virus but could neutralize the virus of the same type(R1194),with the highest neutralizing titer of 1∶240.Conclusion Neutralizing antibody titer could reflect the immunogenicity of avian influenza vaccine correctly,thus determination of neutralizing antibody might be used as the potency test on avian influenza vaccine.