Safety and immunogenicity of influenza A H1N1 virus split vaccine in animals

Objective To evaluate the safety and immunogenicity of influenza A H1N1 virus split vaccine in animals. Methods Abnormal toxicity test was performed according to the requirements in Chinese Pharmacopoeia(Volume Ⅲ, 2005 edition). Kunming mice were randomly divided into seven groups,ten for each. The mice in three test groups were injected i. m. with influenza A H1N1 virus split vaccine at hemagglutinin(HA)contents of 15,30 and 45 μg / 0. 5 ml, while those in three parallel control groups with seasonal influenza H1N1 virus split vaccine at the corresponding HA con-tents,and those in negative control group with PBS,respectively. The vaccines were given at a dosage of 0. 1 ml for 2 times at an interval of 21 d. Venous blood samples were collected 0,21,28,35 and 42 d after the first immunization, from which sera were separated and determined for hemagglutination inhibition(HI)antibody level. Results The abnormal toxicity test result met the requirements in Chinese Pharmacopoeia(Volume Ⅲ,2005 edition). The serum antibody levels in three test groups 21, 28,35 and 42 d after the first immunization increased significantly as compared with those in negative control group,which reached a high level on 21 d and a peak value on 28 d(each P 0. 01). However,the antibody levels in test groups 0,21,28 and 42 d were higher than those immunized with the control vaccine at the corresponding HA contents(P 0. 05). The serum HI antibody positive rates of mice 21 d after immunization with test vac-cine at HA contents of 15,30 and 45 μg / 0. 5 ml were 80%,90% and 90%,while the protection rates were 100%,90% and 90%,respectively,which showed no significant difference with those in parallel control groups(each P 0. 05). The HI antibody positive rates of mice 28,35 and 42 d after immunization with 15 and 45 μg / 0. 5 ml were more than 80%, while that with 30 μg / 0. 5 ml was slightly low. However,the protection rates of HI antibody in three test groups were 90% ~ 100%. Conclusion Influenza A H1N1 virus split vaccine showed good safety and immunogenicity in Kunming mice.