Immunogenicity of recombinant hepatitis B virus-like particles in mice
Objective To evaluate the immunogenicity of recombinant hepatitis B virus-like particles(HBV VLPs)in mice.Methods A series of doses of NLMS vaccine,namely HBV VLPs containing NL,M and S proteins(0.2,0.1,0.05,0.025,0.012 5 μg/mL)and marketed vaccine(4,2,1,0.5,0.25 μg/mL)were used to immunize female BALB/c mice intraperitoneally in a single dose,0.5 mL/mouse,20 mice for each group.Four weeks later,the blood samples were collected from the inner canthal vein of mice,and the serum was separated.The positive conversion rate of serum HBsAb was detected by HBsAb detection kit,and the half effective dose(ED50)was calculated.The mice were immunized intra-peritoneally with NLMS vaccine(1 μg/mL)and the marketed vaccine(20 μg/mL)at 0 and 2 weeks,0.5 mL/mouse,separately.At 2,3,4,5,6 and 7 weeks after the initial immunization,the blood samples were collected from the inner canthus vein of mice,and the serum was separated,which was detected for the serum S antibody level by corresponding kit;the antibody levels of preS1 and preS2 and the contents of IFNγ,IL-2 and IL-6 in serum were detected by correspond-ing kits 7 weeks after the initial immunization.Results After 4 weeks of immunization,the ED50 of the NLMS vaccine was 0.039 μg/mL,with a 95％confidence interval of 0.032-0.049 μg/mL,and the ED50 of the marketed vaccine was 1.095 μg/mL,with a 95％confidence interval of 0.881-1.406 μg/mL.The difference in ED50 between the two groups was significant(x2=34.0,P＜0.05).After two doses of immunization,the serum antibody titers in mice of both groups reached the highest at the 7th week after the initial immunization.The S antibody titer of NLMS vaccine group was 1∶4 096,the preS1 antibody titer was 1∶64,and the preS2 antibody titer was 1∶128;the S antibody titer in the marketed vac-cine group was 1∶1 024,and the preS1 and preS2 antibodies were below the limit of detection.There were significant dif-ferences in the titer of three antibodies between the two groups(t=-2.025,17.433 and-7.844,respectively,each P＜0.05).Both vaccines stimulated different levels of IFNγ,IL-2 and IL-6 in spleen lymphocytes of mice,which were signifi-cantly higher than those in negative control group(F=250.1,425.6 and 652.8,respectively,each P＜0.05).Conclu-sion NLMS vaccine can induce stronger humoral immune response in mice,induce S,preS1 and preS2 antibodies at the same time,and can also induce corresponding cellular immune response.
Hepatitis B virus(HBV)Virus-like particles(VLPs)ImmunogenicitySerum antibodyCytokine
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