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Objective:To express virus-like particles of poliovirus type 2 (PV2-VLP) in insect cells using a recombinant baculovirus expressing P1 and 3CD and to preliminarily evaluate its immunogenicity.Methods:Based on the codon preference of High 5 cells, the sequences of P1 gene and 3CD gene of PV2 were optimized and inserted into pUC57-Amp to construct pUC57-PV2-P1 and pUC57-PV2-3CD. UC57-PV2-P1s mutant that carried P1 gene mutation affecting thermostability was then constructed. Recombinant baculovirus strains of rBac-PV2-P1s-3CD and rBac-PV2-P1-3CD (wild type) were constructed using homologous recombination. The expression of target proteins was detected by Western blot. PV2-VLP was purified by ion exchange chromatography. The structure of VLP was observed under transmission electron microscopy to evaluate the assembly efficiency. The immunogenicity of PV2-VLP was assessed in a rat model.Results:The recombinant baculovirus with stable expression of P1s and 3CD proteins was successfully constructed. Western blot results showed that the yield of VLP was higher after thermostability mutation than that of the wild type. A three-dimensional structure with a diameter of about 30 nm was observed under electron microscopy, indicating that the VLP was successfully assembled. Animal experiment showed that the recombinant PV2-VLP had immunogenicity and could effectively induce the production of neutralizing antibodies.Conclusions:Effective VLP vaccines could be successfully prepared using the insect cell-baculovirus expression system, which provided reference for the development of polio VLP vaccine.
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Objective:To develop a new method based on neuraminidase (NA) activity for detec-ting virus titers of cell culture-based influenza vaccines and preliminarily analyze its application.Methods:Reaction conditions including the substrate concentration for enzymatic reaction, stop solution, the number of initially infected target cells and cell lysis buffer were optimized. The titers of cell culture-based influenza vaccine strains were detected by the established method and the results were compared with those by the traditional viral titration test.Results:The optimal substrate concentration for enzymatic reaction was 25 μmol/L, and the optimal stop solution was 0.2 mol/L Na 2CO 3. In the detection of NA activity in infected cells, the maximum relative fluorescence value was obtained by infecting 4×10 4 cells/well with influenza virus for 48 h and using 0.5% TritonX-100 for lysis. The developed method showed no significant differences with the traditional virus titration test in detecting the titers of four batches of influenza vaccine virus strains ( P>0.05), indicating that the two methods had a good consistency. Conclusions:This study established a new method based on NA activity to detect virus titers of cell culture-based influenza vaccines. The method could be used for the detection of virus strains used in the production of cell cultured-based influenza vaccines.
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Objective To develop an enzyme-linked lectin assay ( ELLA ) for measuring neuraminidase inhibition (NI) antibody titers in subjects vaccinated with H7N9 influenza vaccine. Methods Neuraminidase substrate, the dilution and incubation time of enzyme-labeled antibody, the concentration of influenza antigen for coating and pH value of the dilution buffer were optimized. Based on that, ELLA was established and used to detect anti-influenza neuraminidase antibody titers in serum samples of 34 subjects before and after vaccination with H7N9 influenza vaccine. Results The optimal neuraminidase substrate was fetuin at a coating concentration of 7. 5 μg/ml. The optimal dilution of enzyme-labeled antibody was 1 : 500. The virus strain of influenza H7N9 vaccine was used as antigen at a concentrations of 4. 5lgCCID50/ml in solution with a pH of 6. 5. Influenza-specific NI titers detected after immunization with vaccine were significantly higher than those before vaccination (P<0. 001). In the 34 subjects receiving H7N9 vaccine, the seroconversion rate of NI antibody was 47％ (≥40 in NI titer ), which was lower than that of HI antibody (P<0. 05). Conclusions An ELLA with natural substrate for measurement of anti-in-fluenza NI antibody was developed. It is simple and practical and might be used in the establishment of im-mune evaluation system for influenza vaccines and NI antibody.
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Objective@#To compare the safety and immunogenicity of two different sequential schedules of inactivated poliomyelitis vaccine made from Sabin strain (sIPV) followed by typeⅠ+Ⅲ bivalent oral poliovirus vaccine (bOPV) in Drug Candy (DC) form or liquid dosage form).@*Methods@#This randomized, blinded, single center, parallel-group controlled trial was done from September 2015 to June 2016 in Liuzhou, Guangxi province. Healthy infants aged ≥2 months were eligible for enrollment and divided into 1sIPV+2bOPV or 2sIPV+1bOPV sequential schedules. According to the bOPV dosage form each sequential schedules, the subjects again were divided into drug candy(DC) form or liquid dosage form group, being 1sIPV+bOPV (DC)/1sIPV+2bOPV(liquid)/2sIPV+1bOPV(DC)/2sIPV+1bOPV(liquid). According to 0, 28, 56 d immunization schedule, Each group were given 3 doses. We recorded adverse events during the clinical trial (399 participants who receive at least one dose). 28 days post-Dose 3, we receive a total of 350 blood samples (excluding the quitters or subjects against trial plan), using cell culture trace against polio virus neutralization test Ⅰ, Ⅱ, Ⅲ neutralizing antibody (GMT), calculating the antibody positive rate.PolioⅠ,Ⅱand Ⅲ antibody titers were assessed by virus-neutralizing antibody assay and the seroconversion (4-fold increase in titer) from pre-Dose 1 to 28 days post-Dose 3 was calculated (total 350 samples) .@*Results@#During the vaccination, the incidence of AEs in 1sIPV+2bOPV(DC), 1sIPV+2bOPV (liquid), 2sIPV+1bOPV(DC), 2sIPV+1bOPV (liquid) group were 79%, 76%, 80% and 74% (χ2=1.23, P=0.747) , respectively. The severe AEs in groups were 6%, 5%, 6% and 4% (χ2=0.57, P=0.903) , respectively, and none was considered to be vaccination related. 28 days after 3rd vaccination, the seroconversion rates in 1sIPV+2bOPV (DC), 1sIPV+2bOPV (liquid), 2sIPV+1bOPV (DC), 2sIPV+1bOPV (liquid) group, were 99%, 100%, 99% and 99% (χ2=0.94, P=0.815) , respectively, for type Ⅰ poliovirus; and 47%, 57%, 80%, 79% (χ2=31.56, P<0.001) , respectively, for type Ⅱ; and were 100%, 99%, 100%, 99% (χ2=2.02, P=0.568) , respectively, for type Ⅲ. In each group, the GMT of antibody against poliovirus typeⅠ were 4 539.68, 6 243.43, 6 819.53 and 7 916.29 (F=25.87, P<0.001) , respectively; Type Ⅱ were 12.98, 10.54, 63.75 and 84.21 (F=8.68, P=0.034) , respectively; Type Ⅲ were 1 172.55, 1 416.03, 2 648.89 and 3 250.75 (F=14.50, P=0.002) , respectively.@*Conclusion@#On the same sequential schedules, there was no significant difference between the dosage forms, all of them showed good safety and immunogenicity. In the same dosage forms with different sequential schedules, the seroconversion rate was higher in 2 dose sIPV group than the 1 dose sIPV group, especially at the neutralizing antibody GMT level against polio type Ⅱ and Ⅲ after vaccination.
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Objective To analyze the laboratory testing data of 2009 pandemic influenza A (H1N1) vaccines during lot release procedure, thus to know the overall quality status of this vaccines.Methods National Institutes for Food and Drug Control(NIFDC) carried out the laboratory test according to the specifications of each manufacture, and the results was analyzed and compared between manufacturer and NIFDC. Results 99.8% of vaccines batches were released by NIFDC, haemagglutinin contents were between 90% to 103 % of labeled values, and testing results slightly differ between manufactures and NIFDC,other items related to safety were all meet specifications. Conclusion The quality of H1N1 vaccines in China were satisfying, the lot release and independent test by NIFDC play important roles to ensure the vaccines' quality.