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Yin Y.-S.,Sinovac Dalian Vaccine Technology Co. | Gu Y.-X.,Sinovac Dalian Vaccine Technology Co. | Huang J.-F.,Sinovac Dalian Vaccine Technology Co.
Chinese Journal of Biologicals | Year: 2015

Taking account of the safety of live attenuated vaccines, monkey neurovirulence test is required for isolation of attenuated vaccine strains from the wild strains targeting central nervous system in regulations for registration of drugs in most countries. However, monkey neurovirulence tests are different in various regulations, and unsuitable for individual live attenuated vaccines. Therefore it is recommended that once monkey neurovirulence test will be conducted, the necessary should be fully assessed by considering the clinical characters of wild strain, the experience in clinical applications of commercial vaccines as well as the available results of some in vitro and in vivo tests. This paper reviews the problems of monkey neutrovirulence test, some replacement methods as well as their application in safety assessment of various live attenuated vaccines. Source


Meng F.-H.,Sinovac Dalian Vaccine Technology Co. | Liu X.-C.,Sinovac Dalian Vaccine Technology Co. | Wang S.,Sinovac Dalian Vaccine Technology Co. | Li J.,Sinovac Dalian Vaccine Technology Co. | And 3 more authors.
Chinese Journal of Biologicals | Year: 2014

Objective To develop and verify a fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay for infectious titer of live attenuated mumps vaccine. Methods Primers and TaqMan fluorescent probe were designed specific to the conserved region of hemagglutinin (H) gene of live attenuated mumps vaccine virus strain S79. The final product prepared with strain S79, with a lot No. of 05008, was served as a reference. Vero cells were inoculated with the reference or test sample, then broken by hypoosmotic method combined with freeze-thawing method, of which the supernatant was collected and determined by fluorescent quantitative RT-PCR. The time for virus infection was optimized, and the developed method was verified for specificity, precision and accuracy. Results The optimal time for virus infection was 18 h. The developed fluorescent quantitative RT-PCR assay was specific to live attenuated mumps vaccine, while no amplification curves were observed in the vaccine after inactivation, varicella virus, rabies virus, measles virus, rebulla virus or Vero cells. The relative standard deviations {RSDs) of six groups of data on samples at four concentrations (1, 1 : 5, 1 : 52 and 1:53) were less than 5%. The R2 values of regression equation of standard curves of samples at four concentrations ( 1, 1 -5, 1 : 52 and 1 : 53) determined by various personnel on various dates were more than 0. 97, with RSDh of less than 5%. The difference between determination results of 11 batches of live attenuated mumps vaccine by the developed method and by CPE method was not more than 0. 2 LgCCID50/ ml, which showed no significant difference (P > 0. 05). Conclusion The developed fluorescent quantitative RT-PCR assay for infectious titer of live attenuated mumps vaccine showed high specificity, precision and accuracv, which was rapid, simple, and suitable for the in-house quality control during production. Source


Meng F.-H.,Sinovac Dalian Vaccine Technology Co. | Yu W.,Sinovac Dalian Vaccine Technology Co. | Zhang W.,Sinovac Dalian Vaccine Technology Co. | Yang L.-W.,Sinovac Dalian Vaccine Technology Co. | And 4 more authors.
Chinese Journal of Biologicals | Year: 2015

Objective: To investigate the genetic stability of varicella-zoster virus (VZV) Oka strain during subculture in human diploid cell SV-1 strain, and analyze the complete gene sequences and differential sites of Oka strain of various passages. Methods: Oka strain was subcultured in SV-1 cells to passage 48, and determined for virus titer. The complete genes of passages 33, 35, 38, 39 and 48 were sequenced, of which the data were spliced and analyzed by using DNASTAR. Lasergene. v 7. 1 software. Results: The virus titers of Oka strain of passages 33 ∼ 48 were 4. 000 ∼ 4. 625 lgCCID50/ml, with an arithmetic mean of 4. 292 lgCCID50/ml. The full-length of genome of Oka strain was 125 114 bp, while the GC content was 46%. The homology of nucleotide sequences of Oka strain of passages 33, 35, 38, 39 and 48 was 99. 99%, while that of the five passages to standard vaccine strain V-Oka was 99. 96%. One differential site was observed in the complete gene sequence of Oka strain subcultured to passage 38 in MRC-5 and SV-1 cells. High homologies were observed in the gene sequences of Oka strain of various passages. However, as compared with those of vaccine strains Varivax and Varilrix, wild strain Dumas and parent strain p-Oka, the homology of gene sequence of Oka strain to that of vaccine strain V-Oka strain was high. Conclusion: VZV Oka strain showed high adaptability and genetic stability in SV-1 cells. Source

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