Behind the prequalification of Sinovac's varicella vaccine, the "SV-1 cell line" is indispensable

Different from other approved vaccine products before, the pre-certified Sinovac chickenpox vaccine uses Sinovac's independent intellectual property rights SV-1 cell line, which represents the "breakthrough" achievements of China's independent research and development of vaccines and has gained international recognition and far-reaching
significance.

In the process of vaccine development, in addition to the virus strain, the most basic key raw material is to cultivate the cells of the virus
.
At present, the internationally accepted human cell line for vaccine antigen has been used for many years, and the widely used and latest 2BS human embryonic lung diploid cells were also isolated and established in 1973, and most cell lines will encounter problems such as high cell generation and unsatisfactory virus yield in the process of antigen preparation, and there are still restrictions on intellectual property rights for Chinese vaccine companies
.

According to Song Lifei, general manager of Dalian Kexing, in order to ensure clear cell traceability, safety and stability, Sinovac varicella vaccine has chosen to use the younger and more vigorous SV-1 cell line independently developed and isolated by Sinovac since the beginning of the project in 2010, so as to maximize the growth of the virus and the quality control
in the production process.
After more than two years of research and efforts, Sinovac SV-1 cell line successfully passed expert demonstration
in 2012.

SV-1 As one of the human diploid cell lines, the limited survival of cell lines is also its most important constraint, and in a study on the genetic stability and gene sequence difference site analysis of varicella-zoster virus (VZV) Oka strain on human diploid cell line SV-1", SV-1 was not only demonstrated, VZV The 33rd, 35th, 38th, 39th, and 48th generation virus homology obtained by the Oka strain in its passage was 99.
99%.

At the same time, in the comparison of homology of 38 generation strains of different cell lines, the VZV differential site cultured by SV-1 cell line and the standard vaccine strain (V.
Oka) were the same merger bases (single base on MRC-5 cell lines), which indicated that SV-1 was the same Compared with MRC-5 cell lines, the genetic stability
of VZV Oka strains is better maintained.

Image source: Screenshot of reference source

Therefore, at least for VZV Oka strain, its expression fitness and genetic stability on SV-1 cells are good, and in some cases even exceed that of MRC-5 cell lines
.

From the evaluation of vaccine safety and immunogenicity, relevant studies published in the journal "Vaccine" in June this year showed that a single dose of Sinovac live attenuated vaccine has good immune durability, and the antibody positive rate after the second dose is as high as 100%.

A variety of data combined to see, Sinovac Compared with WI-38, MCV-5, KMB-17, 2BS and other old cell line matrices, SV-1 cell lines have quite good performance in terms of expression adaptability and genetic stability, even surpassing the expression of some cell lines, and have incomparable advantages
in virus yield, survival generation control and intellectual property convenience.

Sinovac varicella vaccine passed prequalification, indicating that the international first recognition of vaccine research and development with SV-1 cell line as the matrix, is expected to provide more raw material choices and imagination space
for the development of new vaccines worldwide.

China's vaccine innovation needs more "Sinovac"