News
The E. coli expression system embeds the ORF2 open reading frame encoding the Cap protein into the plasmid of E. coli, and then expands the E. coli to massively express the Cap protein of porcine circovirus type 2 (PCV2). This expression method has advantages such as high expression level, strong controllability, easy genetic modification, and the ability to assemble into virus-like particles (VLPs). However, it also has problems such as endotoxin production, limited soluble protein, and limited post-translational modifications.
Therefore, in the PCV2 vaccine production process, a stable production process, high purity standards, and assembly into VLPs are required to achieve better immune effects.
The recombinant baculovirus expression system inserts the ORF2 open reading frame into the baculovirus gene promoter, obtains the recombinant baculovirus, and infects insect cells to allow the virus to replicate in the insect body, thereby obtaining the target protein. This expression method has advantages such as intact protein spatial structure, high safety, and the ability to introduce post-translational modifications. However, it also has disadvantages such as high production costs, high process requirements, and limited expression levels.
In the PCV2 vaccine production process, it is necessary to rely on one's own mastery of the production process and breakthroughs to achieve stable expression and mass production.
Therefore, for the E. coli expression system and the baculovirus expression system, as two different expression methods, there is no distinction between good and bad, but each has its own advantages and disadvantages. Enterprises should flexibly choose different expression methods based on their own production management level and process stability, in order to produce safe, efficient, and stable PCV2 vaccines.
Clinical Prove
In a 3,000 head basic sow farm in Jiangxi Province, two different genetically engineered subunit circular vaccines were used to evaluate the immunization effect. 2,356 lactating piglets of 23 days of age in good health were selected and divided into two groups of 1,178 piglets each, of which Group A: 1,178 piglets were vaccinated with an imported baculovirus vaccine.
Group A was immunized with an imported baculovirus expression system PCV2 vaccine, and group B was immunized with the Pulike Yuan Ke Xin E. coli expression system PCV2 vaccine.
At weaning (23 days of age), and 3 weeks later (44 days of age), 15 piglets from each group were immunized.After 3 weeks (44 days of age), 15 piglets from each group had their blood analyzed and the serum analyzed for the detection of circulating antibodies.
Data analysis shows that the PCV2 antibody levels in pigs immunized with PCV2 vaccines using the two different expression methods did not show significant differences, except for greater discrete differences.
PCV2 antibodies, as one of the indicators for evaluating the immune effect of different circovirus vaccines, may be affected by many factors such as wild-type PCV2 infection, and need to be comprehensively evaluated in combination with production indicators.
In the subsequent verification, it was found that the key production indicators such as mortality rate, daily weight gain, and feed-to-meat ratio of pigs vaccinated with PCV2 vaccines using the two different expression methods also did not show significant differences.
Therefore, this case proves that the clinical application effect of circovirus vaccines is not closely related to the antigen expression method.
