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Construction of swine influenza virus genetic engineering subunit vaccine There are several ways in which more reports include:
1) the use of prokaryotic expression system (E. coli system) or eukaryotic expression system (yeast) in the in vitro expression of swine influenza virus strains in the HA gene and NA genes, and then harvested, concentrated and purified target protein, the system further vaccination with . This approach has the advantage of simple preparation process, the purpose of protein yield, the main component can be quantitatively configuration. However, in vitro expression of the protein is difficult to maintain or restore the spatial structure of natural proteins, protein purification process is complicated and costly, but not the overall effects of immunization and traditional whole-virus inactivated vaccine, and therefore from the technological aspects of such vaccines needs further improvement .
2) The swine influenza virus immunogen (HA and NA) gene alone or with cytokines (interleukin -6, Y interferon, etc.) in series after the encoding gene was cloned into the eukaryotic expression plasmid, and then recombinant DNA quality particles into the body cells through the body-derived expression and presented to the immune system to induce specific immune response produced by a host, to play a protective effect, which is the so-called DNA vaccine. The results show that relying solely on swine influenza virus HA gene DNA vaccine immunization results were not ideal (low levels of specific antibodies, to attack drug to protect poor), if co-expression of some immune regulatory role of cytokines, or the use of DNA vaccine and then with conventional inactivated vaccines to enhance immunity, you can significantly improve the immunity level of protection. Overall, however, the immune effect of such DNA vaccines is not true that repetition is poor, with the traditional than the whole inactivated virus vaccines are still a certain gap from the laboratory stage to develop a molding products also require a longer time asked.
3) live vector genetically engineered subunit vaccine. At present, this is the people placed great hope, and a possible commercialization of the vaccine. Be used as a carrier including human adenovirus type 5 (human adenovirus 5, HAd5), porcine adenovirus type 3 (porcine adenovirus 3, PAV3), porcine pseudorabies virus (PRV), baculovirus (baculovirus) and so on. One study based on more mature adenovirus vectors genetically engineered swine influenza subunit vaccine, such as the South China Agricultural University and other units in the development of some products have entered the safety assessment of genetically modified and clinical experimental stage, is expected to develop good prospects. Adenovirus vector has many advantages: ① relatively stable particles of adenovirus, the virus genome rearrangement in low frequency in the packaging cells can replicate efficiently; ② good safety has not been found in adenovirus integration with the host genome; ③ adenovirus group than in large (about 36kb), the capacity of exogenous genes are also large (now confirmed that exogenous DNA insert capacity of up to 7.5kb); ④ In addition to adenovirus reproduction in the intestinal and respiratory tract, it also can infect the liver cells, vascular endothelial cells , vascular smooth muscle cells, glial cells and other somatic cells, and, for the receptor cells infected with adenovirus in the mitosis is not strictly required; ⑤ adenovirus vector is very easy to direct the transfer of foreign genes into target cells, allowing their access to effective expression. Study confirmed that, with carrying H1N1 subtype swine influenza virus HA S ~ HNA gene recombinant adenovirus vaccine (2 × 109TCID) on the 40-day-old experimental pigs 2 weeks after immunization, Hl antibody level of more than 1:160, can be effective against the same sub - type swine influenza virulent attacks. It is constantly developing new genetic engineering of live vector vaccine, it is also concentrated efforts to resolve the antigen, the second by the initial immune antibody immune interference, part of the pig cell vaccine allergies and other issues, hoping in the near future of such vaccines can be widely application, as a traditional whole-virus inactivated vaccine supplement.

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