The Brief Downstream Purification Process Of Foot-and-mouth Disease Vaccine
Foot-and-mouth disease (FMD) is an acute, hot and highly contagious infectious disease caused by foot-and-mouth disease virus, which can infect almost all cloven-hoofed animals (pigs, cattle and sheep, etc.). It is the most infectious animal disease found so far and the most harmful to animal husbandry.
The main routes of transmission of foot-and-mouth disease are the digestive and respiratory tract, damaged skin, mucous membranes and intact skin (e.g. breast skin), mucous membranes (eye conjunctiva). It can also be transmitted through the air, as well as through urine, milk, semen and saliva. The prevention and control of foot-and-mouth disease in our country is mainly through vaccination, and the outbreak of foot-and-mouth disease is hunted. Vaccination is an effective means of specific prevention of foot-and-mouth disease.
Vaccination is a reliable and effective means of specific prevention of foot-and-mouth disease, and a safe and effective vaccine is a prerequisite for the successful prevention, control and eventual elimination of foot-and-mouth disease. Attenuated and inactivated vaccines and other conventional vaccines have good immunogenicity and play an important role in the prevention and control of foot-and-mouth disease. However, outbreaks of foot-and-mouth disease in some parts of the world seem to be related to the residual live virus in inactivated vaccines due to unsafe factors such as strong viral virulence, incomplete inactivation of viruses, and live virus escape processing plants. Prompting the search for a safer and more effective foot-and-mouth vaccine. With the rapid development of molecular biology technology, foot-and-mouth disease virus (FMDV) genetic engineering vaccines, such as subunit vaccine, feedable vaccine, synthetic peptide vaccine, protein carrier vaccine, gene deletion vaccine, live carrier vaccine, nucleic acid vaccine, etc., are emerging.
Production process of attenuated/inactivated foot-and-mouth disease vaccine
Production technology of genetic engineering vaccine of foot-and-mouth disease virus
Clarification filtration
Deep filtration membrane: Filtration technology is widely used in the production process of biological products such as vaccines, among which DC filtration technology is usually used in the harvest process of disease venom to separate insoluble impurities such as cell debris. In the early FMDV clarification, the surface filtration technology represented by the folding membrane filter element was mainly adopted. With the change of culture conditions, the increase of cell debris impurities, surface filtration is difficult to achieve the clarification effect, and because the surface filtration load is low, the cost of filter materials is becoming higher and higher.
Under the above background, deep filtration has been applied more and more in the process of cytoliquid separation of FMDV, and is one of the most widely used harvesting methods at present. The deep filter membrane is usually composed of cellulose, porous filter AIDS (such as diatomaceous earth) and positively charged ion filter AIDS, and the channels formed after the film are often very tortuous, similar to the labyrinth aperture structure. Impurity particles are often trapped inside the filter material rather than on the surface, and the wall of the filter channel often absorbs some extremely fine particle impurities by electrostatic action or intermolecular force. Due to the addition of some filter AIDS, deep filtration can also remove some soluble impurities, thereby reducing the pressure of subsequent purification steps.
However, when the cultivation scale is too large, a large number of deep filter membranes will be required, resulting in a substantial increase in the cost of consumables. At the same time, the high density of cell culture will reduce the load of the deep filter membrane, resulting in increased costs and excessive product dilution.
Microfiltration Microfiltration method, the main use of tangential flow filtration device, membrane components are flat membrane cassette and hollow fiber. Tangential flow filtration (TFF) is driven by the transmembrane pressure difference. Substances and impurities smaller than the membrane pore size pass through the membrane, while impurities such as cells with larger particles are trapped. The pore size of the membrane used for microfiltration is 0.45/0.22μm. Hollow fiber tangential flow microfiltration can directly process high solid content liquid, such as high-density cell culture medium, can eliminate centrifugation and pre-filtration steps, fewer steps, simple operation, membrane can be used repeatedly through cleaning, reducing equipment investment and operating costs, in line with the requirements of modular automated production.
Ultrafiltration(Concentration change)
Ultrafiltration can remove some small molecular weight of miscellaneous proteins and process related impurities, such as inactivators, and greatly reduce the volume of harvested liquid, which is conducive to subsequent process operations. Ultrafiltration method, the main use of tangential flow filtration device, membrane components have membrane envelope and hollow fiber two, under normal circumstances, the application of ultrafiltration system can make the virus concentration of more than 100 times, the removal rate of miscellaneous proteins up to 99%. Among them, hollow fiber membrane components have the advantages of mild and low shear force, not easy to plug, flexible operation, long life and low cost, and easy to enlarge, so it is recommended to choose hollow fiber for virus enrichment and purification.
When using ultrafiltration method to concentrate liquid, it is very important to select a suitable membrane aperture, which directly determines the efficiency of concentration and product quality. On the one hand, it is necessary to select the membrane aperture to effectively trap the target molecules to ensure the yield, and on the other hand, the removal effect and processing speed of heteroproteins should be fully considered. Therefore, the best principle is to select the membrane with the largest pore size that can trap the target molecule, and try to select the filter membrane with uniform pore size distribution.
For attenuated/inactivated FMD vaccines, the 100-750kd aperture ultrafiltration membrane is generally used to complete the interception of FMDV. For FMD genetically engineered vaccines, a membrane aperture 3-6 times (preferably 5 times) of the molecular weight of the target substance is generally selected.
Guidling Technology
Hangzhou Guidling Technology Co., Ltd. is a production-oriented national high-tech enterprise focusing on the downstream clarification, separation and purification of biopharmaceuticals. Products are widely used in vaccines, monoclonal antibodies, diagnostics, blood products, serum, endotoxin and other biological products filtration process; We have "flat membrane cassette", "hollow fiber column", "Tangential flow filter device", "virus filter", "deep membrane stack", "bacteria filter" and other products; We have a wide range of product lines, from small disposable laboratory filtration to production filtration systems, to meet the needs of testing and production. Guidling Technology is looking forward to cooperating with you!
