Nucleic acid vaccine is also called gene vaccine or DNA vaccine. Because nucleic acid vaccine does not need carrier and adjuvant when it is injected into muscle, it is also called naked nucleic acid vaccine. By intramuscular injection, this kind of vaccine can obtain more lasting antigen expression in muscle cells. This antigen can induce antibody production, T cell proliferation and cytokine release, especially the cytotoxic T cell (CTL) killing effect. The specific immune response mediated by cytotoxic T cells plays an important role in anti-tumor, anti-virus and elimination of intracellular parasitic infection. Among the numerous vaccines, nucleic acid vaccine has attracted much attention due to its unique advantages.

With the rapid development of molecular biotechnology, biochemistry, genetics and immunology, the theoretical basis and technical level of vaccine development have been constantly improved and improved. Some traditional classical vaccine varieties have been further transformed into new vaccines, while others that cannot be developed with classical technologies have found ways to solve the problem. Therefore, subunit vaccines, recombinant vaccines, nucleic acid vaccines and other new vaccines for different infectious diseases and non infectious diseases are constantly coming out.

The great contribution of Pasteur, known as the father of vaccines, is that he selects pathogenic microorganisms with strong immunogenicity to be cultured, inactivated by physical or chemical methods, and then purified. Inactivated vaccines generally use strong strains, but attenuated weak strains also have good immunogenicity, such as the inactivated polio vaccine produced with Sabin attenuated strains. Live attenuated vaccine is a kind of vaccine which is made of live microorganisms with highly weakened virulence or basically non-toxic selected from nature by means of artificial directional mutation, and is used to inoculate people to prevent infectious diseases.

In the long history of human beings, people have been seeking ways to get rid of various plagues and diseases, but there is only a short history to fight against diseases through vaccination. It was not until the 20th century that the routine vaccination of large populations was gradually popularized, and was increasingly widely known and accepted by the public.

According to their different physical states, culture media can be divided into four categories: liquid, fluid, semi-solid and solid. The physical state of culture media depends on whether coagulant is added to the culture media or the amount of coagulant added.

Due to the wide variety of microorganisms, the demands for nutrients are different, and the required culture media are complex and diverse. According to incomplete statistics, there are about 1700 kinds of commonly used culture media at present. Moreover, with the development of biological science, the types of culture media are constantly increasing. At present, the classification method of culture medium is not unified, and it is usually distinguished according to the composition, physical state and use of culture medium.

Biopharmaceutical is the use of biotechnology to produce natural active substances in living organisms. Its effective ingredients are usually some bioactive proteins, DNA, viruses, cells or tissues, etc. the administration method is direct tissue injection. The preparation of drugs is very dependent on the direct culture of biological tissues / cells and usually cannot be accurately replicated.