What kinds of virus vaccines are there?

Any preparation with antigenicity, which can produce specific active immunity and resist the occurrence or prevalence of infectious diseases is called vaccine.

Classification of vaccines: At present, there are four categories.

Traditionally, biological products that can stimulate the body to produce specific antibodies or cellular immunity against pathogenic microorganisms after attenuated or inactivated are collectively called vaccines. But from the specific concept, biological products made of bacteria are called bacterial vaccines (vaccines), while biological products made of viruses, rickettsia, spirochetes and so on. It's called a vaccine Traditional vaccines include inactivated vaccine and attenuated live vaccine.

1. Inactivated vaccine: select pathogenic microorganisms with strong immunogenicity, cultivate them, inactivate them by physical or chemical methods, and then purify them. Viruses used in inactivated vaccines are generally virulent strains, but attenuated strains also have good immunogenicity, such as the inactivated polio vaccine produced by Sabin attenuated strain. Inactivated vaccine has lost its infectivity to the body, but it still maintains its immunogenicity, which can stimulate the body to produce corresponding immunity and resist the infection of wild strains. Inactivated vaccine has good immune effect, and can be stored for more than one year at 2 ~ 8℃, and there is no risk of virulence reversal. However, the inactivated vaccine cannot grow and reproduce after entering the human body, and the stimulation time to the human body is short. In order to obtain strong and lasting immunity, adjuvants are generally needed, and many large doses of injections are needed, lacking local immune protection from natural infection. Include bacteria, viruses, rickettsia and toxoid preparations.

2. Attenuated live vaccine: It is a vaccine made by artificial directional mutation or screening highly attenuated or basically nontoxic living microorganisms from nature. After the live attenuated vaccine is inoculated, it has a certain growth and reproduction ability in the body, which can make the body produce a reaction similar to recessive infection or mild infection, but it does not produce clinical symptoms. The immune effect is strong and lasting. Generally, it only needs to be inoculated once, and the dose is small. In addition to stimulating the body to produce cellular immunity and humoral immunity, it can also produce local immune protection. However, the attenuated live vaccine must be stored and transported at low temperature, and its validity period is relatively short, so there is a risk of virulence reversion.

3. Subunit vaccine: Among all kinds of specific antigenic determinants carried by macromolecular antigens, only a few antigenic sites play an important role in protective immune response. Natural protein is separated by chemical decomposition or controlled protein hydrolysis, and the special protein structure of bacteria and viruses is extracted, and the vaccine made of immune active fragments is screened out, which is called subunit vaccine. Subunit vaccine has only a few main surface proteins, so it can eliminate many antibodies induced by unrelated antigens, thus reducing the side effects of vaccine and related diseases caused by vaccine. Group A meningococcal polysaccharide vaccine and typhoid Vi polysaccharide vaccine are relatively early subunit vaccines, which reduce the adverse reactions in the use of whole bacteria vaccine. In addition, the immune effect and safety of influenza split vaccine have been affirmed in the wide application at home and abroad. The disadvantage of subunit vaccine is its low immunogenicity, and it needs to be combined with adjuvant to produce good immune effect. Therefore, if the whole bacteria (virus) vaccine has no serious adverse reactions, it should still be the first choice.

4. Genetic engineering vaccine: It is a vaccine that uses DNA recombination biotechnology to directionally insert natural or synthetic genetic materials that can induce immune response in the shell of pathogens into bacteria, yeast or mammalian cells, fully express them, and then purify them. Genetic engineering technology can be used to produce subunit vaccines without infectious substances, stable attenuated vaccines with live viruses as carriers and multivalent vaccines that can prevent many diseases. This is the second generation vaccine after the first generation of traditional vaccine, which has the advantages of safety, effectiveness, long immune response time and easy realization of combined immunization. At present, both hepatitis A and hepatitis B vaccines developed by our school are genetic vaccines.