Senior two biology examination questions

Vaccine refers to the preventive biological products of vaccine used for human inoculation to prevent and control the occurrence and prevalence of infectious diseases.

Vaccines are divided into two categories. Category I vaccines refer to vaccines provided by the government to citizens free of charge and accepted by citizens in accordance with government regulations, including vaccines determined by the national immunization program, vaccines added by the people's governments of provinces, autonomous regions and municipalities directly under the Central Government in the implementation of the national immunization program, and vaccines organized by people's governments at or above the county level or their health authorities for emergency vaccination or mass vaccination; The second category of vaccines refers to other vaccines that citizens voluntarily vaccinate at their own expense.

Vaccine is an active immune preparation made of pathogenic microorganisms (such as bacteria, rickettsia, viruses, etc.). ) and its metabolites are artificially attenuated, inactivated or genetically engineered to prevent infectious diseases. The vaccine retains the characteristics that pathogenic bacteria stimulate the immune system of animals. When animals come into contact with this harmless pathogen, the immune system will produce certain protective substances, such as immune hormones, active physiological substances and special antibodies. When animals come into contact with this pathogen again, the animal's immune system will follow the original memory and produce more protective substances to prevent the harm of pathogens.

The discovery of vaccine is a milestone in the history of human development. Because in a sense, the history of human reproduction is the history of human constant struggle with diseases and natural disasters. Prevention is the most important means to control infectious diseases, and vaccination is considered to be the most effective measure. Facts have proved that smallpox virus, which threatened human beings for hundreds of years, was completely eliminated after the appearance of vaccinia vaccine, which ushered in the first victory of human beings against viruses with vaccines, and also made human beings more convinced of the role of vaccines in controlling and eliminating infectious diseases. In the next 200 years, the vaccine family has been expanding and developing. At present, there are more than 20 kinds of vaccines used for the prevention and treatment of human diseases, which are divided into traditional vaccines and new vaccines according to their technical characteristics. Traditional vaccines mainly include attenuated live vaccines and inactivated vaccines, while new vaccines are mainly genetic vaccines.

Biological products refer to preparations made from microorganisms or their toxins, enzymes, human or animal serum and cells for prevention, diagnosis and treatment. Biological products used for vaccination include vaccines, vaccines and toxoids. Among them, the vaccine is made of bacteria; Vaccines are made of viruses, rickettsia and spirochetes, sometimes collectively referred to as vaccines.

An artificial active immune preparation

1. Dead vaccine

Choose bacteria, viruses, rickettsia and spirochetes with good immunogenicity, cultivate them artificially, and then kill them by physical or chemical methods. The vaccine lost its reproductive ability, but retained its immunogenicity. The dead vaccine can't grow and reproduce after entering the human body, and the stimulation time to the body is short. To obtain lasting immunity, repeated vaccination is needed.

2. Live vaccine

Live vaccine or attenuated live vaccine is made by artificial directional mutation or screening live microorganisms with weakened toxicity or basically non-toxic from nature. Commonly used live vaccines include BCG, measles vaccine and polio vaccine. After inoculation, it can grow and reproduce in the body, close to natural infection, and can stimulate the body's lasting immunity to pathogens. The dosage of live vaccine is small, and the immune duration is long. The immune effect of live vaccine is better than that of dead vaccine.

3. Subunit vaccine (component vaccine)

Vaccine is made by removing the components of pathogens that have no protective immune function or even harmful, and retaining their effective immunogen components. Influenza virus can be cracked by chemical reagents and made of hemagglutinin and neuraminidase. A subunit vaccine was made from meningococcal membrane polysaccharide.

4. Gene recombination vaccines

It is made by genetic engineering technology, such as inserting the gene encoding HBSAg into yeast genome to make recombinant hepatitis B vaccine. Gene recombination can also produce more kinds, cheaper, safer and more effective vaccines or multivalent vaccines.

5.DNA vaccine

DNA vaccine is to clone all or part of protein antigen gene of pathogen or tumor into eukaryotic expression vector and inject it directly into the body, so that its antigen can stimulate the body to produce immune response after being expressed in vivo. The preparation method is simple, safe and effective. Since the appearance of 1992, two kinds of DNA vaccines have appeared in the market.

6. Toxoid

After formaldehyde treatment, extracellular toxins lose their toxicity and still retain their immunogenicity, so they are toxoid. A proper amount of aluminum phosphate and aluminum hydroxide are added to obtain the adsorption refined toxoid. Slow absorption in the body can stimulate the body for a long time, produce higher titer antibodies and enhance the immune effect. Commonly used toxoids include diphtheria toxoid and tetanus toxoid.

Passive immune preparation

1. antitoxin

2. Antibacterial serum and antiviral serum

3. Gamma globulin

4. Specific immunoglobulin

5. immune RNA

6. Transfer factor

7. Thymosin

8. Interferon

Both artificial active immunity and artificial passive immunity can increase the body's disease resistance, but the latter lasts for a short time and is mainly used for treatment and emergency prevention.