First of all, the body is very small and can generally pass through a bacterial filter. Therefore, the virus was originally called "viral virus" and must be observed under an electron microscope.
Second, there is no cell structure, and the main components are only nucleic acid and protein, so it is also called "molecular biology".
Third, each virus contains only one kind of nucleic acid, either DNA or RNA.
4. There is no productive enzyme system, protein and nucleic acid synthetase system, so we can only use the ready-made metabolic system in the living cells of the host to synthesize our own nucleic acids and protein components.
Fifthly, the assembly of "elements" such as nucleic acid and protein can realize its mass reproduction.
6. In vitro, it can exist as an inanimate biomacromolecule and keep its infectivity for a long time.
Seven, not sensitive to general antibiotics, but sensitive to interferon.
Eight, some viral nucleic acids can also be integrated into the host genome, and induce latent infection.
3. How important is the pathogenicity of the virus?
A: The virus has no cell structure and cannot replicate itself. It can only be replicated with the help of host cells. The main pathogenic mode is direct attack on host cells.
4. What is the meaning of virus genetic characteristics and the development law of virus genetic variation?
Significance: The molecular genetic research of virus began in 1970s. We mainly used gene cloning and sequencing technology to study the genome structure and regulatory function of many viruses, antigenicity and function of protein expressed in virus genome, pathogenic transformation mechanism and drug resistance of viruses. Understanding and solving the biological characteristics, genetic variation, pathogenic mechanism and effective prevention and treatment of viruses at the molecular level have made great progress in virology research.
Studying the genetic law of virus and making use of the characteristics of virus genetic variation can be widely used in medical theory and practice, including the diagnosis, treatment and prevention of viral diseases. Among them, the preparation of specific vaccines such as attenuated live vaccine, genetic engineering vaccine, nucleic acid vaccine and polypeptide vaccine by using virus mutant (attenuated strain) and gene recombinant strain is the most effective measure to prevent viral diseases, and has made great achievements in the history of preventive medicine in the past hundred years. Vaccination against smallpox and the eradication of smallpox on the earth are the best witness.
Law: The basis of transmitting genetic information by nucleic acid lies in the sequence of its bases. Most viruses are RNA single-stranded viruses, and their instability leads to base deletion, exchange,
5. What does virus immunology include and how can it be used for the diagnosis of viral diseases?
A: Molecular virology and immunology.
Tissue culture technology, serology and immunology methods, ultrastructure research, chemical analysis methods and electron microscope technology.
6. What are the principles for determining the pathogens of infectious diseases, especially viral diseases, and how important is it to evaluate the effectiveness of vaccines?
A: Collection and inspection of infectious diseases, isolation, culture and identification of viruses, serological tests, morphological immunology tests and nucleic acid tests.
7. The profound meaning and importance of the physical and chemical characteristics of the virus. Are physical and chemical characteristics used for virus identification?
First, the basic principles of virus identification:
The basic principles of virus identification include: according to the biological characteristics of the virus, such as the shape, size and structure of the virus; According to the host range of the virus and the symptoms of the infected host, determine the host range of the virus; According to the physical and chemical properties of the virus, such as the type of nucleic acid and its resistance to physical and chemical factors, it is identified according to the serological reaction of the virus.
Second, briefly describe the basic principles of virus classification:
The basic principles of classification include:
1, type, structure and molecular weight of nucleic acid;
2. The shape, size and basic structure of the virus body;
3. The sensitivity of virosome to fatty solvents such as ether and chloroform;
4. The relationship between serological characteristics and antigens;
5. Reproductive characteristics of virus in cell culture;
6. Sensitivity to physical and chemical factors other than fatty solvents
7. Epidemiological characteristics
8. What is natural science, including several disciplines, and what is the scientific method?
The science that studies the structure, shape, properties and laws of motion in nature. Generally divided into basic theoretical science and applied technology science. Basic theoretical science includes mathematics, physics, chemistry, astronomy, geology, biology and so on. Applied technology science includes material science, energy science, information science, space science, agricultural science, medical science, engineering technology and so on. The two most important pillars of natural science are observation and logical reasoning. By observing nature and logical reasoning, natural science can guide the laws in nature. If the observed phenomenon is different from the prediction of the law, it is either because the observation is wrong or because the law that has been considered to be correct so far is wrong, and supernatural factors are not considered. According to the traditional usage, natural science can be understood as biological science (involving biological procedures), and physical science (involving the physical and chemical laws of the universe) can be distinguished from chemical science.
9. What is the scientific paradigm? Why did the pathogenicity of virus rise from the main biological characteristics of virus to the interaction between virus and host, which became a major change in scientific paradigm around 1990?
Scientific paradigm is a collection of beliefs, values and technologies. Shared by members of the same group. Refers to the theoretical basis and practical norms on which conventional science operates, and is the world outlook and behavior pattern followed by researchers engaged in a certain science.
Understand the immune function of human body to pathogenic microorganisms, the relationship between infection and immunity and its law; Understand the laboratory diagnosis methods and prevention principles of infectious diseases. Mastering the basic theory, knowledge and skills of medical microbiology can lay a foundation for the study of basic medicine and clinical medicine and help to control and eliminate infectious diseases.
10. What is the connection, difference and importance between the physical and chemical characteristics of the virus? How to determine the spatial structure of virus or protein crystal, and what is the guiding role for drug or vaccine development?
The nature that bacteria can cause diseases is called pathogenicity or pathogenicity. Bacteria that can make the host sick are called pathogenic bacteria or pathogenic bacteria. The pathogenic effect of pathogenic bacteria is related to its virulence, the number of bacteria entering the body, and whether it is a suitable portal and site to invade the body. (1) The virulence of bacteria refers to the pathogenicity of pathogenic bacteria. The material basis of virulence mainly includes invasiveness and toxin. 1. Invasiveness: Invasiveness means that pathogenic bacteria (including conditional pathogenic bacteria) break through the body's defense ability and invade the body. The ability to grow, reproduce and spread in vivo mainly includes the surface structure of bacteria and invasive enzymes. (1) The surface structure of bacteria mainly includes envelope and other surface substances. Capsule has the function of resisting phagocytosis of phagocytes and bactericidal substances in body fluids. Some bacteria have capsule-like substances (thinner than capsules) on their surfaces, such as microcapsules, Vi antigens, K antigens, etc. They all have anti-phagocytosis, anti-antibody and complement effects. (2) fimbriae: Many kinds of Gram-negative bacteria have fimbriae, which can bind to the corresponding receptors on the surface of host cells, adhere to and settle on the mucosal surface, and contribute to bacterial invasion. (3) Invasive enzymes: extracellular enzymes related to pathogenicity produced during the metabolism of some bacteria are secreted around the bacteria. It can help bacteria resist phagocytosis or help bacteria spread in the body. The main invasive enzymes are: 1) plasma coagulase: its function is to convert fibrinogen in plasma into fibrin, so that plasma coagulates. Coagulation is deposited on the surface of bacteria or around lesions to protect bacteria from being swallowed and killed by phagocytes. 2) Hyaluronidase, also known as diffusion factor, can decompose hyaluronic acid which plays an adhesive role in connective tissue. Enlarges the intercellular space and increases the permeability, which is beneficial to the diffusion of bacteria and their toxins to the surrounding and deep layers. 3) Streptokinase, also known as streptokinase, can activate plasma fibrinolytic enzyme to become fibrinolytic enzyme, thus dissolving fibrin clots and making bacteria easy to spread. 4) Collagenase, a proteolytic enzyme, can decompose collagen in connective tissue. Promote the spread of bacteria between tissues. 5) deoxyribonuclease: It can hydrolyze the DNA released when the tissues and cells are necrotic, and make the mucopus thinner, which is beneficial to the spread of bacteria. 6) Other soluble substances: killing white blood cells can kill neutrophils and macrophages; Hemolysin can dissolve cell membrane, and has cytotoxic effect on white blood cells, red blood cells, platelets, macrophages, nerve cells and other cells. 2. Toxins: Toxins of bacteria are the main pathogenic substances of pathogenic bacteria. According to its source, chemical properties and toxic effects, it can be divided into exotoxin and endotoxin. There are also protein and enzymes released by some bacteria, which have similar effects to toxins. (1) exotoxin is a toxic substance synthesized and secreted by bacteria during their growth and reproduction. Exotoxin is mainly produced by gram-positive bacteria, but a few gram-negative bacteria can also be produced. Exotoxins are highly toxic, mostly peptides. Exotoxins produced by different bacteria are highly selective to tissues and cells. It can also cause special pathological changes and symptoms. The chemical properties of exotoxin are protein, which is not heat-resistant, easily destroyed by heat (56℃ ~ 60℃, 20min ~ 2h), unstable in nature and easily inactivated by acid and digestive enzymes. Exotoxin has specific tissue affinity and selectively acts on target tissue, causing specific symptoms and signs. Exotoxin has good antigenicity, ranging from 0.3% to 0.4%. But it still retains the immunogenicity of exotoxin, which is called toxoid. Toxoid can stimulate the body to produce antitoxin and has the function of neutralizing exotoxin. (2) Endotoxin is a structural component of the cell wall of many Gram-negative bacteria (lipopolysaccharide), which will only be released when the bacteria die, rupture, autolysis or artificially lyse. The endotoxin components of various bacteria are basically the same. It consists of lipid A, nonspecific core polysaccharide and bacterial specific polysaccharide (O- specific polysaccharide). Lipid A is the main toxic component of endotoxin. Endotoxin is stable and heat-resistant. It needs to be heated at 160℃ for 2 ~ 4 hours, or boiled with strong acid, alkali or strong oxidant for 30 minutes before it can be inactivated. The antigenicity of endotoxin is weak. Toxins cannot be detoxified with formaldehyde. LPS can stimulate macrophages and vascular endothelial cells to produce IL- 1, IL-6, TNF-α and so on. A small amount of endotoxin can induce these cytokines and cause immune protective reactions such as fever, microvascular dilatation and inflammatory reaction. If a large amount of endotoxin is released, it will often lead to high fever, hypotension shock and disseminated intravascular coagulation. Because the structural components of lipopolysaccharide in the cell wall of all gram-negative bacteria are basically the same, the toxic effects caused by endotoxin are similar. The toxic effect of endotoxin is weak, and it has no strict selective toxic effect on tissues and cells. The pathological changes caused by endotoxin are similar to clinical symptoms, and its main biological activities are: ① pyrogenic effect; ② Leukocytosis; ③ septic shock; ④ Diffuse intravascular coagulation (DIC). (3) Other toxic proteins and enzymes: hemolysin produced by some bacteria can cause hemolysis rings around the colonies on blood plates, such as streptolysin S, α hemolysin and β hemolysin produced by Escherichia coli, and leukocyte killing by staphylococcus and streptococcus can damage and destroy neutrophils, resulting in a decrease in the number of leukocytes during infection.
Crystal determination methods: X-ray crystallography, nuclear magnetic resonance, circular dichroism spectrum and low temperature microscope.
1 1, the consistency between virus pathogenicity and Koch's law and the role of gold standard in vaccine immune protection evaluation?