What are viruses: Viruses are a relatively primitive, non-cellular organism with life characteristics, capable of self-replication and strict intracellular parasitism. Subviruses are divided into viroids, mimetic viruses, and prions.

Characteristics that distinguish viruses from other microorganisms: 1. Lack of cellular structure. 2. Contains only one kind of nucleic acid. 3. Virus reproduction relies on its own nucleic acid replication and expression to produce progeny viral nucleic acids and proteins, which are then assembled into complete viruses. 4. Lack of enzyme system and energy production mechanism to complete metabolism. 5. Not sensitive to general antibiotics, but sensitive to interferon. 6. Certain viral nucleic acids can be integrated into the host's DNA.

The development of virology: divided into four periods: the experience period, the development period of viruses, the research period of the nature of viruses, and the modern virus period.

The significance of studying viruses: 1. Control and eliminate viral diseases. 2. Use viruses for biological control. 3. Deepen your understanding of the nature of life.

Virus morphology: Measurement units: microns. Methods for studying virus size: 1. Electron microscopy measurement. 2. Graded ultrafiltration method. 3. Ultracentrifugal precipitation method. 4. X-ray crystal diffraction analysis method. The shapes of viruses are divided into spherical or oval, rod-shaped, brick-shaped, filament-shaped, and tadpole-shaped.

Structural characteristics of the virus: 1. Structural composition: Basic structure: nucleocapsid (core + capsid) + non-basic structure envelope. 2. Three-dimensional structure: spiral symmetry type, icosahedral three-dimensional symmetry type, consistent symmetry type.

Chemical composition of viruses: nucleic acids, proteins, lipids

Virus culture: strictly intracellular parasitism, it must be in living cells to grow and proliferate. 1. Animal vaccination. 2. Uses of animal vaccination: research on the pathogenicity of viruses, research on drug treatment of viral diseases, analysis of vaccine immune protection effects, preparation of antisera and cloned antibodies.

Chicken embryo vaccination: Characteristics and uses of chicken embryo vaccination: Chicken embryo tissue has a low degree of differentiation and young cells, which are more conducive to virus infection and proliferation. 1. Isolate and culture the virus. 2. Identification and titer determination of the virus. 3. Chicken embryos are inoculated with viruses to prepare vaccines and diagnostic antigens.

Bird embryo inoculation routes and methods: 1. Allantoic cavity inoculation 2. Chorioallantoic membrane inoculation 3. Yolk sac inoculation 4. Amniotic cavity inoculation.

Cell culture; concept: using mechanical, enzymatic, and chemical methods to disperse animal tissues or passaged cells into single or even 2-4 cell mass suspensions for culture. The advantages of using cells cultured in vitro to propagate viruses: 1. Each cell has basically the same physiological characteristics and equal susceptibility to viruses. 2. No individual differences, good accuracy and repeatability. 3. Strictly implement aseptic operation and the culture conditions are easy to control. 4. Direct observation of cell changes shows the growth characteristics of the virus. 5. Plaque technology can be used to detect and quantify viruses. 6. It can be inoculated in batches, which improves the yield and quality of the virus.

Types of cell culture: 1. Primary cells 2. Diploid cells 3. Passage cells. Cell culture methods: 1. Exquisite culture 2. Rotation culture 3. Suspension culture 4. Microcarrier cell culture

Proliferation effects of viruses in cultured cells: 1. Cell shedding and morphological changes 2. Cell aggregation into clusters 3. Intracellular vacuole formation 4. Formation of multinucleated giant cells 5. Inclusion bodies

Quantitative determination of viruses--Determination of virus disease price: Methods for determining the number of viable viruses in virus fluids: plaque method, plaque method

1. The virus uses its gene as a template in a cell, and under the action of enzymes, it synthesizes viral genes and proteins respectively, and then assembles them into complete virus particles. This method is called replication. 2. The replication process from the adsorption of the virus to the host cell to the production of mature progeny viruses that are released from the infected cell to the outside of the cell is called a replication cycle. 3. The virus replication cycle mainly includes six consecutive steps: adsorption and penetration, uncoating, biosynthesis, assembly and release.

The multiplication process of viruses: adsorption, invasion, uncoating, biosynthesis, assembly, and release.

Heredity and mutation of viruses: One thing about viruses: it refers to the similarity between the parent virus and the offspring virus. It keeps the characteristics of the virus stable and is the basis for the existence of various viruses. Virus mutation: refers to the differences between parent and offspring and offspring viruses, allowing the virus to develop and evolve.

Virus mutation mechanism: Virus mutations are divided into conditional lethal mutants, host range mutants, plaque mutants, drug-resistant mutants, and defective interference mutants. Genetic recombination of viruses is divided into intramolecular recombination, reassortment, resurrection, and gene integration. Viral nongenetic variation: complementation, phenotypic mixing, and phenotypic interchange.

The biological significance of viral genetic variation: 1. Application in re-study of viral pathogenesis 2. Application in diagnosis of viral diseases 3. Application in treatment of viral diseases 4. Application in prevention of viral infection 5. Application in genes Application in engineering 6. Application in basic theoretical research on genetics.

The influence of physical and chemical factors on viruses: Physical factors: temperature, PH, rays and ultraviolet rays. Chemical factors: lipid solvents, chemical disinfectants, antibiotics and Chinese herbal medicines.

During inactivation, only the nucleic acid of the virus is destroyed, and the effect on the protein is small. The virus only loses its infectivity, but still maintains its antigenicity, hemagglutination, cell transformation, cell fusion, induction of interferon and other biological characteristics. .

Types and mechanisms of virus infection: The virus invades the host in a certain way, replicates and expresses genes in the host's susceptible cells, and spreads further in the host body. Types of viral infections are divided into latent infection and overt infection, acute infection and persistent infection, latent infection, chronic infection, and lentiviral infection.

How the virus invades and spreads: the infection route of the virus, the spread of the virus in the body, the tissue affinity of the virus, the shedding and spread of the virus

The pathogenic mechanism of viral infection: viral infection has the pathogenic effect of host cells, the immunopathological effect caused by viral infection, the immunosuppressive effect caused by viral infection, and the autoimmunity caused by viral infection.

Baltimore Classification

ICTV classification

Principles and basis of virus classification: 1. Principle: Emphasis on stability, practicality, recognition and flexibility. 2. Classification basis: 1. Characteristics of virus particles 2. Viral antigenic substances 3. Biological characteristics of viruses

Virus naming and writing rules

1. Collection and submission of specimens for inspection: pay attention to sampling timing and sampling parts

2. Isolation and identification of viruses: The isolation and culture of viruses are divided into: cell culture, chicken embryo culture, and animal inoculation. Morphological identification of viruses: electron microscopy, light microscopy. Virus serology identification: identification of virus species, types, and subtypes.

Serological diagnosis of viral infection: 1. Neutralization test: virus + neutralizing antibody = virus loses infectivity. 2. Complement fixation test. Rapid diagnosis of viral infection: 1. Morphological examination 2. Viral component detection 3. Early antibody detection.