Virology
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Virology (virology, English: virology) is one of the biology dealing with non-cellular organisms (viruses, viroids, etc.). With the spread of the new coronavirus infection, further development in this field is expected.
Viruses are currently classified as microorganisms, but their handling is often too different from existing biological cells. Therefore, a special experimental system that specially treats only viruses is required.
Classification method
The taxonomy proposed by Andre Michael Lwoff et al. In 1962 is the most widely used. According to this classification method, viruses are classified according to the properties of virions. A virion is an extracellular state of a virus, which is metabolically inactive but is an infectious agent.
The classification criteria are as follows.
Nucleic acid type (DNA or RNA)
Structure of capsid (shell composed of virion protein)
Presence or absence of envelope (lipid surrounding the capsid)
The size of the capsid Furthermore, as a feature other than the virion
Number of nucleic acid chains
Characteristics of virus formation
Host-viral interaction Also, the type of normal host
Microorganisms
animal
Even plants are classified. However, it is not possible to draw an evolutionary tree by the above classification.
Proliferation
Cells infected with virus cause lysis and release a large number of virus particles. For bacterial viruses, the bacteria that caused lysis form lytic spots (also called lysate or plaque) on the agar plate. The method of confirming growth using plaque is used to isolate the virus from nature.
In addition, the virus shows one-stage growth that explosively grows by an order of magnitude after a certain period of time, instead of logarithmic growth like microorganisms. With this one-step proliferation experiment, data such as the time required for virus formation can be obtained.
Separation
In addition to the plaque method, a method of filtering a natural sample by 0.22 μm or performing a chloroform treatment by taking advantage of the fact that virion is chloroform-resistant is adopted. However, the plaque method is finally used to confirm the separation. If the accuracy of separation is to be improved, the plaque method is repeated. To collect virions purely, density gradient centrifugation, which is similar to collecting plasmids and short nucleic acids, is used.
Pathogenicity
Viruses that infect humans cause many diseases, but oncoviruses that cause tumors have also been discovered. The presence of oncovirus was suggested in 1908 for chicken leukemia. By Bittner in 1936
Organisms infected with the tumor virus at birth do not develop tumors until maturity
It has been clarified that the tumor induction of the virus depends on specific environmental factors (hormones, etc.) such as the physiological characteristics of the host.
Also, in recent years, the existence of new pathogenic viruses such as SARS and avian influenza has begun to be generally recognized. The pathogenicity of the virus is said to be enhanced by mutation and many hosts.
Related items
virus
History of virology, social history of viruses
DNA virus / RNA virus
Microbiology / Bacteriology (Oral Bacteriology)
Genetics / Immunology
Medicine / Dentistry
Mycoplasma
Malignant tumor
Human immunodeficiency virus
Japanese Society of Virology
External link
Japanese Society of Virology
Japanese Society of Clinical Microbiology
Clinical Microorganism Rapid Diagnosis Study Group
Japanese Society of Tropical Medicine
Japan Society for Infectious Diseases
Japanese Society for Infection Control
