What are the main classifications of viruses?
What are the main classifications of viruses?
Baltimore Classification
- Group I viruses contain double-stranded DNA (dsDNA) as their genome.
- Group II viruses have single-stranded DNA (ssDNA) as their genome.
- Group III viruses use dsRNA as their genome.
- Group IV viruses have ssRNA as their genome with a positive polarity.
Who proposed the classification of virus?
A Classification of Viruses One general scheme of virus classification was proposed by Lwoff, Horne, and Tournier (1962) and Lwoff and Tournier (1966), based on the characteristics of the virion.
What is the most important factor of virus classification?
Because the viral genome carries the blueprint for producing new viruses, virologists consider it the most important characteristic for classification.
How are viruses classified by size?
Most viruses vary in diameter from 20 nanometres (nm; 0.0000008 inch) to 250–400 nm; the largest, however, measure about 500 nm in diameter and are about 700–1,000 nm in length. Only the largest and most complex viruses can be seen under the light microscope at the highest resolution.
What are the 5 characteristics of a virus?
These are: 1) attachment; 2) penetration; 3) uncoating; 4) replication; 5) assembly; 6)release. As shown in , the virus must first attach itself to the host cell. This is usually accomplished through special glycoprotiens on the exterior of the capsid, envelope or tail.
How are viruses classified and why?
Virus classification is based mainly on characteristics of the viral particles, including the capsid shape, the type of nucleic acid (DNA or RNA, double stranded (ds) or single stranded (ss)) within the capsid, the process of replication, their host organisms, or the type of disease they cause.
What are the two main parts of a virus?
The most important part is a small piece of DNA or RNA (never both). That strand of nucleic acid is considered the core of the virus. The second big part is a protein coat to protect the nucleic acid. That coat is called the capsid.
What are the 3 components of a virus?
Viral Structure. In the simpler viruses the virion consists of a single molecule of nucleic acid surrounded by a protein coat, the capsid; the capsid and its enclosed nucleic acid together constitute the nucleocapsid.
What is the classification of virus?
Classification of virus. February 4, 2019 by. Viruses are small obligate intracellular parasites, which by definition contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat. Viruses range from the structurally simple and small parvoviruses and picornaviruses to the large and complex poxviruses and herpesviruses.
How do you classify viruses by their capsid structure?
Virus Classification by Capsid Structure 1 Naked icosahedral: Hepatitis A virus, polioviruses 2 Enveloped icosahedral: Epstein-Barr virus, herpes simplex virus, rubella virus, yellow fever virus, HIV-1 3 Enveloped helical: Influenza viruses, mumps virus, measles virus, rabies virus 4 Naked helical: Tobacco mosaic virus
What are the two main types of virus projections?
Two main types: •Glycoproteins that form the projections know as spikes •Matrix protein –layer on inside envelope-added rigidity •No envelope = naked virus, hydrophilic -so are protected from organic solvents BacteriophagesBacteriophages T2 T4 Properties of VirusesProperties of Viruses •Small – can pass through 0.22μm filters -20 -350nm in szei
Are there any unclassified viruses that cause nonbacterial infections?
Several viruses of medical importance still remain unclassi fied. Some are difficult or impossible to propagate in characterization. Hepatitis E virus, the Norwalk virus and similar ag ents (see Ch. 65) that cause nonbacterial