Mind Map Gallery Virus
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Virus
This is a mind map that contains information about the virus.
Edited at 2020-10-08 06:40:30
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- Outline
Virus
Characteristics
- smaller than bacteria
- not retained by bacterial filters
- not visible in the light microscope
- smaller than bacteria
- not retained by bacterial filters
- not visible in the light microscope
- obligately intracellular parasites
- virion : intact, fully assembled, infective virus
- viroid : piece of RNA without a protein coat
HostRange
- infect invertebrates, vertebrates,plants, protest, fungi or bacteria
- narrow host range
- determined by presence ofspecific receptors on the cell
- some are very specific
Size
- smaller than bacteria
- wide range
GeneralMorphology(capsidarchitecture)
- helical viruses
- polyhedral viruses
- enveloped viruses
- complex viruses
Bacteriophages
- lytic cycle
- host cells lyse and die
- lysogenic cycle
- host cell remains alive
Isolation and Cultivation
- growth of bacteriophages
- plaque method : mixbacteriophages with host bacteriaand nutrient agar
- quantifying viruses
- plaque assay : the number of plaque directlyrelates to numbers of infectious virus particlesapplied to the plate
- growth of animal viruses
- in living animal hosts
- in embryonated eggs
- in cell cultures
- viral infections
- infection by individual human viral pathogens
- patterns of viral infection or disease
- latent
- persistent
Taxonomy
- used to be classified based onhost preferences
- animal viruses
- plant viruses
- bacterial viruses
- International Commitee forTaxonomy of Virus (ICTV)
- nucleic acid type
- nucleic acid strandedness
- the sense (+ve/-ve) of single stranded RNA
- presence/absence of envelope
- type of host
- names of viruses
- family : ends with viridae
- subfamily : ends with virinae
- genus and sp. : virus
- characteristics to divide virusesinto taxonomic groups
- nature of host
- nucleic acid characteristics
- capsid symmetry
- presence of envelope
- diameter of the virion or nucleocapsid
- number of capsomers in icosahedral viruses
- type of virus release
- with/without tails
- with/without envelope
- presence/absence DNA intermediate
Viral Structure
- nucleic acid
- contain either DNA/RNA but never both
- DNA
- linear – single stranded , double stranded
- circular – single stranded, double stranded
- RNA
- single linear, segmented linear,segmented double strandedlinear
- capsid
- protein coat surrounding the nucleic acid
- composed of subunits, capsomers
- envelope
- covered the capsid
- spikes : structures that protrudeout of the envelope
- protein envelope
- lipid envelope
- carbohydrate envelope
Family
- DNA Virus
- DNA is released into thenucleus of the host cell
- transcription and translationproduce viral DNA
- capsid protein which is synthesisin the cytoplasm
- example : Adenoviruses,Herpesviruses, Papovaviruses andHepadnaviruses
- RNA Virus
- multiplication occurs in the cytoplasm
- dependent RNA polymerasessynthesizes the double strandedRNA
- after maturation, viruses are released bybudding or through ruptures in the host cellmembrane
- example : Picornaviruses,Togaviruses, Rhabdoviruses andRetroviruses
Viruslike Agents
- viroids
- an infectious RNA particlesmaller than a virus
- plant infected
- differ from viruses in six ways
- consists of a single circular RNAmolecule of molecular weight
- exist inside cells as particles
- do not require a helper virus
- does not produce proteins
- copied in the host cell nucleus
- viroid particles are not apparent in infectedtissue without the use of specialtechniques
- prions
- resistant to inactivation byheating to 90 degree celcious
- not sensitive to radiation treatment
- sensitive to protein denaturing agents