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Sunday, December 05, 2004

Classification of Viruses

Viruses are classified in the following ways:

-- Genome Structure. (This is the main way viruses are classified).
---- DNA viruses (all are double-stranded except Parvoviriridae and Hepadnaviridae)
---- RNA viruses (all are single-stranded except Reoviridea)
-- Shape. Isohedrical, Rod shape, Irregular, or Complex
-- Enveloped or Naked
-- Taxonomy. Informally grouped prior to Family
-- Nomenclature. Uses Family and Genus
-- Species. Includes the common name based on the disease it is associated with and always ends the word "virus". Rabies virus, Polio virus, etc.

Major Characteristics of Bacteriophages
-- Normally complex in shape and are naked viruses
-- Phages can be productive, extruded, or temperate in nature.
-- Has a host of range factors
----attachment protein is needed to bind to a specific receptor site on the bacteria. Normally on the cell wall, but occasionally on the flagella or pilli.
Replication Cycle
Steps of Lytic Replication
-- Replication of animal viruses is the same basic replication pathwa as bacteriophages.
----Differences include:
1) Presence of envelopes around some viruses
2) Eukaryotic nature of animal cells
3) Lack of cell wall in animal cells

-- Assembly and Release of Animal Viruses
----Most RNA viruses develop soley in the cytoplasm
---- Number depends on type of virus and size and initial health of the host cell
---- Enveloped viruses cause persistant infections
---- Naked viruses released by exocytisis may cause lysis and death of the host cell


At 11:47 PM, Blogger sonu said...

classification and techniques of virues,importance of viruses.
send me notes on adityakashyap798@rediffmail.com student of microbaiology,sec-45 ,noida U.P,India

At 7:07 AM, Blogger Hari Prasad Chaudhary said...

Here is the Notes on Virus, Have a Look => Virus – Characteristics and Transmission


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