Difference between revisions of "Retroviridae"

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#REDIRECT[[:Category:Retroviridae]]
 
 
{{toplink
 
|linkpage =Viruses
 
|linktext =VIRUSES
 
|pagetype=Bugs
 
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<br>
 
 
 
=Introduction=
 
Retroviruses are persistent, non-cytopathic, systemic viruses that give rise to secondary disease, such as tumors, immune-complex disease, or immunosuppression.
 
 
 
=Morphology=
 
*Fragile, enveloped RNA viruses with roughly spherical spike proteins
 
*Genome has 3 genes:
 
**''gag'': group-specific antigen coding gene, encodes capsid proteins
 
**''pol'': encodes reverse transcriptase (RT) and integrase
 
**''env'': encodes envelope spikes, and can be used in diagnosis and subunit vaccines
 
*Both ends of genome show a promoter (LTR: long terminal repeat)
 
 
 
=Virulence and Pathogenesis=
 
*Replication involves integrating into the host cell genome:
 
**'''Uncoating''' to release RNA and RT
 
**+RNA '''transcribed''' to -DNA by RT
 
**-DNA becomes circular dsDNA and is '''integrated''' into host chromosome by integrase
 
**DNA '''codes''' for viral proteins using cellular organelles and enzymes
 
**Because of this technique, virus replication is much '''slower''', and retroviruses can remain '''latent'''
 
*Tumor production takes 2 forms:
 
**Viruses can carry oncogenes within their genome --> tumor production occurs quickly
 
**Insertion of the viral LTR switches on proto-oncogenes in the host cell genome --> tumor production can take years
 
 
 
=Types and Subtypes=
 
7 Genera, including these of veterinary relevance:
 
#Mammalian Type C retrovirus
 
#*[[Feline Leukemia Virus (FeLV)]]
 
#*Feline sarcoma virus (rare)
 
#*Porcine type C oncovirus (rare)
 
#Mammalian Type D retrovirus
 
#*[[Sheep Pulmonary Adenomatosis]]
 
#Avian Type C retrovirus
 
#*[[Avian Leukosis Virus]]
 
#Spumavirus
 
#*Feline and bovine syncitial viruses (common, nonpathogenic)
 
#BLV-HTLV retroviruses
 
#*Bovine Leukosis Virus
 
#Lentiviruses
 
#*[[Feline Immunodeficiency Virus (FIV)]]
 
#*Bovine Immunodeficiency Virus
 
#*[[Visna-Maedi Virus of Sheep]]
 
#*[[Caprine Arthrirtis Encephalitis Virus]]
 
#*[[Equine Infectious Anemia]]
 
#*Jembrana of Bali cattle
 
#*Human Immunodeficiency Virus (HIV)
 
 
 
=Antigenicity=
 
*Group-specific antigens (gag's) are shared by all isolates of each virus
 
**This can be exploited by diagnostic tests
 
*Lentiviruses show variation by mutation, making vaccination difficult
 

Latest revision as of 12:00, 23 May 2010