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