Element:HTLV-2

From The Gypsy Database

Description

Human T-Lymphotropic Virus Type 2 (HTLV-2) is a complex retrovirus originally identified in a T-cell line from a patient with hairy-cell leukemia (Kalyanaraman et al. 1982). Along with the HTLV-1, this retrovirus presents lymphocyte tropisms, and also induces chronic lymphocytic leukemia in human T cells. Two major and closely related molecular subtypes of HTLV-2 designated HTLV-2A and 2B have been described differing in the p21 ENV gene by 4%. HTLV-2A is mainly present in intravenous drug addicts of United States, while 2B is found primarily in the native populations of North, Central, and South America. Both HTLV-2 subtypes are present in Africa. Most recently, a divergent variant of subtype A, termed HTLV-2C, has also been described in Amerindian tribes and Brazil (Dube et al. 1993; Hall et al. 1994; Pardi et al. 1995; Poiesz et al. 1993; Switzer et al. 1995; Eiraku et al. 1996; Covas and Kashima 2003).

The genomic structure of HTLV-2 is 8.9 Kb in size including LTRs of 0.7 Kb. The internal region displays a Primer Binding Site (PBS) complementary to a tRNAPro; Open Reading Frames (ORFs) for gag, pol and env genes characteristic of retroviruses. HTLV-2 displays a region termed the pX region, which contains the accessory genes rex and tax (both essential for viral replication and cellular transformation in infected cells), as well as two ORFs that encode for the proteins Tof and Rof (see accessory genes), and the Polypurine Tract (PPT) common to all retroviruses (Shimotohno et al. 1984; Covas and Kashima 2003).

Structure

Htlv-2.png


Figure not to scale. If present, long terminal repeats (LTRs) have been highlighted in blue. Amino acid motifs noted with lines indicate the conserved residues in each protein domain, abbreviations below mean:

MA=matrix PR=protease DU or DUT=dUTPase TM=transmembrane TAV or IBMP=transactivator/viroplasmin or inclusion body matrix protein
CA=capsid RT=reverse transcriptase INT=Integrase CHR=chromodomain
NC=nucleocapsid RH=RNaseH SU=surface MOV=movement protein
PPT=polypurine tract PBS=primer binding site ATF=aphid transmission factor VAP=virion associated protein

Related literature

Genbank accession:AF326584
Clade:Oncovirinae C-type
Cluster or genus:Deltaretrovirus
Branch or class:Class 2
Family:Retroviridae
System:LTR retroelements
Host:
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