Tas is a potential retrovirus described in the genome of the "giant intestinal roundworm" Ascaris lumbricoides (Aeby et al. 1986). Tas is the first retrovirus-like element found in any nematode species and received its name standing for transposon-like element of Ascaris (Aeby et al. 1986). Two variant forms present in the germ line - Tas-1 (the most abundant) and Tas-2 - have been characterized and approximately 50 copies are dispersed over about of 20 different chromosomal sites (Aeby et al. 1986). Tas gives the name and belongs to Tas clade (Copeland et al. 2005) within Branch 1 of the Bel/Pao family (Llorens et al. 2009). The genome of Tas is 7.6 Kb in size (7627 bp in length), including LTRs of respectively 256 (5’LTR) and 250 nts (3’LTR). The internal region of this element contains a Primer Binding Site (PBS), complementary to a tRNAArg, a coding region and a Polypurine Tract (PPT) upstream of the 3´LTR (Aeby et al. 1986; Felder et al. 1994). Although the coding region is disrupted by several stop codons and frameshiftings, the distinct gag and pol domains typical of LTR retrotransposons are clearly evident. In the Tas genome has also been identified an env-like gene located adjacent to the 3' LTR (Felder et al. 1994).



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: 453579
Clade: Tas
Cluster or genus: Undetermined
Branch or class: Branch 1
Family: Bel/Pao
System: LTR retroelements
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Ascaris lumbricoides
Cortesy of CDC-DPDx
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Welcome to the Gypsy Database (GyDB) an open editable database about the evolutionary relationship of viruses, mobile genetic elements (MGEs) and the genomic repeats where we invite all authors to contribute with their knowledge to improve and expand the topics.
Cite this project:

Llorens, C., Futami, R., Covelli, L., Dominguez-Escriba, L., Viu, J.M., Tamarit, D., Aguilar-Rodriguez, J. Vicente-Ripolles, M., Fuster, G., Bernet, G.P., Maumus, F., Munoz-Pomer, A., Sempere, J.M., LaTorre, A., Moya, A. (2011) The Gypsy Database (GyDB) of Mobile Genetic Elements: Release 2.0 Nucleic Acids Research (NARESE) 39 (suppl 1): D70-D74 doi: 10.1093/nar/gkq1061

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