Primate T-lymphotropic virus 3

Molecular biology

VIRION

Enveloped. Spherical to pleomorphic, about 80-100 nm in diameter.

GENOME

Monopartite, linear, dimeric, ssRNA(+) genome of 8,9 kb, with a 5’-cap and a 3’poly-A tail. There are two long terminal repeats (LTRs) of about 600nt long at the 5’ and 3’ ends. The LTRs contain the U3, R, and U5 regions. There are also a primer binding site (PBS) at the 5’end and a polypurine tract (PPT) at the 3’end.

GENE EXPRESSION

The integrated provirus utilizes the promotor elements in the 5’LTR to drive transcription. This gives rise to the unspliced full length mRNA that will serve as genomic RNA to be packaged into virions or used as a template for translation of gag, gag-pro (1 ribosomal frameshift), and gag-pro-pol (2 ribosomal frameshifts) polyproteins. The singly spliced mRNA encodes env that is cleaved into SU and TM envelope proteins. Completely spliced mRNAs encode Rex and Tax. Rex escorts unspliced and singly spliced RNAs out of the nucleus of infected cells. Tax is a transcriptional activator that activates viral and cellular genes.

REPLICATION

NUCLEAR

Lytic replication:

  1. Virus attaches to host receptors through the SU glycoprotein. TM glycoprotein mediates fusion with cell membrane.
  2. Internalization and uncoating.
  3. ssRNA(+) genome is copied into a linear dsDNA molecule by the reverse transcriptase.
  4. Nuclear entry of the viral dsDNA which is covalently and randomly integrated into the cell’s genome by the integrase (=provirus).
  5. Transcription of provirus by Pol II produces viral spliced and unspliced RNAs.
  6. Translation of spliced viral RNAs produces tax and rex proteins.
  7. Rex mediates nuclear export of the uncompletely spliced RNAs.
  8. Translation of unspliced viral RNAs produces Env, Gag, Gag-Pro and Gag-Pro-Pol polyproteins.
  9. Assembly of the virion at the host cellular membrane and packaging of the viral RNA genome.
  10. Budding through the plasma membrane and release of the virions.
  11. Proteolytic processing of the precursors polyproteins by viral protease and maturation of the virions.

Latent replication : replication as a provirus integrated in the host chromosome.

Matching UniProtKB/Swiss-Prot entries

12 entries grouped by strain (browse by keywords)

6 entries

Human T-cell leukemia virus 3 (strain 2026ND) (HTLV-3) reference strain

Select_all Deselect_all  
ENV_HTL32Envelope glycoprotein gp63 (Env polyprotein)
GAG_HTL32Gag polyprotein (Pr53Gag)
POL_HTL32Gag-Pro-Pol polyprotein (Pr160Gag-Pro-Pol)
PRO_HTL32Gag-Pro polyprotein (Pr76Gag-Pro)
REX_HTL32Protein Rex (Rev homolog) (Rex-3)
TAX_HTL32Protein Tax-3 (Trans-activating transcriptional regulatory protein of HTLV-3)

6 entries

Human T-cell leukemia virus 3 (strain Pyl43) (HTLV-3)

Select_all Deselect_all  
ENV_HTL3PEnvelope glycoprotein gp63 (Env polyprotein)
GAG_HTL3PGag polyprotein (Pr53Gag)
POL_HTL3PGag-Pro-Pol polyprotein (Pr160Gag-Pro-Pol)
PRO_HTL3PGag-Pro polyprotein (Pr76Gag-Pro)
REX_HTL3PProtein Rex (Rev homolog) (Rex-3)
TAX_HTL3PProtein Tax-3 (Trans-activating transcriptional regulatory protein of HTLV-3)