Betaretrovirus

VIRION

Enveloped, spherical to pleomorphic in shape, 80-100 nm in diameter.

GENOME

Monopartite, linear, dimeric, ssRNA(+) genome of about 8-10 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 promoter 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 spliced mRNAs encode env that is cleaved into SU and TM envelope proteins and sag, a superantigen encoded at the 3’end of the MMTV genome.

REPLICATION

NUCLEAR

  1. Virus attaches to host receptors through the SU glycoprotein. TM glycoprotein mediates fusion with cell membrane.
  2. Internalization and partial uncoating.
  3. ssRNA(+) genome is copied into a linear dsDNA molecule by the reverse transcriptase.
  4. Nuclear entry of the viral dsDNA when the nuclear membrane is disassembled at mitosis.
  5. Viral dsDNA is covalently and randomly integrated into the cell’s genome by the viral integrase (=provirus).
  6. Transcription of provirus by Pol II produces viral spliced and unspliced RNAs.
  7. Nuclear export of the incompletely spliced RNAs.
  8. Translation of unspliced viral RNAs produces Env, Gag and Gag-Pol polyproteins.
  9. Assembly of the virion as intracytoplasmic particles.
  10. Intracytoplasmic particles relocate to the plasma membrane, become enveloped, and are released.
  11. Proteolytic processing of the precursors polyproteins by viral protease and maturation of the virions.

Host-virus interaction

Superantigen

Mouse Mammary Tumour virus expresses a superantigen to evade innate immune response

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Matching UniProtKB/Swiss-Prot entries

31 entries grouped by protein (browse by keywords)

Only complete proteome entries are shown (view all 36 entries)

7 entries

Envelope glycoprotein (Env polyprotein)

Select_allDeselect_all
ENV_MMTVB
Mouse mammary tumor virus (strain BR6) (MMTV) reference strain

Envelope glycoprotein gp70 (Env polyprotein)

ENV_MMTVC
Mouse mammary tumor virus (strain C3H) (MMTV) reference strain

Envelope glycoprotein gp70 (Env polyprotein)

ENV_JSRV
Sheep pulmonary adenomatosis virus (Jaagsiekte sheep retrovirus) (JSRV)
ENV_MPMV
Mason-Pfizer monkey virus (MPMV) (Simian Mason-Pfizer virus)
ENV_SMRVH
Squirrel monkey retrovirus (SMRV-H) (SMRV-HLB)
ENV_SRV1
Simian retrovirus SRV-1
ENV_SRV2
Simian retrovirus SRV-2

7 entries

Gag polyprotein (Core polyprotein)

Select_allDeselect_all
GAG_MMTVB
Mouse mammary tumor virus (strain BR6) (MMTV) reference strain

Gag polyprotein

GAG_MMTVC
Mouse mammary tumor virus (strain C3H) (MMTV) reference strain

Gag polyprotein

GAG_JSRV
Sheep pulmonary adenomatosis virus (Jaagsiekte sheep retrovirus) (JSRV)
GAG_MPMV
Mason-Pfizer monkey virus (MPMV) (Simian Mason-Pfizer virus)

Gag polyprotein (Core polyprotein) (Pr78)

GAG_SMRVH
Squirrel monkey retrovirus (SMRV-H) (SMRV-HLB)

Gag polyprotein (Core polyprotein) (Pr72)

GAG_SRV1
Simian retrovirus SRV-1
GAG_SRV2
Simian retrovirus SRV-2

7 entries

Gag-Pro-Pol polyprotein

Select_allDeselect_all
POL_MMTVB
Mouse mammary tumor virus (strain BR6) (MMTV) reference strain
POL_MMTVC
Mouse mammary tumor virus (strain C3H) (MMTV) reference strain
POL_JSRV
Sheep pulmonary adenomatosis virus (Jaagsiekte sheep retrovirus) (JSRV)
POL_MPMV
Mason-Pfizer monkey virus (MPMV) (Simian Mason-Pfizer virus)

Gag-Pro-Pol polyprotein (Pr180)

POL_SMRVH
Squirrel monkey retrovirus (SMRV-H) (SMRV-HLB)
POL_SRV1
Simian retrovirus SRV-1
POL_SRV2
Simian retrovirus SRV-2

2 entries

Protein PR73

Select_allDeselect_all
PR73_MMTVB
Mouse mammary tumor virus (strain BR6) (MMTV) reference strain
PR73_MMTVC
Mouse mammary tumor virus (strain C3H) (MMTV) reference strain

Protein PR73 (Superantigen) (Sag)

7 entries

Gag-Pro polyprotein

Select_allDeselect_all
PRO_MMTVB
Mouse mammary tumor virus (strain BR6) (MMTV) reference strain
PRO_MMTVC
Mouse mammary tumor virus (strain C3H) (MMTV) reference strain
PRO_JSRV
Sheep pulmonary adenomatosis virus (Jaagsiekte sheep retrovirus) (JSRV)
PRO_MPMV
Mason-Pfizer monkey virus (MPMV) (Simian Mason-Pfizer virus)

Gag-Pro polyprotein (Pr95)

PRO_SMRVH
Squirrel monkey retrovirus (SMRV-H) (SMRV-HLB)
PRO_SRV1
Simian retrovirus SRV-1
PRO_SRV2
Simian retrovirus SRV-2

1 entry

Protein Vpu (ORF-X protein)

VPU_JSRV
Sheep pulmonary adenomatosis virus (Jaagsiekte sheep retrovirus) (JSRV)