Betapolyomavirus (taxid:1891714)
VIRION
Non-enveloped capsid with a T=7d icosahedral symmetry, about 50 nm in diameter.
GENOME
Circular dsDNA about 5 kb in size, associated with cellular histones in a chromatin-like complex. Encodes for 5-9 proteins. On rare non-specific recombination, the viral genome can be integrated in host chromosome. This inactivates the integrated virus but can give the host cell a replicative advantage sometimes leading to malignant tumours.
GENE EXPRESSION
Transcription is nuclear, in two phases; early (replication), late (virion assembly/exit). 5-9 proteins are expressed from the two pre-MRNA by alternative splicing. All genes are transcribed by host RNA pol II.
REPLICATION
NUCLEAR
- Attachment of the viral proteins to host receptors triggers lipid-mediated endocytosis of the virus into the host cell.
- Virion transits through endoplasmic reticulum where host protein disulfide isomerases rearrange its capsid structure
- Export of misfolded virion to the cytoplasm possibly through host ERAD pathway
- Loss of VP1 in the low-calcium conditions of the cytosol
- Import of genomic DNA into host nucleus.
- Transcription of early genes (LT and sT genes)
- Replication of the DNA genome in the nucleus.
- Transcription of late genes encoding for structural proteins (VP1, VP2 and VP3).
- Assembly of new virions in nuclear viral factories.
- Virions are released by lysis of the cell.
Host-virus interaction
Cell-cycle modulation
The large T antigen binds to host key cell cycle regulators retinoblastoma protein RB1/pRb and TP53 and induces the disassembly of host E2F1 transcription factors from RB1, thus promoting transcriptional activation of E2F1-regulated S-phase genes.
Matching UniProtKB/Swiss-Prot entries
(all links/actions below point to uniprot.org website)46 entries grouped by protein
5 entries
Agnoprotein (Agno)
10 entries
Large T antigen (LT) (LT-AG) (EC 5.6.2.4) (DNA 3'-5' helicase large T antigen)
1 entry
SV40 early leader protein (SELP)
10 entries
Small t antigen (ST) (ST-AG)
10 entries
Major capsid protein VP1 (Major structural protein VP1)
10 entries
Minor capsid protein VP2 (Minor structural protein VP2)
African elephant polyomavirus 1 taxid:1399914
BK polyomavirus taxid:1891762
Bank vole polyomavirus taxid:1737522
Bat polyomavirus 6a taxid:1623685
| Protein | ModelArchive |
| Capsid protein VP1 | ma-jd-viral-14724 |
| Large T antigen | ma-jd-viral-21152 |
| Minor capsid protein | ma-jd-viral-31177 |
| Small t antigen | ma-jd-viral-16540 |
Bat polyomavirus 6b taxid:1623689
| Protein | ModelArchive |
| Capsid protein VP1 | ma-jd-viral-14711 |
| Large T antigen | ma-jd-viral-21112 |
| Minor capsid protein | ma-jd-viral-31138 |
| Small t antigen | ma-jd-viral-16577 |
Bat polyomavirus 6c taxid:1623688
| Protein | ModelArchive |
| Capsid protein VP1 | ma-jd-viral-14741 |
| Large T antigen | ma-jd-viral-21195 |
| Minor capsid protein | ma-jd-viral-31176 |
| Small t antigen | ma-jd-viral-16572 |
Betapolyomavirus calbifrons taxid:1236392
Betapolyomavirus cercopitheci taxid:1236395
| Protein | ModelArchive |
| Agnoprotein | ma-jd-viral-59846 |
| Capsid protein VP1 | ma-jd-viral-14797 |
| Large T antigen | ma-jd-viral-21107 |
| Minor capsid protein | ma-jd-viral-29840 |
| Small t antigen | ma-jd-viral-16538 |