Non-enveloped, rod of filaments of 7nm in diameter and 700 to 2000nm in length. Helical capsid with adsorption proteins on one end.


Circular, ssDNA genome (+) of 4.5 to 8kb encoding for 4 to 10 proteins. Replication occurs via dsDNA intermediate and rolling circle.


Each gene is transcribed by host cellular machinery, via a specific promoter. Some genes end by a transcription terminator.



  1. Viral g3p protein mediates pilus-mediated adsorption of the virus onto host cell. Pilus retraction pulls the virion to the host internal membrane.
  2. The proteins of the capsid perform the injection of the viral DNA through bacterial membranes into cell cytoplasm.
  3. Host polymerase convert the (+)ssDNA viral genome into a covalently closed dsDNA called replicative form DNA (RF).
  4. dsDNA transcription by host RNA polymerase gives rise to viral mRNAs.
  5. Viral g2p protein nicks RF DNA strand at the origin of replication.
  6. (+) strand replication occurs by rolling circle.
  7. New (+)ssDNA genomes are converted into new RF molecules, and further transcription occurs.
  8. When enough g5p protein is synthesized, conversion into RF dsDNA is inhibited, as neo-synthesized genomic ssDNA is covered with g5p.
  9. g5p are replaced by g8p proteins to trigger the assembly of the viral capsid.
  10. New virions are secreted from host cell.
  11. Infected cells continue to divide and produce virions indefinitely.

Matching UniProtKB/Swiss-Prot entries

25 entries grouped by strain (browse by keywords)

13 entries

Spiroplasma virus SpV1-C74 (SpV1) reference strain

CAPSD_SPV1C Putative capsid protein ORF9
INTG_SPV1C Putative integrase ORF3
ORF10_SPV1C Uncharacterized protein ORF10
ORF15_SPV1C Uncharacterized protein ORF15
ORF7_SPV1C Uncharacterized protein ORF7
ORF2_SPV1C Uncharacterized protein ORF2
ORF11_SPV1C Uncharacterized protein ORF11
ORF4_SPV1C Uncharacterized protein ORF4
ORF14_SPV1C Uncharacterized protein ORF14
ORF1_SPV1C Uncharacterized protein ORF1
ORF5_SPV1C Uncharacterized protein ORF5
ORF12_SPV1C Uncharacterized protein ORF12
ORF13_SPV1C Uncharacterized protein ORF13

12 entries

Spiroplasma virus SpV1-R8A2 B (SpV1) (Spiroplasma virus 1) reference strain

CAPSD_SPV1R Putative capsid protein ORF9 (Gene 9 protein)
INTG_SPV1R Putative integrase ORF3 (Gene 3 protein)
ORF11_SPV1R Uncharacterized protein ORF11 (Gene 11 protein)
ORF5_SPV1R Uncharacterized protein ORF5 (Gene 5 protein)
ORF2_SPV1R Uncharacterized protein ORF2 (Gene 2 protein)
ORF6_SPV1R Uncharacterized protein ORF6 (Gene 6 protein)
ORF10_SPV1R Uncharacterized protein ORF10 (Gene 10 protein)
ORF1_SPV1R Uncharacterized protein ORF1 (Gene 1 protein)
ORF7_SPV1R Uncharacterized protein ORF7 (Gene 7 protein)
ORF12_SPV1R Uncharacterized protein ORF12 (Gene 12 protein)
ORF4_SPV1R Uncharacterized protein ORF4 (Gene 4 protein)
ORF8_SPV1R Uncharacterized protein ORF8 (Gene 8 protein)