Non-enveloped, round, T=1 icosahedral symmetry, about 30 nm in diameter. The capsid consists of 12 pentagonal trumpet-shaped pentomers. The virion is composed of 60 copies each of the F, G, and J proteins, and 12 copies of the H protein. There are 12 spikes which are each composed of 5 G and one H proteins.


Circular, ssDNA(+) genome of 4.4 to 6.1kb. replication occurs via dsDNA intermediate and rolling circle.


Early and late genes promoters tightly regulate the timing of gene expression, which is crucial for the replication cycle.



  1. Pilus-mediated adsorption of the virus onto host cell
  2. The proteins of the capsid perform 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 I (RF-I).
  4. Early viral genes are transcribed by host RNA polymerase, producing viral replication proteins.
  5. Viral protein A cleaves RF-I(+) DNA strand at the origin of replication and covalently attaches itself to the DNA.
  6. (+)strand replication occurs by rolling circle, which is converted to dsDNA by host polymerase, generating RF-II molecules (amplification of RF-I).
  7. Late viral genes are transcribed by host RNA polymerase.
  8. Procapsid assembly in the cytoplasm.
  9. Viral protein C binds to replication complex, inducing synthesis and packaging of neo-synthesized (+)ssDNA genomes (RF-III) into procapsids.
  10. Procapsids maturation occurs in host cytoplasm
  11. Mature virions are released from the cell by lysis.

Matching UniProtKB/Swiss-Prot entries

20 entries grouped by strain (browse by keywords)

10 entries

Enterobacteria phage phiX174 (Isolate Sanger) (Bacteriophage phi-X174) reference strain

CAPSD_BPPHS Capsid protein F (F protein) (GPF)
C_BPPHS Protein C
E_BPPHS Lysis protein E (Protein E) (GPE)
G_BPPHS Major spike protein G (G protein) (GPG)
SCAFD_BPPHS External scaffolding protein D (Scaffolding protein D) (GPD)
SCAFB_BPPHS Internal scaffolding protein B (Scaffolding protein B) (GPB)
H_BPPHS Minor spike protein H (H protein) (Pilot protein)
J_BPPHS DNA-binding protein J (J protein) (Small core protein)
K_BPPHS Protein K
REPA_BPPHS Replication-associated protein A (EC 3.1.21.-) (EC (RepA)

10 entries

Enterobacteria phage S13 (Bacteriophage S13)

G_BPS13 Major spike protein G (G protein) (GPG)
SCAFB_BPS13 Internal scaffolding protein B (Scaffolding protein B) (GPB)
SCAFD_BPS13 External scaffolding protein D (Scaffolding protein D) (GPD)
VGF_BPS13 Capsid protein (F protein) (GPF)
VGJ_BPS13 Small core protein (J protein)
VGA_BPS13 A' protein (GPA)
VGH_BPS13 Minor spike protein (H protein) (Pilot protein)
VGK_BPS13 K protein
VGC_BPS13 C protein
VGE_BPS13 Lysis protein (E protein) (GPE)