Podoviridae

The Podoviridae are a family of bacteriophages. Unlike the other families of tailed viruses this family has short tails that are noncontractile.

There are at least 74 species in this family.

Virology

The viron is nonenveloped with a head-tail structure. There are 9 structural proteins.

The head is ~60 nanometers (nm) in diameter, consists of 72 capsomers and is icosahedral with a T = 7 symmetry. The head protein has a molecular mass of ~38 kiloDaltons and is present in 460 copies per virion.

The tail is non-contractile and has 6 short subterminal fibers. It is thick and rod-shaped and built of stacked disks. The maximum length is ~17 nm.

The double stranded DNA genome is linear ~40-42 kilobases in length and encodes ~55 genes. The guanine + cytosine content is ~50%. It has terminally redundant sequences and is nonpermuted. By weight, the genome constitutes ~50% of the viron.

The genome encodes 9 structural proteins, an adenylated transferase B type DNA polymerase and an RNA polymerase. Three internal proteins constitute the polymerase complex.

Two classes of genes are recognized (early and late). This classification is based on the timing of transcription that is temporally regulated. Genes with related functions are clustered together. Genome replication is bidirectional.

In general, these viruses tend to be lytic rather than lysogenic.

Life cycle

Phages are adsorbed using tail first to specific receptors located on the cell wall and then enter host cells after digestion of the cell wall with lysozyme. Virus uncoating occurs in the cytoplasm. The viral DNA remains linear. In latent infections the infecting genome integrates into the host genome. Genome replication occurs by a semi-conservative mechanism. During replication the viral DNA forms concatamers. In lytic cycles the host genome degenerates.

Viral proteins accumulate in the cytoplasm and are associated with the periphery of the perinuclear space of the nucleoplasm. The capsid proteins associate with the viral DNA after being cut into size to form the provirion preformed capsids. The mature viruses assemble in the perinuclear space. They may also be found in the cytoplasm in crystalline arrays. The viruses are released from host cell by lysis.

Taxonomy

Genera within this family have ~40% homology between corresponding proteins. Subfamiles have ~20% homology between corresponding proteins.

This family is divided into two subfamiles (Autographivirinae and Picovirinae) and a number of genera awaiting classification into subfamilies.

• Subfamily Autographivirinae
  • Genus PhiKMV-like viruses; type species: Pseudomonas phage phiKMV
    • Species:
      • Pseudomonas phage LKA1
      • Pseudomonas phage LKD16
      • Pseudomonas phage phiKMV

• • Genus SP6-like viruses; type species: Enterobacteria phage SP6
    • Species:
      • Enterobacteria phage K1-5
      • Enterobacteria phage K1E
      • Enterobacteria phage K5
      • Enterobacteria phage SP6
      • Enterobacteria phage Era103

• • Genus T7-like viruses; type species: Enterobacteria phage T7
    • Species:
      • Enterobacteria phage BA14
      • Enterobacteria phage K11
      • Enterobacteria phage PTB
      • Enterobacteria phage R
      • Enterobacteria phage T7
      • Enterobacteria phage ViIII
      • Enterobacteria phage Y
      • Kluyvera phage Kvp1
      • Pseudomonad phage gh-1
      • Vibrio phage III
      • Rhizobium phage S
      • Rhizobium phage 2
      • Pseudomonas phage Psy9220

• • Genus Unassigned
    • Species:
      • Prochlorococcus phage P-SSP7
      • Synechococcus phage P60
      • Synechococcus phage syn5

• Subfamily Picovirinae
  • Genus AHJD-like viruses; type species: Staphylococcus phage AHJD
    • Species:
      • 44AHJD
      • Staphylococcus phage AHJD
      • Streptococcus phage C1

• • Genus Phi29-like viruses; type species: Bacillus phage phi29
    • Species:
      • Bacillus phage B103
      • Bacillus phage GA-1
      • Bacillus phage phi29
      • Bacillus phage M2
      • Bacillus phage MY2
      • Bacillus phage Nf
      • Bacillus phage SF5
      • Staphylococcus aureus bacteriophage 2
      • Streptococcus C1
      • Staphylococcus P68
      • Kurthia phage 6
      • Kurthia phage 7

• • Genus Unassigned
    • Species:
      • Actinomyces phage Av-1
      • Mycoplasma phage P1
      • Streptococcus phage Cp-1

Other genera awaiting classification into subfamilies:

• Genus BPP-1-like viruses; type species: Salmonella phage BPP-1
  • Species:
    • • BIP-1
      • Bordetella phage BPP-1
      • Burkholderia phage BcepC6B
      • Salmonella phage BPP-1

• Genus Epsilon15-like viruses; type species: Salmonella phage epsilon15
  • Species:
    • • Escherichia phage PhiV10
      • Salmonella phage epsilon15

• Genus LUZ24-like viruses; type species: Pseudomonas phage LUZ24
  • Species:
    • • Pseudomonas phage LUZ24
      • Pseudomonas phage PaP3

• Genus N4-like viruses; type species: Enterobacteria phage N4
  • Species:
    • • Enterobacteria phage N4
      • Pseudomonas phage LIT1
      • Pseudomonas phage LUZ7
      • Pseudomonas phage PEV2

• Genus P22-like viruses; type species: Enterobacteria phage P22
  • Species:
    • • Aeromonas phage Aa-1
      • Azotobacter phage A12
      • Enterobacteria phage HK620
      • Enterobacteria phage L
      • Enterobacteria phage LP7
      • Enterobacteria phage MG40
      • Enterobacteria phage P22
      • Enterobacteria phage PSA78
      • Enterobacteria phage Sf6
      • Enterobacteria phage ST64T
      • Hyphomicrobium phage Hyf30
      • Pseudomonas phage 525
      • Salmonella phage HK620
      • Salmonella phage ST64T
      • Shigella phage Sf6
      • Vibrio phage O6N-72P

• Genus Phieco32-like viruses; type species: Enterobacteria phage Phieco32
  • Species:
    • • Enterobacteria phage Phieco32

• Genus Unassigned
  • Species:
    • • Acinetobacter phage A36
      • Bacillus phage phiBa1
      • Brucella phage Tb
      • Burkholderia pseudomallei phage phi Bp-AMP1
      • Clostridium phage HM2
      • Coryneforms phage AN25S-1
      • Coryneforms phage 7/26
      • Cyanobacteria phage SM-1
      • Cyanobacteria phage LPP-1
      • Cyanobacteria phage AC-1
      • Cyanobacteria phage A-4(L)
      • Enterobacteria phage 7480b
      • Enterobacteria phage 7-11
      • Enterobacteria phage Esc-7-11
      • Enterobacteria phage sd
      • Endosymbiont phage APSE-1
      • Lactococcus phage KSY1
      • Mycobacterium phage phi17
      • Mollicutes phage C3
      • Pseudomonas phage F116
      • Pasteurella phage 22
      • Phormidium phage Pf-WMP3
      • Phormidium phage Pf-WMP4
      • Pseudomonas phage 119X
      • Pseudomonas phage F116
      • Roseobacter phage SIO1
      • Vibrio phage VpV262
      • Roseobacter phage SIO1
      • Rhizobium phage phi2042
      • Streptococcus phage 182
      • Streptococcus phage 2BV
      • Streptococcus phage Cvir
      • Streptococcus phage H39

References

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