Nanovirus

VIRION

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Non-enveloped, round, T=1 icosahedral symmetry, about 18-19 nm in diameter.

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GENOME

Multipartite ssDNA genome (+) composed of 6 to 8 circular segments about 1kb in size. Each ssDNA segment have a common stem-loop region and are encapsidated in a separate particle.
In addition to genomic DNA, up to 4 satellite-like DNAs are commonly found, usually encoding for accessory Rep proteins (para-Rep). These satellite-rep proteins are only able to initiate replication of their genomic DNA, unlike genomic encoded Master-Rep (M-Rep) which promotes replication of all 6-8 viral genomic ssDNAs (trans-replication).

GENE EXPRESSION

Each ssDNA genome segment is monocistronic.

REPLICATION

NUCLEAR

  1. Virus penetrates into the host cell.
  2. Uncoating, the viral ssDNA genome penetrates into the nucleus.
  3. The ssDNA is converted into dsDNA with the participation of cellular factors.
  4. Bidirectional dsDNA transcription from the IR promoter produces viral mRNAs and translation of viral proteins.
  5. Replication is initiated by cleavage of the (+)strand by REP, and occurs by rolling circle producing ssDNA genomes.
  6. These newly synthesized ssDNA can either
    a) be converted to dsDNA and serve as a template for transcription/replication
    b) be encapsidated by CP and form virions that will be released in the extracellular space. c) be transported outside the nucleus, to a neighboring cell through plasmodesmata (cell-cell movement) with the help of viral movement proteins.

Host-virus interaction

Cell-cycle modulation

Nanovirus Clink protein is responsible for inhibiting host retinoblastoma protein and inducing transition from the G1 to S phase in preparation for virus replication since the virus targets differentiated non-dividing cells. .

Matching UniProtKB/Swiss-Prot entries

(all links/actions below point to uniprot.org website)

44 entries grouped by strain

11 entries

Faba bean necrotic yellows virus (isolate Egyptian EV1-93) (FBNYV) reference strain

Select_allDeselect_all
MREP_FBNY1 Master replication protein (M-Rep) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase ...
REP1_FBNY1 Para-Rep C1 (Rep1) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C1) ...
REP9_FBNY1 Para-Rep C9 (Rep9) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C9) ...
REP7_FBNY1 Para-Rep C7 (Rep7) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C7) ...
CLINK_FBNY1 Cell cycle link protein (Clink)
U4_FBNY1 Protein U4
MVP_FBNY1 Putative movement protein (MP)
CAPSD_FBNY1 Capsid protein (CP) (Coat protein)
NSP_FBNY1 Putative nuclear shuttle protein
U1_FBNY1 Protein U1
U2_FBNY1 Protein U2

11 entries

Faba bean necrotic yellows virus (isolate SV292-88) (FBNYV) reference strain

Select_allDeselect_all
REP1_FBNY2 Para-Rep C1 (Rep1) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C1) ...
MREP_FBNY2 Master replication protein (M-Rep) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase ...
REP7_FBNY2 Para-Rep C7 (Rep7) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C7) ...
REP9_FBNY2 Para-Rep C9 (Rep9) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (ATP-dependent helicase C9) ...
MVP_FBNY2 Putative movement protein (MP)
CAPSD_FBNY2 Capsid protein (CP) (Coat protein)
NSP_FBNY2 Putative nuclear shuttle protein
CLINK_FBNY2 Cell cycle link protein (Clink)
U4_FBNY2 Protein U4
U1_FBNY2 Protein U1
U2_FBNY2 Protein U2

8 entries

Subterranean clover stunt virus (strain F) (SCSV) reference strain

Select_allDeselect_all
REP2_SCSVF Para-Rep C2 (Rep2) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
REP6_SCSVF Para-Rep C6 (Rep6) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
MREP_SCSVF Master replication protein (M-Rep) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-)
MVP_SCSVF Putative movement protein (MP)
CLINK_SCSVF Cell cycle link protein (Clink)
NSP_SCSVF Putative nuclear shuttle protein
CAPSD_SCSVF Capsid protein (CP) (Coat protein)
U1_SCSVF Protein U1

12 entries

Milk vetch dwarf virus (isolate N) (MDV)

Select_allDeselect_all
MREP_MDV1 Master replication protein (M-Rep) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-)
REP10_MDV1 Para-Rep C10 (Rep10) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
REP3_MDV1 Para-Rep C3 (Rep3) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
REP2_MDV1 Para-Rep C2 (Rep2) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
REP1_MDV1 Para-Rep C1 (Rep1) (EC 2.7.7.-) (EC 3.1.21.-) (EC 3.6.1.-) (Replication-associated protein of ...
U4_MDV1 Protein U4
MVP_MDV1 Putative movement protein (MP)
NSP_MDV1 Putative nuclear shuttle protein
CLINK_MDV1 Cell cycle link protein (Clink)
CAPSD_MDV1 Capsid protein (CP) (Coat protein)
U2_MDV1 Protein U2
U1_MDV1 Protein U1

1 entry

Milk vetch dwarf virus (isolate 9) (MDV)

CAPSD_MDV9 Capsid protein (CP) (Coat protein)

1 entry

Subterranean clover stunt virus (strain J) (SCSV)

CAPSD_SCSVJ Capsid protein (CP) (Coat protein)