Kappatorquevirus

VIRION

Non-enveloped, T=1 icosahedral symmetry, with a diameter of about 19-27nm.

GENOME

Circular ssDNA genome (-) genome of about 2.7 kb.
The genome is replicated through double-stranded intermediates. There are 3 ORFs that encode 4 proteins.

GENE EXPRESSION

ORF1 expresses two different proteins by alternative splicing of pre-mRNA.

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. dsDNA transcription gives rise to viral mRNAs.
  4. viral mRNAs are transcribed and translated to produce viral proteins.
  5. Replication may be mediated by a “Rep-like” protein, and would occur 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 capsid protein and form virions released by cell lysis.