Lambdatorquevirus

VIRION

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

GENOME

Circular ssDNA genome (-) genome of about 2.1 kb.
The genome is replicated through double-stranded intermediates. There are two major overlapping ORFs and a third ORF.

GENE EXPRESSION

The two major overlapping ORFs encode the relicase protein and the capsid protein. The third ORF may be expressed separately (or perhaps with ORF1 by alternative splicing).

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.