Alefpapillomavirus

VIRION

Non-enveloped. Small, icosahedral, about 60 nm in size. A single molecule of circular dsDNA is contained within the T=7 icosahedral capsid, which is composed of 72 pentamers.

GENOME

Circular dsDNA, about 5.7 kb in size, associated with cellular histones.

GENE EXPRESSION

Only one strand of the genome is transcribed and yield two classes of proteins expressed by alternative splicing :
a) Early Proteins: non-structural regulatory proteins (E1-E2), and possibls 0RF1-3.
b) Late Proteins: the structural proteins L1 and L2.

REPLICATION

NUCLEAR

Replication is divided in two distinct steps that are linked to the differentiation state of the host epithelial cell:

a) The plasmid replication takes place in the basal squamous epithelial cells. It corresponds to viral DNA replication in synchrony with the host cell chromosome in order to ensures an average of one viral genome per basal cell.

  1. Attachment of the viral proteins to host receptors mediates endocytosis into the host cell.
  2. Transport to the nucleus and uncoating of the viral DNA.
  3. Early-region transcription and translation of the early proteins.
  4. Viral genome replication.
  5. Transcription of the late region.
  6. Capsid proteins L1 and L2 synthesis.
  7. Nuclear capsid assembly and release of viruses.