Aspiviridae

VIRION

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Highly flexuous, naked nucleocapsids about 3 to 4 nm in diameter, forming open circles.

GENOME

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Segmented negative-stranded RNA linear genome
Contains 3 to 4 segments coding for up to seven proteins.

GENE EXPRESSION

The viral RNA dependent RNA polymerase (L) binds to a promoter on each encapsidated segment, and transcribes a messenger RNA. Translational frameshift may occur on RNA-4 mRNA.

REPLICATION

CYTOPLASMIC

  1. Virus enters host cell either carried out by a fungus, or by insect vector: ribonucleocapsid segments are released in the cytoplasm.
  2. Transcription, viral mRNAs are capped in the cytoplasm.
  3. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
  4. The ribonucleocapsids newly synthetized can infect neighbour plant cells or be transported by fungus or insect to new plant.