These viruses have segmented genomes. Each genome segment is transcribed separately to produce monocistronic mRNAs. Translation results in the formation of a polyprotein product, which is subsequently cleaved to form the mature proteins. Complex Transcription e. g. Togaviruses. Non-segmented e. g. Rhabdoviruses.
Replication occurs as above and monocistronic mRNAs are produced.
This group of viruses also relies on reverse transcription, but unlike the Retroviruses, this occurs inside the virus particle on maturation. On infection of a new cell, the first event to occur is repair of the gappedgenome, followed by transcription. The only absolute requirement is an origin of replication in the nucleic acid. The leprosy baciili rickettsiae and chlamydia have all evolved in this direction. Mitochondria and chloroplasts are often suggested to have been derived from intracellular parasites.