Orthoretrovirinae is the subfamily of Retroviridae containing Lentivirus and several other retroviral genera. It includes human immunodeficiency virus and feline immunodeficiency virus. The family placement describes a replication strategy; it does not imply one host range or one disease outcome for all members.[ref]
Orthoretrovirinae report by the International Committee on Taxonomy of Viruses. Subfamily classification and Distinguishing features
A typical virion packages two copies of its RNA genome. After entry and release of the viral core into a host cell, reverse transcription produces DNA that can become an integrated provirus. Proteolytic processing of a viral polyprotein also releases functional components during maturation.[ref]
Orthoretrovirinae report by the International Committee on Taxonomy of Viruses. Distinguishing features, RNA copies, reverse-transcription timing and protease processing
[ref]Retroviridae report by the International Committee on Taxonomy of Viruses. Table 1, replication and integration
An invented counting example clarifies the two-copy description. If each packaged RNA molecule has 10,000 nucleotides, the pair contains 20,000 RNA nucleotides in total. The length of one genome copy is still 10,000 nucleotides. A corresponding 10,000-base-pair double-stranded DNA molecule contains 20,000 DNA nucleotides, but its length is conventionally reported in base pairs. Copy count, nucleotide count and base-pair length answer different questions.
The subfamily's genera are distinguished in part by phylogenetic analysis of conserved reverse-transcriptase regions. A shared enzyme mechanism can coexist with differences in accessory proteins, host distribution and cellular targets. Observing the shared mechanism therefore provides a classification clue while leaving those other biological properties to be determined.[ref]
Orthoretrovirinae report by the International Committee on Taxonomy of Viruses. Genus demarcation criteria and differences among members
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