1. Retrovirus: RNA oncovirus that contain Reserve transcriptase which can convert viral RNA into DNA. They are able to integrate DNA into cellular chromosomes as a part of their normal replication cycle.
2. Provirus: Provirus is a product of Retrovirus. Reverse transcriptase cannot only copy DNA from viral RNA, but also can degrade RNA strand from RNA/ DNA hybrid resulted from reverse transcription. It then uses the remaining DNA strand asa template to synthesize DNA double helix completely to the viral RNA. This DNA is linearly integrated into the host chromosome is named as Provirus.