are, naturally, viruses
. But they are also retroelements
. This means that they can produce reverse transcriptase
. However, unlike retroviruses
, they cannot insert themselves into the host's chromosome
Pararetroviruses are double stranded or partially double stranded circular DNA viruses. Unlike other double-stranded DNA viruses, though, they replicate using only one strand. The strand is replicated in the regular manner, to yield the complimentary strand. And then it is transcribed to RNA and reverse transcribed to DNA to yield the original strand.
There are 3 types of pararetroviruses: