This fragment can then be incorporated into a host genome.

Most phages that do integrate into the host genome encode a recombinase.

They are used by viruses to insert their genetic material into the host genomes.

It ensure that the plasmid divides in step with the host genome.

This results (initially) in the excision of any inserted genomes from the host genome.

The genome remains inserted into the host genome in a dormant state.

They contain a reverse transcriptase that allows integration into the host genome.

Such reasoning relies upon the untested postulate that these genes carry the mark of a previous host genome.

There is concern that insertional mutagenesis due to integration into the host genome might lead to cancer or leukemia.

It does not integrate into the host genome.