Question

retroviruseshave no DNA however the DNA of infected host cell does possess viral DNA how is it possible?

Answer 1

After attacking the host cell, retrovirus enters into macrophages (as in case of HIV). In the macrophages, replication of RNA genome of the virus occurs to form viral DNA using reverse transcriptase enzyme. The viral DNA produced gets incorporated into the host's cell DNA where it directs the infected cells to produce more viruses. Hence, the infected host cell possesses viral DNA.