Explain the difficulties in developing antiviral drugs against dna viruses, when compared to rna viruses.

The  DNA   virus  uses  nucleus  of  the  host  to  replicate it  genetic  material since  it  lack reverse  transcriptase enzyme.The similarities between  the  DNA virus  with human  protein it  make  difficult  to  treat  this  virus without  damaging  the  host cell.
                    while
RNA  virus  has  reverse  transcriptase  enzyme which  is  used to  replicate  its  genetic material,  but  it  lack  ability  to check  errors,  which  led  to  higher mutation  rate.The  transcriptase  enzyme  is  used  to make vaccine  which  is  used  to treat  RNA  virus

No they’ve not done that