▁gen ome ▁rep lication ▁and ▁reg ulation ▁of ▁host ▁cell ▁cycle . ▁SV 4 0 ▁is ▁a ▁double - str and ed , ▁circular ▁DNA ▁virus ▁belonging ▁to ▁the ▁Poly om av ir idae ▁( ear lier ▁Pap ov av irus ) ▁family , ▁Orth opol y om av irus ▁genus . ▁Poly om av ir uses ▁inf ect ▁a ▁wide ▁variety ▁of ▁verte br ates ▁and ▁cause ▁solid ▁tum ours ▁at ▁multiple ▁sites . ▁SV 4 0 ▁was ▁isolated ▁by ▁S weet ▁and ▁Maurice ▁H ille man ▁in ▁ 1 9 6 0 ▁in ▁primary ▁mon key ▁kid ney ▁cell ▁cult ures ▁being ▁used ▁to ▁grow ▁Sab in ▁OP V . ▁ ▁Dom ains ▁ ▁The ▁T Ag ▁has ▁a ▁C UL 7 - binding ▁domain , ▁a ▁T P 5 3 - binding ▁domain , ▁a ▁Z inc ▁finger , ▁and ▁a ▁Super family ▁ 3 ▁ATP ase / Hel ic ase ▁domain . ▁It ▁has ▁two ▁mot ifs , ▁one ▁for ▁nuclear ▁local ization ▁signal , ▁the ▁other ▁being ▁the ▁L X C X E ▁mot if . ▁ ▁Mechan ism ▁ ▁After ▁entering ▁the ▁cell , ▁the ▁vir al ▁gen es ▁are ▁trans cribed ▁by ▁host ▁cell ▁R NA ▁polym er ase ▁II ▁to ▁produce ▁early ▁m R N As . ▁Because ▁of ▁the ▁relative ▁simplicity ▁of ▁the ▁gen ome , ▁poly om av ir uses ▁are ▁heavily ▁dependent ▁on ▁the ▁cell ▁for ▁trans cription ▁and ▁gen ome ▁rep lication . ▁The ▁c is - act ing ▁regul atory