It really just replicates it exactly.
The way a child discovers the world constantly replicates the way science began. You start to notice what's around you, and you get very curious about how things work. How things interrelate. It's as simple as seeing a bug that intrigues you. You want to know where it goes at night; who its friends are; what it eats.
The clock keeps ticking. Every time this virus replicates, it makes mistakes, ... Sooner or later it will make the mistakes that will allow it to go human to human.
When you stop drugs what will happen is the virus reactivates itself and it replicates and then you get a rebound in your viral load.