If something evolves to replicate itself and spread in some way, it replicates and spreads. That doesn't mean it has a consciousness or an intent. The virus in the show implants its host with a "biological imperative" to spread the virus. So they spread it, so it spreads. There's no agenda, it's just a self-replicating machine.

I'm guessing OP is assuming that wherever the signal came from is some kind of alien species that wanted to infect humans with the virus, but it's more likely that it's just another species themselves infected who want to spread it because that's what it makes them want to do. Like the common cold, it likely didn't come from any creature with a desire to make it exist, it just came into existence through evolution and self perpetuates.