First, humans aren't able to create anything like that. Current level of science is far from fully understanding how this thing actually work and why it doesn't destroy itself.

Second, if you're thinking that HIV was developed as a bioweapon then you must consider that FIV (Feline Immunodeficiency Virus, a cat-specific equivalent of HIV) was artificially created as well. But why would bioweapon engineers need to infect your pet? It's pointless.