Engineering a virus, in the sense that you're talking about, is not what was meant. Allowing the virus to naturally mutate in an animal host, over thousands of

Engineering a virus, in the sense that you're talking about, is not what was meant. Allowing the virus to naturally mutate in an animal host, over thousands of generations, will get you to the same endpoint. This is gain of function research, the whole point is to find out if the virus could naturally evolve some feature you are interested in. Engineering it to do so would defeat the point.