The main issue with replication is, we really have no way to know how to build the virus for the next species.
To do what this virus does would require intricate knowledge of a species genetic code to allow for engineering.
I guess you could assume that the virus is so incredibly well made that it just adapts to whatever species it encounters…but the issue is that the message we got were earth based nucleic acids. So that means the signal was tailored to our biology…how did they know?
We may not get an answer to that which is honestly fine…the virus is already fully in crazy sci fi territory so if you accept the basic premise these kind of details are pretty minor