Is there any difference between strain and mutation/mutant?
You can think of &quot;strain&quot; roughly analogous to how you would think of &quot;breed&quot; in the context of dogs or horses.
There might be some key mutation that identifies members of a strain over non-members, but you would expect to find other genetic differences as well. &quot;Strain&quot; for a virus is not referring to a particular mutation but to the viruses on one side of some fork in their evolutionary history.