Thank you very much Alexander for your valuable inputs. It is very helpful

What entirely depends on the epitopes your antibodies recognize and the sequence difference between the strains. A polyclonal antiserum usually contains antibodies against various epitopes and is therefore more likely to show crossreaction between strains than a monoclonal that recognizes only one particular epitop. Of course, there is evolutionary pressure on the viruses to accumulate sequence changes in epitopes recognized by neutralizing antibodies , which may drive the differentiation of strains

Dear Annemarie,

Thank you very much for your thoughts. Very insightful.