In the transgenes of the invention, the non cognate switch region may be {HEAD ~ a switch region} from a different species than {TAIL ~ the constant region coding segment} 
In the transgenes of the invention , the non cognate switch region may be { HEAD ~ a switch region } from a different species than { TAIL ~ the constant region coding segment }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL