The method for the cultivation of primary cells may be one step in a method for {HEAD ~ the amplification} of viruses, wherein the cells are then infected with a subject virus and the infected cells are cultivated in {TAIL ~ serum free medium} until progeny virus is produced 
The method for the cultivation of primary cells may be one step in a method for { HEAD ~ the amplification } of viruses , wherein the cells are then infected with a subject virus and the infected cells are cultivated in { TAIL ~ serum free medium } until progeny virus is produced
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