The method for the cultivation of primary cells may be one step in {HEAD ~ a method} for 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 { HEAD ~ a method } for 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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