Objective To express recombinant human β nerve growth factor(rhβ-NGF) in insect cells,purify the expressed product and determine its biological activity.Methods Recombinant plasmid Bacmid +[rhβ-NGF]was constructed and transfected to insect cell line Sf9 in mediation of liposome cellfection Ⅱ.Sf9 cells were repeatedly infected with the supernatant of transfected cells,of which the culture supernatant containing target protein was collected in a large quantity.The rhβ-NGF was purified by ion exchange and mole...