Biological activity was determined by egf dependent balb / c 3t3 cell line and with mtt colorimetric assay . extracts of the recombinant virus - infected and mock - infected cells , haemolymph of the recombinant virus infected and mock - infected silkworm larvae could all support the proliferation of balb / c 3t3 cell . this phenomena implied that there were some egf - like growth factors in the haemolymph of normal silkworm larvae , which could enhance the proliferation of the cell line 用小鼠balb c3t3成纤维细胞和mtt法测定表达产物的促细胞增殖作用,发现重组病毒感染家蚕细胞72小时的胞内样品与正常家蚕细胞裂解物,以及重组病毒感染4天的蚕血淋巴与正常蚕血淋巴均具有相似的促细胞增殖作用,甚至野生型病毒感染的细胞裂解物和蚕血淋巴也有一定的细胞促生长作用,提示家蚕系统本身可能含有能促进细胞生长、类似于egf的细胞因子。