Abstract:  Insect cell line is one of the key components in baculovirus expression vector system and plays essential roles in baculoviral biology, identification of gene function, and expression of recombinant proteins, etc. In this study, a new cell line designated as Bm-Em-1 from the embryonic tissue of Bombyx mori (Lepidoptera: Bombycidae) strain Dazao was established， and this cell line had been subcultured over 40 passages on TNM-FH medium supplemented with 10% fetal bovine serum. Inverted microscope observation showed that this cell line has two major morphological types, i.e., round cells and spindle-shaped cells, and the chromosomes of the cell line were condensed into short rods and granule, typical of lepidopteran cell line. Random amplification of polymorphic DNA (RAPD) analysis showed that the DNA profile of the cell line Bm-Em-1 was similar with that of the embryonic tissue of B. mori, but different from that of BTI-Tn5B1-4 and Sf-9 cell lines. Growth curve analysis indicated that the population doubling time of the 28th passage cells was 82.2 h. Virus infection data proved that Bm-Em-1 was highly susceptible to B. mori nucleopolyhedrovirus (BmNPV) with the infection ratio up to 91.3% at 96 h post infection, but not susceptible to the Autographa californica multiple nucleopolyhedrovirus (AcMNPV). With such high infection rate by BmNPV, this cell line will be an ideal tool for BmNPV replication in vitro, BmNPV expression system and gene function study of B. mori.

Key words: Bombyx mori, cell line, karyotype analysis, RAPD fingerprint, nucleopolyhedrovirus, virus susceptibility