| Insect cell lines have become important tools in biological, biotechnological biopharmaceutical, and biopesticide research. As silkworm is a model insect, culturing silkworm cells in vitro, researching the cultural cells theoretically and applying them to industry have been attaching great importance over decades. Although a lot of efforts have been made, the number of established cell lines from silkworm is still deeply deficient, especially those that can be applied into industry. After drawing the frame of silkworm genome, functional genome researches are in great need of providing numerous silkworm cell lines as research platform,which are of different developmental stages, different differentiation levels, or with different tissue-specific. In order to meet with these requirements in cytobiology, developmental biology and molecular biology, establishment of new baculovirus expression vector systems and studies on cell engineering, establish and study new cell lines from slikworm are in great need.Based on previous studies,primary culture was carried out for over two years by using ovary tissue from silkworm 21-872nlw. After separation and purification, we finally obtained cell population with high ability to multiply, and established ovarian cell line BmN-SWU1. Biological characteristics are summed up as follows:1. The cell population consists of polygon, round and short spindle-shape cells. The diameter of round cells is 9～31μm, shuttle-like cells is about 19～52μm×5～21μm. The cell line belongs to adhesive-type epithelium.2. BmN -SWU1 grew in high speed. The logarithm eperiod was 72 h to192 h after inoculation. At 192 h, the cell concentration came to the peak. Finally, the spread percentage rate was more than 80%. The population doupling time of the cell line was 57.74 h. 3. The chromosomes of Bran -SWU1 cell line had typical features of Lepidoptera insects, namely the chromosomes in metaphase were short pole-like or granule-like and the centromeres were dispersed-type. The ratio of diploid cells(2n=56) was high up to 80.5 %, thus, it belongs to diploid cell line. Abnormal mitosis had not been observed, the cell line had preferably maintain the features of ovarian cell mitosis and chromosomes.4. Nucleo-polyhedrons had been observated after inoculation BmNPV for 48 h in a few BmN-SWU1 cells. At 96 h, polyhedronshad been observated in 50.29% of the cells. The infection rate rapidly reached to 83.01% at 120h and arrived at 89.91% at 144h, the majority of cells lysed. TCID50 value was 1.626×10-6.5. It was observed that micro filament in the shuttle-like BmN-SWU1 cells was fibre which had the same orientation with long axis when stained by Coomassie Blue R-250. Sometimes the microfilament became arc at ends. The length of lengthways micro filament ranged, many bestrided two ends and divarication and union were often observed in micro filament which linked the whole microfilament into a gridding. Microfilament of round BmN-SWU1 cells arrayed in a radial manner centring on nucleus and pointing to membrane. Divarication and union which formed a gridding were also observed. These microfilaments made up of basic figure of cell shape.Over two years' endeavors, a new cell line of Bombyx mori, namely, Bran -SWU1 has been established from ovary tissues with different differentiated types. These cells are polygonal, round or shot shuttle-like, highly reproducible and duplized. Moreover, they are highly susceptive to BmNPV virus. Thus the cell line can be a new material to study cell biology, molecular biology, developmental biology and baculovirus expression vector systems. Furthermore, it will supply better research base for researches on silkworm functional genome, highly expression of extrinsic genes help to promote the status of silkworm as a kind of model insect.
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