Multiplication of a granulosis virus isolated from the potato tuber moth in a new established cell line of Phthorimaea operculella.

A newly established cell line was obtained from the culture of embryonic cells of the potato tuber moth Phthorimaea operculella in low temperature conditions (19 degrees C) using modified Grace's medium supplemented with 10% fetal bovine serum. The population doubling time was about 80 h when cells were cultivated at 19 degrees C and 38 h at 27 degrees C. The cell line had a relatively homogeneous population consisting of various sized spherical cells. The cells were cultivated for more than 25 passages. Their polypeptidic profile was different from profiles of other P. operculella cell lines we previously described and from other lepidopteran cells. The new cell line was designated ORS-Pop-95. The complete replication of the potato tuber moth granulosis virus (PTM GV) was obtained in vitro by both viral infection and DNA transfection. PTM GV multiplied at a significant level during several passages of the cell line that was maintained at 19 degrees C. As long as the cells were maintained at 19 degrees C, virus multiplication could also be obtained at the same rate at 27 degrees C. To compare PTM GV multiplied both in vivo and in vitro, we used morphological identification, serological, DNA probe diagnosis and endonuclease digest profile analysis and confirmed the identity of the virus.