Kidney cells of canine embryos were separated into single cells using collagenase and dispase. Primary culture was conducted using these cells. To remove fibroblasts, these cells were treated with edetate disodium dihydrate (Na2EDDA), and pure epithelial cells were separated. Recombinant retrovirus particles that manifest teromerase were produced and inoculated into primary culture cells to produce immortalized canine cell strains (JNUCK-1 and JNUCK-2). To examine the characteristics of the produced cell strains, the growth curve, maximum cultured households, and expressed proteins (keratin) were identified. The JNUCK-1 and JNUCK-2 cell lines showed division ability until the 30th generation without growth retardation. JNUCK-1 and JNUCK-2 cell lines clearly expressed telomerase until the 25th generation. The canine distemper virus (CDV) was inoculated into the JNUCK-1 and JNUCK-2 cell lines, as well as in the Madin–Darby canine kidney (MDCK) cell line. The maximum titer of CDV from the JNUCK-1 cell strain was about 200 times higher than that from the MDCK cell strain. However, the JNUCK-2 cell strain produced a lower titer than the MDCK cell strain. We established a new canine kidney epithelial cell line (JNUCK-1) that could produce CDV with high titer.

Introduction
 Materials and Methods
  Preparing Materials
  RBC Removal and Enzyme Processing
  Removing Fibroblasts
  Producing Recombinant Retrovirus Particles
  Cloning and Selecting Cells
  Measuring the Passage Count
  Examination of Telomerase Manifestation
  Immunofluorescent Staining
  Measuring the Virus Titer of the Immortalized Cells
 Results
  Subculture Count of Primary Culture Cells
  Observation on Culture Characteristics and Shapes
  Selection of Immortalized Cells and Cell Cloning
  Examination of the Telomerase Manifestation Pattern
  Immunofluorescent Staining
  CDV Susceptibility Test
 Discussion
 Acknowledgements
 ORCID
 References

• Kyong-Leek Jeon(Laboratory of Veterinary Preventive Medicine)
• Kyu-Kye Hwang(Laboratory of Veterinary Preventive Medicine, Veterinary Medical Research Institute, College of Veterinary Medicine, Jeju National University, Jeju 690-756, Korea)