Establishment of guinea pig kidney cell lines with potential application in the production of a classical swine fever live GPE(−) vaccine

Classical swine fever (CSF) live vaccine used in Japan, GPE(−) strain, is produced using guinea pig kidney (GPK)-derived primary culture cells. This means that a large number of guinea pigs are used to generate the primary GPK cells needed to produce the CSF live vaccine, and alternative solution is desired. Hence, we established two GPK cell lines capable of culturing the GPE(−) strain: spontaneously immortalized GPK (GPK-SI) cells were generated by repeated passaging of primary GPK cells, and the other cell line, artificially immortalized GPK (GPK-AI) cells, were obtained by introducing the SV40 large T antigen gene into primary GPK cells. Both cell lines were susceptible to the GPE(−) virus, and the virus grew more efficiently in GPK-SI cells at 37°C. When the culture temperature was set to 30°C, the virus titer reached 10(4.8) 50% Tissue Culture Infectious Dose (TCID(50))/mL in GPK-SI cells 7 days after virus inoculation at a multiplicity of infection (MOI) of 1, which was equivalent to that in cells cultured at 37°C. When the virus was inoculated at MOI <1, the virus titer 7 days after inoculation was higher when cultured at 30°C than when cultured at 37°C in both cell lines, reaching 10(5.63) TCID(50)/mL in GPK-SI cells. These results indicate that GPK-SI and GPK-AI cells can potentially replace primary GPK cells for the production of CSF live vaccines. This could also contribute to stable CSF vaccine production and animal welfare.