Growth of Japanese encephalitis virus in Culex tritaeniorhynchus cell cultures
Hsu, S.H.; Wang, B.T.; Huang, M.H.; Wong, W.J.; Cross, J.H.
American Journal of Tropical Medicine and Hygiene 24(5): 881-888
1975
ISSN/ISBN: 0002-9637 PMID: 1238028 Document Number: 89503
Ovarian cells of Culex tritaeniorhynchus Giles established in continuous tissue cultures were found to support the growth of Japanese encephalitis virus with titres reaching as high as 107.36 mouse ICLD50's/0.03 ml. Virus-cell cultures were serially subcultured 60 times over a period of 300 days, and the virulence of the virus was determined after each passage. A gradual loss in virus titre was observed, titres always being higher in the medium than in the cells. Cytopathogenic effects were not observed in the infected cell cultures, either in primary or subsequent passages. However, the cell growth rate suggested that the cells may have been metabolically or mechanically damaged. The chromosome complement of the cells remained unchanged. Direct-fluorescent antibody studies during early and late passages revealed a loss in virus infectivity from chronically infected cells, which may have been due to a gradual decrease in virus replication as the passage increased. The infectivity of virus particles, however, returned to the previous levels after passage into fresh cell cultures. The loss of virus particles during serial passage may be correlated with the condition of the cells.