Studies on latent infections of tissue cultures with dengue virus

Summary

Dengue virus maintained in a carrier culture (CD) through 164 passages of the cells over a period of more than three years has undergone changes with respect to its detectability in the carrier system and with respect to its growth capacity and virulence for the newborn mouse and especially for the weanling mouse.

The decreased mouse virulence persisted over several serial mouse brain passages. The time at which the change took place was not established as the earliest experiments on mouse virulence were not done until CD cell subculture 62. It is possible that the changes in the virus occur late in the history of a carrier system, because in a newly established carrier culture (D3) there has been no evidence of loss of virulence up to passage 14. Similarly, there has been no decrease in detectable virus in the D3 cultures; in fact, an increase in demonstrable virus was noted in passages up to number 20.

At the present it is not known whether the change in mouse virulence and the growth of the virus in tissue culture are linked in any way.