Study of Attenuation of Dengue Type 4 Virus by Consecutive Passages in Primary Hamster Kidney Tissue Culture

A dengue type 4 virus Ban18 strain, isolated from non-epidemic area in China, was chosen for attenuation by consecutive passages in primary hamster kidney tissue culture(PHKTC). During the course of passage from 20 to 70, the CPE in PHKTC became more and more apparent and a high virus titer up to 10~6-10~7 TCID_(50) per ml could be reached. Meanwhile the neurovirulence to suckling mice was gradually reduced from 10~6-10~7LD_(50)/ml for the parental virus to no death or only individual death of animal for th...