Safety of yellow fever vaccine strain (Tiantan strain) in China and WHO vaccine strain 17D-213

Abstract

Objective To study the intracerebral pathogenicity of the yellow fever vaccine strains of Tiantan strain used in China and WHO vaccine strain 17D-213 in mice. Methods Mice of different ages and strains were intracerebrally injected with same amount of Tiantan strain and 17D-213 strain. The death and survival of mice were observed and recorded. The LD50/ml and half survival time of the two vaccine strains were compared and analyzed. Results There was no difference in LD50/ml between the Tiantan strain and 17D-213 strain when used through intracerebral injection in one-day-old suckling mice, 7-9 g mice or 12-14 g mice. Moreover, no significant difference in survival trend was found in 7-9 g mice or 12-14 g mice injected with the two vaccine strains. However, the two strains had statistically different influences on the survival trend of one-day-old suckling mice. The half survival time of the Tiantan strain was 11 d, while that of the WHO vaccine strain 17D-213 was 6 d. Excepting in NIH mice, no significant differences in LD50/ml were detected between the same amount of two strains in BALB/c, KM, ICR or C57 mice. Conclusions The yellow fever Tiantan vaccine strain and WHO vaccine strain 17D-213 have no significant difference in the intracerebral pathogenicity in mice of different ages and strains with good safety. Key words: Yellow fever; Vaccine strain; Intracerebral pathogenicity; Safety