Tissue Culture Studies on Japanese B Encephalitis Virus.

IV. Viral growth curves in cultures of human tissues.

Abstract

The present investigations were undertaken for the purpose of extending the results obtained previously (Refer to: Hotta et al., this Journal, Vol.37, pp.335-342, 1963). Human tissues, adult, embryonic or newborn, were cultivated by the plasma-embedded roller tube method, the same as described in the former report. Viruses used were Gi strain JBE virus, of the 240th to 245th mouse brain passages, JATH 260 strain JBE virus, of the 1st to 4th mouse brain passages, and Negishi strain virus, a member of the RussianSpring-Summer encephalitis group, of the 7th to 10th mouse brain passages. At intervals following inoculation of the viruses of a given concentration, portions of the culture fluids were taken and measured for active virus contents. The viral growth curves obtained are summarized as follows:
(a) Fb: Cultures in which fibroblastic cells are dominant.
Ep: Cultures in which epithelial cells are dominant.
Rd: Cultures in which round wandering cells are dominant.
*Sp: Cultures consist mostly of spindly myoblast-like cells.
**: Cultures consist of cells of various kinds (fibroblastic, glial and nerve cells, as well as macrophages).
(b) Legends indicate the highest points of virus titers (mouse-intracerebral LD₅₀/0.02ml
in logarithmic numbers) obtained in viral growth curves.
(+++): Highest titer is more than 10⁴.
(++): Highest titer is in 10⁴-10².
(+): Highest titer is below 102, but active_ virus is unequivocally detected.
(-): No active virus is detected 1 day after viral inoculation or later.
Legend (*) is nearly equivalent to Category I (“convex” curve) proposed in the previous report, (+) to Category II (“flattened” curve), (++) to an intermediate of Categories I and II, and (-) to Category III (“continuously declining” curve).
^(c) n. t.: Not tested.