From the reason that the outbreaks with group B Coxsackie virus were recently experienced in Japan and even in adults, the invasion grade of the virus group in Tokyo area was studied by the author with the following methods. 1) The antibody possessing ratio in each age group against B 1 to B 5 of Coxsackie virus was tested by HeLa cell culture using the 4-fold dilution of serum which was obtained from 207 healthy people during October of 1961 to March of 1962 (Table 1). 2) Considering the finding that the infections with Coxsackie B 5 virus were proved only in 1960 in Tokyo, the antibody possessing ratio was compared with each other among the sera obtained in 1959 and in, 1961 in the group of 1 to 2 years old.
As shown in Table 2 and Fig. 1, the antibody possessing ratio against group B Coxsackie virus was considerably lower in each type than the ratio against polioviruses in Tokyo. The ratio against B 3 and B 5 viruses was the lowest (about 30% in adult). The neutralizing antibody titer of pooled serum in each age group was also tested (Fig. 2).
In comparison with the antibody possessing ratio of the sera obtained before and after 1960 in the group of 1 to 2 years old, the ratio against B 1 to B 4 viruses was not different in both. However, the ratio against B 5 virus increased from 3.3% in the former (before 1960) to 18.5% in the latter (after 1960).
On the other hand, group B Coxsackie virus infections were proved in 9 cases (3.1%) from the etiological study in 287 cases of viral CNS infections tested between 1959 to 1962. Eight cases except 1 case were the infection with B 5 virus, and 6 cases out of them occurred in 1960 (Tables 6 and 7). Four cases of them were 11 years old or older. These findings coincide with the above mentioned results, i.e. the low antibody possessing ratio in adult and the increasing ratio against B 5 virus in infants in 1961 or later.
From these results, group B Coxsackie virus, especially B 5 virus, infections may occur in adults as well as in children, and moreover may occur even epidemically.

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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.

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