The authors have hitherto been engaging in the study on the pattern of experimental infection and immunity of animals against the Japanese B encephalitis virus. In the study of this kind, it is most desirable to make the host-parasite system as simple as possible, and it may be best if the host of this system could be reduced to a single cell or cells.
With such an intention, many attempts were made recently and have become available, namely the attempts of virus propagation in de-embryonated chicken eggs, in monolayer cell culture of Dulbecco, in culture of suspended cells that were made free by digestion with enzymes and also those in the HeLa cell culture etc., and it has become possible to make the investigation of the host-virus relationship in a very simple host-parasite system as mentioned above.
Since Ackermann had succeeded in 1952 to propagate the influenza virus of WS strain on the Ehrlich's ascites tumor cells of mouse, it became available with good results to employ this ascites tumor as the medium of propagation for certain viruses in the study on the pattern of infection and multiplication of them.
The authors succeeded to apply as the host cell the Ehrlich's ascites tumor cell of mouse to the study on the pattern of infection with and immunity against the Japanese B encephalitis virus and could obtain some interesting results. The results obtained may be possible to be summarized as follows.
1. The Japanese B encephalitis virus (Nakayama strain) can easily propagate in the Ehrlich's ascites tumor cells of mouse that are propagating in the peritoneal cavity of mouse.
2. The Japanese B encephalitis virus seems not to exert the oncolytic effect upon the Ehrlich's mouse ascites tumor cells.
3. The propagation of the virus attains to its peak in tumor cells in the peritoneal cavity of mouse approximately 5 days after the intraperitoneal inoculation of the cells infected with the virus. Eight days after the inoculation, the titer of the virus in the ascites fluid falls remarkably and 11 days after it, the virus becomes already impossible to be recovered directly from both ascites fluid and tumor cells.
4. Eight days after the inoculation of the tumor cells infected with the virus, the neutralizing antibody against the virus which had been produced in the body of the mouse appears in the ascites fluid of it in significant titer and the virus in the ascites fluid becomes unable to get rid of the inactivating action of it.
5. If the tumor cells, in the stage when the virus had become unrecoverable at all from both the ascites fluid and the cells, were washed and made free of the ascites fluid which contains the neutralizing antibody and were inoculated anew to the mouse intraperitoneally, the virus begins to multiply again in those cells in this antibody free new medium in accordance with the propagation of the cells and appears in the ascites fluid in high titer as usual.
6. The facts above mentioned should allow us to infer that the neutralizing antibody can exert a reversible inactivating or a multiplication inhibitting effect on the virus which occupies the intracellular site in the tumor cell.
7. The mechanism, by which the neutralizing antibody acts inactivating or inhibitory against the intracellularly located virus, is not yet made clear. Above all, it remains to be elucidated, whether the neutralizing antibody can permeate into the active tumor cell or not.
8. It may be possible to be considered as follows, that in the tumor cells that are present in the medium which contains neutralizing antibody significantly, the virus can persist in the latent state for considerably long period of time. In another expression, the long persistence of the virus in the host cells after the recovery from infection may be possible to be postulated.

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The quantitative observations were carried out on metabolic actions of the Satsuma orange, Citrus unshu MAR., affected with the Dwarf disease by transmission of green broad-winged plant heoppr, Geisha distinctissima WAL. And they were compared with those of the orange plant infected to the Dwarf disease by graft-transmission. The results obtained are as follows:
(1) The amount of oxygen uptake (QO₂) and the value of the respiratory quotient (HQ) are smaller in the affected leaf with the disease by graftor insect-transmission than those in the healthy leaf of the sound plant. This shows that the respiration of the orange plant becomes poorer as infected to the disease (Table 1 and Fig. 1).
(2) In the diseased leaf of the orange plant, the activity of the succinic dehydrogenase is stronger severely but the cytochrome oxidase activity become weaker considerably (Table 4 and Fig. 2). Those facts may suggest that the succinic oxidase activity is unsound in the infected leaf tissues.
(3) The value of the apparent P-O ratio at the oxidative phosphorylation of the examined plant is smaller in the affected leaf with the disease than in the healthy leaf (Table 5).
(4) The amount of the total phosphorous compounds in the diseased leaf is slightly less than that of the sound leaf. When, however, the contents of the various phosphorous fractions are converted into those of the total phosphorus in percentage; it appears that, in affection with the disease, the inorganic and protein phosphorous decrease but the organic, lipid and nucleic acid phosphorous increase in weight (Table 6 and Fig. 3).
According to the above mentioned facts, it is known that the unsound metabolisms in the diseased leafon the insect-transmitted plant are completely same with those of the graft-transmitted plant. And it may safely be concluded that the virus of the Dwarf disease of Satsuma orange is transmitted to the host plant by the examined plant hopper.

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In the previous report of the studies, it was known that the green brood-winged plant hopper, Geisha distinctissima WAL., was an insect vector of the Dwarf disease of Satsuma orange, Gitrus unshu MAR. The various observations were carried out upon the metabolisms of the plant hopper, when it is virulif erous after its acquisition feeding for 10 days on the diseased plant. Some of the results obtained are dealed with in this paper.
(1) Oxigen consumption or QO₂ of the viruliferous insect becomes less in about 30 per cent than that of the nonviruliferous insect. It appears that the respiration of the vector is poorer as affected with the disease (Fig. 1).
(2) The value of the oxidative phosphorylation or P-O ratio is smaller in the affected insects than in the healthy insects (Table 1).
(3) The succinic dehydrogenase activity become stronger in the diseased insect than in the healthy insect (Fig. 2).
(4) As the insect become viruliferous, the alkali-phosphatase is weaker remarkably in activity than that of the nonviruliferous insect. But, on the neutral and acid-phosphatase in the examined insect, no difference of the activity is found between the two tested enzymes (Fig. 3).
(5) The amounts of the organic phosphorous and lipid phosphorous compound are more, but the contents of the inorganic phosphorous and nucleic acid phosphorous fractions become less in the diseased insects than in the healthy insects. And the total phosphorous in the infected insects are smaller than in the healthy ones (Fig. 4).
From the results above revealed, it may be concluded that the insects examined show the unsound respiration and phosphorous metabolisms, when they become viruliferous with the virus of the Dwarf disease of Satsuma orange.

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The pathogenicity of two strains of Coxsackie A group of virus, namely OKUMOTO strain of type 2 and DOHI strain of type 19 both isolated from the patient with Guillain-Barré syndrome, were systematically followed by the histopathological analysis employing the suckling mice of age 48 hours.
(1) The most striking changes were observed in the striated muscle tissues. These were characterized by the diffuse hyaline degeneration and necrosis of muscle fibres. Presumably, the cellular infiltration which were abundantly seen in the site, could be of secondary nature.
(2) The interalveolar pneumonia, nephrotic picture in the kidney cells and the cloudy swelling of liver cells of minor degree would seem to be produced secondarily by the extensive involvement of the muscle tissues.
(3) No significant changes were obviated in the central nervous tissue, spinal ganglia and spinal posterior root respectively.
(4) By and large, pathogenic pictures produced by these two strains were similar. The changes in the muscle tissue were more extensive by OKUMOTO strain.
(5) The experience illustrates the difference of the manifestation of the initial lesions through the different route of inoculations, namely the changes in the muscle from the hind limb through intraperitoneal route and from fore limb through intracerebral route. Oral administration of OKUMOTO strain revealed the initiation from the hind limb and general manifestation required time interval.
(6) Rapid involvement in the muscle hampered the detailed analysis on the mode of viral spread in the individual.

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The SARAGAI strain of coxsackie group of viruses was challenged with the suckling mice of age 48 hours to compare the pathogenic pictures with two strains investigated in the preceeding paper.
(1) The changes in the pancreas were remarkable. These were characterized by the severe pancreatitis with destructive necrosis of glandular cells after 2 days of inoculation, and occasionally soon after 1 day, which could be considered to be a direct cause of fatal episode.
(2) The lung lesion were initiated by the catarrh and subsequently turned into interalveolar pneumonia of minor degree. The liver cell revealed cloudy swelling.
No significant changes were observed in the kidney tissues. Nephrotic picture was seen in the several instances after 2 days of inoculation.
(3) No extensive muscular involvement illustrated by the necrosis of the fibre and cellular infiltration shown in the previous OKUMOTO and DOHI strain was not observed in this case. Atrophic degeneration of fibre in the striated muscle and the hyaline degeneration of minor degree was the only manifestation.
(4) There were mild changes in the central nervous system in a few cases, illustrated by the pycnosis of nucleus and swelling of nerve cells. Generally, no acceptable involvement was obtained in this system.
(5) Fat tissue revealed no significant changes except few cases which demonstrated atrophic degenerations and cellular infiltrations.
(6) The alternative selection of intraperitoneal route and intracerebral route manifested no significant difference.
(7) The systemic changes caused in this strain were of minor degree except of pancreas. The incidence and the type of lesion might be elucidated by the difference of the strains and the age of host.

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