The morphological studies were extended further mainly by the electron microscopy of the ultra-thin sectioned specimens and revealed the presence of two different types of inclusion bodies which were observed inside of the Ehrlich ascitic tumor cells infected with ectromelia virus, especially at the terminal stages of transplanted animals.
Two strains of ectromelia virus were distinctly differentiated each other by the mode of viral multiplication within their blue staining inclusion bodies.
In the case of A strain of the virus, a close co-relationship was evident between the electron density of the ground substance of the inclusion bodies and the number of the viral particles within them. The destructive picture of the inclusion bodies were never observed along the whole course of the infection.
On the other hand, B strain of the virus did not show any morphological evidence to invade the blue staining inclusion bodies which were formed up independently from the viral particles.

View full abstract

The prophage state of lysogenic bacterium KA (β+) was analysed upon curves of inactivation of plaque forming capacities by ultraviolet light which method had been devised by Luria & Latarjet.
At first. KA-β complexes established by infection of temperate phages β to the sensitive host cells KA (Shigella flexneri type 5) were followed by ultraviolet irradiation during the latent period, and then in the same manner, inactivation curves of induced complexes of KA (β+) were obtained. Thus the possible interpretation was given upon the prophage state on the basis of these findings.
The latent period of infected complexes were conventionally divided into three different phases, that is, the stage of lag, duplication and of maturation. It was considered that the inactivation curves of plaque forming capacities of infected complexes KA-β have consisted of both inactivation of phage material itself and of the ability supporting phage production in host cell side [C]. It become, however, evident that the plaque forming capacity of uninfected host cells KA [H] has had nothing of agreement with the ability supporting phage production in infected cells [C], and no reasonable explanation has been found in regard to this discrepancy between plaque forming capacities given by two kinds of host cells. By ultraviolet light irradiation, the change of plaque forming ability in the induced KA (β+) was observed to be almost similar to those of β infected KA during latent period. The inactivation curve at the moment of induction corresponds to inactivation of intracellular phage material having an ultraviolet sensitivity equivalent to free phage and also of the ability supporting phage production in host cell side [C].
It therefore would be reasonable to recognize prophage as a target showing an ultraviolet sensitivity equivalent to free phage. Thus it may be concluded that about three prophages are contained in a lysogenic cell and transmitted through cell to cell indefinitely. Referring to results of E. M. Lederberg, G. Bertani and E. L. Wollman, it would be, in reason, considered to come to the conclusion that these several prophages are intimately associated with cardinal physiological organization, possibly genetic apparatus.

View full abstract

The work reported here mainly concerns the amounts of phosphorus compounds in various fractions of the tobacco or tomato leaves during the course of tobacco mosaic virus-infection. The homogenized juices of leaf tissue were fractionated by Schneider's method and inorganic phosphate liberated was determined by Allen's method using electrophotometer. Most noticeable effect of virus infection on phosphorus compounds was on nucleic acid fraction either from the experiments on detached leaf placed in nutrient solution or those on plants grown in pots. Usually 20-50 per cent increased amounts of them, especially of ribonucleic acid, were demonstrated in detached leaf 24-48 hours after inoculation. Essentially the same results ware obtained in the upper leaves when the lower leaves of the same plants were inoculated with the virus.
By way of the same fractionation procedure of leaf-homogenized juices, it happens that the increased RNA content was, in one case, observed in the supernatant fraction after centrifuging ×20, 000g, or, in another, in the precipitates by 100g centrifugation. No attempt was made to solve this problem. P³² in nutrient solution in which the inoculated leaves were floated, was found to incorporate into virus nucleic acrd 3 days after inoculation. Apart from this, the locally respond leaves of Nicotiana glutinosa showed no increased amount of nucleic acid when they are inoculated with TMV.
The amounts of acid soluble phosphorus compounds, especially inorganic P, was higher in the inoculated leaf than in the sound. The difference in organic P content betwen the sound and infected leaves was still inconclusive, although it seemed likely to decrease in the latter. Further, the protein and lipid of the infected tobacco leaf comprised much amount of P than those of the sound throughout the infection. At our present level of understanding, it seems more reasonable to emphasize the fact, from these findings, that no evidence about a shift of the metabolic process of leaves incited by viruses could be demonstrated except the increased amount of virus nucleic acid.

View full abstract

Properties of the phosphatases in green leaves and the change of their activities in the course of virus infection were investigated. The pH optimum of this enzyme lies between 5.8 to 6.0 using β-sodium glycerophosphate as substrate. Adding MgCl₂ as an activator, alkaline (optimum pH, 9.4) pyrophosphatase was demonstrated in the green juices, while only a little alkaline glycerophosphatase. The acid glycerophosphatase activity was reduced by half for 5 minutes' exposure to 60°C and inhibited by NaF, but not influenced by Mg ion. The fractionation of the juices of the mosaic leaves revealed that the plastid fraction has no its activity, nevertheless that the fraction of the resultant precipitates by adding ammonium sulphate until 0.6 saturated to the supernatant after centrifuging the homogenized juice at 1, 000 G has about 90 per cent activity.
The detached leaves of tobacco, tomato, turnip, and spinach inoculated with tobacco mosaic virus or turnip mosaic virus were placed in water or in nutrient solution and their phosphatase activities were estimated at the different times from inoculation. Sometimes the plants grown in pots in greenhouse were also tested. From these experiments it appears that the acid phosphatases have the tendencies to decrease in the later stage of infection. Despite of that some of the data concerning the increased activities of phosphatases, especially those of alkaline pyrophosphatase, were obtained in an initial stage of the infection, it is thought desirable to conduct a more detailed experiment on this problem in future. In some case, however, it happens that the inoculated leaves, especially those of tobacco plants, do not show during virus infection any detectable difference in the activity compared with the uninoculated leaves. On the basis of these findings, the metabolic process of the virus-infected leaves was discussed.

View full abstract

Deembryonated eggs 13-14 days old, as used in the experiment I, were employed to cultivate the Nakayama strain of Japanese B encephalitis virus for 48 hours.
The nutrient fluid was improved. It usually contained 1, 000 units/ml penicillin and chick embryo extract in concentration of 1%.
Yolk treated with ether or glacial acetic acid was used as the nutrient fluid. The 1% yolk fluid treated with glacial acetic acid was better than the 2% yolk saline. LD₅₀ of the culture fluid was 10^-8.0 at maximum and 10^-7.4 averagely.
The results of cultures using the nutrient fluid treated with ether was inferior to them using the yolk fluid treated with acetic acid.
When the yolk fluid treated with acetic acid is prepared, the following conditions should be taken into consideration. Fresh eggs must be chosen. The pH of the yolk fluid should be adjusted with sodium hydroxide solution to be at 7.2-7.4. The yolk fluid must be used within 14 days after prepared. Buffered phosphate solution must be used to make 1% diluted yolk fluid.
The yolk sac and other parts of deembryonated eggs infected with Japanese B encephalitis was treated with glacial acetic acid in the same manner as above and used for culture. The results were not so well as described above. However, LD₅₀ of the cultivated fluid was 10^-6.5-10^-7.0; namely, it was higher than those of infected chick embryo.

View full abstract

Vaccinia virus inactivated by ultraviolet irradiation interfered with multiplication of active homologous virus on the chorioallantoic membrane of developing eggs. Emulsions of infected chorioallantoic membranes lost infectivity first, and then interfering activity, when irradiated by ultraviolet rays, with a relatively narrow range of ultraviolet dose between inactivation of infectivity and of interfering activity. A relatively large dose of inactive virus was necessary to produce interference. Under our experimental conditions the phenomenon occurred most strongly when inactive virus was inoculated 24 hours previous to active virus. The phenomenon was observed only when active and inactive viruses were inoculated on the same site of the membrane. Emulsions of normal chorioallantoic membranes, Seitz filtrates of irradiated emulsion of infected membranes, and irradiated supernatants after high-speed centrifugation had no interfering activity. In contrast virus suspensions partially purified by differential centrifugation showed marked interfering activity after irradiation.
According to these findings it is reasonably concluded that interference observed in this system may be due to direct action of ultraviolet-inactivated virus particles on cells susceptible to vaccinia virus.

View full abstract

In smear preparations of vaccinia virus inoculated on rabbit cornea or on the chick chorioallantoic membrane, I have found that with the Giemsa stain two types of inclusion body can be observed. One is a pale blue staining inclusion body, the “A” type inclusion body and the other a red staining inclusion body, the “B” type inclusion body or the so-called Guarnieri body.
The Guarnieri body seen in section preparation is identical with the pale blue staining “A” type inclusion body seen in Giemsa stained smear preparations. Therefore there are two types of inclusion bodies that are called Guarnieri body.
The “B” type inclusion body of the vaccinia virus is morphologically and in developmental procedure, very similar to the “B” type inclusion body of ectromelia virus and fowlpox virus. The “A” type inclusion body, however, in comparison to the “A” type inclusion bodies of ectromelia and fowlpox virus is seen less frequently.

View full abstract

OP_1t phage, one step mutant of OP₁ (Xanthomonas oryzae phage), is found to be a new type mutant. It is called growth temperature mutant on account of its optimum growth temperature (25°C) differs from that of the wild type (30°C).
When these two phages attack simultaneously the same host bacterial cell, they both penetrate and multiply.
The phage producing potency of the cell is divided not in accordance with the different multiplicity of the inoculated phages but with the faculties or reproducing speed of them; and the cell releases both types of phage progenies in a definite proportion.
Scarecely any difference on the average burst size between the case of mixed infection and that of simple infection is found.

View full abstract

In this communication a report is made on hemagglutination by dengue virus (Hawaiian strain).
The results are summarized as follows.
The physico-chemical properties of dengue virus hemagglutinin.
1. Dengue virus hemagglutinin was appeared in the 2 to 3 day-old mouse brain at 3rd day after inoculation.
2. The hemagglutination of dengue virus was completely inactivated by heating at 56°C for 5 minutes. It could be said, from these results mentioned above, that the dengue hemagglutinin was thermolabile.
3. The hemagglutinins absorbed to horse red cells were eluted in calcium chloride solution by heating at 37°C, but it was also conformed that hemagglutinins were rapidly and easily eluted in normal saline solution by keeping at 4°C.
4. The hemagglutination titer and LD₅₀ of the dengue virus were parallel with the difference of 10^2.2-10^2.8, but that was not always parallel by physico-chemical trial.
The role of calcium chloride in the hemagglutination.
1. Calcium chloride solution had the action of protection of dengue hemagglutinin.
2. The object to which calcium chloride acted was red cell.
3. Calcium ion had the important effect of calcium chloride.
4. Calcium ion was adsorbed by horse red cells.
5. Calcium ion in the calcium chloride solution seemed to produce the receptor by combining with pre-receptor which was situated on the surface of horse red cell.

View full abstract