On many experiments I conclude that there is not always close relation between infectivity on chickembryos or mice and CCA potency of influenza viruses. CCA activity, infectivity and immunizing ability have their own indifferent factor and they can be separated.

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When influenza viruses (A type PR8, A-prime type FM1 and Matsumoto, B type Lee) are denaturated by ultraviolet irradiation or urea, their infectivity is easy destroyed but their hemagglutinating activity is relatively reserved. On their immunizing ability we must study more on detail.

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It is the well established fact that after the recovery from the typical course of the Tsutsugamushi disease the patients acquire the solid immunity against it which was proved to last at least for a decade or thereover. However, in regard to the aspect of the immunity development in the case in which the disease was suppressed with antibiotics as soon as the specific symptoms became manifest, there remains much to be made clear.
The author, in order to make this aspect clear, made some trials on human beings. Namely the patients of general paralysis, which had to receive the fever treatment, were infected with the inoculation of the virus of the Tsutsugamushi disease, Pescadores strain, of certain titer of mouse LD 50, and received the drug therapy with antibiotics to recovery at the various stadium of the disease. The investigation of the immunity development just mentioned was performed upon them. A part of the results obtained is presented preliminary in this paper as the first report. Namely it can be described summarily as follows.
1. The experimental minimal infectious dosis (M. I. D) of the virus of the Tsutsugamushi disease to human beings is of approximate value to mouse LD 50 titer of it.
2. Below the M. I. D., the virus cannot elicit the immunity development at all in the human body, althogh it had certainly invaded into it.
3. The specific symptoms of the disease become just manifest when the invaded virus multiplied somewhere in the body to such an extent to elicit the rickettsiemia of approximately 10^-2 LD 50.
4. The patient is far more sensitive to the drug therapy with antibiotics at the height of the disease or still later than at the beginning of it.
5. The specific reaction of the site of the skin, where the virus had certainly been inoculated, can sometimes be failed, though the inoculated person contracted the disease typically.
6. A certain correlation can be observed between the length of duration of the disease and the degree of rise of OXK agglutinin titer.

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I. Brain and spinal cord of mouse infected and paralyzed with poliomyelitis virus Lansing strain were inserted into bananas and were orally administered to 9 cynomolgus monkeys. Tokyo strain virus (type 2) was also administered to 6 monkeys in the same way. None of of all the 15 monkeys manifested the signs of apparent infection by the oral administration of the virus.
II. Viremia was recognized on 6 of 15 monkeys during the period ranging from the very day of the virus administration to 4-5 days after it. Also of 3 among 7 groups the viruses were positive in stool specimens only on the next day of the virus administration.
III. Two monkeys which had inoculated with cow serum γ-globulin were both viremia negative, and their stool specimens were also virus negative.
IV. Noticable increase of neutralizing antibody of the monkey sera was not observed after the oral administration of the viruses.

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A poliomyelitis virus strain was isolated by intracerebral and nasal administration on monkey from the spinal cord of a paralytic poliomyelitis case died in Scptember, 1950 in Tokyo, which was stored in dry ice until the day of inoculation in March, 1952. The spinal cord of the sacrificed monkey was successfully transfered to mouse by intracerebral inoculation.
The mouse adapted Tokyo strain was applied to the neutralization test against each immune monkey serum of Lansing, Brunhide, Leon, B-34 (a type 2 poliomyelitis virus, recovered in Tokyo, 1948, using mouse only.) and also of Tokyo strain. The result of the neutralization test showed that the newly mouse adapted Tokyo strain was well neutralized by the immune sera of Lansing, Tokyo and B-34, and hardly neutralized by Brunhilde and Leon immune sera. Hence it is understood that mouse adapted Tokyo strain is to belong to type 2 together with B-34 and Kawasaki strains.
At the brain passage, the harmonic mean of the incubation period of this Tokyo strain is 5.4 days which shows 2 days shortening, comparing with that of Lansing strain which is 7.3 days.

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Five nitrogen mustards; methyl bis (beta-chloroethyl) amine hydrochloride, tris (beta-chloroethyl) amine hydrochloride, amyl-bis (beta-chloroethyl) amine hydrochloride, diethyl (beta-chloroethyl) amine hydrochloride and N, N'-tetrakis (beta-chloroethyl) ethylen diamine hydrochloride, and N-oxide of each (N, N'-dioxide with the last amine) were examined in vitro concerning VH or virus inactivating effect (The compounds are referred to only by their initial letters. and vaccinia hemagglutinin is referred to as VH.).
Tetrakis was found to be the most effective in inactivating vaccinia hemagglutinin, whereas diethyl. ox was scarcely effective even at the concentration of 1/25 M. VH inactivating activity appeared to depend on the number of betachloroethyl radicals and the N-oxide of each compound was in general less effectiev than the original compound with the exception of tris and its N-oxide. Amyl, which has the same structure as bis except that the former has an amyl-radical in place of methyl-radical in the latter, was far more effective than the latter. A gross parallelism was observed between the VH (inactivating effect) and viral infectivity inactivating effect of the compounds, but diethyl and diethl. ox were effective in inactivating viral infectivity in vitro at the concentration (where VH was hardly inactivated).
The order of the compounds in regard to VH inactivating activity will be described as follows: tetrakis>amyl>tris. ox>tetrakis. ox>amyl. ox>tris>bis>bis. ox>diethyl>diethyl. ox.
The effect of potassium periodide, hydrogen peroxide or Fenton's reagent on VH was also examined and it was proved that VH was inactivated by potassium periodide, whereas hydrogen perioxide or Fenton's reagent was ineffective under the same conditions.

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Vaccinia hemagglutinin, either so-called thermolabile or thermostable, was inactivated by ultraviolet irradiation.
Inactivation was retarded by a certain dialysable substance contained in normal or infected chorioallantoic membrane and was accelerated by sodium chloride in the suspension.
Sodium chloride was also proved to be an important factor which inactivate vaccina hemagglutinin when heated at 56°C for 30 minutes.

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Potency of Japanese B encephalitis vaccine is tested as follows: On 1st and 4th day, intraperitoneal injection with O.1cc of vaccine respectively, into 30 mice of 3 to 4 week-old, and on 8th day, the test animals as well as 30 mice in control are respectively challenged intraperitoneally with 0.2cc of 10^-1 dilution of mouse brain saline suspension infected with Nakayama strain of Japanese B encephalitis virus. On 22nd day, the test animals must survive over 50% under the conditions of virus infectivity in control being that the LD₅₀ is over 10^-3, for example 10^-26, and also the mortality in 10^-1 is over 90%. When the LD₅₀ is under 10^-4, the test must be retested. When the test animals survive over 50%, the vaccine is good.
By using this potency test, authors researched on the antigenic variation of Nakayama strain of Japanese B encephalitis virus.
Mouse brain passaged virus (M: Standard line) was serially passaged through embryonated eggs, and the virus of 2nd, 10th or 20th generation of passage was respectively designated as E₂ E₁₀, or E₂₀.
The vaccine prepared from E₂, E₁₀, or E₂₀ was respectively designated as E₂Vac, E₁₀Vac or E₂₀Vac.
The virus of egg line was serially passaged through mouse brain, and the virus of 2nd., 10th., or 20th, generation of passage was respectively designated as CM₂, CM₁₀, or CM₂₀. The vaccine prepared from CM₂ CM₁₀, or CM₂₀ was respectively designated as CM₂Vac, CM₁₀Vac, or CM₂₀Vac.
The vaccine prepared from M was designated as MVac.
Cross immune tests between E₂Vac, E₁₀Vac, E₂₀ Vac, or MVac and E₂, E₁₀, E₂₀, or M are carried on.
In the case of challenge with M, the potency of vaccines are as follows: E₂ Vac is highest, E₂₀ Vac lowest and E₁₀ Vac intermediace.
That is, the potency decreases parallel with the increase of aggpassage generation. In the case of challenge with E₂, E₁₀, or E₂₀, however, the potencies of E₂ Vac, E₁₀Vac and E₂₀ Vac are almost the same.
Cross immune tests between CM₂ Vac, CM₁₀ Vac or MVac and CM₂, CM₁₀, CM₂₀ or M are carried on.
The potency of MVac is highest in the case of challenge with M or CM₂₀, lowest in the case of challenge with CM₂ and intermediate in the case of challenge with CM₁₀.
CM₂₀ Vac shows the same tendency as MVac.
The potency of CM₂ Vac is highest in the case of challenge with CM₂, and decreases in due order of CM₁₀, CM₂₀ and M.
From the results mentioned above, it is concluded as follows: the antigenicity of mouse brain passaged line of Nakayama strain of Japanese B encephalitis virus varies by serial passage through embryonated eggs and the variation is revresible.
As the antigenic change is caused by host-alternating, it is considerad as “host-controlled variation.”

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In tissue cultures of rabbit, guinea pig or mouse tissues, either adult or embryonic, multiplication of the Newcastle Disease virus has never been evidenced. In these cultures, the end titer of virus after different periods of incubation was always found lower. than the virus titer at the start. In the presence of rabbit brain, however, the end virus titer after a few days incubation was usually a little higher than in the control culture which contained no tissue. This is considered to be due to a favourable influence of the tissue on the survival of the virus in the medium. Such an effect of tissue remained unaltered after the tissue was dipped in the boiling water bath for five minutes.
In the culture with chicken embryo tissue fragments (brain mostly used) simply suspended in Tyrode solution, the virus multiplied easily, and the culture fluid reached the virus titer of 10^-6.5-10^-7.5 (chicken embryo MID) within 3 days of incubation. In this culture, the same level of maximum virus titer was obtained from different amounts of starting virus, i.e. 10², 10⁴ and 10⁶ MID. Addition of embryo extract and/or serum, or fixation of tissue fragments in blood plasma or on a paper piece did not appear to increase the maximum virus titer of the culture. When the tissue previously dipped in the boiling water bath was used, the virus never multiplied, but maintained the same level titer as in the rabbit tissue culture.
In the culture with abult chicken tissue fragments (spleen mostly used) suspended in Tyrode solution, multiplication of the virus was demonstrated by periodical titrations of the culture fluid, though the maximum titer (about 10^-4.5) never reached the level so high as in the culture of the embryo tissue. In this tissue culture, however, multiplication of the virus was remarkably increased, when chicken serum was added to the medium, or the, tissue fragments were fixed on the paper. By the combination of these two conditions, the virus titer became comparable with that which was obtained in the embryo tissue culture.

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The virus in the supernatant fluid of the janudicediseased larval blood was neutralized by the immunized rabbit serum against this antigen when the virus was mixed with the equal volume of immune serum and the resulted mixture was maintained at room temperature for 30 minutes. On the other hand, the dilution phenomenon did not occur when the mixture was diluted with the distilled water.
The neutralizing antibody in this serum was absorbed by the supernatant fluid of the infected larval blood, while not with that of the healthy larval blood.
When the vaccine made from the infected larval blood was injccted to the pupae, the immunized effect was recognized to some extent but the antibody was scarcely present in the blood of the immunized pupae.

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The immunized rabbit serum against the polyhedral bodies or the supernatant fluid of the infected larval blood agglutinated the polyhedral bodies and the agglutinins in each serum was absorbed by the homologous and another antigens.
The immunized rabbit serum against the supernatant fluid of the healthy larval blood did not agglutinate the polyhedral bodies. And also the healthy larval blood did not absorb the agglutinin in the other two serums as mentioned above.
When the pupae were immunized with the vaccine made from the infected larval blood, no increase of agglutination titer of the polyhedral bodies could be recognized.

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The immunized rabbit serum against the supernatant fluid of the infected larval blood was injected to the pupae and then the challenge by the virus was performed after the varying intervals, however, the passive immunity could not be reccegnized.
After the virus inoculation, this serum was injected to the pupae st varying periods and times but the serum therapy was unsuccessful.
As reported before, when the virus is heated at 50 or 60°C for 20-30 minutes, almost all of the activity is lost. The pupae were heated at 50°C for 15 minutes just after the inoculation of the each decimal diluted virus solution, but the heat therapy was unsuccessful in the case of the inoculation of the marked diluted virus solution.
Penicillin or streptomycin solution was mixed with the equal volume of the virus solution and this mixture was maintaiaed at room temperature for 30 minutes and thereafter the inoculation of the mixture was perfomed but the decrease of LD₅₀ or the elongation of the latent perod could not be recognized.
The immnization was effective when the vaccine made from the infected larval blood was inoculated.

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In the present paper some experiments are described on the effect of ultraviolet radiation upon the pathogenicity and antigenicity of tobacco mosaic virus (TMV).
The virus preparation used in this work was the aqueous suspension of TMV which had been purified by Bawden's procedure. The antiserum used was prepared by injecting rabbits with the purified TMV. The infectivity of the irradiated TMV was tested by the so-called half-leaf method on the leaves of Nicotiana glutinosa plants. In serological tests of TMV, the precipitin reaction was used. The virus preparation 2-3mm thick in a Petri dish of 9cm in diameter on a shaking apparatus was irradiated by means of the Matsuda's 15-W germicidal lamp. The wave-length of the ultraviolet light employed was 2537 Å. The pH of the virus preparations were 6.0-6.2 and their temperatures were 15°-20°C at the time of irradiation, and no rising of temperature of the prepations due to the irradiation was recognized.
The experimental results are summarized as followes:
(1) When the logarithm of the surviving fraction has been plotted against the dose of irradiation according to the numder of lesions obtained by the half-leaf method of inoculation, the survival curves were shown by straight lines with the small difference due to the experimental error (Fig. 1 and 2). Consequently, these results seem to agree with the view that the inactivation of virus by ultraviolet light is caused by the absorption of asingle ultraviolet quantum in the same way as that the inactivation of virus by ionizing radiations is attributable to a single ioization of the virus.
(2) The inactivation doses (the 37% doses) were estimated from the survival curves to be 2.5×10³μW and 1.5×10³μW in the case of the virus preparations of 0.2% and 0.02%, respectively.
(3) The preparations of TMV completely inactivated by ultraviolet irradiations always showed as strong serological activity as the control (Table 1, 2, 3 and 4). However, the serological activity was completely lost when the doses of ultraviolet radiations were increased to more than 13×10⁵μW, while the precipitin reaction of TMV irradiated with the doses of 2.6-6.5×10⁵μW became intensifid as compared with the control (Table 5).

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Lysogenic strains, E (α₁, β) and R (α₂) could be obtained from their original strains, E (β) and R, respectively by lysogenization caused by infection with Phage α liberated from lysogenic strain A (α).
Endotoxins of each strains were prepared in electrophoretically homogeneous states for precipitin tests. The endotoxin of strain E (α₁, β) was found to react with the anti-serum against the endotoxin of strain A (α), which didn't show any reaction with the E (β) cndotoxin; that is, the endotoxin of strain E (β) was considered to be so modified by the lysogenization with phageα as to possess a common serological specificity with that of strain A (α).
The similar relationship was obtained between the A (α) endotoxin and that derived from R (α₂) strain.
Our previous studies have shown that the purified endotoxin of Pseudomonas aeruginosa seemed to be mainly composed of polysaccharidenucleoprotein complex and that desoxyribonucleic acid (DNA) component could be readily split off by peptic digestion.
It was found that the split endotoxin had lost the aquired common serological specificity, suggesting the DNA fraction might be related to the modification of antigenic properties of the endotoxin.

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