8-Azaguanine inhibits the maturation step in T₄r multiplication on E. coli R2. Although the mechanism of this inhibition is unknown, we have obtained the evidence to indicate that there is some difference between pool-DNAs, which are synthesized in the presence or absence of 8-azaguanine.

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In delayed addition experiments with a purine-requiring mutant E. coli A-20, it was shown that an external source of purine was not required to support the early stages of phage development until 5 minutes after infection, provided glucose was added to the purine free medium. In this case, both RNA and protein can be formed immediately after infection in purine free medium, while uninfected bacteria can synthesize neither protein nor nucleic acids in this condition.

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The status of adenovirus infections in this country was studied by analysis of patients with acute respiratory infections and other diseases by the complement fixation test. The antigen employed was prepared from HeLa cell culture infected with Type 3 adenovirus. The patients studied were those at the Sagamihara National Hospital, Kanagawa. The incidence of the antibody was studied on 571 patients without respiratory infections in September and October, 1957. The positive rate increased with age and reached a plateau at the age of 17-20 years with some decrease in higher age groups. No significant difference in incidence was observed between male and female. The longer the period in hospital was, the higher the incidence was. In the test on 108 cases of primary atypical pneumonia and 180 cases of upper respiratory infections from April, 1957, to December, 1958, the incidence of the patients with titers of 1:8 or higher was 40.7 and 47.8per cent, respectively, much higher than the control group of patients with other diseases whose incidence was 21.5per cent. In those two groups of patients no difference in incidence distribution by age or sex was observed. Patients with a definite increase and/or decrease in titer (four-fold or greater) were found in 13.6per cent of 81 cases with primary atypical pneumonia and in 21.6per cent of 88 cases with upper respiratory infections. Among patients in which appropriate serum specimens were available in the first and the 3rd-6th week of disease, the detection rate was 25.0per cent of 12 cases and 31.4per cent of 35 cases, respectively. The clinical picture and the appearance and persistence of the antibody was analysed with those serologically diagnosed cases. The cases were found throughout the year, although some difference was noticed between 1957 and 1958.

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In view of the recent discovery of psittacosis in avian species and human beings in this country, a survey was conducted on the patients at our hospital from January, 1956, to December, 1958. The complement fixation test using the psittacosis antigen was extensively employed. The patients examined were consisted of 160 cases with primary atypical pneumonia, 119 cases with acute bronchitis and 3 cases with middle lobe syndrome. As the control a group of patients with other miscellaneous diseases was included in the study.
1. The incidence of the antibody in the miscellaneous disease group increased with age and reached a plateau at the age of 40-49 years. This finding strongly suggests that the disease is endemic in this area.
2. The incidence of the antibody was significantly higher in the groups of pneumonia and bronchitis (46.9 and 38.7per cent, respectively) than in the control group (26.1per cent). The difference in incidence between the pneumonia and bronchitis groups was also highly significant. The incidence in the groups of patients with pneumonia and bronchitis was high already in the age group of 0-9 years and did not show any significant difference among the age groups, while the miscellaneous disease group showed an increase in incidence with age. These findings suggest that the groups of pneumonia and bronchitis contain many psittacosis patients. However, no significant difference in incidence was discernible by week of disease in these patient groups.
3. The incidence of the antibody did not show any difference between male and female.
4. The complement fixing titer was generally low. However, some patients of the groups of pneumonia and bronchitis showed higher titers in contrast with the miscellaneous disease group, a fact supporting the view that those two groups of patients contain psittacosis patients. The distribution of the titer in the control group of patients with miscellaneous diseases gave one of criteria for serological diagnosis of psittacosis.
5. Patients with a definite increase and or decrease in titer or an unusually high titer were found in 11.9per cent (19 cases) in the pneumonia group and 2.5per cent (3 cases) in the bronchitis group. The clinical picture of these patients was in accordance with that of psittacosis. Of the 3 cases with middle lobe syndrome 2 showed serological evidence of recent infection with psittacosis virus. Middle lobe syndrome observed in these cases was probably produced by psittacosis infection. The appearance and persistence of the complement fixing antibody were analysed with those serologically diagnosed cases.
6. A significant correlation shown between the presence of the antibody in the patient and pet birds at his household suggests the importance of parakeets, particularly budgerigars, pigeons, bengalees, Java sparrows, and canaries as the source of human infections with psittacosis virus. Chickens were also suggested to be one of the sources of the virus, although they might be of less importance.
A similar analysis was performed in relation to domestic animals such as cattle, sheep, goats and cats, but no correlation was found.

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A method of preparing ribonucleic acid (RNA) from tobacco mosaic virus (TMV) has been developed, based on denaturation of the protein part by guanidine hydrochloride and precipitation of RNA by neutral salt, avoiding extreme pH, high temperature and use of any organic solvent. The purity of the RNA thus obtained was as high as the RNA obtained by the sodium dodecyl sulfate method (Fraenkel-Conrat) or by the phenol method (Gierer and Schramm). The virus activity of the RNA alone obtained by the guanidine method was usually very low, while the RNA obtained by the phenol method was found as infectious as that reported by Gierer and Schramm. The molecular weight of RNA as determined by sedimentation and viscosity measurements was high (1.5-3×10⁶); this value suggests that one TMV particle contains one single molecule of RNA. The molecule of RNA obtained by the guanidine method was found to be hydrodynamically less resistant than that obtained by the phenol method.

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