Antigenic comparison of strains of Japanese encephalitis virus (JEV) was carried out using the modi -fied hemagglutination-inhibition technique of Casals (Grid HI test). Eight of these JEV strains were isolated from different areas of Japan (Tokyo, Kyoto, Fukuoka, and Gunma Prefecture), and one from Thai land. The strains were isolated from different hosts over a period of 30 years. Antigens for the test were obtained from suckling mice brain by the sucrose-acetone method, and specific hyperimmune sera were prepared in adult mice. The results obtained are as follows: 1. Nakayama-Yoken strain showed an optimum pH of 6.15-6.40 in hemagglutinin activity, and the others a pH of 6.45-6.75. 2. It was found that the final pH of the system in hemagglutination-inhibition test, after the suspen sion of erythrocytes had been added, influenced the results of the test; the inhibitory action of the serum increased with the pH in the limits of an optimum pH of its antigen. 3. There was significant antigenic difference between Nakayama-Yoken strain and Nakayama-RFVL, JaGAr 01, and the recently isolated strains. Hemagglutinins of the latter strains were inhibited by Nakayama-Yoken antiserum but the HI titer of the serum was not so high as when tested against the-homologous antigen. On the other hand, antigen of the Nakayama-Yoken strain was inhibited by anti -sera of the other strains with a titer nearly that of the homologous system. It has been believed that Nakayama-Yoken and Nakayama-RFVL strain, the representative strains of JEV, had the same origin, and it was suggested that the antigenic characteristics of the former had been changed in the course of long passage. 4. There was slight antigenic difference between Nakayama-RFVL strain and JaGAr 01 or the recently isolated strains, but antigenically they were closely related each other. 5. Considerable antigenic discrepancy was present between JaGAr 01 strain and the recently isolated strains, and it was demonstrated that the latter had broader antigenic composition than the former. 6. No antigenic difference was observed among the six recently isolated strains.
Capsular antigens of Klebsiella strains were easily liberated in physiological saline. The saline suspensions of the organisms (ca. 60 billion/ml) grown on an agar medium were heated at 100°C for one hour, centrifuged, and the clear supernatants were used as type antigen. In view of the fact that antigenicity of capsular antigens of some strains (type 1, 2) was occasionally destroyed by heating at 100°C for one hour and, in some types (7, 12, 33, 39, 41, 46, 63), a large amount of O antigen was liberated in saline resulting in getting rise to O cross reaction, means applied here, ins tead of heating, is that saline suspensions of Klebsiella were churned by blender, centrifuged, and the clear supernatants were used as type antigen. In such procedure, type antigens contain only few O antigens. Therefore, cross reaction by O antigens can be removed. It must be taken into consideration, however, that capsular antigens of some types (45, 59, 69) were not easily liberated by this method. Since it was not convenient to perform the identification of organisms with 72 separate type sera, the sera were divided into 9 groups each of which was pooled with 8 type sera. Type Sera showing cross reaction were pooled into the same group.
Comparative studies on bacitracin sensitivity test and haemolysis inhibition test were conducted in the field and the laboratory and the results obtained were as follows: 1) The total of 273 strains of streptococci including 250 strains of group A, 2 of group C, and 10 of group G, were isolated from healthy carriers among school children of the second grade in Kawasaki City. 2) The total of 12 strains (4.6%) among 262 strains showing 18 mm or more inhibition zone with bacitracin disk containing 2 units per disk were identified as group C and G. However, only 4 strains (1.6%) among 255 strains belonging to type 1 in haemolysis inhibition test by Kobayashi were group Cand G. 3) The total of 250 strains among 254 serologically-confirmed group A were screened by bacitracin sensitivity test and 251 strains by haemolysis inhibition test. 4) From these results it was confirmed that both of the methods had almost the same result for the screening of group A but the specificity for group A was better in haemolysis inhibition test than in bacitracin sensitivity test. 5) Bacitracin disk containing 2 units per disk showed the better result specifically in screening of group A than the disk containing 0.3 units per disk. 6) The incubation of the plates in refrigerator for 4 hours before incubation at 37cC had no effect on enhancing the specificity in screening of group A. 7) The concentration of NaCl had more influence on the specific screening of group A than the concentration of agar. 8) It was observed that the difference between the diameter of the growth inhibition and the haemolysis inhibition by bacitracin disk in group C and G was bigger than that in group A and would be useful in the differentiation between group A and the others.
Clindamycin (CLDM), a new antibiotic, was tried orally in the treatment of scarlet fever and hemolyticstreptococcal tonsillitis and evaluated with the following laboratory and clinical data: 1) Sensitivity of 51 hemolytic streptococcal strains against CLDM was investigated. The value: of MIC was found distributed between 0.006 and 0.195 mcg/ml. 2) Relationship between oral dose and bacteriological effects in vivo was studied employing thefindings of pharyngeal hemolytic streptococcus as a marker. One-time dose of 2 mg/kg was almost ineffec. tive in eradicating the cocci from the pharynx, but 5 mg/kg or more yielded the effects in 6-10 hours. 3) Twenty cases of scarlet fever in acute stage were given about 5-9 mg/kg LCDM every 8 hours for 5 days. In all the cases, there found marked clinical effects such as remmission of fever, recovery of ph aryngeal symptoms and disappearance of the cocci from the pharynx. After the halt of the medication, however, reappearance of the cocci in the pharynx was observed in 30% of them and fever recurrence in 20%. 4) Six cases of hemolytic-streptococcal tonsillitis were treated in the same manner as in the case of scarlet fever. The results were excellent in all the cases. Reappearance of the cocci was noted in two cases fever recurrence in no case. 5) As to side effects, vomiting was seen only once in one case who, however, tolerated the further me dication. Blood, urine and liver functions were tested in 19 cases at the end of the medication course, but no particular changes were revealed. From these results, it is concluded that LCDM, used at the one-time dose of 5 mg/kg or more, is as effective to scarlet fever and hemolytic-streptococcal tonsillitis as the other antibiotics such as penicillin or erythromycin which are already authorized to these diseases.