Isolated cell walls of Clostridium botulinum type A strain 190L released an autolysin during autolysis of the cell walls. The autolysin was isolated from the cell walls, and partially purified 18.6-fold by ammonium sulfate precipitation, chromatography on DEAE-cellulose and gel filtration through Sephadex G-100. The purified preparation of the autolysin showed 2 major and 2 minor protein bands on polyacrylamide gel electro-phoresis. Some properties of the autolysin were examined using SDS-treated cell walls of the organisms as a substrate. The autolysin was active over a pH range of 6 to 8, with a maximum near pH 6.8. The lytic activity was stimulated by 10^-4M each of Co⁺⁺, Mg⁺⁺ and Ca⁺⁺ in the order, whereas it was inhibited markedly by Cu⁺⁺. Mercaptoethanol (10^-4-10^-3M) significantly activated the lytic action. Trypsin and nagarse (10μg/ml) also stimulated the lytic activity. The lytic spectrum of the autolysin toward the SDS-treated cell walls obtained from various types of C. botulinum and C. per-fringens indicated a relatively high specificity. After treatment with hot formamide the cell walls of C. botulinum increased in susceptibility to the autolysin.

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Various aro, pyr, pur, and two other markers were located on the genetic linkage map of Klebsiella pneumoniae by employing a mating system in which genetic material was transferred by conjugation. These markers are widely scattered on the chromosome, and their locations were found to be similar to those of Eseherichia coli. Biochemical and genetic investigations suggested that in K. pnewnoniae, as well as in E. coli, the biosynthesis of 3-deoxy-D-arabino-heptulosonic acid-7-phosphate was catalyzed by 3 isozymes. A revised genetic linkage map of K. pneunaoniae including these markers has been presented.

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According to mutation mapping after nitrosoguanidine treatment of successive samples obtained from a synchronized culture of Escherichia coli K12 carrying an R factor, it was found that the majority of mutations of the R factor were produced after a maximum peak of galactose mutant production. According to the order of the chromosome replication and the initiation point of the replication, these facts suggest that the replication of the R factor occurs after the replication of the galactose gene. The transfer frequency of the R factor from a synchronized donor culture to the nonsynchronized recipient was the highest after the replication of the chlotamphenicol gene on the R factor, probably after the replication of the R factor genome. The recipient ability of the R factor in a synchronized recipient culture from a nonsynchronized donor was the highest after a maximum peak of the galactose mutation, and probably after the cell division in the recipient.

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An almost pure population of mononuclear phagocytes (macrophages) was obtained by repeated replacement of the culture medium. When treated in vitro with an immune ribonucleic acid (RNA) preparation extracted from the spleens of mice immunized with horse red blood cells (H-RBC) the rosette forming cells against H-RBC were demonstrated in some of the cultured macrophages but not against calf red blood cells. According to both microscopic observations and phagocytic activity, almost all of the rosette formers in this population were found to be large mononuclear phagocytes. These results support our view that large mononuclear phagocytes of mesenchymal origin constitute another cell line responsible for antibody formation in addition to the plasma and lymphocytic cell lines.

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A marked difference of levels of accumulation of macrolicle antibiotics (Mac) was found between Mac-sensitive (E642-1 and 209P) and Mac-resistant (MS642, MS57, U9, and 606) strains of Staphylococcus aureus by means of qualitative and quantitative bioassay methods. Though the levels of accumulation of the antibiotics in cells of Mac-resistant strains were only one-tenth that of the Mac-sensitives, satisfactory evidence for a relationship between the accumulation of the antibiotics and the degree of sensitivity to those drugs was established in a physiological sense from a kinetic measurement of K_s and v in the accumulation reaction of the antibiotics in the cells. The experiments with tritiated erythromycin or josamycin also support these results. It is suspected, by estimation of the accumulation in heated or UV-irradiated cells, that levels of accumulation of the antibiotics in cells of S. aureus could be reflected by a binding affinity of their ribosomes for these antibiotics. There was no system for inactivating the antibiotics seen in the cells of the Mac-resistants, i. e., MS642, 606, and U9.

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Ten rabbits were given a primary course of immunization by 4 weekly intravenous injections of herpes virus, and 1.5 years later 3 of them showing low titers of neutralizing antibody received 1 booster injection. The serological response in the primary immunization was characterized by an early development of complement-requiring neutralizing (CRN) antibody ahead of that of non-complement-requiring neutralizing (N) antibody, the CRN/N ratio being 8 to 128 within 3 weeks. In contrast, N antibody appeared much faster after the booster immunization, the CRN/N ratio approaching 4 within 1 week. The early type IgG, whose neutralizing activity was enhanced by complement (C') about 16-fold, was distinct from the late type IgG which could not be enhanced by C' more than 4-fold. The late type IgG appeared after 4 weeks and 3 days in the primary and booster immunizations, respectively. Serological examinations of human patients suggested the occurrence of the booster type response in the case of repeated infections among adults.

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Rabbits were immunized by 2 weekly intravenous inoculations of beta-propiolactoneinactivated Western equine encephalitis virus vaccine followed 1 week later by a subcutaneous inoculation of live virus, and complement requirements of early and late neutralizing antibodies were compared. There was no difference between these antibodies, both showing about a 4-fold enhancement of the virus-neutralizing activity in the presence of complement. This was also the case when guinea pigs were given the vaccine by the intraperitoneal route. It is unlikely that previous exposure of the animals to an antigenically related virus caused a booster effect upon the antibody development, because the rabbit antibody could not even neutralize the closely related Sindbis virus either in the presence or in the absence of complement. The reason for the existence of 2 different types of primary responses with respect to the complement requirement of early neutralizing antibody is discussed.

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Glycine, at a concentration of 5-10%, inhibited the growth of Streptomyces griseoflavus. The lysozyme sensitivities of the cell walls of the organisms cultured with and without glycine were the same. However, lysozyme caused 40% lysis of whole cells from cultures with glycine but had no effect on cells from cultures without glycine. The cell walls of organisms grown with and without glycine contained glucosamine, galactosamine, muramic acid, lysine, glutamic acid, glycine, alanine and DAP. Lysine and DAP were present in equimolar amounts. Very small amounts of asparagine, threonine and serine were found in both cell walls. Protoplasts were obtained in a high yield by treating cells from cultures containing glycine with 10mg/ml of lysozyme in 0.01M phosphate buffer (pH7.0) containing 0.1 MgSO₄ and 1M sucrose for 3 hr. The protoplasts were spherical and were surrounded by cytoplasmic membranes. The nucleoplasm appeared less dense with a clear network of nuclear fibers and mesosomes, abundant in whole cells, were scarcely seen. Rod-shaped forms without cell wall materials were sometimes observed under the electron microscope.

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Echovirus type 7 does not multiply in mice, but injection of this virus into mice (intracerebrally or intraperitoneally) increased their resistance to a subsequent infection with Coxsackie B virus, type 5 and to Japanese encephalitis virus by intracerebral route. The effect is evident in the survival rate and the prolongation of life among the mice that did succumb to Coxsackie or Japanese encephalitis virus infection, as well as those that developed paralysis. An adequate dose of active interfering virus and a time interval between the two inoculations were both necessary to obtain a significant interfering effect. Pretreatment of mice with actinomycin D suppressed the interfering effect by Echovirus type 7, and the kinetics of interferon production corresponded to the time of establishment of interference. All these findings suggest that the induction of resistance by Echovirus type 7 is mediated by interferon produced in the early stages of infection.

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