Exocellular phosphomannans produced by four strains of Hansenula yeast were examined as to their interferon-inducing activities in rabbits employing the assay system consisting of vesicular stomatitis virus and primary suckling rabbit kidney cells. The phosphomannan of Hansenula holstii NRRL Y-2155 was shown to be the most potent inducer, and the interferon induced was highly host species-specific, preventing viral cytopathic effects only in the homologous cells. The biological and chemical characteristics of the interferon closely resembled those of endotoxin-induced interferon.

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From a suspension of mouse spleen cells were separated two functionally different cell types on the basis of their ability or inability to adhere to plastic dishes during a short period of incubation. Morphological observations of cells of these two fractions were made with the aid of histochemical methods. The majority of cells in the adherent fraction possessed β-glucuronidase, which is one of the lysosomal enzymes rich in macrophages or phagocytic cells. In contrast, almost all cells in the non-adherent fraction were devoid of this enzyme activity and identified morphologically as small lymphocytes. The adherent and non-adherent cells were found to associate in cell clusters during the cultivation. In the cultures stimulated with sheep red blood cells, some of the non-adherent cells which were located peripherically in the cell clusters began to show alkaline phosphatase activity in their cytoplasm. This may perhaps indicate that antibody synthesis is going on in these alkaline phosphatase-positive cells, since in an in vivo study such cells were found to arise in the lymph nodes of immunized animals concomitantly with the appearance of specific serum antibody.

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In order to find out whether the mouse adenovirus-neutralizing substance, which appeared in the intestinal tract of mice orally infected with mouse adenovirus, was an immunoglobulin, examinations were carried out for the status of 3 classes of immunoglobulin, IgA, IgG, and IgM, in the intestinal tract as well as in the serum of the mouse. In infected mice, as in uninfected mice, the serum contained much IgG, a moderate amount of IgA, and a small amount of IgM, whereas the intestinal wall showed a moderate amount of IgA, a small amount of IgG and no IgM, and the intestinal contents contained a moderate amount of IgA. Secondly, DEAE-cellulose chromatography or Sephadex G-200 gel filtration was done in order to know whether the virus-neutralizing activity was recoverable in the fractions containing some class of immunoglobulin. The result indicated that a large part of the activity in the serum was recovered in the fractions of IgG and a small part in those of IgA. In the case of the intestinal wall, a large part of the activity was found in the fractions of IgA, and only a small part in the fractions containing both IgG and IgA. In the intestinal contents, the activity was detected solely in the fractions containing IgA. Finally, when the substance from the intestinal wall was purified by DEAE and Sephadex, a parallel increase of both IgA and the virus-neutralizing activity per protein content was observed. Thus, it became clear that the mouse adenovirus-neutralizing substance in the intestinal tract was an antibody against the virus, and that it mostly belongs to IgA.

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A delayed type hypersensitivity was demonstrated in hamsters infected with a fresh isolate of Mycoplasma pneumoniae by the following two procedures of macrophage migration inhibition test. In the first procedure, inhibition of migration of peritoneal exudate cells from normal guinea pigs by the addition of splenic cells from infected hamsters in the presence of the mycoplasma antigen was examined. In the second procedure, migration of peritoneal exudate cells, composed of macrophages and lymphocytes, from infected hamsters was examined after the addition of the antigen. Virtually, both procedures gave a similar result, suggesting the presence of cell-mediated immunity in the infected animals. In these infected hamsters, humoral antibody responses were also demonstrated at the same time.

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The requirements for, and conditions influencing, the germination of spores of Clostridium botulinum type E were studied in chemically defined media. Spores of this organism germinated rapidly and completely in various combinations of L-alanine and one of such carbon sources as sugars, lactate, and ribosides in the presence of bicarbonate. The most effective compounds tested were glucose, L- and D-lactate, and inosine. The formation of lactic acid was found to occur during germination of spores in a combination of L-alanine and glucose. Furthermore, the germination in this medium was strongly inhibited by fluoride or iodoacetate. The germination of spores was also initiated with high concentrations (100mM or more) of L-alanine or certain other amino acids alone in the presence of bicarbonate at pH 9.0. The spores germinating in L-alanine alone and those in L-alanine plus other compounds were compared as to the minimal concentration of L-alanine required, pH optimum, temperature optimum for heat-activation, bicarbonate requirement, and effects of various inhibitors. Significant differences among these characteristics led to a conclusion that different metabolic pathways, operating selectively each germinative compound used, might be involved in the germination of spores of the organism. The mode of action of combination in stimulating germination by the different germinative compounds has been discussed.

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The influence of fluctuation of the environmental temperatures on the multiplication of Mycobacterium leprae in mouse foot-pads was investigated. After infection with 10⁴ M. leprae into the foot-pads, mice were divided into the following 4 groups: Group 1, mice were housed in a room maintaining the air temperature at 20C with thermoregulatory devices throughout the experiment; Group 2, kept at 20C for the first 16 weeks, and at a regular animal room where the air temperatures fluctuated seasonally and diurnally for the next 15 weeks and then returned to the 20C room; Group 3, kept at 20C for the first 16 weeks and thereafter at the regular animal quarters; Group 4, kept at the regular animal room throughout the experiment. In the mice in Group 1, M. leprae increased as expected. Acid-fast bacilli also multiplied in the mice kept under fluctuation of air temperatures at the regular animal quarters but distinctly more slowly than in those kept at 20C. Acid-fast bacilli rose in the mice transferred to the 20C room from the regular ones, suggesting that viability of M. leprae is not significantly affected by ordinary fluctuation of air temperatures.

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Establishment of lactobacilli in the digestive tract of germ-free chicks was studied using the organisms isolated from chickens, human infants and sour milk and those received from the American Type Culture Collection. In the case of monocontamination, intestinal lactobacilli such as Lactobacillus acidophilus, L. salivarius and L. fermenti except L. acidophilus ATCC 4356 and non-intestinal lactobacilli such as L. plantarum and L. casei were well established in the digestive tract of germ-free chicks regardless of their origins, although the bacterial numbers of the established strains varied considerably in different parts of the gut. On the contrary, L. acidophilus ATCC 4356 of human origin and L. jugurti, L. helveticus and L. brevis which originated from non-intestinal materials failed to be established in the gut of germ-free chicks. In the case of dicontamination, L. acidophilus from an infant was shown to disappear after administration together with Escherichia coli or L. salivarius from chickens. L. plantarum and L. casei disappeared or showed a suppressed growth in the presence of L. acidophilus or Streptococcus faecalis var. liquefaciens from chickens.

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