Opaque (Op) and translucent (Tr) colonial variants were isolated from Vibrio vulnificus strains. Op-type variants were more resistant than the isogenic Tr-type variants, but the survival rate of the Op-type variants varied with the strains. Antisera were prepared by immunizing rabbit with whole cells of Op and Tr variants of some strains, in which the difference of the sensitivity between Op and Tr cells was remarkable. Then agglutination tests with their living and heat-killed cells were carried out. The results suggested the presence of capsular antigen in Op cells and its absence in Tr cells, with the exception of the existence of a slight amount of capsular material in Tr variants of strain L-180. The thin capsular layer of Tr cells of strain L-180 was also demonstrated electron microscopically, but the layer was thinner than that of the isogenic Op cells. Results of determination of sugar content in the extracted capsular fraction also showed that Op to Tr transformation was due to loss of capsular antigen of the cells. These results confirmed the morphological studies previously reported which suggested the prevention of host defense system by the capsular material of the vibrio.

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Mesosomes were isolated and purified from Micrococcus luteus under hypertonic conditions throughout preparation processes. The purified mesosomal preparation was composed of closed tubules and vesicles. Electron-dense ribosome-like particles were observed within the isolated mesosomal vesicles by electron microscopy. The ribosome-like particles were isolated from the purified mesosomes by a procedure involving solubilization of the membranes with detergents followed by centrifugation on a linear density gradient of sucrose. The isolated particles have a sedimentation coefficient of 70S in the presence of 10mM Mg²⁺, when Mg²⁺ concentration was lowered to 0.1mM, the particles were dissociated into two sub-particles of 30S and 50S. The 70S particles had the same appearance as cytoplasmic 70S ribosome particles upon observations of negatively stained preparations. These findings indicate that mesosomal tubules contain ribosomes. The isolated mesosomal ribosomes had the ability for protein synthesis when polyuridylic acid-directed polyphenylalanine synthesis was assayed. The sensitivity of mesosomal ribosomes to inhibitors, chloramphenicol and streptomycin, for protein synthesis was significantly lower than that of both cytoplasmic and cytoplasmic membrane-bound ribosomes. In addition, three penicillin-binding proteins were detected in the mesosomal membranes. One of these was localized predominantly in the mesosomal membranes and the other two were distributed almost equally in both mesosomal and cytoplasmic membranes.

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Escherichia coli isolates from calves with diarrhea (1 day to 8 weeks old, 140 individuals) were surveyed for the three immunologically distinct fimbrial adhesins FY, 31A, and K99. Of a total of 1, 370 strains isolated, 96 (7.0%), 34 (2.5%), 75 (5.5%), and 13 (0.9%) were identified as FY⁺, 31A⁺, FY⁺•31A⁺, and K99⁺, respectively. The K99⁺ strains also manifested heat-stable enterotoxin production (ST⁺), while FY⁺, 31A⁺, and FY⁺•31A⁺ strains were ST^-. Expression of FY and 31A was repressed at lower temperatures or poor aeration. The FY⁺ and 31A⁺ E. coli showed mannose-resistant hemagglutinating activity with bovine erythrocytes. Electron microscopy revealed that FY is a gently curled fimbria with a mean diameter of 4.2nm, and 31A is a fimbria with a mean diameter of 5.1nm. The molecular mass of protein subunits was found to be approximately 20 kilodaltons (Kd) and 19Kd for FY and 31A, respectively. Lethal diarrhea of neonatal calves was induced by challenge with the combination of a K99⁺•ST⁺ E. coli strain and either a 31A⁺ E. coli strain or a 31A⁺ E. coli strain plus an FY⁺ E. coli strain under the experimental conditions in which lethal diarrhea was not induced by challenge with a K99⁺•ST⁺ E. coli strain alone.

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The present studies were undertaken to characterize the affinity of CMV-induced Fc receptors for each of the subclasses of human IgG and to define the specific region of the IgG Fc fragment interacting with such receptors. To do this, we infected confluent human embryonic lung (HEL) cell monolayers with CMV (strain AD169) and then used a double radiolabel assay to measure adherence of antibody-coated E. coli 06 to such monolayers. Preincubating monolayers with each of the 4 subclasses of human IgG (but not IgA, IgM, or human or bovine albumin) abrogated the enhancing effect of CMV infection on adherence of antibody-coated E. coli 06 to HEL monolayers. Pepsin-derived, purified Fc fragments of human IgG had a similar abrogative effect. Preincubating these with staphylococcal protein A did not reduce their capacity to interfere with binding of antibody-coated E. coli to CMV-induced Fc receptors. These observations establish a broad range of immunoreactivity for CMV-induced Fc receptors, that encompasses all 4 subclasses of human IgG. They also provide indirect evidence that the reaction site of CMV-induced Fc receptors is in the C_H2 domain of the Fc fragment.

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Host-mediated antiviral effect of 2 biological response modifiers (BRM), OK-432, and PS-K, against murine cytomegalovirus (MCMV) was evaluated in chronically or latently infected mice. In the early stage of chronic MCMV infection, the BRM-induced resistance was evidenced by decrease in infectious viruses replicated in the salivary glands and by augmented cytotoxic activity of the spleen cells against YAC-1 cells and MCMV-infected mouse embryonic fibroblasts (MEF). In the late stage of chronic MCMV infection, the BRM treatment did not eliminate MCMV from the mice, but did prevent exacerbation of MCMV infection in the salivary glands induced by administration of cyclophosphamide (CY). In mice latently infected by MCMV, BRM treatment suppressed CY-induced reactivation of MCMV in the salivary glands. It was suggested that the antiviral effect of BRM against MCMV in chronically or latently infected mice was based on activation of natural killer (NK) cells and cytotoxic T lymphocytes (CTL).

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The pathogenic potential of distinct Cryptococcus species has been evaluated in mice rendered leukopenic by one or two injections of the potent immunosuppressive drug cyclophosphamide (Cy). Pathogenicity assessment included enumeration of viable cryptococcal cells in animal organs and histopathological observations. It was found that putatively non-pathogenic species of Cryptococcus, in particular C. cereanus and C. albidus, showed significant lethality for Cy-treated mice. In Cy-immunodepressed mice, challenged with the infectious cryptococcal cells two days after pharmacological treatment, a significant decrease of LD₅₀ (equivalent to at least one order of magnitude) was observed for all Cryptococcus species. However, the pathogenicity enhancement due to Cy immunodepression was greater with C. neoformans. In all cases, brain and kidney were the most invaded tissues as also evidenced by histopathological examination, which showed the typical cystic lesion. All the observations made point to the conclusion that the pathogenic potential, for the immunomodulated host, of Cryptococci other than C. neoformans is significant being quantitatively and not qualitatively different from that of C. neoformans, as evidenced by a similar organotropism and similar type of histological lesions in the target organs (brain and kidney).

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Isohematinic acid, an antibiotic newly isolated from the culture broth of Actinoplanes philippinensis SANK 61681, was assessed for its ability to enhance nonspecific resistance to bacterial infections against Escherichia coli and Pseudomonas aeruginosa in mice. This agent, as well as BM 12, 531 (Azimexon), was found to prolong the survival of normal mice infected with E. coli and also of compromised mice infected with either E. coli or P. aeruginosa, whose defense system had been deteriorated by treatment with carboquone, an alkylating agent. Like BM 12, 531, isohematinic acid administered to normal mice significantly increased the nitroblue tetrazolium reducing potency of polymorphonuclear leucocytes (PMN), indicating that the microbicidal activity of PMN was enhanced by these agents. In addition, in the compromised mice these agents were able to restore the number of peripheral blood leucocytes, which had been reduced to about 30% of the normal level by carboquone. These results suggest that isohematinic acid, like BM 12, 531, enhances nonspecific resistance to these bacterial infections by stimulating the microbicidal activity of PMN and inducing leucocytosis.

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Human T cell hybridoma, H3-E9-6, that produces macrophage activating factors for cytotoxicity (MAF-C) was prepared by somatic fusion of phytohemagglutinin-activated peripheral blood lymphocytes with emetine/actinomycin D-treated cloned human acute lymphocytic leukemia cells (CEM 11). The activities of the following were assayed: (1) macrophage-activating factor for cytotoxicity of monocytes (MAF-C 1 day), (2) macrophage-activating factor for cytotoxicity of monocyte-derived macrophages (MAF-C 6 day), (3) macrophage-activating factor for cytotoxicity of murine macrophages (MAF-Cm), (4) macrophage-activating factor for glucose consumption (MAF-G), (5) macrophage-activating factor for O₂^- formation (MAF-O). The culture supernatant of H3-E9-6 showed MAF-C 1 day-MAF-C 6 day, MAF-Cm, and MAF-G activities. The MAF-Cm activity was considerably enhanced by the addition of murine recombinant interferon gamma (rIFN-γ). The MAF-C 1 day activity in the H3-E9-6 sup was not decreased by heat treatment (56C, 30min), by pH 2 treatment or by the addition of monoclonal anti-human IFN-γ antibody or polymyxin B. These data suggest that MAF-C in H3-E9-6 sup is distinct from human IFN-γ or lipopolysaccharide (LPS).

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Two different factors (MAF-C I and MAF-C II) were obtained by anion exchange chromatography of the culture supernatant of a human T-cell hybridoma, H3-E9-6, which produces macrophage-activating factors for cytotoxicity (MAF-C). These 2 factors induced the cytotoxicity of monocytes synergistically as a priming signal (MAF-C I) and a triggering signal (MAF-C II), respectively. On gel filtration on a column of Superose 12, MAF-C II was eluted mainly at the void volume, whereas MAF-C I was eluted in the fractions corresponding to approximate molecular weights of 30-300K. On the other hand, gel filtration in the presence of sodium deoxycholate revealed that MAF-C II has an approximate molecular weight of 40, 000, but MAF-C I was unstable under these conditions. When the activity for mouse macrophages (MAF-Cm activity) was tested, the MAF-C II fraction showed high MAF-Cm activity in the presence of murine recombinant interferon gamma (rIFN-γ), but the MAF-C I fraction did not show MAF-Cm activity even in the presence of lipopolysaccharide (LPS). These results suggest that MAF-C I (priming lymphokine) has species specificity but MAF-C II (triggering lymphokine) does not.

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