bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of an inducible bacteriophage from a leukotoxic strain of Actinobacillus actinomycetemcomitans
Authors: Stevens R H , Hammond B F , Lai C H
Published: January 2020

A bacteriophage, designated phi Aa17, was isolated by mitomycin C induction from leukotoxic Actinobacillus actinomycetemcomitans strains 651. Electron microscopy of the virus revealed particles with regular, nonelongated, polyhedral heads, and tails consisting of a contractile sheath and core. Spikes emanated from the base of the tail. The head had a diameter of 70 nm. The fully extended tail sheath had a length of 127 nm and a diameter of 22 nm. In its contracted form, the tail sheath measured 47 nm in length and 25 nm in diameter. The phage had a buoyant density of 1.370 in CsCl, and its genome was found to be double-stranded DNA. A single-cycle growth curve revealed that the phage had a latent period of 30 min and a burst size of 435 PFU per cell. The host range of the phage was examined, and A. actinomycetemcomitans strains ATCC 29523 and ATCC 29524 were found to be phage sensitive, whereas strains Y4, ATCC 29522, 2043, 652, 651, 627, 2097, N27, 2112, and 511 were resistant. The host range of this virus does not suggest any association between the phage and leukotoxin production.
Mode of action of staphylococcal leukocidin: effects of the S and F components on the activities of membrane-associated enzymes of rabbit polymorphonuclear leukocytes
Authors: Noda M , Kato I , Hirayama T , Matsuda F
Published: January 2020

The cytotoxic action of the S component of leukocidin from Staphylococcus aureus on rabbit polymorphonuclear leukocytes was supported by the following observations, (i) Leukocytes displayed a large chemotactic response to the S component (10(-10) M) as well as to the chemotactic factor N-formylmethionylleucylphenylalanine (10(-11) M). (ii) The S component stimulated high levels of phospholipase A2 activity in the cell membranes, with concomitant synthesis and release of prostaglandins. (iii) Uptake of 45Ca into leukocytes exposed to the S component was about double the rate of uptake into untreated cells. The increased 45Ca uptake into the cells was not inhibited by trifluoperazine and ruthenium red. (iv) Indomethacin and alloxazine, which had no effects on the binding of the S component to the cells, attenuated markedly the stimulation of phospholipase A2 activity, the syntheses of prostaglandins, and the increased uptake of 45Ca caused by the S component. The F component of leukocidin, bound to rabbit leukocytes with the aid of the S component, rapidly induced complete release of 86Rb from preloaded leukocytes. This release resulted from stimulation of ouabain-insensitive (Na+ + K+)-adenosine triphosphatase activity and inhibition of cyclic AMP-dependent protein kinase.
Induction of the acute-phase protein serum amyloid P in experimental Chagas' disease
Authors: Scharfstein J , Barcinski M A , Leon L L
Published: January 2020

Serum amyloid P protein (SAP), which shares several structural properties with C-reactive protein, has been recently identified as an acute-phase reactant in mice. In this study, the systemic inflammatory response of mice to infection with Trypanosoma cruzi was characterized with respect to induction of SAP as well as to stage-specific alterations on complement C3 and C4 levels. The SAP response depended on the dose and infectivity of the parasites. Kinetic data indicated a close temporal relationship between the onset of parasitemia and induction of SAP. The levels of SAP were maximally enhanced (1,050%) by the time parasitemia started to regress, and the response remained elevated as the infection entered the latency phase. The decline in parasitemia was paralleled by a significant reduction in C3 levels. A reciprocal relationship between the extent of parasitemia and SAP/C3 levels became apparent when these parameters were compared in individual inbred mice during the time of decreasing parasitemia.
Experimental Parainfluenzavirus Infection in Mice: Fatal Illness with Atrophy of Thymus and Spleen in Mice Caused by a Variant of Parainfluenza 3 Virus
Authors: Shibuta Hiroshi , Adachi Akio , Kanda Tadahito , Matumoto Minoru
Published: January 2020

Intracerebral inoculation of the YN strain of parainfluenza 3 virus was found to induce an acute fatal illness characterized by marked thymic and splenic atrophy in newborn mice. Previously we showed that the YN strain contains three distinct plaque-type variants, LT, SC, and M. Of these, the M-type variant induced this fatal illness, whereas the other two variants induced hydrocephalus.
Studies on the mechanism of peptidoglycan- and lipopolysaccharide-induced polyclonal activation
Authors: Dziarski R
Published: January 2020

Peptidoglycan (PG) and lipopolysaccharide (LPS) are T cell-independent B cell mitogens and polyclonal activators in mice. The mechanism of in vitro proliferation and polyclonal activation of mouse splenocytes induced by PG from Staphylococcus aureus and LPS from Escherichia coli was further studied by using [3H]thymidine incorporation and protein A hemolytic plaque assays. Concanavalin A-generated suppressor cells suppressed both polyclonal and proliferative responses induced by PG, LPS, and pokeweed mitogen. The suppression of the proliferative responses was similar for all these mitogens, but was significantly less pronounced than the suppression of the polyclonal antibody response. Polyclonal activation induced by LPS was the most susceptible to suppression by concanavalin A-generated suppressor cells, and the suppression was significantly greater than in the PG-induced polyclonal response. Also, PG-induced polyclonal activation was not susceptible to inhibition by polymyxin B, which is an inhibitor of other B cell mitogens and polyclonal activators. For optimal generation of immunoglobulin-secreting cells, PG of LPS had to be present for at least 48 h after the initiation of the cultures. Removal of the mitogens after 4 or 24 h of incubation resulted in a suboptimal response. For effective induction of the proliferative response, the mitogens had to be present in cultures for over 24 h. Polyclonal-activating properties of staphylococcal cell wall components were also compared. PG was by far the most potent inducer of polyclonal antibodies. Teichoic acid was not active as a polyclonal activator, whereas purified cell wall and protein A were very weak inducers of polyclonal antibodies. These studies demonstrate that PG, in addition to LPS, can be a useful probe for studies on polyclonal activation.
Delayed hypersensitivity to herpes simplex virus: murine model
Authors: Schrier R D , Pizer L I , Moorhead J W
Published: January 2020

Cell-mediated immunity has been shown to be clinically important in recovery from herpes simplex virus (HSV) infections. To investigate the role of delayed hypersensitivity (DH) in immunity and protection against HSV, we developed a murine model using the ear-swelling assay. Mice were infected subcutaneously with HSV-1 and ear-challenged, and the swelling was quantified. Significant ear swelling was detected by 3 to 4 days postinfection and peaked at 6 days. The kinetics of development of ear swelling were typical of DH: maximal swelling occurred 24 h post challenge and was diminished by 48 h, and the cellular infiltrate was predominantly mononuclear. Four-hour swelling, indicative of antibody-mediated, immediate-type hypersensitivity, was not detected until 15 days post immunization. The DH response was virus specific and could be transferred to normal recipients with lymph node T cells, but not with B cells or immune serum. This system will provide a useful model for evaluating the protective role of DH in HSV infection and for studying the specificity and interaction of T cells which mediate the response.
Enhanced resistance to acute infection with Trypanosoma cruzi in mice treated with an interferon inducer
Authors: James S L , Kipnis T L , Sher A , Hoff R
Published: January 2020

For an exploration of the effects of interferon-inducible resistance mechanisms in acute American trypanosomiasis, the synthetic interferon inducer tilerone hydrochloride was administered to mice of the C57BL/6J strain, which is highly resistant to Trypanosoma cruzi, 18 to 24 h before infection with a potentially lethal dose of bloodstream trypomastigotes. Although all of the control mice died within 30 days of the acute infection, approximately 50% of the tilerone-treated animals were able to survive indefinitely (P less than 0.05). The tilerone-treated mice demonstrated significant levels of serum interferon and splenic natural killer cells at the time of infection. Macrophages isolated from the peritoneal cavities of tilerone-treated C57BL/6J mice appeared to kill significant numbers of trypanosomes during 2 to 3 days of in vitro culture, indicating that activated macrophages may contribute to the enhanced resistance to T. cruzi infection in these mice. Beige mice treated with tilerone did not survive T. cruzi infection as well as tilerone-treated heterozygotes did, suggesting a role for natural killer cells in interferon-induced resistance. These results suggest that interferon or effector mechanisms enhanced by interferon induction can play a significant role in influencing resistance to T. cruzi infection.
Human leukocyte antigen-linked genetic controls for T cell-mediated cytotoxic response to mumps virus in humans
Authors: Chiba Y , Tsutsumi H , Nakao T , Wakisaka A , Aizawa M
Published: January 2020

The involvement of human leukocyte antigen determinants for the response of mumps virus-specific cytotoxic T lymphocytes in humans was studied. The cytotoxic T lymphocytes could only lyse virus-infected allogeneic cells with which they shared a particular human leukocyte antigen, e.g., Bw52 or B7. The existence of Bw52 in the subjects who received a booster immunization with live mumps vaccine was associated with a significantly higher cytotoxic T-lymphocyte response than that of subjects without the gene. Although a donor-dependent difference in the recognition of human leukocyte antigen-A2 suggests the complexity of the genetic mechanisms involved, the results are largely consistent with the concept of major histocompatibility complex-linked genetic control of virus-specific cytotoxic T-lymphocyte response.
Serum antibody responses to Pneumocystis carinii among different strains of normal and athymic mice
Authors: Walzer P D , Rutledge M E
Published: January 2020

Pneumocystis carinii infection was produced in normal mice by the administration of corticosteroids and in athymic mice by the transmission of exogenous mouse- or rat-derived organisms. Serum antibodies to P. carinii, measured by an indirect fluorescent-antibody technique, were found in five of six strains of normal mice. Although antibody titers varied widely among the control and steroid-treated mice, they were inversely proportional to the intensity of P. carinii infection in the lungs. In sequential studies, antibody titers were low during steroid administration but rose with steroid withdrawal. Antibodies were mainly of the immunoglobulin G (IgG) class; IgM antibodies also occurred, but IgA antibodies were rare. nu/nu mice rarely produced serum antibodies to P. carinii despite the fact that one strain was sensitive and the other was resistant to exogenous infection. nu/+ mice produced specific antibodies to rat and mouse P. carinii which were primarily IgG. Thus, the host produces antibodies to P. carinii which are mainly IgG and T-cell dependent; yet, these antibodies do not appear to be important in susceptibility or resistance to P. carinii infection.
Essential role of calcium in cellular internalization of Pseudomonas toxin
Authors: Fitzgerald D , Morris R E , Saelinger C B
Published: January 2020

Pseudomonas exotoxin (PE) has been shown previously to enter mouse LM cells by receptor-mediated endocytosis, to block protein synthesis, and to cause cell death. The requirement for the divalent cation calcium in the binding and internalization of PE was examined. Biochemical studies showed that depletion of extracellular calcium with ethylene glycol-bis(beta-aminoethyl ether)-N,N'-tetraacetic acid protected cells from the action of PE when the chelator was present during the internalization step. Extracellular calcium was not required for binding. We observed with immunoelectron microscopy that, in the cold, toxin bound to cell surfaces equally well in the presence or absence of chelator. In the presence of chelator, toxin was not cleared from the cell surface when cells were warmed to 37 degrees C. Replenishment of calcium (2 mM CaCl2), however, allowed normal rapid clearance of PE to occur. We suggest that internalization, but not binding, of PE by LM cells requires extracellular calcium.
Mutant of Bordetella pertussis which lacks ability to produce filamentous hemagglutinin
Authors: Watanabe M , Nakase Y
Published: January 2020

Mutant cultures that lacked the ability to produce filamentous hemagglutinin were obtained by UV irradiation of Bordetella pertussis strain 18-323. Various biological activities of these mutants were compared with those of the parent culture. It was found that the leukocytosis-promoting, histamine-sensitizing, and mouse-protecting activities of the mutants were similar to those of the parent strain but that the virulence to mice was lower. The results seemed to rule out fimbrial hemagglutinin as a protective antigen when the ability to protect mice was measured by the intracerebral challenge test.
Comparison of cytoplasmic extracts of eight Candida species and Saccharomyces cerevisiae
Authors: Greenfield R A , Jones J M
Published: January 2020

Crossed-line immunoelectrophoresis of cytoplasmic extracts of eight Candida species and Saccharomyces cerevisiae demonstrated the presence of antigens reactive with a rabbit antiserum to a C. albicans extract in all species except C. glabrata. A previously defined major cytoplasmic antigen of C. albicans was also present in C. tropicalis and C. guilliermondii.
Cellular Regulation of Gamma Interferon Production: Lyt Phenotype of the Suppressor Cell
Authors: Torres Barbara A. , Yamamoto Janet K. , Johnson Howard M.
Published: January 2020

Suppressor cell activity for in vitro gamma interferon (IFNγ) production can be induced in C57BL/6 mice with the T-cell mitogens staphylococcal enterotoxin A and concanavalin A. The suppressor cell lacked mitogen specificity in that injection of mice with either staphylococcal enterotoxin A or concanavalin A induced potent suppressor cell activity that inhibited the in vitro induction of IFNγ by either mitogen. The suppressor cell is a T cell with a relatively high density of Thy 1 antigen. The IFNγ-producing cell has a low density of Thy 1 and appears to have evolved from cells with a high density of Thy 1.2 or to have required such cells as helpers in the production of IFNγ. Monoclonal anti-Lyt 2.2 antibody completely eliminated the suppressor cell activity, whereas anti-Lyt 1.2 partially, but significantly, reduced the suppressor cell activity. The suppressor cell, then, may be or may require a Lyt 1,2,3
+
cell with a relatively low density of the Lyt 1 antigen for activity. The Lyt phenotype of the IFNγ- producing cells was examined for both virgin and suppressor cell populations. Treatment of cells with either anti-Lyt 1.2 or anti-Lyt 2.2 completely eliminated IFNγ production in both virgin and suppressor cell cultures. Cocultivation of Lyt 1
+
and Lyt 2
+
cells in both virgin and suppressor cell cultures significantly restored the ability to produce IFNγ when cells were stimulated with staphylococcal enterotoxin A. For the virgin cells, this seems to indicate clearly that both Lyt 1
+
and Lyt 2
+
cells are required for IFN production, but that Lyt 1,2,3
+
cells are not required. For the suppressor cell population this type of treatment resulted in IFNγ production comparable to that of the virgin cell population. The treatment eliminated or depleted Lyt 1,2,3
+
cells from the suppressor cell population, thus providing additional evidence that a Lyt 1,2,3
+
cell is required for suppressor cell activity. Treatment of spleen cells with anti-Lyt antibodies at the time that they were involved in ongoing IFNγ production showed that the IFNγ-producing cell is Lyt 2
+
. At least a 1:1 ratio of virgin to suppressor cells was required for optimal suppression of IFNγ production by virgin spleen cells. This suggests that suppression involved cell-to-cell contact. Preliminary data showed that the suppressor cell activity could also be induced in in vitro cultures incubated with mitogen for 4 days. This is evidence that the suppressor cell is inducible and not necessarily recruited to the spleen from other lymphoid organs.
Chemotactic responses of various differentiational stages of neutrophils from human cord and adult blood
Authors: Boner A , Zeligs B J , Bellanti J A
Published: January 2020

Chemotactic response and responsiveness, that is, the ability to respond to various concentrations of the chemoattractant zymosan-activated serum was measured for cord and adult blood neutrophils. Chemotactic response of neutrophils from adult blood was two to seven times greater than that of neutrophils from cord blood. In addition, neutrophils from cord blood showed poor response to concentrations of 25% chemoattractant or less, compared to those from adults, which responded to concentrations of 10%. Further, it was found that approximately 30% of neutrophils in cord blood were the band form compared to only 9% in adult. Based upon this, a simple method was devised to assay mean migrating distance of various differentiational stages of neutrophils incorporating both distance and magnitude of their responses. The results of these assays showed that all differentiational stages of cord blood neutrophils have a mean migrating distance less than those of adults. In addition, the band form from both cord and adult blood had a mean migrating distance less than the polymorphonuclear form. Adherence studies revealed that all differentiational stages of neutrophils adhered in a similar manner, and no difference was detected between cells from cord and adult blood. Assays to test the ability of cord blood to produce chemotactic activity when activated revealed 50% less activity than that obtained from adult serum which further decreased with dilution of attractant. These data suggest that both the cellular and humoral systems involved in chemotactic responses are less in cord blood compared to adult blood.
Glucan as an adjuvant for a murine Babesia microti immunization trial
Authors: Benach J L , Habicht G S , Holbrook T W , Cook J A
Published: January 2020

A vaccination protocol against murine Babesia microti infection, using glucan, a beta-1,3-glucopyranose derivative of yeast cell walls, and glutaraldehyde-fixed infected erythrocytes was evaluated. BALB/c mice were immunized intravenously four times at 2-day intervals with 2 X 10(8) fixed infected erythrocytes with and without glucan (0.45 mg). The mice were challenged 2 weeks after the last immunization with 10(8) viable infected erythrocytes. Peak parasitemia was significantly reduced (8.9 +/- 1.0%; P less than 0.001) in glucan-immunized mice as compared with nonimmunized controls (41.2 +/- 1.4%), glucan-treated controls (31.7 +/- 2.5%; P less than 0.05), or mice which received fixed infected erythrocytes without glucan (21.0 +/- 1.2%; P less than 0.01). Humoral and cellular immunity to B. microti was evaluated before challenge by measuring antibody titers and splenocyte blastogenic responses to B. microti antigens. The in vitro cellular response was inversely correlated with mean peak parasitemia (P less than 0.05). These observations demonstrate that glucan is an effective adjuvant in enhancing immunity to murine babesiosis.
Localization in Yersinia pestis of peptides associated with virulence
Authors: Straley S C , Brubaker R R
Published: January 2020

An avirulent guanine auxotroph of wild-type Yersinia pestis was used to select isogenic mutants lacking invasive determinants of virulence including V and W antigens (Vwa-), genetically linked fibrinolysin, coagulase, and pesticin activities (Pst-), and the capacity to absorb exogenous pesticin and pigments including hemin (Pgm-). After growth in environments known to favor expression of these factors by the parent, cells were converted to spheroplasts and disrupted to obtain preparations of cytoplasm; particulate matter was separated into inner and outer membranes by sucrose gradient centrifugation. Peptides present in these fractions were then solubilized and compared by two-dimensional polyacrylamide gel electrophoresis. Components unique to Vwa+ cells, including V antigen, were restricted to the cytoplasmic fraction. In contrast, peptides possibly corresponding to fibrinolysin and coagulase were located primarily within the outer membrane of the Pst+ parent; pesticin was not identified. Similarly, a major outer membrane peptide, possibly representing the pesticin and pigment receptor, was peculiar to the Pgm+ parent. Accordingly, two of the virulence factors examined (Pst+ and Pgm+) can interact directly with host cells or fluids by virtue of their location on the bacterial surface. The remaining cytoplasmic Vwa+ determinant remains a candidate for a regulatory system whose role in pathogenicity is expression of functions required for intracellular survival.
Microbial Populations Growing in the Presence of Fluoride at Low pH Isolated from Dental Plaque of Children Living in an Area with Fluoridated Water
Authors: Bowden G. H. W. , Odlum O. , Nolette N. , Hamilton I. R.
Published: January 2020

Longitudinal microbiological examinations have been made of dental plaque from a site approximal to the upper central incisors of 10 8-year-old children living in an area with water fluoridation. Differential counts of viable bacteria, made using a selective medium containing various levels of fluoride (0 to 100 μg/ml) at pH levels of 7.0 to 5.5, demonstrated an effect of both pH and fluoride on the numbers and types of bacteria isolated. Strains of
Streptococcus
and
Neisseria
grew after only 16 h of incubation at pH levels as low as 6.0 with fluoride levels up to 50 μg/ml. The most commonly isolated streptococci were
Streptococcus mitior
and
S. salivarius. S. mutans
was isolated less frequently and was inhibited by 20 and 50 μg of fluoride per ml at pH 6.0 and 6.5, respectively.
Veillonella
strains were the most resistant isolates, being isolated after 16 h of incubation on media at pH 6.0 with 100 μg of fluoride per ml. Despite their known fluoride resistance,
Actinomyces
spp. were often only detected on the selective media after 72 h of incubation. The pH of the medium had a definite selective effect, as the number of colonies growing on the fluoride-free basal media at pH 6.0 was only 30% of that at pH 7.0. Representative strains of
S. mutans, S. mitior, S. sanguis
, and
S. milleri
were tested for their ability to utilize glucose at the pH and fluoride levels of the medium on which they were initially isolated. Fluoride reduced the initial glycolytic rate of the cells, but in 5 of the 13 strains tested the final amount of glucose used after 2 h of incubation was the same in the presence or absence of fluoride. The isolation of bacteria capable of growth in the presence of fluoride over a significant portion of the pH range that occurs in plaque in vivo could explain in part the finding that fluoride does not have a dramatic effect on the plaque community. Fluoride in plaque may reduce the ecological advantage afforded to aciduric
S. mutans
strains by carbohydrate substances. In the in vivo situation this could mean that, even with high carbohydrate intake, fluoride may permit
S. mitior
to compete with
S. mutans
within the plaque ecosystem.
Ultrastructural study of long-term canine distemper virus infection in tissue culture cells
Authors: Narang H K
Published: January 2020

The morphogenesis of canine distemper virus was studied in Vero cell cultures for 43 days post-inoculation. Active replication of the virus was observed by electron microscopy and assay from 12 h after inoculation on, and peak production was observed on days 5, 14, and 22. From day 28 on, constant but smaller amounts of infectious virus were detected. Two ultrastructural types of intracytoplasmic nucleoprotein filaments were observed; although they first appeared at different times, their subsequent chronological patterns of development were similar. The cells apparently became free of virus by a mechanism of vacuolation. Intranuclear filaments were seen about day 11 and appeared to increase in number thereafter, whereas the infectious titer declined. Possible mechanisms of persistence are discussed in the light of these findings.
Semliki Forest Virus Neurovirulence Mutants Have Altered Cytopathogenicity for Central Nervous System Cells
Authors: Atkins Gregory J. , Sheahan Brian J.
Published: January 2020

We have analyzed the pathogenicity and host range properties of four neurovirulence mutants of Semliki Forest virus which, unlike the wild type (WT), allow the survival of weanling mice injected intraperitoneally with 10
2
PFU. The mutant M9 showed a sustained multiplication in the brains of infected mice. It produced paralysis in 35%, and 8% died. Demyelination occurred in 94% of the surviving mice and was associated with the destruction of oligodendrocytes. All of the mutants showed a restricted ability to multiply in BHK, C1300 (neuroblastoma), and G26-24 (oligodendroglioma) cells as compared with the WT, and this was not associated with differential interferon production or action. C1300 cells infected with the mutants survived, whereas WT-infected cells were killed. In G26-24 cells all of the mutants and the WT produced a rapid cytopathic effect which was inhibited by pretreatment with 10 U of mouse interferon. Extensive RNA synthesis was detected for all of the mutants and the WT in BHK and C1300 cells, but it was only detectable in G26-24 cells in small amounts early in the infection. The mutant M4 had a defect in the nucleocapsid assembly, whereas M9 had a defect in total RNA synthesis. M136 was defective in the synthesis of 26S RNA, and M103 showed defective synthesis of viral core protein in C1300 cells. It is concluded that C1300 cells can tolerate viral RNA synthesis by a defective virus without showing a cytopathic effect, but the fully virulent WT virus is cytopathic. G26-24 cells are sensitive to small amounts of viral RNA synthesis. These properties of the WT and mutant viruses correlate with changes produced in the neurons and oligodendrocytes of the central nervous system: the virulence of the WT is due to its ability to destroy both neurons and oligodendrocytes, whereas the demyelination produced by the mutants M9 and M136 is due to the destruction of oligodendrocytes alone.
Attachment and ingestion of bacteria by trophozoites of Entamoeba histolytica
Authors: Bracha R , Kobiler D , Mirelman D
Published: January 2020

Entamoeba histolytica trophozoites were found to be very selective in their interactions with bacteria. Two principal mechanisms were shown to be responsible for these interactions. Certain bacteria, such as a number of Escherichia coli and Serratia marcescens strains which are known to contain mannose-binding components on their cell surface, bound to mannose receptors on the amoeba membrane. This attachment was markedly inhibited by alpha-methylmannoside (0.5%), especially when the incubations were done at low temperature (5 degrees C). Other bacterial species, such as Shigella flexneri and Staphylococcus aureus, which do not possess a mannose-binding capacity, attached to the amoebae, but only with the aid of concanavalin A or after opsonization of the bacteria with immune serum. In both types of attachment, between 40 and 100 bacteria bound per amoeba, and considerable ingestion of bacteria into amoeba vacuoles was observed at 37 degrees C. The attachment of opsonized bacteria to the amoebae does not appear to be mediated by Fc receptors since Fab' dimers obtained after pepsin digestion of immunoglobulin were capable of mediating adherence. Furthermore, preincubation of the amoebae with aggregated human immunoglobulin G or with heat-inactivated immune serum and EDTA did not inhibit the attachment of opsonized bacteria. The attachment of opsonized bacteria was markedly inhibited by N-acetylglucosamine-containing glycoconjugates, such as peptidoglycan and chitin oligosaccharides, as well as by N-acetylgalactosamine. These results indicate that amoebae can attach and ingest bacteria either by using their membrane-associated carbohydrate-binding protein or by having their mannose-containing cell surface components serve as receptors.
Influence of Sodium and Potassium Ions on Acid Production by Washed Cells of
Streptococcus mutans
Ingbritt and
Streptococcus sanguis
NCTC 7865 Grown in a Chemostat
Authors: Marsh Philip D. , Williamson Michael I. , Keevil C. William , McDermid Ann S. , Ellwood Derek C.
Published: January 2020

A comparison was made of acid production by cells of
Streptococcus mutans
Ingbritt and
S. sanguis
NCTC 7865 that had been washed twice and incubated in different concentrations of sodium and potassium ions. Organisms were grown under defined conditions in a chemostat under both glucose limitation and glucose excess conditions at a dilution rate of 0.1 h
−1
(mean generation time, 6.9 h). Acid production after a pulse of glucose, sucrose, and fructose was measured by pH fall experiments and as a rate at pH 7.0.
S. mutans
produced more acid than
S. sanguis
as measured by either criterion, although statistically faster rates of acid production and lower terminal pH values were obtained when cells of both species were suspended in KCl rather than in NaCl, with 200 mM KCl resulting in the lowest terminal pH in pH fall experiments. Sodium ions inhibited acid production: 183 mM NaCl reduced the glycolytic rates of
S. mutans
and
S. sanguis
metabolizing glucose at pH 7.0 in 135 mM KCl by 39 and 33%, respectively. The most pronounced stimulatory effect of potassium on acid production was by washed cells of
S. sanguis
that had been grown under arginine and under phosphate limitation. The pH fell by a further 0.86 and 1.21 pH units, respectively, and to below the critical pH for enamel demineralization when these cells were metabolizing glucose in 135 mM KCl compared with the same concentration of NaCl. This enhancement of acid production was not due to potassium translocation, as had been suggested previously, because no movement of potassium ions across the cell membrane could be detected. An alternative explanation is proposed in which sodium ions are excluded from the cell at the expense of membrane energy, i.e., the proton motive force, which could otherwise be used for the transport of sugars.
Early course of infection in susceptible and resistant strains of mice, using [3H]uridine-labeled Trypanosoma brucei subsp. brucei
Authors: Anderson L W , Banks K L
Published: January 2020

A radioisotopic technique utilizing [3H]uridine was developed to determine the tissue distribution of intravenously inoculated Trypanosoma brucei spp. brucei in susceptible (Swiss-Webster) and resistant (deer) strains of mice. The reliability of the technique was tested by using unincorporated [3H]uridine and heat-killed (labeled) trypanosomes in parallel experiments. The inoculations with viable (labeled) organisms showed that during the initial 24 h T. brucei subsp. brucei was cleared from the bloodstream of deer mice to a significantly greater extent than in Swiss-Webster mice. In addition, significantly more radioactivity was found in the liver, spleen, and kidneys of the deer mice. Autoradiographs of trypanosomes in selected tissues supported the distribution observed with labeled organisms. All of the above experiments involved the highly virulent, monomorphic bloodstream form of T. brucei subsp. brucei. Similar experiments with less virulent tissue culture-adapted trypanosomes showed that these organisms were readily cleared from the bloodstream, even in highly susceptible Swiss-Webster mice. The results suggest that avoidance of phagocytosis may be an important virulence factor of T. brucei subsp. brucei and contributes to the variation observed in species and strain susceptible to trypanosomiasis.
Cytotoxic T cells are induced in mice infected with lymphocytic choriomeningitis virus strains of markedly different pathogenicities
Authors: Pfau C J , Valenti J K , Jacobson S , Pevear D C
Published: January 2020

The ability of two lymphocytic choriomeningitis virus substrains to induce cytotoxic T-lymphocyte (CTL) responses in intracerebrally infected mice was examined. One strain, designated A (aggressive), provoked a convulsive type of death in 100% of the mice within 8 to 9 days, whereas the other strain, designated D (docile), killed less than 10% of the mice during 28-day observation periods. CTL activity was assessed by the capacity of partially purified splenocytes to lyse 51Cr-labeled L-cell targets infected with either type of lymphocytic choriomeningitis substrain. The CTL population was identified by its sensitivity to anti-Thy-1 serum and its inability to lyse uninfected target cells or infected target cells with which it differed at the level of antigens controlled by the major histocompatibility gene complex. A strong CTL response developed in mice infected with either lymphocytic choriomeningitis substrain, although the activity provoked by substrain D was somewhat less than that seen after substrain A infection. Peak CTL activities induced by both strains occurred at about the same time. Even though docile virus replicated more extensively in the brain than did aggressive virus and fluorescent antibody staining revealed similar distributions of viral antigen, no inflammatory response was noted in the brains of mice infected with docile virus. These results are discussed with regard to the role of CTLs in mediating classic central nervous system pathology.
Virus-infected colostral cell cytokine stimulation of human leukocyte natural killer cytotoxicity
Authors: Kohl S , Pickering L K , Loo L S
Published: January 2020

Natural killer cytotoxicity is an important antiviral defense mechanism. Human peripheral blood mononuclear cells cultured with herpes simplex virus (HSV)-infected cells produced a cytokine. This substance stimulated adult natural killer cytotoxicity from 53.0 +/- 10.5% to 79.8% (P less than 0.01) against HSV-infected target cells. These data resulted in a calculated cytokine-dependent cellular cytotoxicity (CDCC) value of 65.8%. Cytokine production was not stimulated by uninfected cells and was independent of the presence or absence of antibodies to HSV in sera of donors and mononuclear cells. Cells from human colostrum also produced an HSV-stimulated cytokine which mediated CDCC by using both adult (19.8 +/- 3.9%) and neonatal (18.6 +/- 3.4%) mononuclear effectors cells. Colostral cell cytokine production was also independent of donor HSV serology. Not all colostral cultures produced the cytokine, and in general colostrum-stimulated CDCC was lower than peripheral blood leukocyte-stimulated CDCC. Colostral cell cytokine stimulation of neonatal natural killer cytotoxicity may account in part for the increased nonspecific resistance of breast-fed infants to viral infection.
Enhancement of invasiveness of Yersinia enterocolitica and Escherichia coli in HEp-2 cells by centrifugation
Authors: Vesikari T , Bromirska J , Mäki M
Published: January 2020

Centrifugation enhanced the infectivity of invasive Escherichia coli and Yersinia enterocolitica for HEp-2 cells. Noninvasive bacteria were not endocytosed after centrifugation. The centrifugation procedure may increase the sensitivity of testing for bacterial invasiveness in cell culture without causing false-positive results.
Immunological activities of Capnocytophaga cellular components
Authors: Murayama Y , Muranishi K , Okada H , Kato K , Kotani S , Takada H , Tsujimoto M , Kawasaki A , Ogawa T
Published: January 2020

Whole cells of a clinical isolate (strain S-3) of the genus Capnocytophaga were divided into cell envelope (CE) and cytoplasm (CP) fractions by mechanical disintegration followed by differential centrifugation, and a part of the CE fraction was further fractionated by sodium dodecyl sulfate (SDS) treatment into the peptidoglycan and SDS-supernatant fractions. The other part of the CE was extracted with butanol-water or hot phenol-water to isolate butanol-lipopolysaccharide and phenol-lipopolysaccharide, respectively. All of the test fractions except CP exhibited multifold immunomodulating activities, namely, the adjuvant activities to cellular as well as humoral immune responses against ovalbumin in guinea pigs, the mitogenicity on splenocytes of guinea pigs and BALB/c mice (but not on their thymocytes), the stimulation of guinea pig peritoneal macrophages (in terms of increased glucosamine uptake), and the activation of the human complement system through alternative as well as classical pathways. In addition, the test fractions other than the CP evoked dermatoxic reactions on rabbit skin with characteristic variations among them. The immunomodulating activities of SDS-supernatant were noteworthy in view of the fact that this fraction was essentially free of muramic acid and diaminopimelic acid and did not cause the gelation of horseshoe crab amoebocyte lysate except when it was used at the very high dose, suggesting that there was practically no contamination by peptidoglycans and lipopolysaccharides in the SDS-supernatant.
Monoclonal antibodies against Vibrio cholerae lipopolysaccharide
Authors: Gustafsson B , Rosén A , Holme T
Published: January 2020

A cell line producing monoclonal antibodies directed against the core region of Vibrio cholerae lipopolysaccharide has been established. These antibodies were inhibited by lipopolysaccharide preparations of both O-group 1 vibrios and some non-O-group 1 vibrios as detected in enzyme-linked immunosorbent assay-inhibition experiments. Coagglutination experiments with monoclonal and polyclonal antibodies adsorbed to protein A-carrying staphylococci were performed. All V. cholerae strains tested, regardless of serotype, were agglutinated when mixed with staphylococci coated with the monoclonal antibodies, whereas staphylococci coated with group-specific (O1) polyclonal antibodies only agglutinated with O-group 1 vibrios.
Effect of pyridines on phenotypic properties of Bordetella pertussis
Authors: Schneider D R , Parker C D
Published: January 2020

Several conditions of growth of Bordetella pertussis cause a reversible phenotypic alteration in properties termed modulation. Growth in medium containing nicotinic acid induces normal (X-mode) cells to change to modulated (C-mode) cells. We examined several pyridines and compounds resembling pyridines for their ability to affect modulation, using envelope protein patterns and serological reactivity as indicators of modulation. We found that 6-chloronicotinic acid and quinaldic acid were more effective modulating stimuli than was nicotinic acid on a molar basis. Both 2-chloronicotinamide and isoniazid interfered with nicotinic acid-induced modulation, and can be called antimodulators. Picolinic acid inhibited growth.
Infant rat model of attenuation for recombinant influenza viruses prepared from cold-adapted attenuated A/Ann Arbor/6/60
Authors: Ali M , Maassab H F , Jennings R , Potter C W
Published: January 2020

The pathogenicity of 6 wild-type influenza A viruses and 21 recombinant strains prepared from wild-type viruses and cold-adapted A/Ann Arbor/6/60 virus for infant rats was determined. Thus, the titers of virus present in the turbinates and lungs of virus-infected animals was measured serially for 5 days after intranasal infection, and the ability of virus strains to promote subsequent systemic bacterial infection by Haemophilus influenzae was measured at 48 h after virus infection. The results obtained were assessed with reference to the genetic constitution of the virus strains and to virus virulence for volunteers. The results showed that virulent viruses grew to relatively high titers in rat turbinates and significantly promoted systemic infection by H. influenzae. In contrast, attenuated strains grew to lower titers and failed to promote systemic H. influenzae infection. For the strains tested, the results showed clear differences for attenuated and virulent strains, and the model was a reliable indication of virulence for humans. Although the virulent strains tended to grow to higher titers in rat lungs than did attenuated strains, exceptions were found, and this measurement could not reliably discriminate virulent and attenuated virus strains. The results suggest that infant rats can be used to assess the virulence of cold-adapted recombinant influenza virus strains, and thus, they can facilitate the development of such strains for vaccine production.
Lack of airborne spread of infection by Legionella pneumophila among guinea pigs
Authors: Katz S M , Habib W A , Hammel J M , Nash P
Published: January 2020

Many investigators find no spread of Legionnaires disease from person to person. The present study examined the question of airborne transmission of infection by Legionella pneumophila serogroup 1 from guinea pigs inoculated nasally with the agent to healthy guinea pigs. The nasal inoculation produced confluent peribronchiolar pneumonia similar to the pulmonary lesions observed in humans, but by techniques of clinical observation, serology, culture, and pathology, there was no evidence of airborne spread of infection from 26 inoculated guinea pigs to 64 uninoculated guinea pigs. The results, compatible with epidemiological studies of Legionnaires disease that fail to demonstrate airborne person-to-person transmission of the illness in humans, are useful for scientists who work with animal models of Legionnaires disease.
Influenza type A virus-mediated adherence of type 1a group B streptococci to mouse tracheal tissue in vivo
Authors: Jones W T , Menna J H
Published: January 2020

Influenza type A virus-mediated adherence of pathogenic bacteria to the mucosal surface of the respiratory tract may be one of several mechanisms whereby influenza predisposes to bacterial pneumonia. In the present study, we quantified the adherence of intranasally administered type 1a group B streptococci to the tracheal tissue of influenza type A/PR8/34 (HONI) virus-infected and mock-infected mice. Influenza type A/PR8/34 virus infection effected a 120-fold increase in the adherence of type 1a group B streptococci to tracheal tissue relative to that observed in mock-infected mice. Adherence of type 1a group B streptococci to the trachea of influenza type A/PR8/34 virus-infected mice was reduced by more than 90% by prior intranasal instillation of chicken antiserum to influenza type A/PR8/34 virus, whereas virtually no reduction in adherence was noted with normal chicken serum or rabbit antiserum to herpes simplex virus type 2. These findings suggest that adherence of type 1a group B streptococci to the tracheal tissue of influenza type A/PR8/34 virus-infected mice is effected by a viral component(s).
Phagocytosis of Pseudomonas aeruginosa by polymorphonuclear leukocytes and monocytes: effect of cystic fibrosis serum
Authors: Thomassen M J , Demko C A , Wood R E , Sherman J M
Published: January 2020

It has been shown previously that serum from chronically infected patients with cystic fibrosis inhibits the phagocytosis of Pseudomonas aeruginosa by both normal and cystic fibrosis alveolar macrophages. In the present study, the ability of peripheral monocytes and polymorphonuclear leukocytes from normal volunteers and cystic fibrosis patients to phagocytize P. aeruginosa was shown not to be inhibited in the presence of serum from cystic fibrosis patients.
Protease production by Streptococcus sanguis associated with subacute bacterial endocarditis
Authors: Straus D C
Published: January 2020

A viridans streptococcus (Streptococcus sanguis biotype II) isolated from the blood of a patient with subacute bacterial endocarditis was examined for protease production. In broth culture, extracellular proteolytic enzymes were not produced by this organism until after the early exponential phase of growth, with maximal protease production occurring during the stationary phase. Four distinct proteases were isolated and purified from the supernatant fluids of stationary-phase cultures, employing a combination of ion-exchange column chromatography, gel filtration column chromatography, and polyacrylamide gel electrophoresis. All four proteases could be eluted from a diethylaminoethyl cellulose column at a sodium chloride gradient concentration of 0.25 M but were separable by gel filtration chromatography on a Sephadex G-100 column. They varied in molecular weights as determined by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis from approximately 13,000 to 230,000. All four proteases had pH optima of between 8.0 and 9.0, and two of the proteases were active against casein, human serum albumin, and gelatin but were not active against elastin and collagen. The remaining two proteases were able to degrade only casein and gelatin. These results show that S. sanguis is able to excrete maximal levels of potentially destructive enzymes when the organisms are not actively multiplying. This finding may explain some of the damage caused in heart tissue by these organisms during subacute bacterial endocarditis.
Glucose Uptake by
Streptococcus mutans, Streptococcus mitis
, and
Actinomyces viscosus
in the Presence of Human Saliva
Authors: Germaine Greg, R. , Tellefson Lois M.
Published: January 2020

Glucose uptake was examined by using whole-cell suspensions of
Streptococcus mutans
(strains BHT, Ingbritt, and GS-5),
Streptococcus mitis
(strains 9811 and 72×41), and
Actinomyces viscosus
(strains T6 and WVU626) incubated for up to 90 min in 0 to 82% (vol/vol) human whole salivary supernatant. Glucose uptake by the
S. mutans
strains was completely inhibited at all saliva concentrations. Dithiothreitol (DTT), present during saliva incubation, prevented saliva inhibition. Glucose uptake was also restored when saliva-inhibited cells were subsequently exposed to DTT. The inclusion of catalase in the saliva incubation mixtures resulted in protection equal to that obtained with DTT. The
S. mitis
strains were also inhibited by saliva but to a far lesser extent that
S. mutans.
DTT and catalase also protected
S. mitis
from saliva inhibition. Both
A. viscosus
strains were completely refractory to saliva inhibition of glucose uptake. Based on (i) the sensitivity of the catalase-negative streptococci and the resistance of catalase-positive actinomyces to saliva inhibition and (ii) the equal and complete protection to saliva inhibition afforded by DTT and catalase, we conclude that the lactoperoxidase-SCN
−
-H
2
O
2
system in saliva was the only antibacterial system expressed under our experimental conditions. The relative resistance of
S. mitis
9811 (compared with
S. mutans
BHT) to saliva inhibition was shown not to result from poor H
2
O
2
production in either glucose-supplemented buffer or saliva solutions.
S. mitis
produced inhibitory quantities of H
2
O
2
that equaled or exceeded
S. mutans
H
2
O
2
accumulation. It is suggested that
S. mitis
might possess a greater ability to repair lactoperoxidase-mediated damage than does
S. mutans.
Every organism studied exhibited a saliva concentration-dependent, cell growth-independent stimulation of glucose uptake after 60 to 90 min of incubation. The
A. viscosus
and
S. mitis
strains showed saliva stimulation (or stabilization) of glucose uptake with unsupplemented saliva. In the case of
S. mutans
, saliva stimulation was only observed when DTT was present. The possible role of salivary lactoperoxidase as a modulator of the intraoral site specificities exhibited by
S. mutans
is discussed.