bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Microscopy of Group A Streptococci After Phagocytosis by Human Monocytes
Authors: Glick Alan D. , Getnick Richard A. , Cole Roger M.
Published: January 2020

Group A streptococci were added to cultures of isolated human blood monocytes. The bacteria were readily sequestered within phagocytic vacuoles after being coated with flocculent material, apparently derived from the plasma-containing medium. Progressive lysis of intravacuolar streptococci was observed, characterized by plasmolysis, internal disruption, and eventual plasma membrane dissolution. However, the cell walls remained essentially identical to those of nonphagocytized streptococci, showing no signs of dissolution within the limited in vitro survival time of the monocytes. These results indicate that streptococcal cell walls may persist in migrating human phagocytes in vivo and may be deposited in body tissues. This cell wall material, known to be toxic to animal tissues, may be an important determinant in the pathogenesis of poststreptococcal sequelae in man.
Comparative Neurovirulence of Herpes Simplex Virus Type 1 Strains After Peripheral or Intracerebral Inoculation of BALB/c Mice
Authors: Dix Richard D. , McKendall Robert R. , Baringer J. Richard
Published: January 2020

Twenty-three strains of herpes simplex virus type 1 were compared for their pathogenicity in 4-week-old BALB/c mice after peripheral (footpad) or intracerebral inoculation. Among those strains examined were (i) six clinical isolates of brain or cerebrospinal fluid origin, (ii) seven clinical isolates of oral or genital origin, (iii) five prototype laboratory strains that have been passaged numerous times in culture, and (iv) five syncytial variants capable of producing cell fusion in culture. Based on comparative 50% lethal dose values, the strains appeared to segregate into one of three classes of neurovirulence. Class I strains were highly virulent by both the peripheral and intracerebral routes of inoculation, class II strains were highly virulent by the intracerebral route only, and class III strains were highly attenuated by both routes of inoculation. In vivo growth curves for whole brain homogenates infected with class III strains revealed titers of infectious virus approaching those found in the brains of animals infected with class I or II strains. These results would therefore suggest that (i) a strain-dependent variation in neural spread exists that may influence the ability of the virus to cause acute neurological disease and (ii) the amount of infectious virus present within an infected brain does not necessarily determine or reflect the clinical status of the animal. Of the clinical isolates examined, the strains recovered from brain tissue of humans after fatal episodes of encephalitis were found to be no more neurovirulent in mice than the strains isolated from nonneural sites. However, although syncytial variants were found to be highly attenuated by the peripheral route, as a group these strains proved to be among the most virulent when inoculated directly into the central nervous system.
Studies of leukotoxin from Actinobacillus actinomycetemcomitans using the promyelocytic HL-60 cell line
Authors: Zambon J J , DeLuca C , Slots J , Genco R J
Published: January 2020

The promyelocytic HL-60 cell line was examined for susceptibility to leukotoxin from Actinobacillus actinomycetemcomitans. Strains of A. actinomycetemcomitans which caused lysis of human peripheral blood polymorphonuclear leukocytes also lysed HL-60 cells as determined by release of intracellular lactate dehydrogenase. The killing of HL-60 cells by A. actinomycetemcomitans was dose dependent and temperature dependent, reached maximal levels after 45 min of incubation, and was inhibited by rabbit antisera to A. actinomycetemcomitans. Of 100 oral isolates of A. actinomycetemcomitans from 55 subjects, 16% from 11 healthy subjects, 43% from 13 adult periodontitis patients, 75% from 4 insulin-dependent diabetics, 66% from 2 generalized juvenile periodontitis patients, and 55% from 25 localized juvenile periodontitis patients produced leukotoxin. The same subject could harbor both leukotoxin-producing and -nonproducing isolates. The significantly higher proportion of leukotoxin-producing isolates in the disease groups compared with the healthy group is consistent with the hypothesis that leukotoxin from A. actinomycetemcomitans is an important virulence factor in the pathogenesis of certain forms of periodontal disease.
Induction of angiosarcomas by ring-necked pheasant virus
Authors: Carter J K , Proctor S J , Smith R E
Published: January 2020

Ring-necked pheasant virus, an avian leukosis virus, when injected into 10-day old chick embryos, caused angiosarcomas in the lungs of infected chickens within a short time. Angiosarcomas appeared as localized foci of proliferating cells in the lungs as early as 2 weeks posthatch, and by 6 weeks, the lungs of the infected chickens were frequently filled with tumor cells. Between 3 and 10 weeks of age, 80% of infected chickens died of the angiosarcomas; the 20% which lived 8 weeks or longer had small lung lesions and also developed fibrosarcomas, osteopetrosis, nephroblastoma, and lymphoid leukosis. Chickens with lung tumors were cyanotic, had breathing difficulty, and had packed cell volumes in excess of 50%. Other changes not necessarily correlated with lung tumor mass were stunting, lymphoid organ involution, and profuse diarrhea. Ring-necked pheasant virus has a genome RNA of 8.2 kb. This observation, together with its replication and disease induction after repeated plaque purification, suggests that ring-necked pheasant virus is a replication-competent avian retrovirus. Therefore, our results suggest that ring-necked pheasant virus is an avian leukosis virus which causes angiosarcomas rapidly at high incidence and which, therefore, may induce this type of tumor by a mechanism different from the induction of sarcomas by avian sarcoma viruses.
Ultrastructural distribution of interferon receptor sites on mouse L fibroblasts grown in suspension: ganglioside blockade of ligand binding
Authors: Kushnaryov V M , MacDonald H S , Sedmak J J , Grossberg S E
Published: January 2020

Murine beta-interferon (IFN) receptors on L929 cells grown in suspension culture were visualized by indirect immunoferritin electron microscopy. Ferritin label on these cells was associated primarily with the coated areas and coated pits of the membrane, in contrast to previous observations with L929 cells grown in a monolayer, which did not reveal such coated areas or pits but showed ferritin label distributed randomly on the cell membrane (Kushnaryov et al., Infect. Immun. 36:811-821, 1982). On about 15% of the cell sections from suspension-grown cells, the ferritin label was found outside coated membrane areas. These findings suggest that different cell populations exist with respect to the localization and possibly the affinity of IFN receptors. In the same experiment, exogenously added gangliosides blocked the binding to cell surfaces not only of 125I-labeled IFN but also of unlabeled IFN as revealed by an immunospecific ferritin labeling technique, providing direct evidence that gangliosides interfere with the binding of IFN to specific receptor sites on the surface of mouse L929 cells. These studies establish that the binding of IFN to cell membranes, depending on cell growth conditions, can involve coated areas and coated pits, to which certain hormones and toxins have been shown to bind.
Evaluation of virulence factor testing and characteristics of pathogenicity in Yersinia enterocolitica
Authors: Aulisio C C , Hill W E , Stanfield J T , Sellers R L
Published: January 2020

The virulence of 10 strains of Yersinia enterocolitica containing 42- to 44-megadalton plasmids (serogroups O:3; O:4,32; O:8; O:9; O:13,7; and O:21) was compared in mice and guinea pigs. Adult mice were more responsive than guinea pigs to the Sereny-like conjunctivitis test. In tests on suckling mice, all Yersinia strains harboring plasmids were lethal, whereas all strains without plasmids were nonlethal. All strains of serogroups O:4,32; O:8; O:13,7; or O:21 which harbored a plasmid gave positive results in the mouse Sereny, peroral, and intraperitoneal tests. A positive reaction in these tests was correlated with the ability of the strains to elaborate lipase. Because the Sereny, peroral, and intraperitoneal tests measured the same virulence factor(s), the findings in any of these three tests would accurately predict the results of the other two tests. Mice which survived the Sereny and peroral tests were subsequently challenged intraperitoneally with 1,000 mouse lethal doses of the virulent WA (O:8) strain. Those inoculated with plasmid-harboring strains were protected, whereas those inoculated with plasmid-free strains were not.
Synergistic effect of Bordetella pertussis lymphocytosis-promoting factor on protective activities of isolated Bordetella antigens in mice
Authors: Robinson A , Irons L I
Published: January 2020

The effect of low levels of added lymphocytosis-promoting factor (LPF) on the ability of several antigenic preparations isolated from Bordetella pertussis and other bacteria to protect mice against intracerebral infection with B. pertussis was examined. LPF was found to enhance the protective activities of filamentous hemagglutinin, 22S antigen, and fimbriae isolated from B. pertussis. Outer membrane protein preparations from phase I B. pertussis which had LPF removed by haptoglobin affinity columns or inactivated by glutaraldehyde, sodium dodecyl sulfate, or Formalin had reduced protective activities but were made fully protective by the readdition of LPF. Similarly, outer membrane protein preparations from Bordetella bronchiseptica, Bordetella parapertussis, or phase IV B. pertussis lacking LPF were protective only when low levels of LPF were added to the preparations. Outer membrane protein preparations from Neisseria gonorrhoeae or Escherichia coli were nonprotective even in the presence of added LPF. The purified LPF by itself was nonprotective unless treated with glutaraldehyde. LPF that had been detoxified with glutaraldehyde was, however, ineffective at enhancing the protective activity of antigenic preparations. The synergistic effect of LPF is discussed in relation to its known biological properties.
Cloning and molecular characterization of the B subunit of Escherichia coli heat-labile enterotoxin
Authors: Clements J D , Flint D C , Engert R F , Klipstein F A
Published: January 2020

We have constructed a plasmid containing the gene for production of the B subunit of the heat-labile enterotoxin (LT-B) from a human isolate of Escherichia coli, strain H10407. The 0.8-kilobase gene fragment encoding synthesis of LT-B was cloned onto plasmid pBR322 after sequential digestion of the enterotoxin plasmid of strain H10407 with restriction endonucleases PstI and HindIII. LT-B was isolated by agarose affinity chromatography from cell lysates of recombinant clones expressing the B subunit. The B subunit was isolated in its oligomeric form, was structurally identical to native B subunit when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, dissociated to monomeric B in the presence of 5 M guanidine, was immunologically identical to native B subunit in an enzyme-linked immunosorbent assay, and contained no demonstrable A subunit in any of the assays.
Passive protection against Pseudomonas aeruginosa infection in an experimental leukopenic mouse model
Authors: Cryz S J , Fürer E , Germanier R
Published: January 2020

An experimental leukopenic mouse model was used to evaluate the protective capacities of immunoglobulin G (IgG) fractions directed against toxin A (AT-IgG), elastase (AE-IgG), and lipopolysaccharide (ALPS-IgG) against fatal Pseudomonas aeruginosa infection. Statistically significant protection, as measured by long-term survival, was observed only when mice were treated with serotype-specific ALPS-IgG. The mean lethal dose for P. aeruginosa could be increased by as much as 6,600-fold for mice given ALPS-IgG as compared to mice which received only normal rabbit IgG. ALPS-IgG afforded high levels of protection, even when administered up to 6 h postchallenge. Experiments designed to monitor the growth and spread of a locally administered challenge showed that ALPS-IgG prevented bacteremia and organ colonization, which were pronounced in control animals. The effectiveness of combined antibiotic and immune therapy was tested. Gentamicin alone or in combination with AT-IgG or AE-IgG provided no detectable protection. However, its use with ALPS-IgG afforded substantially higher levels of protection than ALPS-IgG alone.
Demonstration of an iron-siderophore-binding protein in the outer membrane of Pseudomonas aeruginosa
Authors: Sokol P A , Woods D E
Published: January 2020

Outer membranes prepared from Pseudomonas aeruginosa grown in low-iron medium bind three times as much [59Fe]pyochelin as do membranes from cells grown in high-iron medium. The deletion of pyochelin reduced 59Fe binding to background levels. Autoradiographic analysis of sodium dodecyl sulfate polyacrylamide gel electrophoretograms of outer membrane preparations previously incubated with [59Fe]pyochelin revealed that the iron-siderophore complex bound to a low-molecular-weight protein of approximately 14,000.
Purification and characterization of heat-stable enterotoxin from bovine enterotoxigenic Escherichia coli
Authors: Saeed A M , Sriranganathan N , Cosand W , Burger D
Published: January 2020

Heat-stable enterotoxin (ST) from Escherichia coli pathogenic for cattle was mass produced in a chemically defined medium. The toxin was concentrated and purified by sequentially applying batch adsorption chromatography on Amberlite XAD-2 resin, acetone fractionation, and preparative isoelectric focusing in a flatbed granulated gel. Reverse-phase high-performance liquid chromatography was used to purify the toxin further and to eliminate contaminating ampholytes. The toxin was purified more than 2,000-fold and had a minimal effective dose of less than 0.5 ng. It was biologically active after heating to 100 degrees C for 30 min and was not hydrolyzed by trypsin, pronase, and subtilisin, but it was inactivated by treatment with 0.1 M 2-mercaptoethanol or 4 X 10(-5) M dithiothreitol, suggesting that disulfide bonds are essential for retaining its biological activity. The amino acid analysis revealed 18 amino acid residues per molecule, which is in agreement with the composition of ST from a human strain of enterotoxigenic E. coli. The amino acid composition of our ST matched the published coding sequence of the last 18 codons of Tn1618, a transposon isolated from the bovine enterotoxigenic E. coli strain B41 and shown to be present also in some strains of porcine enterotoxigenic E. coli. These findings further support the existence of a form of ST common to bovine, porcine, and human strains of enterotoxigenic E. coli.
Role of Phospholipase-Associated Penetration Mechanism in Cell Injury by
Rickettsia rickettsii
Authors: Walker David H. , Firth William T. , Ballard J. Glen , Hegarty Barbara C.
Published: January 2020

The cholesterol receptor-binding drugs amphotericin B and digitonin reduced rickettsial plaque formation, presumably by blocking rickettsial attachment, even when added to the plaque model on day 4 post-inoculation when infected foci were well established. The phospholipase inhibitor phentermine reduced plaque formation, presumably by inhibiting the phospholipase-associated entry step of penetration.
Hydroxamate siderophore production by opportunistic and systemic fungal pathogens
Authors: Holzberg M , Artis W M
Published: January 2020

It has been suggested that siderophores may function as virulence factors. There have been few studies on production of siderophores by opportunistic and pathogenic fungi. We examined siderophore production by Absidia corymbifera, Aspergillus niger, Rhizopus arrhizus, Rhizopus oryzae, Blastomyces dermatitidis, Histoplasma capsulatum, Sporothrix schenickii, Candida albicans, and Trichophyton mentagrophytes. Fungi were cultured at 37 and 27 degrees C in a chemically defined low-iron media (0.2 microM Fe). Culture supernatants were assayed for siderophores by two nonspecific methods [FeCl3 and Fe(ClO4)3] and three chemically specific assays (catechol, 2,3-dihydroxybenzoate, and hydroxamate). All fungi secreted siderophores. Only siderophores of the hydroxamate type were found. More siderophore was produced at 27 degrees C than at 37 degrees C. The present study adds eight fungi to the list of known siderophore producers and confirms siderophore production by H. capsulatum.
Elevated antibody levels against measles virus P protein in sera of patients with multiple sclerosis
Authors: Wechsler S L , Meissner H C
Published: January 2020

Immune precipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and densitometry was used to estimate immunoglobulin G antibody levels against the H, P, and M proteins of measles virus in the sera of 24 patients with multiple sclerosis and 24 serologically matched controls. Of the 24 multiple sclerosis sera, 5 showed a statistically significant increase in antibody titer to the P protein as compared with the control sera. Antibody titers to the H and M proteins in multiple sclerosis and control sera were not significantly different.
Differences in the adhesive properties of Neisseria meningitidis for human buccal epithelial cells and erythrocytes
Authors: Trust T J , Gillespie R M , Bhatti A R , White L A
Published: January 2020

The ability of clinical and carrier isolates of Neisseria meningitidis to adhere to human buccal epithelial cells and erythrocytes was investigated. Four of the 10 fimbriated strains were able to hemagglutinate. Serial subculture of three of these strains resulted in a loss of ability to hemagglutinate and was coincident with a loss of fimbriation. Other fimbriated strains were unable to hemagglutinate but did adhere to buccal epithelial cells. Subculture of one of these strains for as many as 42 passages did not result in loss of fimbriation or ability to adhere to buccal epithelial cells. The attachment of this strain to buccal epithelial cells was inhibited by glycoconjugates. Further, pH exerted different influences on the attachment of hemagglutinating and non-hemagglutinating fimbriated strains to buccal epithelial cells and erythrocytes. The results suggest that different fimbrial mechanisms are involved in the attachment of N. meningitidis to different cell types and that hemagglutination is not an absolute test for fimbriae.
Longitudinal studies of cytomegalovirus-specific cell-mediated immunity in congenitally infected infants
Authors: Okabe M , Chiba S , Tamura T , Chiba Y , Nakao T
Published: January 2020

Characteristics of specific cell-mediated immunity in infants with congenital cytomegalovirus (CMV) infection were studied by in vitro lymphocyte transformation test, using the whole blood culture technique. Subjects were 6 symptomatic congenitally infected infants, 11 asymptomatic congenitally infected infants, 3 postnatally infected infants, and 5 CMV-free infants. Among them, three symptomatics and seven asymptomatics were studied temporally, together with three postnatally infected infants and five controls. In the congenitally infected group, 18 of 47 (38%) specimens proved to be negative in terms of stimulation index values. Studies of temporal changes in CMV lymphocyte transformation tests revealed that in the postnatally infected group, the response turned positive in accordance with the appearance of CMV viruria and remained positive afterwards. In the congenitally infected group, the delay in development of positive reaction followed initial negativity, a phenomenon conspicuously observed in the symptomatic subjects. No significant difference was seen in phytohemagglutinin-induced lymphocyte transformation tests among congenital, postnatal, and control groups.
Recovery from lethal herpes simplex virus type 1 infection is mediated by cytotoxic T lymphocytes
Authors: Larsen H S , Russell R G , Rouse B T
Published: January 2020

The ability of herpes simplex virus (HSV)-specific, cytotoxic T lymphocytes to mediate recovery of mice lethally infected with HSV was examined. Adoptive transfer of splenocytes from mice that had been primed in vivo with HSV and restimulated with HSV in vitro protected lethally infected normal and cyclophosphamide-immunosuppressed mice from death. In contrast, equal numbers of normal splenocytes or immune splenocytes cultured without antigen failed to mediate recovery. Recovery was also transferred by noncultured, primary immune splenocytes, although the protective efficacy of these cells was 10-fold less than when immune splenocytes restimulated in vitro were used. Treatment of the cells with anti-Thy 1 or anti-Lyt 2.1 plus complement before adoptive transfer abrogated recovery. No decrease in protection was seen when in vitro-restimulated splenocytes were treated with anti-Lyt 1.1 plus complement. Splenocytes expression natural killer activity also failed to effect recovery. The administration of hyperimmune anti-HSV antibody to normal, immunocompetent mice resulted in recovery, whereas no significant protection of immunosuppressed mice by anti-HSV was observed. When antibody was given concurrently with cultured immune splenocytes, the percentage of mice that recovered from infection was greater than that seen with either antibody or cultured immune splenocytes alone. These experiments demonstrate that Lyt 2-positive cells with cytotoxic activity generated by in vitro immunization can mediate recovery from lethal HSV infection, whereas, under the conditions chosen, Lyt 1-positive cells were unable to mediate recovery.
Purification and immunochemical properties of Escherichia coli B polysaccharide cross-reacting with Salmonella typhi Vi antigen: preliminary evidence for cross-reaction of the polysaccharide with Escherichia coli K1 antigen
Authors: Szewczyk B , Taylor A
Published: January 2020

An acidic polysaccharide of Escherichia coli B was isolated by a mild procedure and purified to homogeneity. The polysaccharide was found to react in Salmonella typhi Vi antisera and E. coli K1 antisera. Serological analysis and preliminary chemical characterization of the polysaccharide indicated that it is an aminouronic acid polymer which, although not structurally identical to either Vi or K1, appears more like the Vi antigen, both immunochemically and chemically.
Characterization of the antibody response in inbred mice to a high-molecular-weight polysaccharide from Pseudomonas aeruginosa immunotype 1
Authors: Markham R B , Pier G B
Published: January 2020

We explored the genetic basis for the differing immune responses observed in inbred strains of mice to a high-molecular-weight polysaccharide (PS) from Pseudomonas aeruginosa immunotype 1 (IT-1). Previous studies have shown that C3H mice immunized with this antigen produce only immunotype-specific antibody. BALB/c mice immunized with IT-1 PS produce both anti-IT-1 PS antibody and antibody cross-reactive with PS from P. aeruginosa immunotype 2 (IT-2). In the current study, we observed that, in addition, these two strains differ in their ability to respond to low immunizing doses of IT-1 PS. C3H mice generated a protective antibody response after a 1-microgram immunization, whereas BALB/c mice failed to produce protective antibody after receiving 1 microgram of PS. Both strains generated protective levels of antibody after a 50-micrograms immunization. Genetic analysis of these response patterns indicates that the ability to produce cross-reactive antibody and the ability to respond to a 1-microgram immunization are independently inherited traits. In addition, the responsiveness of C3H mice to a 1-microgram immunization with the production of protective levels of antibody is not linked to the mouse major histocompatibility (H-2) complex, to sex-linked genes, or to a single gene outside the H-2 complex.
Babesia bovis: isolation of a protective antigen by using monoclonal antibodies
Authors: Wright I G , White M , Tracey-Patte P D , Donaldson R A , Goodger B V , Waltisbuhl D J , Mahoney D F
Published: January 2020

Three distinct monoclonal antibody-producing hybridomas have been produced against a partly purified protective fraction of Babesia bovis. All three stain the parasite or infected erythrocytes or both in precise and different manners when fluorescent-antibody techniques are used. The relevant antigens for each monoclonal antibody were isolated by immunoadsorption, their native molecular weights being 1.3 X 10(6), 180 X 10(3), and 44 X 10(3). Each antigen reacted in serological assays with homologous and heterologous bovine antisera to B. bovis. Susceptible splenectomized calves were immunized twice, 4 weeks apart, with the respective antigens and were challenged with virulent homologous organisms 2 weeks later. Strong protective immunity was induced by the antigen with a molecular weight of 44 X 10(3), but no significant protection was induced by either of the other two antigens.
Suppression of adoptive antituberculosis immunity by normal recipient animals
Authors: Lefford M J
Published: January 2020

Adoptive immunity is poorly expressed in normal syngeneic mice. This phenomenon was studied by using experimental antituberculosis immunity as a model system representing pure cell-mediated immunity. Expression of adoptive immunity was facilitated by pretreating recipients with sublethal ionizing radiation (500 rads) or high doses (200 mg/kg) of cyclophosphamide or by using adult thymectomized, lethally irradiated, bone-marrow-reconstituted (TXB) mice. Adult thymectomy was less effective, and a low dose of cyclophosphamide (20 mg/kg) was completely ineffective. The beneficial effect of sublethal irradiation was reduced over time; it persisted for 4 weeks and was absent after 8 weeks. Attempts to restore the suppressed state of normal mice to sublethally irradiated mice by using normal spleen or thymus cells did not succeed. Even in rats, which express adoptive antituberculosis immunity without immunosuppressive treatment, the use of sublethally irradiated or TXB recipients potentiated adoptive immunity. It was concluded that suppression of adoptive immunization in normal recipient mice is mediated predominantly, if not exclusively, by T lymphocytes that are sensitive to a number of immunosuppressive agents. The suppressor cells are long-lived and can be regenerated from precursors that are resistant to 500 but not to 900 rads of ionizing radiation.
In vitro inhibition of lymphocyte proliferation by Pseudomonas aeruginosa phenazine pigments
Authors: Sorensen R U , Klinger J D , Cash H A , Chase P A , Dearborn D G
Published: January 2020

Human lymphocyte proliferation is inhibited in vitro in the presence of killed Pseudomonas aeruginosa or cell-free P. aeruginosa culture supernatants. A comparison of culture supernatants obtained under similar conditions from Staphylococcus aureus, Escherichia coli, P. aeruginosa, and Pseudomonas cepacia strains demonstrated that all P. aeruginosa supernatants were strongly inhibitory, whereas supernatants from other bacteria were mildly inhibitory or not inhibitory at all. These P. aeruginosa inhibitors prevent proliferative responses of resting cells upon mitogen activation and decrease [3H]thymidine uptake when added to human lymphocytes undergoing active proliferation in culture. The inhibitory effect is reversible and not due to cytotoxicity. Most of the inhibitory activity present in crude supernatants was detected in ultrafiltrates of molecular weights below 2,000. Purified P. aeruginosa pyocyanine, a low-molecular-weight phenazine pigment present in culture supernatant, was strongly inhibitory for lymphocyte proliferation. Extraction of pyocyanine and phenazine pigments from inhibitory P. aeruginosa supernatants eliminated their inhibitory activity. Inhibitors were recovered from reverse-phase chromatographic cartridges by both chloroform and methanol elution, indicating that pyocyanine and other phenazine pigments present in P. aeruginosa supernatants are responsible for the inhibition of lymphocyte proliferation. In addition to the identification of phenazine pigments as lymphocyte proliferation inhibitors, several criteria ruled out major contributions of P. aeruginosa polysaccharide, exotoxin A, and proteases to this phenomenon. P. aeruginosa strains selected for very low protease production or for very low exotoxin A production produced supernatants as inhibitory for lymphocyte proliferation as supernatants obtained from clinical P. aeruginosa isolates. Purified P. aeruginosa lipopolysaccharide and protease preparations failed to induce reversible lymphocyte proliferation inhibition. Finally, heat inactivation of P. aeruginosa supernatants at 100 degrees C for 60 min inactivates exotoxin A and proteases but produced only a moderate decrease of the inhibitory activity for lymphocyte proliferation.
Binding of 18F by cell membranes and cell walls of Streptococcus mutans
Authors: Yotis W W , Zeb M , McNulty J , Kirchner F , Reilly C , Glendenin L
Published: January 2020

The binding of 18F to isolated cell membranes and cell walls of Streptococcus mutans GS-5 or other bacteria was assayed. The attachment of 18F to these cell envelopes proceeded slowly and reached equilibrium within 60 min. 18F binding was stimulated by Ca2+ (1 mM). The binding of 18F to cellular components was dependent upon the pH, as well as the amount of 18F and dose of the binder employed. The binding of 18F by cell walls prepared from fluoride-sensitive and fluoride-resistant cells of S. salivarius and S. mutans did not differ significantly. The pretreatment of cell walls or cell membranes for 60 min at 30 degrees C with 1 mg of RNase, DNase, or trypsin per ml did not influence the binding of 18F by the walls and membranes of S. mutans GS-5. However, prior exposure of cell membranes to sodium dodecyl sulfate caused a significant reduction in the number of 18F atoms bound by the membranes. In saturated assay systems, cell membranes of S. mutans GS-5 bound 10(15) to 10(16) atoms of 18F per mg (dry weight), whereas cell walls from S. mutans GS-5, FA-1, and HS-6 or Actinomyces viscosus T14V and T14AV bound 10(12) to 10(13) atoms of 18F per mg (dry weight). 18F in this quantity (10(12) to 10(13) atoms) cannot be detected with the fluoride electrode. The data provide, for the first time, a demonstration of 18F binding by cell membranes and walls of oral flora.
Immunological relationships between cholera toxin and Escherichia coli heat-labile enterotoxin
Authors: Gilligan P H , Brown J C , Robertson D C
Published: January 2020

The antigenic relationships between heat-labile enterotoxin (LT) produced by a human strain of enterotoxigenic Escherichia coli (strain 286C2) and cholera toxin (CT) were examined by using antisera raised against LT and CT and specific antisera prepared against each subunit of both enterotoxins. Double immunodiffusion analysis revealed reactions of partial identity between the A subunits of LT and CT, as well as between the B subunits. Rabbit antisera raised against LT subunit A reacted with only subunit A, whereas rabbits immunized with LT subunit B produced antibodies which reacted with only subunit B. A high degree of CT neutralization was observed with antisera raised against LT. Data from neutralization assays with specific antisera to each enterotoxin showed that LT was more effectively neutralized by homologous anti-LT than CT (3.7-fold); however, anti-CT was only slightly more effective in neutralization of homologous CT compared with LT (1.9-fold). In contrast, antisera raised against the B subunit of CT (choleragenoid) exhibited significantly higher neutralization activity against CT than LT (5.8-fold); however, the amount of CT neutralized by anticholeragenoid was less (4.1-fold) than anti-CT. These results suggested that anti-CT serum contained neutralizing antibodies reactive with a shared determinant formed by interaction of the A and B subunits, whereas anti-LT and anti-choleragenoid sera did not. Sensitive solid-phase radioimmunoassays were developed to examine the affinity and degree of specificity involved in homologous and heterologous antigen-antibody interactions between LT, CT, their subunits, and specific antibodies. Only unlabeled LT competed with radiolabeled LT in polystyrene tubes coated with anti-LT, and only unlabeled CT competed with radiolabeled CT in tubes coated with anti-CT. However, when radiolabeled CT was incubated in tubes coated with anti-LT, competitive inhibition responses were observed with both unlabeled toxins. When radiolabeled LT was incubated with tubes coated with anti-CT, competitive inhibition responses were observed with both unlabeled toxins. Similar competitive inhibition responses were observed with the A subunits of LT and CT and with the B subunits using antisera specific for the subunits of each enterotoxin. Double immunodiffusion analysis and radioimmunoassay data supported the presence of unique and shared immunodeterminants in each subunit.
Coordinated therapeutic effects of immune modulators and interferon
Authors: Cerutti I , Chany C
Published: January 2020

Immune modulators injected 24 h before encephalomyocarditis virus significantly increase antiviral resistance in mice when interferon is administered 1 h after the virus. These immune modulators can be crude bacterial extracts or synthetic drugs. In some cases, the responses are additive; in others, they are clearly cooperative. To protect the mice against the development of 180 TG Crocker sarcomas, the association of bacterial extracts and interferon is highly effective under the condition that the drug concentrations and chronological order and number of injections are well defined. In contrast, the conjunction of interferon and synthetic immune modulators, in particular cimetidine, result in delayed tumor development with no significant change in the final survival rate in the experimental model described here.
Dermal granulomatous hypersensitivity in Q fever: comparative studies of the granulomatous potential of whole cells of Coxiella burnetii phase I and subfractions
Authors: Ascher M S , Williams J C , Berman M A
Published: January 2020

Dermal granulomatous reactivity to Q fever antigens in guinea pigs has been described as a model for vaccine reactions seen in previously sensitized humans. This model has now been applied to study the ability of subfractions of Coxiella burnetii to produce granulomas. Q fever organisms in phase I, trichloroacetic acid-soluble and -insoluble fractions, and the extract and residue of chloroform-methanol extraction were tested for their relative ability to elicit and immunize for dermal granulomatous reactions and specific lymphocyte proliferative responses in guinea pigs. The results suggest that a determinant(s) causing granulomas can be removed by chloroform-methanol extraction of phase I whole cells. The chloroform-methanol residue elicited strong delayed-type hypersensitivity without subsequent granuloma formation. The chloroform-methanol residue appears to possess a determinant(s) for lymphocyte stimulation equivalent to that of whole phase I organisms.
Monoclonal antibodies as probes of tetanus toxin structure and function
Authors: Kenimer J G , Habig W H , Hardegree M C
Published: January 2020

Monoclonal antibodies specific for fragment B, fragment C, and light chain of tetanus toxin were prepared by fusion of P3X63Ag8 BALB/c myeloma cells with spleen cells from BALB/c mice immunized with tetanus toxoid or fragment B. Hybridoma colonies were assayed for antibody production by an enzyme-linked immunosorbent assay. Fourteen positive clones were identified, cloned by limiting dilution, and injected intraperitoneally into mice to obtain ascites fluids. Thirteen of the monoclonal antibodies were of the immunoglobulin G1 subclass and one was immunoglobulin G2. Two of the antibodies were directed against sites on fragment C, nine were directed against the light chain, and three were directed against the portion of fragment B which does not comprise the light chain of tetanus toxin. At least one antibody in each group exhibited significant toxin neutralization activity. However, only one of these neutralizing antibodies strongly inhibited the binding of 125I-tetanus toxin to ganglioside-coated plates. These data indicate that interference with receptor recognition is not the only means of neutralizing tetanus toxin. Monoclonal antitoxins as potential therapeutic and prophylactic reagents are discussed.
Mutagenesis of extrachromosomal genetic determinants for exfoliative toxin B and bacteriocin R1 synthesis in Staphylococcus aureus after plasmid transfer by protoplast fusion
Authors: Masterson R , von David W , Wiley B B , Rogolsky M
Published: January 2020

In previous studies, we have shown that a 27-megadalton plasmid (pRW002) in Staphylococcus aureus contains genetic determinants for exfoliative toxin B (ET B) and bacteriocin (Bac R1) synthesis and Bac R1 resistance. Attempts to transform or transduce this plasmid to S. aureus or Bacillus subtilis recipients were not successful. However, genetic transfer of the plasmid was possible after polyethylene glycol-induced fusion of S. aureus protoplasts containing pRW002 and S. aureus protoplasts lacking this plasmid. Some of the resulting fusants lost the ability to make ET B, Bac R1, or both products. Fusants that were Bac R1-, Bac R1s, ET B- all lacked the 27-megadalton pRW002 plasmid. The largest class of fusants was Bac R1+, Bac R1r, ET B-. Immunodiffusion analyses of ET B extracts from 28 fusants showed that four ET B+ strains were cross-reacting mutants that produced ET B protein that was serologically related to, but not identical to, the wild-type toxin. Results indicated that genetic transfer of pRW002 after protoplast fusion induced molecular rearrangements that resulted in mutation of the genetic determinants for ET B and Bac R1 synthesis. Recombination of chromosomal genes was enhanced after CaCl2 was added to the protoplast-fusion mixture.
Identification of cross-reactive antigens between Mycoplasma pulmonis and Mycoplasma arthritidis
Authors: Minion F C , Brown M B , Cassell G H
Published: January 2020

Serological cross-reactivity between Mycoplasma pulmonis and Mycoplasma arthritidis was investigated by enzyme-linked immunosorbent assay, immunoanalysis of electrophoretic blots, and protein A immunoprecipitation reactions. The results demonstrate that one-way cross-reactivity was present in both hyperimmunized and naturally infected rats and that the predominant cross-reactive antigens were M. pulmonis surface proteins. Distinct immunoblot patterns were demonstrated for M. pulmonis and M. arthritidis, allowing differentiation of the two species. The response to M. arthritidis antigens during natural infections differed greatly from that during hyperimmunization. Evidence suggested that nonprotein antigens were major determinants eliciting the antibody response to this mycoplasma.
Phosphorylation-dephosphorylation of nuclear proteins during infection (Q fever)
Authors: Gonzales F R , Halevy M , Paretsky D
Published: January 2020

The proposal that gene expression may be regulated by phosphorylation of nonhistone chromatin proteins was tested by studying increased transcription resulting from Q fever. Certain liver nuclear phosphoprotein kinase and phosphatase activities were altered after guinea pigs were infected with Coxiella burnetii. Nonhistone chromatin proteins had increased phosphoprotein kinase activity and were differentially phosphorylated. The addition of spermine equally stimulated nuclear phosphoprotein kinases of uninfected and infected livers. Increased nuclear phosphatase activity accompanied infection. It was concluded that protein phosphorylations are altered by infection and are central events in regulating RNA and protein synthesis. A hypothesis is presented which attempts to correlate the findings in previous reports and those in the present paper regarding biochemical sequelae of Q fever. It is suggested that certain features of regulation described here also may be operative in some other infections or diseases.
A Cytophaga species endotoxin as a putative agent of occupation-related lung disease
Authors: Flaherty D K , Deck F H , Hood M A , Liebert C , Singleton F , Winzenburger P , Bishop K , Smith L R , Bynum L M , Witmer W B
Published: January 2020

A previous study suggested that a biologically active bacterial endotoxin was a putative agent of lung disease in a textile-producing facility. The endotoxin was isolated from the biomass growing in a chilled-water spray air humidification system. The bacterial flora of the air humidification system were isolated and taxonomically identified to the genus level. By using indirect immunofluorescence assays, a serologically reactive Cytophaga species was identified. A serologically reactive, biologically active (Limulus assay) endotoxin was purified from phenol extracts of the Cytophaga species. The endotoxin contained sugars, hexosamines, and lipids identical to those found in the humidifier biomass endotoxin. All subjects with biopsy-proven and suspected lung disease had antibodies directed toward the purified Cytophaga endotoxin. The data suggest that the Cytophaga endotoxin is the putative agent of lung disease in the textile facility.
Legionella pneumophila-induced blastogenesis of murine lymphoid cells in vitro
Authors: Friedman H , Widen R , Klein T , Searls L , Cabrian K
Published: January 2020

Legionella pneumophilia antigen preparations, either killed whole cell vaccine, a soluble sonic extract, or a purified large-molecular-weight somatic antigen, stimulated blastogenic responses by splenocytes from both normal and Legionella-sensitized mice. Graded amounts of the bacterial preparations, when added to cultures of normal spleen cells, resulted in increased uptake of thymidine into cellular DNA, indicating that the preparations were mitogenic for normal mouse splenocytes. Spleen cells from mice injected with graded numbers of living bacteria showed blastogenic responsiveness to Legionella preparations generally at a higher level than spleen cells from normal animals. The heightened blastogenic response was mainly evident with spleen cells obtained from mice injected with living bacteria 2 to 3 weeks earlier. Splenocytes from mice infected with legionella less than 1 to 2 weeks or for more than 4 to 5 weeks responded generally similar to those obtained from uninjected mice, indicating that sensitization with living organisms had a relatively short duration. Spleen cell suspensions responding to the L. pneumophila antigens appeared to be mainly B-lymphocytes since cell suspensions from athymic nude mice deficient in T-cells responded as well as cells from conventional mice. Furthermore, passage of splenocytes over nylon wool columns to obtain B-cell-enriched preparations resulted in cell populations capable of responding to Legionella antigen. The cell fractions rich in T-cells were much less capable of responding to the Legionella antigens. In addition, treatment of spleen cell populations with antitheta serum plus complement failed to inhibit the blastogenic response, whereas the same spleen cell preparations treated with anti-mouse immunoglobulin serum plus complement markedly diminished blastogenic responsiveness, again consistent with the likelihood that B-lymphocytes were the major cell class responding to the Legionella preparations.
Immunostimulation by Legionella pneumophila antigen preparations in vivo and in vitro
Authors: Friedman H , Widen R , Klein T , Johnson W
Published: January 2020

Injection of Legionella pneumophila antigen, either killed vaccine or soluble sonicate thereof, resulted in an enhanced antibody response by mouse spleen cells to sheep erythrocytes as determined by the hemolytic plaque assay. Enhancement was dose dependent and reached a peak response at a concentration of 10(7) bacteria or 50 micrograms of sonicate per animal. Larger doses of antigen were less stimulatory or even depressed the antibody response. Similar enhancement of antibody formation by normal spleen cell cultures to sheep erythrocytes in vitro occurred in the presence of graded amounts of L. pneumophila vaccine or sonicate. In addition, the L. pneumophila antigen stimulated enhanced background antibody formation in vitro in the absence of sheep erythrocytes or specific antigen. It appeared likely that the immunoenhancing activity of the L. pneumophila extract may be unrelated to the presence of lipopolysaccharide since boiling the antigen preparation eliminated much of the antibody-enhancing properties of the extract. A large-molecular-weight surface component from L. pneumophila was also immunomodulatory in vitro. Immunostimulation appeared to be related to effects on macrophages since adherent spleen cell populations rich in macrophages, when derived from spleen cell suspensions incubated with L. pneumophila antigen in vitro, stimulated enhanced antibody formation by normal mouse spleen cells in coculture experiments. Further investigations concerning the mechanism of immunomodulation by L. pneumophila antigen in vivo and in vitro appear to be warranted.
A small plasmid in Shigella dysenteriae 1 specifies one or more functions essential for O antigen production and bacterial virulence
Authors: Watanabe H , Timmis K N
Published: January 2020

The role of plasmids in the virulence of Shigella dysenteriae 1 W30864, which contains at least five species, was investigated. By means of a standard plasmid-curing procedure, that is, bacterial cultivation at an elevated temperature, five virulence-deficient derivatives were obtained. One of these lacked a small, 6-megadalton plasmid, designated pHW400, exhibited reduced invasiveness for HeLa cells, and failed to produce the somatic antigen. Transposon tagging of the pHW400 plasmid to produce pHW401 and the transfer of this derivative into a variant of strain W30864 lacking pHW400 confirmed the conclusion that the pHW400 plasmid encodes one or more functions involved in O antigen (lipopolysaccharide) biosynthesis and bacterial virulence. A plasmid of similar size was detected in all of the three other strains of S. dysenteriae 1 examined.
Activation of jird (Meriones unguiculatus) macrophages by the filarial parasite Brugia pahangi
Authors: Jeffers G W , Klei T R , Enright F M
Published: January 2020

Peritoneal macrophages from Mongolian jirds (Meriones unguiculatus) with either lymphatic or intraperitoneal infections of Brugia pahangi were studied to determine the effects of infection on macrophage function and morphology. Macrophages were collected at 40, 90, 140, and 200 days after inoculation of infective third-stage larvae and assayed for phagocytic and bactericidal activity by the acridine orange method and for morphological changes by light and electron microscopy. Significant increases in phagocytic and microbicidal activity (P less than or equal to 0.01) were observed in peritoneal macrophages collected from jirds with intraperitoneal infections when compared with peritoneal macrophages from jirds with lymphatic infections and resident peritoneal macrophages from normal, noninfected jirds. Morphological changes in peritoneal macrophages from jirds with intraperitoneal infections were similar to those found in thioglycolate-elicited macrophage populations. Granuloma formation was also observed in the peritoneal cavities of intraperitoneally infected jirds. The peritoneal cavity may serve as a model to study cell-worm interactions in filarial nematode infections.