bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunochemical analysis of serum-related proteins in the respiratory tract secretions of normal mice
Authors: Osebold J W , Medin N I , Zee Y C
Published: January 2020

Normal mouse lung lavage fluid was analyzed for its content of serum-related proteins by the methods of gel filtration, immunoelectrophoresis, and double immunodiffusion. Lavage samples were collected from exsanguinated mice using three repeated infusions of 0.9% sodium chloride solution. Cells were removed, and the lavage fluid was concentrated. Approximately 0.23 mg of protein per mouse was present in the concentrated solution. Albumin, transferrin, and immunoglobulin G (IgG) were among the proteins in greatest concentration. Albumin, IgG1, IgG2, IgA, and IgM were quantitated by single radial diffusion. Although immunoglobulins could be synthesized locally, albumin and transferrin were assumed to come from plasma. The albumin content was used to estimate the amount of transudated plasma as 0.0027 ml per mouse. The IgA levels were low with an IgA/IgG1 ratio of 0.58 and an IgA/IgG2 ratio of 0.43. IgM was not detected. Goat anti-lung lavage serum revealed the presence of additional lung-related proteins.
Extracellular iron acquisition by mycobacteria: role of the exochelins and evidence against the participation of mycobactin
Authors: Macham L P , Ratledge C , Nocton J C
Published: January 2020

Mycobacterium bovis var. BCG was grown under iron-deficient conditions in the presence and absence of 1% Tween 80. Mycobactin, the iron iron ionophore of mycobacteria, was found solely within the bacteria grown in the absence of Tween, but low concentrations (0.75 mug/ml) of it appeared in the medium in the presence of the surfactant. Both types of medium contain agents, named exochelins, which could solubilize iron. 55Fe added to spent culture media was recovered only chelated to these compounds. Two exochelins were detected, isolated, and purified. Neither were precursors or breakdown products of mycobactin. In the desferri-form, exochelin MB-2, the major component, reversed the inhibitory effect of serum on the growth of BCG, and in their ferri-forms exochelins MB-1, MB-2, and MS (from Mycobacterium smegmatis) stimulated the growth of their producing organism in the presence of serum. Exochelin MB-2 could physically remove iron from ferritin, and BCG used ferritin as a source of iron during growth even when ferritin was separated from the bacteria by a dialysis membrane. As solutions of the exochelins were freely dialyzable, whereas solutions of mycobactin, even in Tween, were not, only exochelin could have been active in this experiment. The exochelins are proposed as the functional extracellular iron-binding agents of BCG and other mycobacteria, the role of mycobactin being confined to that of a cell wall iron transporter.
Effects of BCG, Corynebacterium parvum, and methanol-extration residue in the reduction of mortality from Staphylococcus aureus and Candida albicans infections in immunosuppressed mice
Authors: Sher N A , Chaparas S D , Greenberg L E , Bernard S
Published: January 2020

An immunosuppressed mouse model was devised to test the effects of immunopotentiators on the prevention of bacterial and fungal infections. The effects of BCG and Corynebacterium were tested against Staphylococcus aureus and Candida albicans infection. The effect of methanol-extraction residue (MER-BCG) was tested against S. aureus septicemia. CDF mice were given various doses of BCG, 1.0 mg of C. parvum, or 0.5 mg of MER intraperitoneally at varying intervals before injection of an intravenous bacterial challenge. Four days before challenge, 300 mg of cyclophosphamide per ml was given intraperitoneally. BCG (106 colony-forming units) reduced mortality due to S.aureus at pretreatment intervals of 3, 7, 14, and 28 days. Isonicotinic acid hydrazide treatment elimated the protective effect of the live BCG. C. parvum was as effective as BCG against S. aureus septicemia when given 3 days before infection, but lost most of its protective effect after that time. MER protected at doses as small as 0.25 mg when given 25 days prior to challenge. Both BCG and C. parvum exerted a protective effect against Candida albicans infection.
Quantitative assay of diphtherial toxin and of immunologically cross-reacting proteins by reversed passive hemagglutination
Authors: Holmes R K , Perlow R B
Published: January 2020

A reversed passive hemagglutination (RPHA) assay for diptherial toxin has been developed. Antitoxic antibodies were isolated from commercially available equine diptherial antitoxin by immunoabsorption using highly purified diphtherial toxin covalently linked to Sepharose 4B. Formalinized, tanned sheep erythrocytes sensitized with the purified antitoxic antibodies are specifically agglutinated by diphtherial toxin but are not agglutinated by extracellular antigens of Corynebacterium diptheriae that are unrelated to toxin. The RPHA assay described can detect less than 20 pg of diphtherial toxin and is comparable in sensitivity to intracutaneous tests for toxin. The RPHA assay was shown to be at least 1,000 times more sensitive than quantitative immunological assays for diptherial toxin performed by single radial immunodiffusion or by one-dimensional double diffusion in agar gels. Fragment A prepared from purified diphtherial toxin and nontoxic mutant proteins that cross-react immunologically with toxin can be assayed directly by RPHA, but the sensitivity of the assay for these proteins is less than for native diphtherial toxin. Inhibition of RPHA was also shown to be a sensitive quantitative method for measuring diptherial antitoxin in vitro.
Identification of lethal toxin with the thermostable direct hemolysin produced by Vibrio parahaemolyticus, and some physicochemical properties of the purified toxin
Authors: Honda T , Taga S , Takeda T , Hasibuan M A , Takeda Y , Miwatani T
Published: January 2020

Lethal toxin was purified extensively from the culture filtrate of a Kanagawa phenomenon-positive strain of Vibrio parahaemolyticus. The purified toxin was a protein, and its homogeneity was demonstrated by sodium dodecyl sulfate-polyacrylamide gel disc electrophoresis and analytical ultracentrifugation. It was demonstrated that the thermostable direct hemolysin was identical to the lethal toxin and that it was the main, if not only, lethal toxin in the culture filtrate. The purified toxin had a lethal effect when injected into mice either intravenously or intraperitoneally. Its lethal effect was very rapid, a dose of 5 mug of toxin per mouse killing the animals within 1 min. The lethal activity was inhibited by a ganglioside mixture. Some physicochemical properties of the purified toxin are reported.
Effect of glucose and sucrose on survival in batch culture of Streptococcus mutans C67-1 and a noncariogenic mutant, C67-25
Authors: Donoghue H D , Newman H N
Published: January 2020

The growth and survival of two strains of Streptococcus mutans in 5% (wt/vol) glucose or sucrose broth was investigated. S. mutans strain C67-1 showed little loss of viability after 30 h of incubation in batch culture in the presence of either sugar. S. mutans strain C67-25, a noncariogenic mutant of C67-1 that has lost the ability of the latter to produce sticky, insoluble extracellular polysaccharide when grown in sucrose broth, showed a dramatic loss of viability after 30 h of incubation in either glucose or sucrose broth, the effect being most marked in the presence of glucose. The loss of viability was shown to be due to acid production. Insoluble extracellular polysaccharide production appears to be a phenomenon favoring the survival of organisms subjected to high sucrose levels. Other factors must be involved, however, since there are differences between the two strains as regards their survival in glucose broth.
Comparison of diphtheria intoxication in human and nonhuman cell lines and their resistant variants
Authors: Moehring J M , Moehring T J
Published: January 2020

Differences in sensitivity to diphtheria toxin of several toxin-sensitive and toxin-resistant human and non-human cell lines were compared. A method is described whereby it is possible to compare the sensitivity of one cell line with another and obtain meaningful quantitative results. Based on the concentration of toxin required to produce 50% inhibition of protein synthesis after 24 h of exposure the ID50 (24) value toxin-resistant cells were found to be 105 to 106 times more resistant to toxin than toxin-sensitive cells. There was little variation in the ID50 (24) values for cells in each of the two groups. The toxin-resistant cells used in this study, naturally resistant as well as selected variants, possess elongation factor 2 which is susceptible to inactivation by toxin. It is suggested that they are capable of activation of toxin but either cannot bind toxin or are unable to transport toxin across the plasma membrane. Protein synthesis is inhibited when these resistant cells are exposed to high concentrations of toxin. Under these conditions it is likely that enough toxin is able to bypass the block in toxin-specific entry and reach the cytosol by a second, less efficient, nonspecific mechanism to catalyze the inactivation of elongation factor 2 and inhibit protein synthesis.
Increased survival in calves of Escherichia coli K-12 carrying an Ent plasmid
Authors: Falkow S , Williams L P , Seaman S L , Rollins L D
Published: January 2020

Escherichia coli K-12 strains with and without an Ent plasmid were fed to calves, and the survival of each was monitored by viable bacterial counts of the feces. The E. coli K-12 strain carrying the Ent plasmid survived in the calves at significantly higher levels and for a longer period of time than the E. coli F(-) stain.
Enhancement activity of anti-mycobacterial sera in experimental Mycobacterium bovis (BCG) infection in mice
Authors: Forget A , Benoit J C , Turcotte R , Gusew-Chartrand N
Published: January 2020

The passive transfer of rabbit anti-mycobacterial immunoglobulins was directed against either living or soluble extracts of Mycobacterium tuberculosis strain H37Rv, which promotes the multiplication of the BCG strain of M. tuberculosis in the spleen of mice infected with low doses of this latter strain. This enhancing effect was reduced significantly when antisera were absorbed with living BCG. Moreover, such treatment led to the removal of all hemagglutinating antibodies when antisera were tested against either BCG or H37Rv soluble extracts. Therefore, it is most probable that the enhancing effect is related to the presence of mycobacterial antibodies.
Degradation of 14C-labeled streptococcal cell walls by egg white lysozyme and lysosomal enzymes
Authors: Gallis H A , Miller S E , Wheat R W
Published: January 2020

The resistance of native and trypsin-treated [14C] glucose-labeled cell walls to degradation by lysozyme and human lysosomal enzymes was confirmed. In contrast, chemically N-acetylated cell walls undergo significant degradation by these enzymes in the pH range of 4.5 to 5.5 without prior removal of the group-specific carbohydrate. N-acetylation after removal of the group A carbohydrate by formamide extraction renders the cell walls considerably more susceptible to these enzymes than by formamaide extraction alone. It appears, therefore, that unless N-acetylation can occur in vivo, streptococcal cell walls are minimally degraded, if at all, by human peripheral blood leukocytes or lysozyme. Examination of leukocyte extracts from normal subjects and patients with post-streptococcal syndromes revealed no qualitative differences in ability to dissolve streptococcal cell walls.
Nocardia asteroides and Nocardia brasiliensis infections in mice
Authors: Folb P I , Jaffe R , Altmann G
Published: January 2020

A model for Nocardia asteroides and Nocardia brasiliensis infections in Swiss white mice has been established without the addition to the inocula of any form of adjuvant. Serial histopathological studies revealed that these two actinomycetes cause lesions that are quite different in their features. An acute suppurative abscess characterizes the lesions of N. asteroides. In the case of N. brasiliensis infections a granuloma is produced in which a striking feature is the presence of large numbers of foam-laden macrophages, although occasional exceptions to this pattern were noted. Electron microscopic studies demonstrated that these macrophages contain within their cytoplasm organisms in varying stages of degeneration. Repeated mortality studies in mice failed to demonstrate differences in mortality rates produced by N. asteroides and N. brasiliensis. Thus, despite relatively trivial biochemical and antigenic differences between these two species of Nocardia, the local pathogenic response is quite different. The presence in the "brasiliensis lesion" of foamy macrophages with intracellular organisms is reminiscent of the histopathological features of lepromatous leprosy and of disseminated Myocobacterium bovis infection when this occurs in the immune suppressed situation. It is possible that N. brasiliensis infection produces a depression of cellular immunity that modifies the local host response to the organism.
Strain-dependent differences in murine susceptibility to toxoplasma
Authors: Araujo F G , Williams D M , Grumet F C , Remington J S
Published: January 2020

Susceptibility of seven inbred and outbred strains of mice to infection with trophozoites of Toxoplasma gondii at two different doses was determined. Stroking strain differences in susceptibility and changes of susceptibility with dosage change were seen. The data are consistent with the hypothesis that this may be due to genetic factors.
In vitro studies on Rickettsia-host cell interactions: lag phase in intracellular growth cycle as a function of stage of growth of infecting Rickettsia prowazeki, with preliminary observations on inhibition of rickettsial uptake by host cell fragments
Authors: Wisseman C L , Waddell A D , Silverman D J
Published: January 2020

Two Rickettsia prowazeki seeds, an "early" seed in the logarithmic or exponential growth phase and a "late" seed in the stationary or possibly early decline phase, were prepared in chicken embryo (CE) cell cultures and compared with respect to morphology and infection cycle in CE cells in culture. Differences in size and ultrastructure of the organisms in the two seeds were similar to those seen in other gram-negative bacteria at comparable stages to growth. Vacuolar structures, rare in log-phase organisms, were common in stationary-phase organisms. Minute spherical forms reminiscent of minicells were seen in the stationary-phase preparations. In quantitative uptake experiments, organisms, typical in size and morphology of each preparation, had comparable capacity per plaque-forming unit to penetrate into CE cells in suspension when the seeds had been depleted of host cell membrane fragments and other debris. This suggests that host cell fragments, presumably of membrane origin, competitively inhibit rickettsial uptake by intact CE cells. Organisms of the log-phase organisms displayed a lag phase of about 7.5 h, during which they enlarged and increased in intensity of staining, before entering the log phase of growth.
Chemiluminescence response of phagocytizing human monocytes
Authors: Nelson R D , Mills E L , Simmons R L , Quie P G
Published: January 2020

Chemiluminescence (CL) occurs as a consequence of phagocytosis of bacteria or inert particles by human polymorphonuclear neutrophils. This phenomenon appears to be related to the production of singlet oxygen and/or electronically excited carbonyl groups which relax with light emission. We report that human monocytes also produce CL after phagocytosis of opsonized bacteria, fungi, or zymosan particles. Monocytes produce approximately one-third of the CL produced by polymorphonuclear neutrophils for all three particles, reflecting possible metabolic differences between cells of these types. Addition of exogenous superoxide dismutase reduced the peak production of CL by 65% for cells of both types, whereas raising the temperature of the cultures from 25 to 37 C approximately doubled the peak CL responses.
Purification of cereolysin and the electrophoretic separation of the active (reduced) and inactive (oxidized) forms of the purified toxin
Authors: Cowell J L , Grushoff-Kosyk P S , Bernheimer A W
Published: January 2020

Cereolysin was purified to apparent homogeneity by using ammonium sulfate fractionation, hydrophobic chromatography with AH-Sepharose, isoelectric focusing, and gel filtration. The active form of the toxin had an isoelectric point of 6.6, and the molecular weight of the protein was about 55,500 as judged by sodium dodecyl sulfate-gel electrophoresis, gel filtration, and gel electrophoresis using various concentrations of acrylamide. Cereolysin contained two half-cystine residues and was dependent on reducing agents, such as dithiothreitol, for maximal hemolytic activity and charge homogeneity. By using discontinuous acrylamide electrophoresis, two forms of the toxin could be observed: oxidized and reduced. If the toxin was purified in the absence of dithiothreitol, partial spontaneous oxidation resulted in the formation of an oxidized form of the toxin. Relative to the reduced form, the oxidized form moved slightly closer to the anode in gel electrophoresis at pH 9.0. If the toxin was purified in the presence of 5 mM dithiothreitol or if the spontaneously oxidized toxin was preincubated with dithiothreitol, only the reduced form of the protein was observed. When the logarithims of their relative mobilities were plotted against the concentration of acrylamide in the gels, the slopes for the reduced and oxidized forms were identical. This indicates that the two forms are identical in size and are separable because of different charges. The reduced protein could be inhibited by N-ethylmaleimide, 5,5'-dithiobis(2-nitrobenzoic acid), and p-hydroxymercuribenzoate. Inhibition by the latter two sulfhydryl reagents could be completely reversed by dithiothreitol. The reversibly oxidized form of the toxin did not appear to be inhibited by N-ethylmaleimide and apparently was either unable to bind to or had a decreased affinity for the erythrocyte membrane.
Effect of passive antibody on parainfluenza virus type 3 pneumonia in hamsters
Authors: Glezen W P , Fernald G W
Published: January 2020

Both parainfluenza virus type 3 and respiratory syncytial virus may produce life-threatening pneumonia or bronchiolitis in infants less than 6 months old. Almost all infants in this age group possess passively acquired maternal antibodies to both viruses. It has been suggested that maternal antibodies may actually participate in the pathogenesis of these diseases in early infancy. This investigation examined the effect of moderate levels of passive antibody on the development of pneumonia in hamsters infected intranasally with parainfluenza virus type 3. The pneumonitis produced in this model was not enhanced by the presence of moderate levels of serum antibody to this virus. Furthermore, reinfection after an initial "sensitizing" infection under the cover of passive antibody did not result in a more severe pneumonitis. These studies do not support either of the two hypotheses that have been advanced to explain the pathogenesis of infections with respiratory syncytial virus in early infancy.
Modified polyriboinosinic-polyribocytidylic acid, an immunological adjuvant
Authors: Houston W E , Crabbs C L , Stephen E L , Levy H B
Published: January 2020

Stabilization of polyriboinosinic-polyribocytidylic acid against enzymatic hydrolysis by addition of poly-1-lysine and carboxymethylcellulose (PICLC) resulted in a compound with marked adjuvanticity. The primary antibody response of rhesus monkeys to formalin-inactivated Venezuelan equine encephalomyelitis virus vaccine was significantly potentiated if the vaccine was combined with PICLC prior to vaccination. The antibody response was maintained at a significantly higher level than controls for 2.5 months postvaccination and paralleled immunological responses reported for live, attenuated (TC-83) vaccine.
Lysis and killing of bacteria by lysosomal proteinases
Authors: Thorne K J , Oliver R C , Barrett A J
Published: January 2020

The bacteriolytic and bactericidal effects of the human proteinases cathepsin B, cathepsin D, cathepsin G, and elastase were investigated. Cathepsin G and elastase were 5 to 10% as active as egg white lysozyme in the lysis of Micrococcus lysodeikticus. All four enzymes slowly lysed the lysozyme-resistant Staphylococcus aureus. The gram-negative Acinetobacter 199A was rendered sensitive to lysozyme by all of the proteinases. Only elastase caused marked proteolysis of the outer membrane, which would permit access by lysozyme to the underlying peptidoglycan. When the surface layer of regularly arranged a protein was removed, however, the outer membrane proteins became susceptible to the other proteinases. Cathepsin G, elastase, and cathepsin D were bactericidal to Acinetobacter 199A. The bactericidal activity of cathepsin D was shown to be dependent on enzymatic activity, unlike that of cathepsin G, which was related to its cationic nature.
Immunodepression by Rowson-Parr virus in mice; lymphocyte markers and capping response of spleen and lymph node cells after infection
Authors: Bendinelli M , Friedman H
Published: January 2020

Infection with Rowson-Parr virus (RPV) induced a rapid reduction in the number of immunoglobulin-positive and theta antigen-positive cells detectable by immunofluorescence in the spleens of susceptible BALB/c mice. The changes produced by RPV infection in the lymph nodes were different, since the number of immunoglobulin-positive cells was increased and the proportion of theta-positive cells remained unchanged. However, the ability of immunoglobulin-bearing cells to redistribute their receptors into caps was reduced in both types of lymphoid tissue. A similar pattern of changes was produced by infection with Friend leukemia complex, from which RPV was originally obtained. These effects of RPV and Friend leukemia complex may contribute to the immunodepressed state of infected mice.
Nature of the effector cells responsible for antibody-dependent cell-mediated killing of Cryptococcus neoformans
Authors: Diamond R D , Allison A C
Published: January 2020

Studies were performed to identify the types of human peripheral blood leukocytes capable of killing Cryptococcus neoformans in the presence of anticryptococcal antibody in vitro. A total of 24.1 +/- 2.7% (mean +/- standard error of the mean of four experiments) of the original cryptococcal inoculum survived in a mixed mononuclear, cell preparation (approximately 30% monocytes) after 4 h of incubation at 37 degrees C with rabbit anticryptococcal antibody. When phagocytic cells were removed, there was 36.4 +/- 4.6% survival in six experiments, compared with 52.8% survival in the presence of purified granulocytes (mean of two experiments) and 96.9 +/- 1% survival in the presence of purified T cells. There was never any significant killing in control mixtures that contained leukocytes with normal rabbit serum nor in those that contained anticryptococcal antibody without effector leukocytes. Significant antibody-dependent fungicidal activity was seen with ratios of effector to target cells as low as 6.25:1. These observations indicate that multiple types of peripheral blood leukocytes, excluding T cells, are capable of antibody-dependent fungicidal activity.
Evidence for two immune inhibitors from Bacillus thuringiensis interfering with the humoral defense system of saturniid pupae
Authors: Edlund T , Sidén I , Boman H G
Published: January 2020

Mutants of Bacillus thuringiensis lacking either beta-exotoxin or gamma-endotoxin were compared for their virulence using pupae of a giant silk moth. Known doses of viable log-phase bacteria were injected, and the response was followed as the number of viable bacteria in the hemolymph. The results obtained imply that, in the system used, neither the beta-exotoxin nor the gamma-endotoxin and the sporeforming ability are of importance for virulence. Results with sterile culture filtrate from B. thuringiensis have given evidence for the production of two inhibitors, A and B, which interfere with the humoral defense system in pupae of Hyalophora cecropia. Inhibitor A, which blocked the lysis of Escherichia coli,was precipitated by trichloroacetic acid and sensitive to heating. Inhibitor B, which blocked the killing of Bacillus cereus, was soluble in trichloroacetic acid and resistant to 90 degrees C for 5 min. Both inhibitors are believed to contribute to the insecticidal nature of B. thuringiensis.
Isolation of a temperature-sensitive dengue-2 virus under conditions suitable for vaccine development
Authors: Eckels K H , Brandt W E , Harrison V R , McCown J M , Russell P K
Published: January 2020

Dengue virus, type 2, in viremic human sera and after passage in cell cultures produces mixtures of small and large plaques when assayed in LLC-MK2 cells. Clones of dengue virus type 2 obtained by plaque selection in primary green monkey kidney cell cultures were tested for temperature sensitivity in vitro and for virulence by intracerebral inoculation of suckling mice. Sublines of a small-plaque clone were found to have lower nonpermissive temperatures than the parent virus by both plaque formation and release of infectious virus into the culture media. Small-plaque sublines were significantly less virulent in suckling mice than was the parent virus. Sublines from a large-plaque clone were not temperature sensitive and closely resembled parent virus mixed-plaque morphology. When small-plaque sublines were serially passaged using undiluted inocula, reversion occurred as evidenced by the appearance of large plaques and return of mouse virulence. Small-plaque virus could be maintained through several serial passages without reversion by using low-input inocula. Desirable passage history as well as temperature-sensitive and attentuation characteristics of the S-1 small-plaque subline make it appear suitable as a vaccine candidate virus.
Mechanisms for the microbicidal activity of cationic proteins of human granulocytes
Authors: Odeberg H , Olsson I
Published: January 2020

One oxygen-independent antimicrobial system of human granulocytes consists of granular chymotropsin-like cationic proteins possessing heat-stable microbicidal activity. For elucidation of the mode of action of the cationic protein, effects on bacterial synthesis of macromolecules, ion transport, and oxygen consumption have been studied. Inhibition of incorporation of radioactive precursors into protein, ribonulceic acid, and deoxyribonucleic acid of both Staphylococcus aureus and Escherichia coli was found concomitantly with inhibition of colony formation. Cationic protein inhibited 86Rb+ influx but did not increase the leakage of intracellular 86Rb+, indicating inhibition of energy-dependent membrane transport without a breakdown of the semipermeable character of the membrane. Oxygen consumption was inhibited. Mg2+ and Ca2+ displayed a protective effect against the microbicidal activity, indicating the operation of charge interactions between cationic protein and bacterial surface. The various effects of cationic protein were more pronounced with S. aureus than with E. coli, parallelling the microbicidal activity.
Induction of Escherichia coli and Vibrio cholerae enterotoxins by an inhibitor of protein synthesis
Authors: Levner M , Wiener F P , Rubin B A
Published: January 2020

Enterotoxigenic Escherichia coli or Vibrio cholerae 569B (Inaba) grown in the presence of the antibiotic lincomycin, an inhibitor of protein synthesis, produced elevated levels of heat-labile enterotoxin or choleragen, respectively, as assayed by both vascular permeability factor and capacity to elicit fluid accumulation in rabbit ileal loops. This induction of enterotoxin did not reflect either a coupling of lincomycin resistance with increased enterotoxigenicity or an effect of lincomycin on cellular release of enterotoxin, since spontaneously isolated lincomycin-resistant mutants of both E. coli and V. cholerae still required lincomycin for induction, and large increases in E. coli permeability factor activity were found intracellularly as well as extracellularly. After the period of exponential growth, E. coli became refractory to induction by lincomycin, although most of the induced enterotoxin activity appeared only after this period. No increase in copy number of the enterotoxin plasmid in E. coli 711 (P307) was found in induced cells by analysis of deoxyribonucleic acid reassociation kinetics. These and other data suggest that synthesis of enterotoxin, or at least its accumulation, is normally limited by cellular factors whose synthesis is preferentially inhibited by lincomycin. A possible connection between this phenomenon and lincomycin-associated diarrhea is considered.
K99 surface antigen of Escherichia coli: purification and partial characterization
Authors: Isaacson R E
Published: January 2020

K99, a presumed colonizing factor of enterotoxigenic Escherichia coli of calf origin, has been purified. K99 was removed from K99+ bacteria by salt extraction and subsequently purified by ammonium sulfate precipitation and column chromatography on diethylaminoethyl-Sephadex. The purified material was homogenous in size, having an s20,w of 13 to 15 S. It was composed of two subunits: a major component with a molecular weight of 22,500 and a minor component of 29,500. When observed in the electron microscope, K99 appeared to be rod-shaped, with a strong tendency for self-aggregation. At concentrations where aggregation was minimized, individual rods were observed with diameters of 8.4 nm and mean lengths of 130 nm. Based on the subunit structure, exterior location, and rod-like shape of K99, it is concluded that K99 is a pilus or pilus-like structure. Chemically, K99 is composed primarily of protein and has an isoelectric point of greater than 10. Purified K99 did not hemagglutinate guinea pig erythrocytes.
Bacteriostatic effect of human milk and bovine colostrum on Escherichia coli: importance of bicarbonate
Authors: Griffiths E , Humphreys J
Published: January 2020

At pH 7.4 and in the presence of NaHCO3, human milk and bovine colostrum inhibited the growth of Escherichia coli O111. Adding sufficient iron to saturate the iron-binding capacity of the lactoferrin present in the milk or colostrum prevented bacteriostasis. At pH 6.8 neither molk nor colostrum inhibited E. coli 0111. Adjusting the pH to 7.4 with NaHCO3 resulted in the development of bacteriostatic activity. Adjusting the pH to 7.4 with NaOH was ineffective. Dialyzed colostrum and milk inhibited bacterial growth at pH 6.8 in the absence of added NaHCO3; addition of citrate or iron abolished bacteriostasis. The chromatographic elution profile of tyrosyl-transfer ribonucleic acid (tRNA) from iron-replete E. coli differs significantly from that of tyrosyl-tRNA from iron-deficient organisms. Examination of the elution profile tyrosyl-tRNA from E. coli 0111 growing in colostrum without added NaHCO3 showed that such bacteria were fully replete in iron. The nature of the elution profile of tyrosyl-tRNA also showed that iron was freely available to the bacteria when citrate was added to dialyzed colostrum but not available in its absence, even at pH 6.8. Results support the idea that the bacteriostatic action of milk and colostrum, due to the combined action of antibody and lactoferrin, depends on the addition of bicarbonate to counteract the iron-mobilizing effect of the citrate normally present in these secretions.
Persistence of cytomegalovirus in human lymphoblasts and peripheral leukocyte cultures
Authors: St Jeor S , Weisser A
Published: January 2020

The in vitro susceptibility of human peripheral lymhpocytes and lymphoblastoid (F265) cells to infection by human cytomegalovirus was examined. Infection of these cell types with cytomegalovirus resulted in a persistent type of infection rather than the typical growth curve observed with permissive fibroblastic cells. When infection of peripheral lymphocytes was associated with a blastogenic response, the virus persisted for a longer time and at a higher titer than in cells in which a blastogenic response did not occur. Autoradiographic studies and infectious-center assays indicated that only a small number of cells, resembling lymphocytes, were involved in virus persistence. Whether or not the persistence of the virus indicates release of input virus or synthesis or new virus was not determined.
Oncogenicity of avian leukosis viruses of different subgroups and of mutants of sarcoma viruses
Authors: Purchase H G , Okazaki W , Vogt P K , Hanafusa H , Burmester B R , Crittenden L B
Published: January 2020

Leukosis viruses of seven subgroups were tested for oncogenicity in chickens susceptible to virus infection and to development of lymphoid leukosis (LL) tumors. All subgroup A viruses and the subgroup B virus tested produced a high incidence of LL and other related neoplasms. Viruses of subgroup C and RAV-61 of subgroup F produced a low level of LL. The RAV-50 of subgroup D produced osteopetrosis. In these tests, the viruses of subgroup E and G and one virus of subgroup F were not pathogenic, possibly because infection was not established in the chickens, the chickens were not susceptible to tumor development by these viruses, or the viruses lacked oncogenicity. All temperature-sensitive mutants of Rous sarcoma virus produced sarcomas, but the level varied. One nontransforming mutant produced sarcomas, and the other three tested produced LL. All three mutants that cause cells to grow as colonies in agar produced a high incidence of sarcomas. Thus, sarcoma viruses, by back-mutation, may lose the ability to transform cells in vitro, to make cells grow in agar colonies, or to induce sarcomas in vivo, yet they retain the ability to produce LL. Conversely, it was previously shown that leukosis viruses may be changed into viruses that transform cells in vitro and produce sarcomas in vivo by suitable passage in chicks.
Serological identification of pig enterotoxigenic Escherichia coli strains not belonging to the classical serotypes
Authors: Guinée P A , Agterberg C M , Jansen W H , Frik J F
Published: January 2020

Escherichia coli strains isolated from pigs suspected to have succumbed to E. coli enterotoxicosis and not belonging to the commonly incriminated (classical) serotypes (O8:K87:K88, O45:K88, O138:K81:K88, O141:K85:K88, O147:K89:K88, O149:K91;K88, and O157:K88) were tested for enterotoxigenicity in the ligated gut test (LGT) using pig intestine. Of 202 strains tested, 54 strains belonging to 13 different O groups were positive in the LGT. Four of these strains had K88 antigen and one possessed K99 antigen. The majority of the strains was not agglutinated by any of the standard OK antisera. Four new K antigens ("K200", "K442", "K2346" and "K2347") were provisionally designated. K200 was found in pig enterotoxigenic strains belonging to O group 8 and carrying flagellar antigen H31 and in non-enterotoxigenic non-motile strains of O group 8, as well as in O group 20 strains isolated from calves succumbing to E. coli septicemia in two countries. The provisional antigen K2346 was encountered in 18 enterotoxigenic strains with various O antigens from two countries. It is proposed to include these two K antigens into the international E. coli antigens scheme. Attempts to demonstrate a common antigen in the nonclassical enterotoxigenic strains lacking K88 and K99 antigens failed.
Neisseria gonorrhoeae and ABO isohemagglutinins
Authors: Miler J J , Novotny P , Walker P D , Harris J R , MacLennan I P
Published: January 2020

Depending on the ABO blood group, gonorrhea may affect the titers of isohemagglutinins compared with those of uninfected controls. The isohemagglutinin titers in group O patients were significantly increased (P less than 0.001) against erythrocytes A, B, and AB. In group A patients, only the titer against AB erythrocytes was significantly increased. In group B patients, the titer against AB erythrocytes was significantly lower (P less than 0.001) as compared with that in sera of healthy persons. In six of eight volunteers, an increase in isohemagglutinin titer was observed after an injection of small doses of killed gonococci. However, guinea pigs, rabbit, or small monkeys, i.e., species for which gonococci are not apthogenic, when immunized with gonococci either did not form ABO hemagglutinins or did so with very low titers. In white gonorrhea patients, there was a significantly higher frequency of group B individuals over those with group A, AB, or O. No such correlation was found in black patients. Isohemagglutinins from human sera could be absorbed by cultured gonococci. The implications of these findings in the pathogenesis of gonococcus infection and the problems associated with vaccine development are briefly discussed.
Neutralization of Salmonella toxin-induced elongation of Chinese hamster ovary cells by cholera antitoxin
Authors: Sandefur P D , Peterson J W
Published: January 2020

A partially purified preparation of the delayed skin permeability factor from Salmonella typhimurium caused Chinese hamster ovary cells to elongate. The elongation effect and the skin test activity were blocked by monospecific rabbit antisera against cholera toxin and against the B fragment of cholera toxin,
Differentiation of several isolates of Peptococcus magnus by counterimmunoelectrophoresis
Authors: Markowitz A , Lerner A M
Published: January 2020

Uniform sonicated suspensions of three clinical isolates of Peptococcus magnus that were morphologically, chromatographically, and biochemically identical were used to produce hyperimmune antisera in rabbits. Similar hyperimmune serum was prepared to a single strain of Peptostreptococcus anaerobius. When these antisera and antigens were tested by counterimmunoelectrophoresis, the three isolates of Peptococcus magnus were immunologically distinct. None of the antisera to Peptococcus magnus formed precipitin lines with Peptostreptococcus anaerobius.
Superoxide dismutase in anaerobic bacteria of clinical significance
Authors: Tally F P , Goldin B R , Jacobus N V , Gorbach S L
Published: January 2020

Twenty-two anaerobic bacteria isolated from infected sites and normal fecal flora were assayed for superoxide dismutase (SOD). The organisms were also classified according to their oxygen tolerance into aerotolerant, intermediate, and extremely oxygen-sensitive groups. There was a correlation between the enzyme level and the oxygen tolerance, in that the aerotolerant and intermediate organisms had SOD, whereas the extremely oxygen-sensitive isolates had low or undetectable enzyme. Among the oxygen-tolerant organisms, gram-negative bacteria had higher levels of SOD than gram-positive organisms. Oxygen was shown to induce SOD production in a strain of Bacteriodes fragilis grown in minimal medium under continuous-culture conditions. Enzyme levels in this isolate grown under static conditions were lower in minimal medium than in complex medium, indicating that other components in the complex medium were stimulating the production of SOD. Our data suggest that the variation in oxygen tolerance of anaerobes is usually related to their level of SOD. It is postulated that SOD may be a virulence factor that allows pathogenic anaerobes to survive in oxygenated tissues until the proper reduced conditions are established for their growth.
Bactericidal activity of the normal, cell-free hemolymph of silkworms (Bombyx mori)
Authors: Kinoshita T , Inoue K
Published: January 2020

Cell-free hemolymph from silkworm (Bombyx mori) larvae can kill Escherichia coli B/SM. The bactericidal principle can be resolved into at least two factors. One is a lysozyme-like enzyme that can be absorbed on crab shell chitin and on bentonite, and the other (cofactor) is an anionic factor that is of low molecular weight, can pass through the chitin column and a carboxymethyl-cellulose column, and can be eluted from a diethylaminoethyl-cellulose column at mu = 0.15 and pH 7.5. Egg-white lysozyme cannot replace the silkworm lysozyme-like enzyme for restoring the bactericidal activity when it is mixed with the cofactor, although it can enhance the bactericidal activity of the mixture of silkworm enzyme and cofactor. Mg2+ and Ca2+ can inhibit the bactericidal activity.
Immunoprophylaxis of experimental Mycoplasma pneumoniae disease: effect of aerosol particle size and site of deposition of M. pneumoniae on the pattern of respiratory infection, disease, and immunity in hamsters
Authors: Jemski J V , Hetsko C M , Helms C M , Grizzard M B , Walker J S , Chanock R M
Published: January 2020

The distribution of Mycoplasma pneumoniae infection in the respiratory tract and the extent of pulmonary pathology were determined by the site of deposition and the number of organisms administered to hamsters. Infection of the upper and lower areas of the respiratory tract occurred when organisms were introduced into both areas by small-particle aerosol (2.3 micrometer) or by intranasal (i.n.) instillation of a 200-microliter inoculum. In contrast, when organisms were delivered primarily to the upper respiratory tract by large-particle aerosol (8 micrometer) or by i.n. instillation of a small volume of inoculum (2 or 20 microliter), infection remained limited to this area in most or all instances. When the lungs became infected after i.n. administration of a 200-microliter inoculum, the most extensive pulmonary lesions were seen in the animals given the largest number of organisms. Each of the modes of administration of M. pneumoniae initiated an infection which conferred measurable resistance to a subsequent challenge capable of inducing extensive pulmonary disease. The most effective resistance was induced by the two modes of administration which produced an infection involving the entire respiratory tract, i.e., small-particle aerosol or i.n. instillation of a 200-microliter inoculum.
Efficacy of herpes simplex virus type 1 immunization in protecting against acute and latent infection by herpes simplex virus type 2 in mice
Authors: McKendall R R
Published: January 2020

ICR mice were immunized with herpes simplex virus type 1 (HSV-1) and later challenged with HSV-2 by footpad inoculation. Both immunized animals and age-matched, nonimmunized controls were observed for ascending neurological disease and latent infection of spinal ganglia resulting from the HSV-2 challenge. Control animals had a 78% incidence of acute and latent infection compared with a 1.7% incidence in immunized mice. The data show immunity to HSV-1 is protective against both acute and latent infection by HSV-2.
Hepatic clearance of Salmonella typhimurium in silica-treated mice
Authors: Friedman R L , Moon R J
Published: January 2020

Scanning electron microscopy demonstrates that crystalline silica destroys liver Kupffer cells but has no other obvious deleterious effects on the liver. Silica-treated livers still retain the ability to trap large numbers of bacteria perfused through the portal vein even though the rate of clearance is well below normal. In vivo, silica treatment decreases the rate of bacterial clearance from the blood, alters the in vivo organ distribution of cleared bacteria, and decreases the mean lethal dose of Salmonella typhimurium over 100-fold. Cumulatively, the data indicate that silica treatment enhances susceptibility to gram-negative infection, probably by destruction of macrophages.
Simple method for purifying choleragenoid, the natural toxoid of Vibrio cholerae
Authors: Mekalanos J J , Collier R J , Romig W R
Published: January 2020

Choleragenoid, a nontoxic aggregate of the B subunit of cholera toxin, has been purified from concentrated culture filtrates in a single step by ion-exchange chromatography on phosphocellulose or other cation-exchange resins. This procedure is far simpler than others currently used to isolate choleragenoid and yields a preparation essentially free from nucleic acid, lipopolysaccharide, toxin, and other proteins present in the crude culture filtrates. The purified choleragenoid retained the specific receptor-binding capacity of the toxin but exhibited no enterotoxic activity by either the ileal loop assay or the skin permeability assay. This purification methods may therefore be superior to others currently used for obtaining choleragenoid for immunization or other purposes.
Enzymatically active peptide from the adenosine diphosphate-ribosylating toxin of Pseudomonas aeruginosa
Authors: Chung D W , Collier R J
Published: January 2020

A nontoxic peptide (molecular weight, 26,000), which is active in catalyzing the adenosine diphosphate (ADP)-ribosylation of elongation factor 2, has been isolated from the culture supernatant of Pseudomonas aeruginosa strain 103 in stationary phase. Like fragment A from diphtheria toxin, the active peptide catalyzed the hydrolysis of nicotinamide adenine dinucleotide as well as the ADP-ribosylation of elongation factor 2 and showed similarities to fragment A in specific activity, kinetic constants, pH optimum, and ionic sensitivity. These results provide strong evidence for a high degree of homology in the structures of their active sites. That the peptide is not identical to fragment A is shown by the fact that it was not neutralized by fragment A-specific antiserum and was different in amino acid composition and pH and thermal labilities. Although definitive evidence is lacking, there are data suggesting that this peptide is a proteolytic fragment from the ADP-ribosylating toxin (exotoxin A; molecular weight, 66,000) produced by the same strain of P. aeruginosa.
Role of T lymphocytes in recovery from murine cytomegalovirus infection
Authors: Starr S E , Allison A C
Published: January 2020

Congenitally athymic nude (Nu/Nu) mice inoculated intraperitoneally with murine cytomegalovirus (MCMV), in doses as low as 1.3 X 10(1) plaque-forming units succumbed to the infection. In contrast, the mean lethal dose for heteroxygous euthymic (Nu/+) littermates was 4 X 10(3) plaque-forming units. Though histopathological changes consistent with MCMV infection were found in the spleen, lungs, and adrenals of nude mice, there were only small focal areas of involvement in the liver. In contrast, Nu/+ mice dying from infection had pathological evidence of severe hepatitis. Spleen cells from immune and control BALB/c mice were injected intravenously into syngeneic mice that had been inoculated previously with lethal doses of MCMV intraperitoneally. Mice receiving 1 X 10(7) or more immune spleen cells were protected against the infection, whereas mice receiving 1 X 10(8) control spleen cells or immune serum were not. Treatment of immune spleen cells with anti-theta serum and complement significantly reduced their protective effect. Immune mechanisms associated with T lymphocytes appear to be critical for recovery from MCMV infection.