bluuebunny/crossref_metadata_2025 huggingface dataset:
Adhesion of Aeromonas salmonicida strains associated with net electrostatic charges of host tissue cells
Authors: Sakai D K
Published: January 2020

The adhesion of Aeromonas salmonicida, the pathogenic bacterium of fish furunculosis in salmon and trout, to the surface of host tissue cells was investigated with two fish tissue culture cell lines (RTG-2 cells from rainbow trout, Salmo gairdneri, and CHSE-214 cells from chinook salmon, Oncorhynchus tshawytscha) and four A. salmonicida strains. Bacterial cells of pathogenic strains were highly adhesive to RTG-2 and CHSE-214 cells and were negatively charged in the net electrostatic charges, as determined by electrophoresis on filter paper strips at pH 7, whereas bacterial cells of nonpathogenic strains were nonadhesive and positively charged. The electrophoresis of RTG-2 and CHSE-214 cells with balanced salt solution (BSS), phosphate-buffered saline, or fish serum diluted with BSS (pH 7) was carried out with an appropriate electrophoretic apparatus that was devised for this study. After electrophoresis with 20 mA of direct current for 15 min at pH 7, the electrophoretic dispositions of these tissue culture cells were determined by the mode of frequency of occurrence of these cells in the partitioned chambers of the device. RTG-2 and CHSE-214 cells with BSS and fish serum were attracted from the central chamber (to which each cell sample was added) to the cathode chambers, but no attraction was detected when these cells were used with phosphate-buffered saline. Noradrenaline- and phosphoenolpyruvate-pretreated RTG-2 cells migrated more to the cathode chambers, whereas succinate- and valine-pretreated RTG-2 cells moved to the anode chambers. These movements to the cathode and anode were alleviated by the use of RTG-2 cells preincubated with pathogenic and nonpathogenic bacterial cells, respectively. The adhesion of the pathogenic bacteria to RTG-2 cells was enhanced by the use of RTG-2 cells pretreated with noradrenaline and phosphoenolpyruvate, whereas the nonpathogenic bacteria were adherent to RTG-2 cells pretreated with succinate and valine. These findings indicate that the adhesion of A. salmonicida strains to host tissue cells is closely associated with mutually converse net electrostatic charges.
Development of an experimental animal model for reactive arthritis induced by Yersinia enterocolitica infection
Authors: Hill J L , Yu D T
Published: January 2020

We attempted to induce experimental arthritis in rats by systematically testing the effect of Yersinia infections in five strains of rats, using the intragastric, intraperitoneal, and intravenous routes of inoculation. We observed that Lewis rats which were given 10(4) to 10(5) Yersinia enterocolitica WA organisms via the intravenous route consistently developed arthritis. The arthritis was most severe at 3 weeks and subsided at 6 weeks. No arthritis was observed when this bacterial strain was administered to Buffalo, Fisher, DA, and LDA rats. No replicable bacteria were detected in the joints. This aseptic characteristic parallels that seen in the human condition and establishes this as an animal model of Yersinia-induced arthritis. The probable reason for arthritis development in only the Lewis rats became apparent when we analyzed the numbers of live bacteria in the spleens and livers of these infected animals. The arthritis-susceptible Lewis rats harbored 10-fold more bacteria than the arthritis-resistant rat strains, and this systemic infection also persisted for a significantly longer period. Speculations as to why human subjects who develop Yersinia-induced arthritis are genetically predisposed have been centered principally around the role of the HLA-B27 histocompatibility antigens. The present study reveals a heretofore unrecognized critical factor: the susceptibility of the hosts to the virulence of the infectious organisms. In addition, the present animal model will provide the necessary tool for the investigation of this and other important host and bacterial factors.
Serum antibody and cellular responses in LEW and F344 rats after immunization with Mycoplasma pulmonis antigens
Authors: Simecka J W , Cassell G H
Published: January 2020

Mycoplasma pulmonis causes a chronic respiratory disease in rats which is more severe in LEW than in F344 rats. This study compared the ability of each of these rat strains to produce specific immune responses to M. pulmonis antigens. By an enzyme-linked immunosorbent assay, LEW rats were found to produce approximately 10 times lower levels of specific immunoglobulin G (IgG) after immunization with M. pulmonis antigens than F344 rats, while no significant difference was found in the levels of IgM. The difference in IgG levels was due to much greater levels of specific IgG2b (about 50 times) in F344 rats; no differences were found in other subclasses. Nonimmune LEW rats were found to have as much total IgG2b in their sera as unimmunized F344 rats by a single radial immunodiffusion test; thus, the difference was not due to the inability of LEW rats to produce IgG2b. In contrast to the antibody response to M. pulmonis antigens, anti-keyhole limpet hemocyanin IgG responses in LEW and F344 rats were similar, but F344 rats produced significantly more (about 21 times) IgG2b than was found in M. pulmonis responses. Antisera from F344 rats recognized several additional M. pulmonis antigens than antisera from LEW rats; however, this could not explain the differences in the level of IgG2b in LEW and F344 rats. In vitro stimulation of splenic lymphocytes with M. pulmonis antigens from immunized F344 rats produced much greater proliferative responses than in LEW and nonimmune F344 cells. Thus, the susceptible rat strain LEW produced lower cellular and humoral immune responses to M. pulmonis antigens than the resistant rat strain F344 after immunization.
An outer membrane protein (porin) as an eliciting antigen for delayed-type hypersensitivity in murine salmonellosis
Authors: Udhayakumar V , Muthukkaruppan V R
Published: January 2020

The porin, an outer membrane protein of Salmonella typhimurium, was found to be a suitable antigen for eliciting delayed-type hypersensitivity in mouse salmonellosis. Histological examination of the reaction site revealed that the porin was superior to other antigenic preparations in eliciting a typical delayed-type hypersensitivity reaction consisting of mononuclear cell infiltration without polymorphonuclear cell contamination. This study indicates the importance of using a suitable protein antigen from S. typhi for human application.
Neutralizing activity of monoclonal antibodies to heat-sensitive and heat-resistant epitopes of Rickettsia rickettsii surface proteins
Authors: Anacker R L , McDonald G A , List R H , Mann R E
Published: January 2020

Antiprotein monoclonal antibodies derived from mice inoculated with Rickettsia rickettsii heated at 56 degrees C for 15 min are of two types: one is type specific for epitopes denatured by moderate temperatures, and the other is specific for epitopes resistant to 100 degrees C for 5 min. The heat-resistant epitopes are found by immunoblotting on multiple polypeptides after solubilization of the rickettsiae at temperatures of 56 degrees C or higher. Most, but not all, antibodies to the heat-sensitive epitopes passively protected mice against two 50% lethal doses of R. rickettsii, whereas none of the antibodies to heat-resistant epitopes did.
Specific and nonspecific mediation of protective immunity to Toxoplasma gondii
Authors: Reyes L , Frenkel J K
Published: January 2020

We studied the specificity of protection conferred by Toxoplasma gondii immune lymphocytes and their supernatants on infected hamster kidney cells, using Besnoitia jellisoni immune lymphocytes as a nonspecific control. The intracellular growth of the organisms was measured by [3H]uracil incorporation, and inhibition of multiplication was used as a measurement of immunity. Although the immune lymphocytes restricted principally the multiplication of homologous organisms, partial protection, expressed against the heterologous organism, was found. This was true for either parasite with intact lymphocytes or their supernatants. Exposure of immune lymphocytes to antigen for 18 to 24 h and treatment of kidney cells with supernatant fluids for 18 to 24 h were required for maximal protection. The specific protective mediator in supernatants of immune lymphocytes was characterized by dialysis as having a molecular weight between 3,000 and 12,000 and was found in the 3,000 to 5,000 peak after Sephadex G-50 chromatography. Nonspecific protective activity was greater than 12,000 by dialysis; it chromatographed in the excluded peak, measuring over 43,000, and was destroyed by exposure to pH 2. In vitro production of lymphokines from toxoplasma immune lymphocytes was first detected 7 to 10 days after vaccination of hamsters. At about the same time, hamsters began to resist challenge infection with the pathogenic RH strain of T. gondii and were able to prevent its multiplication in lungs, liver, spleen, and the subcutaneous infection site. The expression of tissue immunity and the production of toxoplasma-immune lymphokines appear to be time-related events.
Salmonella typhi 205aTy, a strain with two attenuating auxotrophic characters, for use in laboratory teaching
Authors: Brown R F , Stocker B A
Published: January 2020

The need for p-aminobenzoic acid of a previously reported pab mutant in a Salmonella typhi strain causes loss of virulence (mouse median lethal dose by the intraperitoneal route with mucin, ca. 10(7) CFU, versus less than 200 CFU for related pab+ strains). This strain, however, gave p-aminobenzoic acid-independent revertants at a low frequency (ca. 4 X 10(-10) per bacterium per generation). It was therefore given, by transduction and mutation, a transposon-generated, nonreverting (rate, less than 3 X 10(-11) per bacterium per generation) mutation at purA, causing a requirement for adenine; such a mutation in a wild-type strain caused about the same loss of virulence as the pab mutation. The pab purA strain, 205aTy, has mouse median lethal dose of ca. 5 X 10(7) and is expected to be unable to cause typhoid fever. Since strain 205aTy behaves like a typical Vi-positive S. typhi strain in nearly all common tests, we propose that it is a safe strain for use in laboratory teaching, proficiency testing, and the like.
Cecectomy causes long-term reduction of colonization resistance in the mouse gastrointestinal tract
Authors: Voravuthikunchai S P , Lee A
Published: January 2020

Removal of the cecum from normal mice caused a major perturbation of the microbial ecology of the gastrointestinal tract. There was a permanent reduction in colonization resistance resulting in a 1,000-fold increase in the concentration of facultatively anaerobic coliform bacteria. The animals were significantly more susceptible to peroral challenge by the intestinal pathogen Salmonella enteritidis. Coincident with this increase in coliform counts and susceptibility to salmonellae was a decrease in the numbers of strictly anaerobic fusiform bacteria that dominate the rodent intestinal tract, resulting in reduced levels of acetic, propionic, and butyric acids. Cecectomized mice are likely to be a useful model for study of the interaction between intestinal pathogens and the normal microbiota and for studies of translocation of bacteria into host tissues after loss of colonization resistance.
Antibody specific for Escherichia coli J5 cross-reacts to various degrees with an Escherichia coli clinical isolate grown for different lengths of time
Authors: McCallus D E , Norcross N L
Published: January 2020

Rabbit antiserum raised against the rough mutant of Escherichia coli O111:B4, designated J5, was examined for cross-reactivity to an E. coli clinical isolate (A2385). In whole-cell enzyme-linked immunosorbent assays, J5 antiserum reacted to a greater extent with A2385 grown for 5 h than with the same bacteria grown for 19 h, while the homologous antiserum reacted similarly with bacteria grown for different lengths of time. J5 antiserum reacted to the greatest extent with lipopolysaccharide (LPS) from A2385 grown for up to 10 h, and reactivity greatly diminished thereafter; homologous antiserum showed no difference in reaction over time. LPS from smooth bacteria grown for 19 h showed no reaction with J5 antiserum in immunoblots, while LPS from A2385 grown for 5 or 10 h showed a positive reaction. Little or no difference among the three LPS samples could be seen when homologous antiserum was used. Mice vaccinated with J5 LPS before lethal challenge with live A2385 were protected from this challenge, whereas most nonimmunized mice died. Toxicity tests in mice showed LPS from A2385 grown for 19 h to be twice as lethal as LPS from A2385 grown for 3 h. Mice vaccinated with J5 LPS were protected to a greater extent when challenged with a lethal dose of LPS from A2385 grown for 3 h than when challenged with LPS from A2385 grown for 19 h. The results reported here may explain the means by which J5 vaccination (active or passive) sometimes protects against heterologous challenge.
Augmentation of endotoxin fever by recombinant human beta interferon in rabbits
Authors: Kawasaki H , Moriyama M , Tanaka A
Published: January 2020

Nonpyrogenic amounts of endotoxin (0.1 to 1 ng/kg), hardly detectable by conventional Limulus amoebocyte lysate tests, could produce a fever of around 1 degree C when injected with a nonpyrogenic dose (6 X 10(5) U/kg) of recombinant human beta interferon (IFN-beta) in rabbits. Release of endogenous IFN and tumor necrosis factor by endotoxin was also dramatically increased by recombinant human IFN-beta, and their levels in the blood were closely correlated with the increase of body temperature. These data suggest, if the synergism between IFN and endotoxin also operates in the homologous system (human IFN-human cells), that contaminating endotoxin in IFNs, even if not detectable by Limulus amoebocyte lysate test, can contribute to IFN fever to a considerable extent in humans.
Use of monoclonal antibodies in local passive immunization to prevent colonization of human teeth by Streptococcus mutans
Authors: Ma J K , Smith R , Lehner T
Published: January 2020

Local passive immunization with monoclonal antibodies (MAbs) raised against streptococcal antigen (SA) I/II protects monkeys against colonization of teeth by Streptococcus mutans and the subsequent development of dental caries. In this study we extended the preclinical experiments to human subjects. In the first study of eight healthy subjects, four had anti-SA I/II MAb (immunoglobulin G2a [IgG2a]) and four had saline applied to their teeth on three occasions. A streptomycin-resistant S. mutans strain (Guy K2 strain, serotype c) was then implanted onto the teeth, and the organism was cultured sequentially from dental plaque and saliva up to 100 days after the first treatment with MAb. Decreased colonization by S. mutans was found in the dental plaque collected from smooth surfaces and fissures and in saliva of subjects whose teeth were treated with the MAb, as compared with the saline-treated control subjects. The experiment was then repeated on seven new subjects, and the effect of anti-SA I/II MAb was compared with that of an unrelated MAb to Campylobacter jejuni. The results again showed a consistently lower level of colonization of teeth in the anti-SA I/II MAb-treated subjects as compared with those sham immunized with the unrelated MAb. There was little difference in serum IgG, IgM, or IgA, gingival fluid IgG, or salivary IgA anti-SA I/II antibodies between the immunized and sham-immunized subjects, before and after the investigation. No side effects were observed, and the gingival and plaque indices remained unchanged. A sensitive radioimmunoassay failed to detect changes in anti-MAb (IgG2a) antibodies in any of the three fluids examined. We suggest that local passive immunization by means of MAb might be an alternative approach in the prevention of colonization of teeth by S. mutans and the development of dental caries.
Efficacy of immune therapy in early experimental Naegleria fowleri meningitis
Authors: Lallinger G J , Reiner S L , Cooke D W , Toffaletti D L , Perfect J R , Granger D L , Durack D T
Published: January 2020

Naegleria fowleri meningoencephalitis is usually fatal in humans despite treatment. As a new approach, we tested intracisternal passive immune therapy in rabbits with amebic meningoencephalitis by using antinaegleria immune serum, an immunoglobulin G fraction, and a newly developed monoclonal antibody to N. fowleri. Both the immune serum and an immunoglobulin G fraction isolated from it by affinity chromatography provided a consistent, although temporary, protective effect, shown by prolongation of survival (P = 0.001). Multiple doses of immune serum further prolonged survival (P = 0.005). The protective effect of serum was retained after heating to 56 degrees C. We then developed a monoclonal antibody to N. fowleri which provided similar protection. Passive intracisternal antibody therapy might serve as an adjunctive component in the treatment of amebic meningoencephalitis.
Characterization of a 96-kilodalton thermostable polypeptide antigen of Plasmodium falciparum related to protective immunity in the squirrel monkey
Authors: Jouin H , Dubois P , Gysin J , Fandeur T , Mercereau-Puijalon O , da Silva L P
Published: January 2020

Protective immunity against Plasmodium falciparum malaria in the squirrel monkey (Saimiri sciureus) is, in part, antibody mediated. We have previously shown that polypeptides of 41, 76, and 96 kilodaltons (kDa) are specifically immunoprecipitated with monkey sera which are protective in passive transfer experiments. We report here that three different 96-kDa polypeptides, of pI 5.15, 5.25, and 5.35, can be visualized when parasite extracts are analyzed in bidimensional gels. Only one of them (of pI 5.25) was stable after being heated at 100 degrees C for 5 min. The 96-kDa thermostable polypeptide of pI 5.25 was immunoprecipitated by protective monkey sera and by sera from adult humans living in hyperendemic areas and thus seems to be correlated with humoral protective immunity. This antigen was found in culture supernatants at the time of schizont rupture. It was synthesized during the schizont stage and is apparently not a glycoprotein.
Flow cytometric analysis of the DNA synthetic cycle of Candida species
Authors: Dvorak J A , Whelan W L , McDaniel J P , Gibson C C , Kwon-Chung K J
Published: January 2020

The total DNA per cell and DNA synthetic cycle phases were determined by flow cytometry in five Candida isolates including three species: Candida albicans 208R1, Candida tropicalis ATCC 750, and Candida parapsilosis 970, 3138, and ATCC 22019. The cells were prepared for flow cytometry by fixation in Carnoy fixative followed by staining with mithramycin. Marked but stable and reproducible inter- and intraspecific differences in total DNA per cell of stationary-phase cultures were found which did not correlate directly to diphenylamine estimates of the same parameter. This discrepancy was resolved by mathematically converting flow cytometry data into diphenylamine data. The reason for the discrepancy was found in studies of the DNA synthetic cycle of these yeasts: a large but isolate-specific variable proportion of the population is arrested in the S and G2-M phases after the culture passes from exponential to stationary phase. Histograms of exponential-growth-phase Candida isolates demonstrate that the majority of the population is in the G2-M phase of the DNA synthetic cycle. The DNA content of the C. tropicalis and C. parapsilosis isolates studied is as high as or higher than that of C. albicans. Extranuclear fluorescent particles were observed in the C. tropicalis isolate. No equivalent particles could be detected in the other four Candida isolates. The nature of the particles is unknown.
Genetic relationships and clonal population structure of serotype 2 strains of Neisseria meningitidis
Authors: Caugant D A , Zollinger W D , Mocca L F , Frasch C E , Whittam T S , Frøholm L O , Selander R K
Published: January 2020

Two hundred and thirty-four strains of Neisseria meningitidis, including 94 serotype 2a, 111 serotype 2b, and 19 serotype 2c isolates, together with 10 isolates that were serotyped as 2 with polyvalent antiserum but did not react with monoclonal antibodies, were characterized by the electrophoretic mobilities of 15 metabolic enzymes. Of these enzymes, 14 were polymorphic, and 56 distinctive combinations of alleles at the enzyme loci (electrophoretic types) were identified, among which the mean genetic diversity per locus was 0.413, or about 75% of that recorded for the species N. meningitidis as a whole. Mean genetic diversity among electrophoretic types of the same serotype (2a, 2b, or 2c) was, however, on average, less than half the total species diversity, and no multilocus genotypes were shared between isolates of the different serotypes, which belong to distinctive clonal lineages. Recent temporal changes in the frequencies of recovery of pathogenic strains of serotypes 2a and 2b in South Africa and North America resulted from clone replacement in these populations rather than evolutionary modification of the serotype protein of the initially dominant clones.
Transcription of cholera toxin operon in wild-type and mutant strains of Vibrio cholerae
Authors: Mishra L , Holmes R K
Published: January 2020

mRNA for cholera toxin (CT) was measured in wild-type, hypertoxinogenic, and hypotoxinogenic strains of the classical biotype. The amount of CT-specific mRNA was directly related to the amount of CT that the strains could produce. Estimates of the size of the mRNA for CT in individual experiments varied between approximately 900 and 1,100 nucleotides.
Activities of Aeromonas hydrophila hemolysins and their interaction with erythrocyte membranes
Authors: Kozaki S , Kato K , Asao T , Kamata Y , Sakaguchi G
Published: January 2020

The activity of hemolysin produced by Aeromonas hydrophila CA-11, isolated from an environmental source, was more sensitive to temperature than that of hemolysin produced by strain AH-1, isolated from a diarrheal case. CA-11 hemolysin failed to elicit hemolysis below 10 degrees C. Immunoblotting analyses showed that both hemolysins formed into oligomers in rabbit erythrocyte membrane even when no hemolysis occurred. suggesting that the binding and the subsequent oligomerization are temperature independent. Sodium salicylate inhibited lysis of rabbit erythrocytes by both hemolysins, but selected monosaccharides and oligosaccharides did not. Thin-layer immunostaining indicated that both hemolysins bound to phosphoglycerides with net negative charge but weakly to the ones with no net negative charge. Neither sphingomyelin nor lysophosphoglyceride reacted with the hemolysins, whereas the hemolysins bound to free fatty acids. These results suggest that the binding of either hemolysin to the membrane component, probably phospholipid, requires both negative charge of the polar head group and suitable hydrophobicity of the nonpolar tails.
Evidence for sialyl glycoconjugates as receptors for Bordetella bronchiseptica on swine nasal mucosa
Authors: Ishikawa H , Isayama Y
Published: January 2020

The nature of the receptors for Bordetella bronchiseptica was investigated by using the in vitro adherence assay system. The results indicated that sialyl glycoconjugates acted as receptors on swine nasal mucosa. These results were obtained by two independent approaches: inhibition of epithelial cell adherence with sialic acid-containing compounds but not with compounds lacking sialic acid residues and loss of adherence after treatment of epithelial cells with periodate or neuraminidase. B. bronchiseptica seems to have strong affinity for mucin. This may help the bacterium to colonize the mucosal surfaces of the swine nasal cavity.
Stimulation by target cell membrane lipid of actin polymerization and phagocytosis by Entamoeba histolytica
Authors: Bailey G B , Day D B , Nokkaew C , Harper C C
Published: January 2020

The identity of molecules of mammalian target cells that stimulate contact-dependent attack by Entamoeba histolytica was sought using human erythrocytes (RBC) as a model. Protein-free liposomes prepared from RBC membrane lipids stimulated the same rapid E. histolytica actin polymerization and phagocytosis as did whole target cells. Liposomes constructed from the major phospholipids of RBC stimulated these responses but only if a negatively charged phospholipid was included. The addition to these liposomes of digalactosyl diglyceride significantly enhanced their stimulatory activity. The results demonstrate that ligands that trigger attack-related responses by E. histolytica reside in the target cell membrane lipid fraction and suggest roles for both glycolipid and phospholipid components.
Colonization and pathogenesis of Cryptococcus neoformans in gnotobiotic mice
Authors: Salkowski C A , Bartizal K F , Balish M J , Balish E
Published: January 2020

Congenitally immunodeficient nude (nu/nu) mice and their immunocompetent littermates (nu/+) were used to determine whether the absence of thymus-matured T cells would alter the capacity of Cryptococcus neoformans to colonize their mucosal surfaces or enhance their susceptibility to systemic cryptococcosis, or both, following oral challenge. We present data demonstrating that an encapsulated strain of C. neoformans serotype A colonized the alimentary tracts of germfree, conventional, and antibiotic-treated conventional nu/nu mice. Scanning electron microscopy showed that C. neoformans adhered to the epithelial surfaces of the oral cavities, esophagi, and gastrointestinal tracts of monoassociated nu/nu and nu/+ mice, and culture data showed that there were more viable C. neoformans cells in the alimentary tracts of nu/nu mice than of nu/+ mice. Tetracycline-treated conventional nu/nu, but not nu/+, mice were also colonized with C. neoformans following intragastric challenge. C. neoformans-monoassociated and tetracycline-treated conventional nu/nu mice succumbed to disseminated cryptococcosis with cerebral involvement 3 to 4 weeks after oral challenge, whereas no mortality was observed for similarily challenged nu/+ mice. These results demonstrate that an encapsulated strain of C. neoformans can colonize mucosal surfaces and cause systemic cryptococcosis in immunodeficient nu/nu mice, suggesting that the alimentary tract can be a portal of entry for C. neoformans in an immunodeficient host. These data also indicate that functional T cells play an important role in resistance to systemic cryptococcosis of endogenous origin.
Protease degradation of Escherichia coli heat-stable, mouse-negative, pig-positive enterotoxin
Authors: Whipp S C
Published: January 2020

Enterotoxigenic Escherichia coli produces three enterotoxins: heat-labile toxin, a mouse-positive heat-stable toxin, and a mouse-negative heat-stable toxin (STb). The only species in which a response to STb has been documented is the pig, and this response is inconsistent. When STb was placed in 60 ligated jejunal segments (loops) in six pigs, a positive response (net secretion) was observed in only 40 loops. In contrast, when the jejunal lumen was pre-rinsed with 50 ml of saline, the same STb preparation induced net secretion in 60 of 60 loops. STb did not induce secretion in rinsed loops when jejunal luminal washings were collected and mixed with STb in vitro. The anti-STb activity of jejunal luminal washings was filterable through 0.45-micron-pore-size filters, was destroyed by heating at 100 degrees C for 15 min, and was blocked by soybean trypsin inhibitor. STb was inactivated when incubated with trypsin in vitro for 60 min at 37 degrees C. It is concluded that STb is susceptible to trypsin degradation and that variable amounts of trypsin-like activity in swine jejuna are responsible for inconsistent responses to STb in jejunal loops of swine. These results also suggest that the concept of species specificity of the STb response should be reexamined.
Activation of the classical and alternative pathways of complement by Treponema pallidum subsp. pallidum and Treponema vincentii
Authors: Fitzgerald T J
Published: January 2020

Both in vivo and in vitro studies have indicated that complement plays an important role in the syphilitic immune responses. Few quantitative data are available concerning activation of the classical pathway by Treponema pallidum subsp. pallidum, and no information is available on treponemal activation of the alternative pathway. Activation of both pathways was compared by using T. pallidum subsp. pallidum and the nonpathogen T. vincentii. With rabbit and human sources of complement, both organisms rapidly activated the classical pathway, as shown by hemolysis of sensitized sheep erythrocytes and by the generation of soluble C4a. With human sources of complement, both organisms also activated the alternative pathway, as shown by hemolysis of rabbit erythrocytes and by the generation of soluble C3a in the presence of magnesium ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). During incubation, organisms remained actively mobile and did not lyse, indicating that activation was a function of complement reactivity with the intact outer treponemal surface. In addition, freshly harvested T. pallidum subsp. pallidum immediately activated both pathways of complement; preincubation of organisms did not enhance complement reactivity. T. vincentii was a more potent activator of this pathway. T. pallidum subsp. pallidum contained almost four times as much surface sialic acid as T. vincentii did. When sialic acid was enzymatically removed from T. pallidum subsp. pallidum, enhanced activation of the alternative pathway was detected. It is proposed that T. pallidum subsp. pallidum retards complement-mediated damage by the alternative pathway through surface-associated sialic acid. This may be an important virulence determinant that enables these organisms to readily disseminate through the bloodstream to infect other tissues.
Enhancement of resistance to Escherichia coli infection in mice by dihydroheptaprenol, a synthetic polyprenol derivative
Authors: Araki S , Kagaya K , Kitoh K , Kimura M , Fukazawa Y
Published: January 2020

The effect of a chemically synthesized polyprenol derivative, dihydroheptaprenol (DHP), on the nonspecific resistance of mice to infection with Escherichia coli was investigated. Mice that had been injected intramuscularly with 100 mg of DHP per kg of body weight, prepared as a microemulsion with lecithin, 1 to 4 days before infection showed enhanced resistance to subcutaneous (s.c.) infection with E. coli. When DHP-injected mice were inoculated s.c. with 3 X 10(8) E. coli, which induces fatal acute systemic infection in normal mice, propagation of bacteria in the blood, liver, and spleen was significantly inhibited. Enhanced resistance of athymic (nude) mice to E. coli infection was also induced by DHP. DHP markedly stimulated the generation of peripheral blood neutrophils, significantly enhanced clearance of E. coli from the bloodstream, and activated neutrophils and peritoneal macrophages for H2O2 generation. DHP restored the resistance to E. coli infection in cyclophosphamide-treated mice over the normal level. Furthermore, DHP shortened the period of the recovery of neutrophils and also enhanced clearance of E. coli from the bloodstream in cyclophosphamide-treated mice. DHP was nontoxic for mice and rats (400 mg/kg intramuscularly and 800 mg/kg s.c.) and nonpyrogenic at a dose of 30 mg/kg when administered intravenously to rabbits. These results suggest that the mechanism of action of DHP for enhancing resistance in mice may be, at least in part, its ability to stimulate the generation of potent neutrophils and to activate macrophages in the reticuloendothelial system.
Identification of two different hemolysin determinants in uropathogenic Proteus isolates
Authors: Welch R A
Published: January 2020

DNA sequences similar to those of the Escherichia coli hemolysin genes were detected among uropathogenic isolates of Proteus vulgaris and Morganella morganii by using the Southern blotting technique and hly gene-specific DNA probe. Immunoblotting revealed that among the hemolytic P. vulgaris and M. morganii isolates there was expressed a polypeptide species similar in molecular size (110 kilodaltons) and antigenicity to Escherichia coli HlyA. A plasmid-mediated P. vulgaris hemolysin determinant identified by Southern blotting analysis was molecularly cloned, and the recombinant plasmid (pWPV100) was characterized by restriction endonuclease fragment mapping. A second recombinant library of genomic DNA prepared from a hemolytic, urinary tract isolate of Proteus mirabilis was constructed in E. coli. A 5.5-kilobase XhoI fragment encoding an extracellular hemolytic activity was molecularly cloned (pWPM100), and this plasmid was subjected to transposon-mediated mutagenesis with TnphoA. The P. mirabilis hemolytic phenotype was determined to be encoded by a polypeptide species (HpmA) with an estimated molecular size of 140 kilodaltons based on minicell polypeptide analysis of pWPM100 and its mutant derivatives. Southern blotting analysis with a HpmA-specific DNA probe revealed that this novel determinant is commonly found in both Proteus species but is not present in hemolytic isolates of M. morganii, E. coli, Citrobacter freundii, and Serratia marcescens.
Reduced immune responsiveness and lymphoid depletion in mice infected with Ehrlichia risticii
Authors: Rikihisa Y , Johnson G C , Burger C J
Published: January 2020

The histopathology of the thymus and spleen and the response of spleen cells to mitogenic stimuli were evaluated in Sprague-Dawley CF-1 mice infected with Ehrlichia risticii. Intraperitoneal injection of 10(4) or 10(6) E. risticii-infected U-937 cells into mice resulted in 100% morbidity and partial mortality. Thymic atrophy became significant between 1 and 2 weeks postinfection and remained for the duration of the study. The atrophy appeared associated with antecedent destruction and rarefaction of lymphocytes, resulting in the loss of corticomedullary demarcation. Splenomegaly was prominent; significantly increased weights were detected 7 days postinfection. Histopathologic examination revealed rarefaction of lymphocytes around central arteries, the presence of necrotic debris in histiocytes, and replacement of erythropoiesis by granulopoiesis in the red pulp. Marked and acute reduction of in vitro proliferative responses of spleen cells to concanavalin A (ConA) and phytohemagglutinin were observed in mice infected with 10(4) or 10(6) E. risticii-infected U-937 cells. Interleukin-2 activity in the supernatant of ConA-stimulated spleen cells was also severely reduced. Both changes were time- and dose-dependent and were not associated with decreased spleen cell viability. Neither morbidity nor mortality occurred in mice infected with 10(2) E. risticii-infected U-937 cells. Although there was temporal reduction in phytohemagglutinin-driven lymphocyte proliferation, reduction in neither ConA-driven lymphocyte proliferation nor interleukin-2 activity was observed with this dosage. All E. risticii-inoculated mice seroconverted between days 18 and 25, as detected by the indirect fluorescent-antibody procedure. The findings indicate for the first time the hypoimmune responsiveness and histopathologic changes in lymphoid organs associated with E. risticii infection.
Biological activities of chemically synthesized 2-keto-3-deoxyoctonic acid-(alpha 2----6)-D-glucosamine analogs of lipid A
Authors: Shimizu T , Akiyama S , Masuzawa T , Yanagihara Y , Nakamoto S , Achiwa K
Published: January 2020

The mitogenicity, lethal toxicity, and Shwartzman reaction of three derivatives of chemically synthesized 2-keto-3-deoxyoctonic acid-linked 2,3-diacyloxyacylglucosamine-4-phosphate (KDO-GlcN-4-P) were determined. The compounds, A-301 (with di-3-hexadecanoyloxytetradecanoyl at the C-2 and C-3 positions), A-303 (di-3-tetradecanoyloxytetradecanoyl), and A-305 (3-dodecanoyloxytetradecanoyl and 3-tetradecanoyloxytetradecanoyl), induced a significant incorporation of [3H]thymidine into splenocytes of C57BL/6 mice. The compounds A-301 and A-303 showed lethality at a high dose of 50 micrograms per mouse in C57BL/6 mice sensitized with D-galactosamine, whereas A-305 caused toxicity even at a dose of 10 micrograms per mouse. However, the three compounds did not elicit the local Shwartzman reaction in rabbits. These findings indicate that the addition of 2-keto-3-deoxyoctonic acid enhances the mitogenic activity of 2,3-diacyloxyacylglucosamine-4-phosphate but does not affect the lethal toxicity and the induction of Shwartzman reaction.
Deficiency of peptidoglycan and lipopolysaccharide components in Rickettsia tsutsugamushi
Authors: Amano K , Tamura A , Ohashi N , Urakami H , Kaya S , Fukushi K
Published: January 2020

Analyses of chemical composition in whole cells of Rickettsia tsutsugamushi were performed and compared with those of the other rickettsiae and gram-negative bacteria. The results indicated that R. tsutsugamushi does not contain detectable amounts of 3-deoxy-D-mannooctulosonic acid, heptose, muramic acid, or glucosamine (less than 2, less than 2, less than 3, and less than 3 nmol/mg, respectively). The microorganism was found to contain four kinds of fatty acids (16:0, 18:0, 18:1, and 18:2), but not hydroxy fatty acids. Furthermore, in analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver or Coomassie blue staining, lipopolysaccharide bands were not detected in preparations treated with proteinase K. It is concluded that R. tsutsugamushi has little or no peptidoglycan or lipopolysaccharide.
Role of capsule in adherence of Haemophilus influenzae type b to human buccal epithelial cells
Authors: LiPuma J J , Gilsdorf J R
Published: January 2020

The role of capsule in the adherence of Haemophilus influenzae type b to human epithelial cells in vitro was examined. A group of 30 nonadherent isolates did not differ in degree of encapsulation compared with their respective adherent variants. Furthermore, capsule-deficient mutants of both nonadherent and adherent variants did not differ significantly in degree of adherence compared with their respective encapsulated parents. These data indicate that capsule does not significantly influence the adherence of H. influenzae type b to human epithelial cells.
Transposon mutagenesis of group B streptococcus beta-hemolysin biosynthesis
Authors: Weiser J N , Rubens C E
Published: January 2020

Beta-hemolysin production by group B streptococci (GBS) is speculated to be a major virulence factor of the organism. A virulent, beta-hemolytic group B streptococcus strain was mutagenized with the self-conjugative transposon Tn916 to derive isogenic strains with mutations only in the gene(s) responsible for beta-hemolysin biosynthesis. There was no significant difference between the virulence of the parent strain and that of the mutant strains in a neonatal rat sepsis model.
Determinants of immunogenicity and mechanisms of protection by virulent and mutant Vibrio cholerae O1 in rabbits
Authors: Pierce N F , Cray W C , Kaper J B , Mekalanos J J
Published: January 2020

The colonizing capacities of 16 Vibrio cholerae strains, including nine genetically and/or phenotypically defined parent-mutant pairs, were determined in unobstructed adult rabbit small bowel. There were marked interstrain differences in colonizing capacity, which was enhanced by bacterial motility and the production of cholera holotoxin but was unrelated to production of cholera toxin B-subunit or hemolysin or to bacterial serotype or biotype. The role of colonizing capacity and other bacterial features in determining the immunizing efficiency of live V. cholerae was studied by determining the efficiency with which graded inocula of each strain immunized against attempted recolonization of the ileum or induction of choleralike diarrhea by the RITARD (removable intestinal tie-adult rabbit diarrhea) challenge technique using standard inocula of virulent V. cholerae. Mucosal colonizing capacity was the only quantitative predictor of bacterial immunizing capacity; none of the other bacterial features cited above influenced bacterial immunogenicity against either type of challenge, except as they affected colonizing capacity. Live V. cholerae immunized much more efficiently than Formalin-killed bacteria; the former caused marked protection after a single inoculum of 10(2) CFU, whereas the latter gave only partial protection after three inoculations of 10(11) killed organisms. Protection induced by live bacteria was due largely to resistance to colonization and included marked inhibition of bacterial growth within the bowel lumen. These findings strongly suggest that an optimally efficient oral cholera vaccine would be composed of avirulent live V. cholerae selected for their capacity to colonize the small-bowel mucosa.
Suppression of cytotoxic responses by a supernatant factor derived from Mycoplasma hyorhinis-infected mammalian cell lines
Authors: Teh H S , Ho M , Williams L D
Published: January 2020

A class of interleukin-2-dependent T-cell clones, isolated from a murine fetal thymus, was previously shown to suppress the induction of cytotoxic responses to alloantigens (H.-S. Teh, M. Ho, and W. R. McMaster, J. Immunol. 135:1582-1588, 1985). In that article, the immunosuppressive properties of these T-cell clones were shown to be a direct consequence of infection by Mycoplasma hyorhinis. Suppression of cytotoxic responses was mediated by both the mycoplasmas and a 200-kilodalton factor present in supernatants of infected cultures. This factor was sensitive to proteases but was resistant to heating to 60 degrees C for 1 h and to incubation on ice at pH 2 or pH 14 for 4 h. The production of suppressor factor in infected cultures was independent of the viability or the protein synthesis capability of the mammalian cells, suggesting that it was produced by M. hyorhinis. The factor was most suppressive when it was added during the early stages of the cytotoxic response. Its suppressive effects on cytotoxic responses were not reversed by the addition of an excess of recombinant interleukin-2. This factor also suppressed mitogenic responses to lipopolysaccharide. However, it is not a growth inhibitor since it did not affect the proliferation of tumor cell lines. A simple method for detecting M. hyorhinis in the infected T-cell clones and for eliminating it is described.
Control of endotoxin activity and interleukin-1 production through regulation of lipopolysaccharide-lipoprotein binding by a macrophage factor
Authors: Warren H S , Riveau G R , de Deckker F A , Chedid L A
Published: January 2020

Lipopolysaccharides (LPSs) extracted from gram-negative bacteria are much less active when bound to serum lipoproteins. We present evidence here that the binding of radiolabeled LPS extracted from Escherichia coli O113 and Salmonella typhimurium to lipoproteins in rabbit serum is increased 8 to 24 h after a single intravenous injection of homologous or heterologous LPS. Supernatants of activated macrophages containing interleukin-1 also stimulate increased binding. The isolated product of this binding does not induce the production of interleukin-1 by macrophages in vivo or in vitro and is unable itself to stimulate increased binding of LPS to lipoprotein. Normal rabbit sera spiked with lipoprotein fractions prepared from tolerant but not normal rabbit sera bind increased amounts of LPS. These data suggest that there may exist a self-regulated mechanism for decreasing the toxicity of LPS and the production of LPS-induced interleukin-1; this mechanism is controlled by a macrophage factor and functions through altering the binding of LPS to certain serum lipoproteins.
Identification of regions on a 230-kilobase plasmid from enteroinvasive Escherichia coli that are required for entry into HEp-2 cells
Authors: Small P L , Falkow S
Published: January 2020

Certain strains of Escherichia coli can cause an invasive diarrheal disease in humans which clinically resembles shigellosis. These strains share with Shigella species the ability to enter and replicate within colonic epithelial cells and the ability to bind Congo red dye in vitro when grown at 37 degrees C. Like shigellae, they contain a large plasmid essential for virulence. A 230-kilobase (kb) plasmid from enteroinvasive E. coli was genetically marked with a transposon and mobilized into an E. coli K-12 background. This plasmid conferred upon E. coli K-12 the ability to enter and multiply within cultured epithelial cells, as well as the ability to bind Congo red. Expression of these phenotypes required growth at 37 degrees C. Transposon mutagenesis was used to identify regions on the 230-kb plasmid required for virulence. All transposon insertions which resulted in loss of the ability to enter epithelial cells, as well as the ability to bind Congo red dye, were mapped to a single 25-kb BamHI fragment. Subclones from this 25-kb region were tested for the ability to complement invasion in noninvasive derivatives. A subclone containing about 8 kb of the left end of the 25-kb BamHI fragment was capable of complementing noninvasive mutants with Tn5 insertions in this region and restored to these noninvasive mutants the ability to enter epithelial cells.
Evidence for the phagocytic transport of intestinal particles in dogs and rats
Authors: Wells C L , Maddaus M A , Erlandsen S L , Simmons R L
Published: January 2020

Fluorescent latex beads of two different colors were implanted into separate intestinal segments in individual dogs and rats. Mesenteric lymph node phagocytes subsequently contained multiple beads of one or the other color but rarely both colors, indicating that intestinal phagocytes transported the latex beads to the draining lymph node. Fluorescent labeled Escherichia coli was implanted into rat ligated intestinal segments, and rare mesenteric lymph node phagocytes subsequently contained fluorescent bacteria, suggesting that intestinal bacteria might be transported in the same manner as inert latex beads.
Specific parasitism of purified vaginal epithelial cells by Trichomonas vaginalis
Authors: Alderete J F , Demeś P , Gombosova A , Valent M , Fabusová M , Jánoska A , Stefanovic J , Arroyo R
Published: January 2020

Human vaginal epithelial cells (VECs) from vaginal swabs obtained from normal women or from patients with trichomoniasis were purified, and VEC parasitism by Trichomonas vaginalis was examined. Trichomonads bound equally well to live or dead VECs, and up to 20% of VECs were parasitized. Trichomonal cytadherence of human VECs was time, temperature, and pH dependent. Saturation binding levels of live trichomonads to VECs gave approximately 2 organisms adherent to parasitized VEC. No differences in cytadherence levels were detected by different isolates to VECs from the same patient compared with adherence to VECs from normal individuals. Trypsinized, live T. vaginalis organisms failed to recognize VECs. A ligand assay identified four adhesin candidates, and only organisms without a prominent immunogen on the surface (negative phenotype) cytadhered to VECs and synthesized the adhesins, confirming the results of a recently published report by us on adherence to HeLa cell monolayers (J. F. Alderete and G. E. Garza, Infect. Immun. 56:28-33, 1988). These data show the ability of T. vaginalis to parasitize human vaginal epithelial cells in a specific receptor-ligand manner.