bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence that the spontaneous blastogenesis of lymphocytes from bovine leukemia virus-infected cattle is viral antigen specific
Authors: Thorn R M , Gupta P , Kenyon S J , Ferrer J F
Published: January 2020

Cattle lymphocytes cultured for 3 days were found to spontaneously incorporate thymidine (3STI). Under optimal conditions of culture, the median magnitude of 3STI activity in lymphocytes from bovine leukemia virus (BLV)-infected cattle was higher than that of BLV-free cattle, but the ranges of the values overlapped. However, the 3STI activity of most BLV-infected cattle was specifically inhibited by serum containing BLV antibodies, whereas the 3STI activity of BLV-free cattle was not. The 3STI inhibitor copurified with immunoglobulin, and its activity could be absorbed with BLV. Rabbit anti-BLV serum inhibited 3STI, but rabbit anti-BLV p25 did not. These results indicate that BLV infection induces or expands a BLV-specific lymphocyte population. Spontaneous blastogenesis may be indicative of an immune response which controls virus spread.
Immunological nonidentity of heat-labile enterotoxins from human and porcine enterotoxigenic Escherichia coli
Authors: Honda T , Tsuji T , Takeda Y , Miwatani T
Published: January 2020

The Ouchterlony double-gel diffusion test demonstrated that heat-labile enterotoxin (LT) from human strains of enterotoxigenic Escherichia coli was antigenically related but not identical to that from porcine E. coli. All human strains examined produced immunologically identical LTs, and all porcine strains examined produced immunologically identical LTs. The Biken test (modified Elek test), developed for detection of E. coli LT (Honda et al., J. Clin. Microbiol. 13: 1-5, 1981), was useful for confirmation of these results.
Replication of avian influenza A viruses in mammals
Authors: Hinshaw V S , Webster R G , Easterday B C , Bean W J
Published: January 2020

The recent appearance of an avian influenza A virus in seals suggests that viruses are transmitted from birds to mammals in nature. To examine this possibility, avian viruses of different antigenic subtypes were evaluated for their ability to replicate in three mammals-pigs, ferrets, and cats. In each of these mammals, avian strains replicated to high titers in the respiratory tract (10(5) to 10(7) 50% egg infective doses per ml of nasal wash), with peak titers at 2 to 4 days post-inoculation, similar to the pattern of human and other mammalian viruses in these animals. Most avian strains were recovered for 5 to 9 days post-inoculation. One avian H1N1 virus initially replicated poorly in pigs, but was adapted to this host and even transmitted to other pigs. Replication of the avian viruses occurred in the respiratory tracts of mammals, whereas, in birds, they replicate in the intestinal tract as well. The infected mammals had no significant disease signs and produced low levels of humoral antibodies; however, challenge experiments in ferrets indicated that they were immune. These studies suggest that influenza A viruses currently circulating in avian species represent a source of viruses capable of infecting mammals, thereby contributing to the influenza A antigenic pool from which new pandemic strains may originate.
Mode of Action of Staphylococcal Leukocidin: Relationship between Binding of
125
I-Labeled S and F Components of Leukocidin to Rabbit Polymorphonuclear Leukocytes and Leukocidin Activity
Authors: Noda Masatoshi , Kato Iwao , Matsuda Futami , Hirayama Toshiya
Published: January 2020

The binding of
125
I-labeled S component to rabbit polymorphonuclear leukocytes was found to be concentration dependent and saturable at 37°C. Scatchard analysis of the binding curve gave a straight line, indicating that S component binds to a single population of sites. The dissociation constant,

K
D

, derived from the Scatchard plot was 5.57 × 10
−9
M, and the number of binding sites per leukocyte was calculated to be approximately 5,300. Unlabeled S component (10
−8
M) or subunit B of cholera toxin (10
−7
M) readily competed with
125
I-labeled S component binding, and the labeled S component, preincubated with ganglioside G
M1
at equimolar proportions for 5 min, lost the binding capacity to the leukocyte membranes. The binding number of
125
I-labeled F component to leukocidin-sensitive cells, such as rabbit polymorphonuclear leukocytes and the established human myelocytic leukemia cells, in the absence and in the presence of the unlabeled S component (2.1 nM), was calculated to be 50 and 1,300 molecules per cell, respectively. This increased binding of the labeled F component was time and temperature dependent. The binding number of labeled F component to other cell types comparatively insensitive to leukocidin, such as erythrocytes, adipocytes, intestinal cells, and HeLa cells, was calculated to be less than 50 molecules per cell in spite of the sufficient amount of unlabeled S component bound to their cells. These observations are consistent with the view that in rabbit leukocyte the S component, preferentially bound to the cell surface at 5,300 molecules per cell, contributes to enhance the F component binding up to about 1,300 molecules per cell and may thus play a role of synergistic action of both leukocidin components on the cell membranes in the leukocytolysis.
Characterization of the Glycoprotein Antigens Which Mediate the
Schistosoma japonicum
Circumoval Precipitin Reaction
Authors: Long Gary W. , Lewert Robert M. , Pelley Ronald P.
Published: January 2020

The circumoval precipitin test is a serological test used for diagnosis of schistosomiasis japonica. Soluble egg antigens of
Schistosoma japonicum
block the formation of the circumoval precipitin by serum from infected humans. Consequently, circumoval precipitin inhibition was used to monitor purification of the soluble egg antigens of
S. japonicum
. Crude egg antigens were separated into protein and glycoprotein fractions by lectin chromatography on concanavalin A Sepharose. The glycoprotein fraction produced two intense precipitin lines upon immunodiffusion analysis with human chronic infection sera. The protein fraction produced two faint precipitin lines which did not cross-react with those of the glycoprotein fraction. The glycoprotein fraction contained 90% of the circumoval precipitin inhibitory activity. Isoelectric focusing of
125
I-labeled concanavalin A Sepharose fractions revealed at least four groups of potential
S. japonicum
antigens, termed JAG I, II, and III, and a JAG IV complex. These had isoelectric points ranging from 3.2 to 6.7. In these respects, the
S. japonicum
egg antigen glycoproteins are similar to those of
Schistosoma mansoni
. The glycoproteins were further separated by diethylaminoethyl ion-exchange chromatography. On immunodiffusion analysis it was found that one of the strong Ouchterlony precipitin lines was associated with glycoproteins that did not adsorb to diethyl-aminoethyl columns, whereas the second Ouchterlony precipitin was heterodisperse, being present in the first, second, and third of the four peaks eluted from the diethylaminoethyl column. Immunoelectrophoresis of the diethylaminoethyl fractions demonstrated that the antigen present in highest concentration in soluble egg antigen glycoproteins, JAG II, was extremely heterodisperse in its behavior on diethylaminoethyl columns. This is unlike the
S. mansoni
antigens which can be easily separated by diethylaminoethyl ion-exchange chromatography.
Effects of proteases on the structure and activity of Pseudomonas aeruginosa exotoxin A
Authors: Morihara K , Sanai Y , Tsuzuki H , Jyoyama H , Hirose K , Homma J Y , Kato I
Published: January 2020

The effects of various proteases on the enzymatic or biological activity and structure of exotoxin A from Pseudomonas aeruginosa were systematically studied. The toxin was extremely resistant to treatment with various enzymes. The lethality of the toxin disappeared upon treatment with P. aeruginosa protease and elastase, thermolysin, and trypsin with a long incubation time (5h) in the presence of a high enzyme concentration (molar concentration of enzyme to toxin, 1:10 or 1:20), but was little altered by either alpha-chymotrypsin or subtilisin. The decrease of adenosine diphosphate ribosylation activity was moderate when the same treatment was used, regardless to the protease source, except in the case of papain, which was tested in the presence of reducing agents. The increase in activation of the treated toxin determined in the presence of a denaturant and a reducing agent was less than that of the intact toxin, except in the case of trypsin. The differences in disc and sodium dodecyl sulfate gel electropherograms of the toxins treated with these proteases, except for those treated with papain, suggested that the toxins had been nicked by the protease, which resulted in their degradation by sodium dodecyl sulfate treatment. Papain degraded the toxin into fragments and caused the disappearance of lethality or a marked decrease of adenosine diphosphate ribosylation activity.
Correlation between the production of extracellular substances by type III group B streptococcal strains and virulence in a mouse model
Authors: Durham D L , Mattingly S J , Doran T I , Milligan T W , Straus D C
Published: January 2020

Twelve strains of serotype III group B streptococci (8 isolated from cases of neonatal disease, 3 isolated from asymptomatically colonized infants, and 1 laboratory reference strain) were examined for the vitro production of three potential extracellular virulence products: type-specific antigen, neuraminidase, and protease. In addition, virulence in a mouse model, expressed as 50% lethal dose, was determined for the 12 strains to determine whether a relationship existed between the production of any of the three extracellular products and virulence. Only production of extracellular type-specific antigen showed a correlation with virulence in the mouse model. The high producers of extracellular type-specific antigen were an average of 166-fold more virulent for mice than low producers of the same component. There was no correlation between virulence and either neuraminidase or protease production, nor was there a correlation between either of these two extracellular products and the levels of extracellular type-specific antigen. When levels of group B streptococci of each type (a high and low producer of extracellular type-specific antigen) in organs of infected mice were examined, comparable levels of organisms were found in the brain, spleen, and lungs of mice near death regardless of the initial inoculum. However, the high producer of extracellular type-specific antigen caused death in mice with a 2 to 3 log lower inoculum than the low producer, suggesting that these strains may be more invasive.
Vaccinal properties of Salmonella abortus ovis mutants for streptomycin: screening with a murine model
Authors: Lantier F , Pardon P , Marly J
Published: January 2020

Streptomycin-dependent and streptomycin-independent reverse mutants of Salmonella abortus ovis were selected on medium with and without added streptomycin. Their in vivo properties were tested with a murine model. Reduced capacities of dissemination and multiplication of all mutant strains were evidenced by means of subcutaneous, intraperitoneal, and intravenous inoculations of two outbred strains of mice with different susceptibilities to experimental S. abortus ovis infection. A factorial immunization experiment demonstrated the effects of vaccinal strains and doses. It showed large differences among the mutants. First-time infection with the fully virulent parent strain excepted, the best protection was given by independent reverse mutants which had kept residual capacity of in vivo dissemination and multiplication. This screening partly determined the selection of strain Rv6 as a potential live vaccine.
Role of iron in the pathogenesis of Vibrio vulnificus infections
Authors: Wright A C , Simpson L M , Oliver J D
Published: January 2020

Infections with Vibrio vulnificus resulting in septicemia and high mortality have been correlated with pre-existing liver disease and hemochromatosis. As these conditions are associated with impaired iron metabolism and as iron availability in the host has been implicated in the pathogenicity of a number of bacterial infections, the role of iron as a possible factor in the pathogenesis of V. vulnificus was examined. Injection of mice with iron resulted in a lowering of the 50% lethal dose from 10(6) to 1.1 cells and in a reduction in the time of death postinfection. Elevated serum iron levels were also produced by damaging livers with injections of CCl4. The inoculum size required to kill these mice was directly correlated with serum iron levels. Since the portal of infection of this organism may be ingestion of contaminated seafood, the effects of iron upon orally induced infection were also studied. The effects of adding iron, transferrin, or Desferal (an iron chelate) upon the growth of V. vulnificus in human and rabbit sera were also examined. Iron appeared to be the limiting factor in the ability of this organism to survive or grow in mammalian sera. These results, both in vitro and in vivo, provided strong evidence that iron may play a major role in the pathogenesis of V. vulnificus.
Subpopulations of suppressor cells in chickens infected with cells of a transplantable lymphoblastic leukemia
Authors: Theis G A
Published: January 2020

Three distinct subpopulations of cells with suppressor activity were separated by Ficoll density gradient centrifugation methods from the spleens of 3- to 4- week-old chickens infected with cultured lymphoblastoid cells (JM-VLC), derived from JM-V leukemia: (i) a subpopulation of nonadherent cells, which separated in the T-cell-rich gradient fraction of leukemic chicken spleen, inhibited proliferative responses to concanavalin A in mixed cultures with normal chicken spleen cells; (ii) phagocytic cells (macrophages), which were the most effective suppressor cells of all subpopulations in the mixed culture assay, were recovered among the cells of greatest density in the spleens of both normal and leukemic chickens; (iii) JM-VLC cells in the buoyant gradient fractions of leukemic chicken spleens also effected suppression. In the later stages of lymphoproliferative disease, the number of spleen cells of buoyant density was increased, apparently as a result of infiltration of the spleens with JM-VLC cells.
Involvement of cells of hematopoietic origin in genetically determined resistance of Syrian hamsters to vesicular stomatitis virus
Authors: Fultz P N , Shadduck J A , Kang C Y , Streilein J W
Published: January 2020

Susceptibility of Syrian hamsters of the inbred LSH and MHA strains to injection of as few as 10 plaque-forming units of vesicular stomatitis virus (VSV) was shown to occur only after intraperitoneal and intrapleural injection and not after injection of VSV intravenously, intranasally, or in the footpads. Despite the fact that fewer LSH hamsters died when VSV was injected via the latter routes, the histopathology of the VSV-induced disease at early times after infection was identical irrespective of the route of virus administration. Histological examination of tissues at various times after administration of VSV by the various routes revealed that VSV exhibited tropism for lymphoreticular tissue, with the greatest amount of necrosis in the splenic periarteriolar lymphoid sheath. A similar pattern also was observed in VSV-infected tissues from genetically resistant UT1 hamsters. Infectivity titrations of various tissues at different times after intraperitoneal injection of VSV revealed that resistant UT1 hamsters began to clear virus from tissues between 40 and 48 h postinfection, whereas virus titers remained high in susceptible animals. Resistance of UT1 hamsters appeared to require an intact spleen since survival of splenectomized animals was less than that of sham-splenectomized UT1 controls. Sublethal whole-body irradiation was also able to reduce resistance of UT1 hamsters (survival was reduced from 100 to 50%). Bone marrow cells from resistant (UT1 X LSH) F1 females were transferred into lethally irradiated susceptible LSH hamsters, and hematopoietic chimeras were produced. After intraperitoneal injection of 100 plaque-forming units of VSV, all of the female chimeras survived, but only 33% of male chimeras survived. These data indicate that resistance to VSV in Syrian hamsters is mediated, at least partially, by cells of hematopoietic origin.
Encephalitogenicity of measles virus in marmosets
Authors: Albrecht P , Lorenz D , Klutch M J
Published: January 2020

Marmosets infected intracerebrally with the wild Edmonston strain of measles virus developed encephalitis, demonstrated histologically and by the fluorescent-antibody technique. The infection remained clinically silent over a 14-day observation period. Animals infected intracerebrally with the JM strain of wild measles virus had only mild encephalitic changes but died of the visceral form of measles infection. Marmosets inoculated with measles vaccine had no encephalitis and remained clinically well. Marmosets appear to be a sensitive indicator of the viscerotropic and neurotropic properties of measles virus.
Strain differences in resistance to infection reversed by route of challenge: studies in blastomycosis
Authors: Morozumi P A , Brummer E , Stevens D A
Published: January 2020

The inbred mouse strains C3H/HeJ and DBA/1J have been shown to represent the extremes of susceptibility and resistance, respectively, to pulmonary blastomycosis. This pattern was completely reversed when challenge was performed by the intraperitoneal route, whether a virulent or an attenuated strain of Blastomyces dermatitidis was utilized. By a third route (subcutaneous), the differences were insignificant. Inhibition of replication of blastomyces in vitro by macrophages from both strains, before or after activation by subcutaneous infection, was similar.
Failure of hamster macrophages to discriminate between infective and noninfective promastigotes of Leishmania donovani during attachment in vitro
Authors: Giannini M S , D'Alesandro P A , Garcia C R , Saraiva E M
Published: January 2020

The attachment of infective and noninfective promastigotes of Leishmania donovani to hamster macrophages derived from spleen, lymph nodes, and peritoneal exudate was studied in vitro. Regardless of macrophage origin, no significant differences were observed between attachment of promastigotes that were infective and those that were noninfective for hamsters.
Production of mouse lymphotoxin by phytohemagglutinin-stimulated spleen cells requires two cell fractions
Authors: Aksamit R R , Leonard E J
Published: January 2020

The appearance of lymphotoxin in the culture fluid of phytohemagglutinin (PHA)-stimulated mouse spleen cells required two cell fractions that were separated by adherence to plastic. Upon stimulation with PHA, neither cell fraction alone produced significant amounts of lymphotoxin; however, when the cell fractions were combined and then stimulated with PHA, full activity was produced. Cytotoxic activity was not fully restored by combining PHA-stimulated cultured fluids from adherent and nonadherent cell fractions. This indicated that the cytotoxic activity was not the result of two factors, one produced by each cell fraction, that acted on the target cells, but rather, two cells interacted to produce lymphotoxin. Treatment of the unfractionated spleen cells with monoclonal anti-Thy1.2 and complement before PHA stimulation greatly reduced the production of lymphotoxin and indicated that at least one of the cells was a T cell. Lymphotoxin production was partially restored by the addition of nonadherent cells to the anti-Thy1.2-treated cells, suggesting that the T cell was nonadherent. Treatment of unfractionated cells with either silica or carrageenan had no effect on the subsequent production of lymphotoxin by PHA, suggesting that the adherent cell was not actively phagocytic.
Infection enhancement of dengue type 2 virus in the U-937 human monocyte cell line by antibodies to flavivirus cross-reactive determinants
Authors: Brandt W E , McCown J M , Gentry M K , Russell P K
Published: January 2020

Dengue type 2 virus replication was detected in the U-937 human monocyte cell line when the virus inoculum and the culture medium contained flavivirus antibodies diluted beyond their neutralizing titers. This was in marked contrast to yellow fever virus, which replicated very well in the absence of antibodies; however, 10-fold-higher yields of yellow fever virus could be obtained in the presence of flavivirus antibodies. These infection-enhancing antibodies were obtained from either a dengue type 2 human antiserum or reference hyperimmune obtained from either a dengue type 2 human antiserum or reference hyperimmune mouse ascitic fluid. The infection enhancement phenomenon, previously shown to be due to infection of Fc receptor-bearing cells with virus-antibody complexes, was completely blocked by preincubation of the cells with aggregated gamma globulin. The blocking results suggested an Fc receptor-mediated infection of the U-937 cells as well. A panel of monoclonal antibodies, previously characterized as either virus type specific or flavivirus cross-reactive and with mouse immunoglobulin subclasses G1 and G2a in both categories, were tested for their infection enhancement characteristics. A type-specific neutralizing monoclonal antibody preparation that was diluted beyond its neutralization titer did not cause infection enhancement, nor did low-level neutralizing monoclonal antibodies that were dengue serotype specific by the hemagglutination inhibition test. Only flavivirus cross-reactive monoclonal antibodies caused infection enhancement, irrespective of whether the immunoglobulins were G1 or G2a. These cross-reactive flavivirus determinants may reside at the tips of the glycoprotein projections on the virus particles, enabling the Fc ends of the cross-reactive antibodies attached to these determinants to interact with Fc receptors on susceptible cells.
Pathogenesis of anemia in Trypanosoma brucei-infected mice
Authors: Amole B O , Clarkson A B , Shear H L
Published: January 2020

The pathogenesis of anemia was studied in trypanosome-infected mice. A strain of Trypanosoma brucei, TREU 667, was used which first produces an acute phase marked by waves of parasitemia. Erythrocytes from infected animals were coated with immunoglobulin M during or just before the waves of anemia and parasitological crises. Erythrocytes from normal animals could be sensitized with "precrisis" sera presumably containing antigen and antibody. These data suggest that anemia during the acute phase is due to sensitization of erythrocytes with immunoglobulin M-antigen complexes. The anemia is partially compensated by a strong erythropoietic response. The acute phase is followed by a chronic phase marked by a constant high parasitemia and immunosuppression. The less marked anemia occurring during this latter phase is due to hemodilution and perhaps a low but significant immune response to the parasites, which causes continuing erythrocyte sensitization by immunoglobulin M-antigen complexes.
Role of surface components in serum resistance of virulent Aeromonas salmonicida
Authors: Munn C B , Ishiguro E E , Kay W W , Trust T J
Published: January 2020

The ability of virulent strains of Aeromonas salmonicida to resist the bactericidal activity of serum was quantitated. The A. salmonicida strains tested included virulent strains, mutants lacking the major surface A-protein, and mutants lacking A-protein and having a modified lipopolysaccharide structure. The sera evaluated included normal human, rabbit, and trout sera, immune trout serum, and immune rabbit serum containing antibodies to A-protein and lipopolysaccharide. Virulent strains of A. salmonicida displayed high or intermediate resistance to the bactericidal activity of complement both in the presence and absence of specific antibody. In normal sera, both A-protein and lipopolysaccharide contributed to serum resistance. In immune trout serum, the protection was conferred by A-protein.
Adoptive transfer of resistance to Plasmodium berghei with spleen cells and serum from Fansidar-cured mice
Authors: Ferraroni J J , Speer C A
Published: January 2020

The ability of splenic leukocytes or serum to transfer immunity to Plasmodium berghei was studied in C57BL/6 mice. Splenic leukocytes or serum was removed from mice which had been inoculated previously 1 to 4 or 5 times with P. berghei and cured 1 to 4 or 5 times with Fansidar (pyrimethamine plus sulfadoxine) and transferred to syngeneic recipients 1 or 2 days before parasite challenge. Partial protection was observed in recipients of immune serum or unfractionated splenic leukocytes. Significantly more protection was observed in recipients of preparations from immune mice enriched for immunoglobulin-positive (B-lymphocyte) cells or B-lymphocyte plus immunoglobulin-negative (T-lymphocyte) cells than in recipients of preparations enriched for T-lymphocytes. Recipients of B- or B+T-lymphocyte-enriched spleen cells from immune mice had significantly longer survival times than did recipients of T-lymphocyte-enriched spleen cells and recipients of spleen cells from normal mice. Transferred immunity lasted less than 2 months and did not protect recipients against death induced by the malarial parasite. The ability of splenic leukocytes to transfer resistance to recipients was independent of the number of times donors were inoculated with P. berghei and cured with Fansidar.
In vitro interactions of immune lymphocytes and Cryptococcus neoformans
Authors: Fung P Y , Murphy J W
Published: January 2020

CBA/J mice immunized subcutaneously with emulsions of heat-killed Cryptococcus neoformans in complete Freund adjuvant displayed delayed-type hypersensitivity to cryptococcal culture filtrate antigen and developed sensitized splenic lymphoid cells which inhibited the growth of C. neoformans in vitro. The in vitro assay of growth inhibition served to investigate further the kinetics of the effect of sensitized lymphoid cells on the pathogen. There was a close correlation between the delayed-type hypersensitivity response in mice and inhibition of growth of C. neoformans by lymphoid cells. Sensitized splenic lymphocytes capable of inhibiting the growth of the cryptococci were detected at day 6 after immunization and reached maximum levels by days 8 through 16. Inhibition of growth was highest with effector-to-target cell ratios of 300:1 or greater. Inhibition of growth of C. neoformans by sensitized lymphoid cells was detectable as early as 4 h after effector and target cells were mixed and increased gradually, reaching a maximum at 24 h, but dropped significantly by 48 h. By supplementing the reaction mixtures with fresh medium or additional sensitized effector cells during incubation, the inhibition of growth of C. neoformans could be maintained through 48 h. C. neoformans-sensitized effector lymphoid populations not only inhibited the growth of the pathogen in vitro but also restricted C. neoformans proliferation in various vital organs upon transfer to naive recipient animals, indicating that the in vitro growth inhibition assay may be a means of assessing the resistance of animals to C. neoformans. The effector cells from sensitized animals were nylon wool-nonadherent Thy-1+ and Ia+ lymphocytes.
Association of type 1 pili with the ability of livers to clear Salmonella typhimurium
Authors: Leunk R D , Moon R J
Published: January 2020

The role of type 1 pili in the adherence of Salmonella typhimurium strain SR-11 to hepatic sinusoidal cells was investigated. An average of 66.7% of piliated organisms was cleared by perfused livers on a single pass. Mannose and alpha-methyl-D-mannoside inhibited such trapping in a dose-dependent manner. Preincubation of the bacteria, but not the liver, with either sugar also inhibited trapping, suggesting that the sugar binds to bacterial, not hepatic, receptors. Significant numbers of previously trapped bacteria could be eluted by adding mannose to the wash medium. Bacteria with reduced piliation, obtained either by growing bacteria on agar or by using a nonpiliated variant of the parent strain, were trapped to a significantly lesser extent than the parent strain. The liver appears to selectively trap heavily piliated organisms since reperfusion of bacteria through a second liver results in significantly less trapping than occurs with the first perfusion. In vivo, the nonpiliated variant strain was cleared much more slowly than the piliated parent strain. Mannose and alpha-methyl-D-mannoside, but not glucose, decreased clearance rates of piliated organisms. Cumulatively, the data suggest that type 1 pili are a major factor in hepatic clearance of S. typhimurium.
Nonphagocytic clearance of Staphylococcus aureus from murine lungs
Authors: Nugent K M , Pesanti E L
Published: January 2020

Several investigations of host and bacterial factors critical to staphylococcal clearance from lungs suggest that alveolar macrophages may not provide the principal defense against inhaled staphylococci. We evaluated possible contributions of extracellular bactericidal activities in lungs with a standard aerosol challenge model by using methods which allowed recovery of macrophages for in vitro bactericidal assays and recovery of intrapulmonary staphylococci for clearance studies. Macrophages recovered by a gentle lavage technique immediately after aerosol exposure contained 6.0 +/- 2.3 colony-forming units of viable staphylococci per 100 glass-adherent macrophages. These intracellular staphylococci were killed in vitro with a half-life of 10.8 +/- 2.1 h, which is identical to our results with a completely in vitro system for ingestion and killing. However, 99.4 +/- 0.2% and 94.9 +/- 1.5% of the viable cocci recovered in bronchoalveolar lavage at 0.5 and 6.0 h after aerosol exposure were sensitive to lysostaphin, a rapidly bactericidal enzyme with no demonstrable activity against intracellular organisms and therefore, presumably extracellular. Photomicrographs from lavage pellets obtained 0.5, 1.5, 3.0, and 5.5 h after aerosol exposure confirmed the presence of numerous extracellular cocci. These extracellular cocci were eliminated at the same rate as whole lung cocci (half-life = 3.07 and 3.14 h, respectively) and at a much faster rate than intracellular cocci. In summary, we found large numbers of extracellular staphylococci in bronchoalveolar spaces during the first 6 h after aerosol exposure that are inactivated at the same rate as the whole lung bacterial population. Since only a small number of staphylococci are ingested by macrophages and intracellular bactericidal activity appears too slow to explain intrapulmonary killing, we conclude that an as yet unidentified extracellular killing process contributed to staphylococcal clearance.
Antibodies against the Ag2 fimbriae of Actinomyces viscosus T14V inhibit lactose-sensitive bacterial adherence
Authors: Revis G J , Vatter A E , Crowle A J , Cisar J O
Published: January 2020

Monospecific antisera against the Ag1 and Ag2 fimbrial components of Actinomyces viscosus T14V were produced by immunizing rabbits with immune precipitates of each antigen harvested from crossed-immunoelectrophoresis plates. The Fab fragments prepared from these sera were used as specific reagents in immunoelectron microscopy to identify each fimbrial component on the bacterial surface and also were assayed for their abilities to prevent the coaggregation of A. viscosus T14V with Streptococcus sanguis 34, an interaction that is lactose sensitive. Each Fab preparation appeared to react with different fibrillar structures present on the actinomycete, and only the Ag2-specific Fabs blocked coaggregation. These results provide strong support for the presence of distinct types of fimbriae on A. viscosus T14V and indicate the exclusive involvement of Ag2 fimbriae in lactose-sensitive adherence.
Contribution of toxin A and elastase to virulence of Pseudomonas aeruginosa in chronic lung infections of rats
Authors: Woods D E , Cryz S J , Friedman R L , Iglewski B H
Published: January 2020

A chronic pulmonary infection model in rats was employed to assess the role of individual Pseudomonas aeruginosa exoproducts in disease due to this organism. Groups of rats were inoculated transtracheally with agar beads in which were embedded approximately 10(4) colony-forming units of P. aerugijnosa PAO and the PAO derivatives PR1, T1, E64, and a mixture of T1 and E64 in equal numbers (10(4)). Eight animals from each group were sacrificed at 3, 9, and 30 days after challenge, and their lungs were examined for histopathological changes, bacterial numbers, and the presence of P. aeruginosa exoproducts. The Tox- mutant T1 and the PR1 mutant, which produces enzymatically inactive toxin A, were both found to be less virulent in the rat lung model than was the toxigenic parental strain PAO. Pathological changes seen in animals infected with these mutants were restricted to intra- and peribronchial inflammation, whereas the toxigenic parental strain caused parenchymal changes, including a dense mononuclear-cell infiltration in the alveolar spaces in addition to intra- and peribronchial inflammation. Additionally, mutant E64, which produces a temperature-sensitive elastase, was also found to be less virulent in the rat lung model than was the parental strain. These data demonstrate that both active toxin A and elastase are required for maximum virulence of P. aeruginosa in this model.
Expression of Treponema pallidum antigens in Escherichia coli K-12
Authors: Stamm L V , Folds J D , Bassford P J
Published: January 2020

A colony bank of recombinant plasmids harboring Treponema pallidum DNA inserts has been established in Escherichia coli K-12. By using an in situ immunoassay, we identified four E. coli clones that expressed T. pallidum antigens. Thus, recombinant DNA technology may provide powerful new tools for studying the pathogenesis of T. pallidum infection.
Release of toxic microvesicles by Actinobacillus actinomycetemcomitans
Authors: Nowotny A , Behling U H , Hammond B , Lai C H , Listgarten M , Pham P H , Sanavi F
Published: January 2020

Oral isolates of Actinobacillus actinomycetemcomitans (strain Y4) release spherical microvesicles in large numbers during normal growth. The biological activities of these products were studied, and it was estimated that approximately 1/10 of their dry weight was made up of heat- and proteolysis-resistant endotoxin. The chicken embryo lethality and bone-resorbing activity of the microvesicles were heat stable but proteolysis sensitive. Other laboratories have reported the presence of a heat- and proteolysis-sensitive leukotoxin in similar preparations. Accordingly, the microvesicles released by strain Y4 may contain, in addition to endotoxin, several potent substances which are highly toxic and active in bone resorption, and these may be significant factors in the pathogenesis of periodontal diseases.
Comparison of enzyme-linked immunosorbent assay and neutralization techniques for measurement of antibody to respiratory syncytial virus: implications for parenteral immunization with live virus vaccine
Authors: Belshe R B , Van Voris L P , Mufson M A , Buynak E B , McLean A A , Hilleman M A
Published: January 2020

The sensitivity of an enzyme-linked immunosorbent assay (ELISA) to detect low levels of antibody to respiratory syncytial (RS) virus was compared with a tube dilution neutralization test (NEUT) on sera obtained from children who received a parenteral live RS virus vaccine. Among the children who developed antibody in response to live RS virus vaccine. ELISA was as sensitive as NEUT at detecting antibody increases. Some children who did not have detectable prevaccine ELISA antibody possessed NEUT antibody; these children were generally less than 12 months old, suggesting that they had low levels of maternal antibody. Low levels of NEUT or ELISA antibody were associated with the absence of antibody increases after injection of live RS virus vaccine. The quantity of antibody stimulated by this live RS virus vaccine was small compared with that which was stimulated by naturally acquired RS virus infection. We concluded that ELISA is a satisfactory test for determining antibody to RS virus in vaccine field trials, given the understanding that low levels of preexisting antibody are not detected in some instances.
Attachment of gonococcal pili to lectin-resistant clones of Chinese hamster ovary cells
Authors: Gubish E R , Chen K C , Buchanan T M
Published: January 2020

Pili facilitate the attachment of virulent Neisseria gonorrhoeae to host cells. Isolated pili and peptides from pili obtained by cyanogen bromide cleavage were used in attachment assays to Chinese hamster ovary cells and their lectin-resistant clones. Pili and the largest cyanogen bromide fragment (CNBrI) from the amino-terminal portion of the pilin molecule attached to a greater degree to the parent cell and showed 40 to 75% reduced attachment to clones deficient in cell surface oligosaccharides. The CNBrI fragment, with a molecular weight of approximately 10,000, bound specifically to host proteins with subunit molecular weights of 14,000 to 16,000 that were electrophoretically transferred onto nitrocellulose sheets from polyacrylamide gel patterns of host cells. Periodate or galactosidase treatment of pili or the CNBrI fragment markedly reduced attachment, suggesting the importance of galactose residues on pili for their attachment function. Similarly, highly purified exoglycosidase or trypsin treatment of the parent cell reduced attachment, suggesting that oligosaccharide moieties of cell surface components (glycoproteins or glycolipids or both) were receptors for pili attachment. This study indicated that the portion of the pilin molecule involved in attachment resides on the CNBrI fragment and that sugar moieties, both on pili and on the host cell, were required for optimal attachment.
Human immune response to various doses of group Y and W135 meningococcal polysaccharide vaccines
Authors: Griffiss J M , Brandt B L , Broud D D
Published: January 2020

A divalent vaccine containing equal weights of Neisseria meningitidis group Y and group W135 capsular polysaccharides was inoculated subcutaneously into groups of 32 military recruit volunteers at doses of 10, 25, 50, and 100 micrograms in 10-microliter/microgram volumes. At 4 weeks, the two higher doses induced significantly greater binding antibody responses than did the two lower doses. Differences in response were not found between the two higher doses or between the two lower doses. An additional 32 volunteers received a dose of 25 micrograms in a 20-microliter/microgram volume. Binding antibody response to this vaccine did not differ from the response to doses of 10 and 25 microgram in 10-microliter/microgram volumes. In contrast, bactericidal antibody responses did not differ among doses. Bactericidal antibody was induced in 100% of individuals with low (greater than 4 log2) preexisting serum bactericidal activity, regardless of dose. Bactericidal antibody nonresponse was restricted to individuals with high preexisting serum bactericidal titers. The discrepant dose response between binding and bactericidal antibody resulted from the induction of nonlytic antibody by the higher doses. We conclude that there are no advantages to doses in excess of 5 micrograms of these two chemically similar polysaccharides for the target population of young adult military recruits.
Immunochemical analysis of streptococcal group A, B, and C carbohydrates, with emphasis on group A
Authors: Fung J C , Wicher K , McCarty M
Published: January 2020

Streptococcal group A, B, and C carbohydrates were analyzed by counterimmunoelectrophoresis, immunoelectrophoresis, and inhibition of immunoprecipitation. Extracts of streptococci group A or C were shown by counterimmunoelectrophoresis to contain both anodic and cathodic migrating components. In immunoelectrophoresis, group A and C substances formed a continuous precipitation line stretching from the anode to the cathode, suggesting a heterogeneous population of molecules with immunochemical identity. This identity was confirmed by inhibition of immunoprecipitation, in which both anodic and cathodic immunoprecipitates were inhibited by the same constituent sugars: group A-anti-A was inhibited by N-acetylglucosamine, and group C-anti-C was inhibited by N-acetylgalactosamine. Extracts of group B showed only anodic migration in counterimmunoelectrophoresis and a narrow, anodic arc in immunoelectrophoresis. The group B-anti-B reaction was inhibited by rhamnose. Carbohydrates of variant strains of group A streptococci were also analyzed by the same methods. The results suggest that the heterogeneity of group A carbohydrate may have resulted from attachment of various amounts of N-acetylglucosamine to the polyrhamnose backbone.
Immunochemical identification of viral and nonviral proteins of the respiratory syncytial virus virion
Authors: Fernie B F , Gerin J L
Published: January 2020

We identified by immunochemical methods 13 polypeptides associated with the infectious respiratory syncytial virus virion. Eight of these polypeptides (VP200, VP84, VP66, VP43, VP40, VP37, VP28, and VP19) were identified as virus specific. Two other polypeptides, (VP) 22 and (VP) 12, are provisionally considered to be of viral origin. Three nonviral proteins are also intimately associated with the infectious virion. These nonviral proteins were identified as cellular actin and two proteins with bovine serum albumin immunospecificity. VP40 was identified as the major ribonucleoprotein. Based on biochemical and biophysical similarities with paramyxovirus proteins, other respiratory syncytial virus proteins are believed to have these specific viral functions: VP84, "hemagglutinin"; VP66, undissociated fusion protein, F1,2; VP43, F1; and VP19, F2, VP66 contains a major determinant involved in viral infectivity since all neutralizing antibodies tested, including a monoclone, precipitated this protein.
Adhesion of Entamoeba histolytica trophozoites to human erythrocytes
Authors: López-Revilla R , Cano-Mancera R
Published: January 2020

To understand the mechanism of Entamoeba histolytica adhesion, we characterized the binding of trophozoites to human erythrocytes (RBC) in suspension by measuring the kinetics of amoeba-RBC complex formation. Adhesion was very efficient, since most of the amoebae were complexed with RBC after only 5 min at 37 degrees C in mixtures containing 10(4) amoebae and 10(6) RBC per ml; the adhesion rate depended on amoeba and RBC concentrations, but not on the A, B, and O human blood groups, and was maximal at 37 degrees C and pH 7.3 in the presence of 4 mM Ca2+ and 1 mM Mg2+. Adhesion was prevented if trophozoites were fixed with glutaraldehyde, but only decreased slightly if RBC were previously fixed; it decreased in the absence of glucose and was inhibited as a function of the concentration of cytochalasin B and of the metabolic inhibitors bathophenanthroline and 8-hydroxyquinoline. From these results we conclude that E. histolytica adhesion is an active process that depends on the amoebal cytoskeleton and metabolic energy and on the mobility of both amoebal and RBC surface ligands.
Human endothelial cell culture plaques induced by Rickettsia rickettsii
Authors: Walker D H , Firth W T , Edgell C J
Published: January 2020

Primary cultures of human umbilical vein endothelial cells were inoculated with plaque-purified Rickettsia rickettsii. After adsorption of rickettsiae, monolayers were overlaid with medium containing 0.5% agarose. Small plaques appeared on day 4 postinoculation, and distinct 1- to 2-mm plaques were observed on day 5. Plaquing efficiency was less than that of primary chicken embryo cells in the same medium. Human endothelial cell monolayers were susceptible to infection by R. rickettsii and underwent necrosis as demonstrated by supravital staining. The topographic association of endothelial cell necrosis and rickettsial infection in the plaque model confirmed the direct cytopathic effect of R. rickettsii on human endothelium. Uninfected cells appeared normal by supravital staining and transmission electron microscopy. This model offers the possibility of investigating rickettsial pathogenesis and mechanisms of enhanced severity of Rocky Mountain spotted fever in specific genetically determined conditions.
Adherence of slime-producing strains of Staphylococcus epidermidis to smooth surfaces
Authors: Christensen G D , Simpson W A , Bisno A L , Beachey E H
Published: January 2020

Slime production is not a generally recognized feature of Staphylococcus epidermidis. In a recent outbreak of S. epidermidis intravascular catheter-associated sepsis, we noted that 63% of clinically implicated strains grew as a slimy film coating the culture tube walls when propagated in tryptic soy broth. Only 37% of randomly collected blood culture contaminants and skin isolates demonstrated a similar phenomenon (p less than 0.05). Transmission electron micrographs of these coating bacteria showed them to be encased in an extracellular matrix that stained with alcian blue. Slime production was most evident in autoclaved media containing Casamino Acids and glucose supplementation (0.25% wt/vol). There were strain and media preparation variability of slime production in the presence of other carbohydrates. Some strains were not able to produce slime under any of the tested conditions. The production or nonproduction of slime did not influence growth rate. When grown in vitro, slime producers accumulated on the surface of intravascular catheters as macrocolonies, whereas non-slime, producers did not. Transmission and scanning electron micrographs showed slime producers to be encased in an adhesive layer on the catheter surface, whereas nonproducers were not encased. These results suggest that slime-mediated adherence may be a critical factor in the pathogenesis of S. epidermidis infections of medical devices.
Colony opacity and protein II compositions of gonococci
Authors: Swanson J
Published: January 2020

Changes in the presence of outer membrane protein II (P.II) constituents of gonococci were demonstrated by selecting opacity variants and defining the 125I-labeled bands of parental and variant organisms. In general, colony opacity phenotype was a convenient, reliable guide for obtaining variants that differed from their parents by the apparent single-step gain or loss of one P.II constituent. Within a given strain (three strains were studied), particular P.II species were associated with particular opacity phenotypes. This was well demonstrated in strain JS3, in which five different P.II constituents were identified and compared. Four of these five P.II moieties were consistently associated with a characteristic degree of colony opacity: presence of the fifth P.II (P.IIa) did not correlate with a discernible increase in opacity when present either alone or in combination with other opacity-associated P.II moieties. The electrophoretic migration characteristics for each of the five P.II constituents of this strain differed with regard to apparent molecular weight and the effects of temperature and 2-mercaptoethanol. The high prevalence of colony opacity variants indicates that gonococcal populations are capable of presenting a variety of surface components to their external environment.
Phagocytosis and killing of Pseudomonas aeruginosa by mouse polymorphonuclear leukocytes in vitro promoted by antiserum to the slime glycolipoprotein
Authors: Bishop O , Orr T , Bartell P F
Published: January 2020

The resistance of Pseudomonas aeruginosa to phagocytosis by polymorphonuclear leukocytes was overcome by opsonization with antibody to slime glycolipoprotein or, to a lesser extent, with complement. Resistance was most effectively overcome in the presence of both. Protection against viable-cell challenge conferred by anti-glycolipoprotein serum in experimental infection is discussed briefly in the light of these findings.