bluuebunny/crossref_metadata_2025 huggingface dataset:
New strain of mouse hepatitis virus as the cause of lethal enteritis in infant mice
Authors: Hierholzer J C , Broderson J R , Murphy F A
Published: January 2020

A new strain of mouse hepatitis virus (MHV) was isolated from pooled gut suspensions from an epizootic of lethal enteritis in newborn mice. Negative-contrast electron microscopy showed an abundance of coronavirus particles in the intestinal contents and intestinal epithelium of moribund mice. We found no other virus in the epizootic. Dams seroconverted to MHV polyvalent antigen and to the agent isolated, but did not develop antibodies to other known mouse pathogens. Virus propagated in NCTC-1469 tissue culture produced enteric disease in suckling mice but not fatal diarrhea; the dams of these mice also developed antibodies to MHV and to the isolates. By complement fixation, single radial hemolysis, and quantal neutralization tests, we found the isolates antigenically most closely related to MHV-S, unilaterally related to MHV-JHM, and more distantly related to MHV-1, MHV-3, MHV-A59, and human coronavirus OC-43. We also studied cross-reactions among the murine and human coronaviruses in detail. Tissues of infected newborn mice were examined by light microscopy, thin-section electron microscopy, and frozen-section indirect immunofluorescence, revealing that viral antigen, virus particles, and pathological changes were limited to the intestinal tract. We have designated our isolates as MHV-S/CDC.
Relationship Between Colicin V Activity and Virulence in
Escherichia coli
Authors: Quackenbush Robert L. , Falkow Stanley
Published: January 2020

Colicin V activity is not essential to ColV plasmid-mediated virulence enhancement in
Escherichia coli.
Passive immune hemolysis for detection of heat-labile enterotoxin produced by Escherichia coli isolated from different sources
Authors: Serafim M B , Pestana de Castro A F , Lemos dos Reis M H , Trabulsi L R
Published: January 2020

Fifty-one strains of Escherichia coli isolated from humans, swine, food, and water and identified as enterotoxinogenic by the Y-1 adrenal cell assay, were examined for heat-labile enterotoxin (LT) production by the passive immune hemolysis test. Cholera antitoxin, anti-choleragenoid and anti-LT were used as antisera. Cholera antitoxin was much more potent than anti-choleragenoid and LT antiserum in the detection of LT-positive strains. All strains isolated from pigs and sausage were negative in tests made with LT antiserum. A few strains isolated from humans, food, and water also gave negative results. These data showed that the passive immune hemolysis test is not as efficient as the Y-1 adrenal cell assay in the detection of enterotoxinogenic E. coli strains.
Autoregulation of germ tube formation by Candida albicans
Authors: Hazen K C , Cutler J E
Published: January 2020

Germ tube formation by Candida albicans is at least partially controlled by a product(s) of the yeast phase of the organism which is released from cells upon incubation at 37 degrees C in tissue culture medium or fetal calf serum. This germination regulatory substance is stable under conditions of lyophilization and heating of 70 degrees C, but becomes inactivated at pH values of 4.0 and 9.5. A germination regulatory substance was produced by both strains of C. albicans tested and by a strain of C. tropicalis. Production does not appear to be a universal characteristic of yeasts because the factor could not be recovered from either Cryptococcus laurentii or Candida parapsilosis. Previously described C. albicans germination inhibitors such as cysteine, tryptophol, and phenylethyl alcohol appear not to be the substance described here. Because of the ability of the factor to influence C. albicans morphology, we have designated it morphogenic autoregulatory substance.
Interaction between 6/94 virus, a parainfluenza type 1 strain, and mouse macrophages
Authors: Verini M A , Lief F S
Published: January 2020

The 6/94 virus, a type 1 parainfluenza virus recovered from multiple sclerosis brain cells after lysolecithin-induced fusion of these cells with African green monkey kidney cells (CV-1), has been found to grow in splenic and peritoneal macrophages obtained from outbred and different strains of inbred mice. Macrophages from C57BL animals were least susceptible to infection, a resistance apparently partially age related. The virus also has been found to replicate in IC21 cells, a line of simian virus 40 virus-transformed mouse macrophages. Viral growth was detected by development of hemadsorption in infected cells, followed by the appearance of infectious virus. The growth of 6/94 virus had different kinetics in mouse macrophages, in the standard continuous cell lines L, 3T3, and CV-1, and in primary mouse kidney and mouse embryo cells. The virus produced in macrophages could be passed in series to other macrophage cultures. In addition, once infected, the cultures continued to produce virus, and permanently infected cell lines were thus obtained. Macrophages from immunized mice with high titers of humoral neutralizing antibodies were found variably able to support virus growth.
Isolation and characterization of homogeneous heat-labile enterotoxins with high specific activity from Escherichia coli cultures
Authors: Clements J D , Finkelstein R A
Published: January 2020

The heat-labile enterotoxin (LT) has been isolated in homogeneous form with high specific activity from three sources: cell-free supernatant, NaCl extract, and whole-cell lysates of an enterotoxigenic Escherichia coli strain. In vitro immunological assays were used in lieu of tedious and highly variable bioassays to recognize fractions with activity. This revealed that the major portion of the LT remained adherent to columns containing agarose, from which it could be eluted quantitatively in practically homogeneous form by galactose. Isolated LT has remarkable similarities to the cholera enterotoxin (choleragen) in both subunit structure and amino acid composition, although there are also notable differences in these two enterotoxins, which are related immunologically and by mode of action. Unlike choleragen, in which the A region is totally nicked, E. coli LT, depending on its source, is activated by proteolytic processing. The activity of LT is equivalent to that of choleragen in bioassays on adrenal cells, in rabbit skin, and in rabbit ileal loops, especially when, depending on the source of material, the LT has been activated by treatment with trypsin. The whole-cell lysate is the richest source of LT.
Immunity to foot-and-mouth disease virus in guinea pigs: clinical and immune responses
Authors: Knudsen R C , Groocock C M , Andersen A A
Published: January 2020

Clinical and immune responses were determined for guinea pigs infected with different doses of foot-and-mouth disease virus (FMDV) type A12, strain 119, administered by different routes. Vesicles developed on the tongue or heel pad 1 day after these areas were intradermally inoculated with FMDV. However, vesicles did not develop on the feet and tongue until 3 to 4 days after the intradermal inoculation of FMDV in the flank skin or after intracardiac or subcutaneous inoculation. Infected guinea pigs developed neutralizing antibody, immediate skin reactivity of the Arthus type (4 h), and delayed skin reactivity. In addition to a delayed skin response, the presence of a cell-mediated immune response to FMDV was shown by the specific production of macrophage migration inhibition factor by peritoneal exudate cells in response to FMDV. Kinetic studies showed that neutralizing antibodies were detected at 3 days postinfection, and Arthus and delayed skin reactivity were detected at 4 days postinfection. Some guinea pigs developed either mild or subclinical infections. Regardless of the dose of infectious virus, the route of inoculation, the severity of disease, or the time of clinical onset of disease, infected guinea pigs developed similar immune responses.
Characteristics of infection of B and T lymphocytes from mice after inoculation with cytomegalovirus
Authors: Wu B C , Ho M
Published: January 2020

Viremia was produced by inoculating intravenously BALB/c mice with murine cytomegalovirus. Virus was detected in plasma and granulocytes only during the first 8 days after infection. Lymphocyte-associated viremia, detectable by cocultivation on syngeneic or allogeneic fibroblasts, persisted for at least 4 weeks. Eight to 10 days after infection, sonicated lymphocytes had no demonstrable free virus. When whole lymphocytes with no demonstrable free virus were enclosed in a Millipore chamber and placed on a fibroblastic feeder layer, T cells produced free virus but B cells did not. Compared to normal calf serum, specific hyperimmune serum reduced B cell-associated infectious centers by 74% and T cell-associated infectious centers by only 38%. Normal mouse sera reduced by 36% and 30% infectious center production by B cells and T cells, respectively. Lymphocytes enriched with Fc receptor-positive cells produced significantly more infectious centers than receptor-negative cells.
Release of soluble peptidoglycan from growing gonococci: hexaminidase and amidase activities
Authors: Rosenthal R S
Published: January 2020

Peptidoglycan (PG) turnover in exponentially growing Neisseria gonorrhoeae RD5 type 4 was accompanied by release of soluble PG fragments into the medium. Turnover of the D-[14C]glucosamine-labeled glycan moiety and of the meso-[3H]diaminopimelic acid (DAP)-labeled peptide region occurred at similar rates (ca. 35% per generation). Turnover of D-[14C]alanine-labeled sites within the peptide side chain of PG occurred at roughly twice this rate; no turnover of L-[3H]proline-labeled protein was detected. Gel filtration of supernatants of cultures grown in the presence of labeled DAP, glucosamine, and D-alanine as described above and paper chromatography of hydrolyzed peak fractions revealed four major types of soluble PG. Two of these contained both peptide and glycan moieties and appeared to represent forms of disaccharide peptide monomers and dimers. The other two were (i) a 3H-labeled product lacking 14C and (ii) a 14C-containing product lacking 3H, which were similar in size to that expected for free tetrapeptides and free disaccharides, respectively. Together the appearance of these PG fragments and the concurrent turnover of glycan and peptide regions indicate that both glycan splitting and amidase PG hydrolase activities are involved in the turnover of PG in growing gonococci. If released during gonococcal infections, similar soluble PG fragments might influence the consequences of host-gonococcus interactions.
Shigella Infection of Henle Intestinal Epithelial Cells: Role of the Host Cell
Authors: Hale Thomas L. , Morris Randal E. , Bonventre Peter F.
Published: January 2020

The process of Henle 407 embryonic intestinal epithelial cell infection by
Shigella flexneri
2a M42-43 was studied in an in vitro model system. The role of the Henle cell was assessed. It was established that entry of
S. flexneri
into cells was suppressed by reagents which inhibit uptake of particles by phagocytic cells. The compounds tested included cytochalasin B, dibutyryl-cyclic adenosine monophosphate, choleragen (
Vibrio cholera
enterotoxin), iodoacetate, and dinitrophenol. Cytochalasin B inhibited infection at concentrations of 1.0 μg/ml or greater. Dibutyryl-cyclic adenosine monophosphate at concentrations of 1 mM and choleragen at 0.1 μg/ml caused significant suppression of infection. Iodoacetate or dinitrophenol, at 0.1 mM concentrations, inhibited internalization of virulent shigellae, and a combination of these compounds inhibited infection at 0.01 mM concentrations. Preincubation of Henle cell monolayers with the combination of iodoacetate and dinitrophenol (0.05 mM) also inhibited infection markedly. The data suggest that infection of epithelial cells by
S. flexneri
in vitro is accomplished by an endocytic process induced by virulent bacteria. The process appears to be similar to uptake of particles by phagocytic cells. Ultrastructural analysis by transmission electron microscopy provided corroborative evidence of phagocytosis of shigellae by Henle cells in that intracellular bacteria were often observed within membrane-limiting vacuoles resembling phagosomes.
Experimental Pneumocystis carinii pneumonia in different strains of cortisonized mice
Authors: Walzer P D , Powell R D , Yoneda K
Published: January 2020

Pneumocystis carinii pneumonia was produced in eight different strains of mice by the administration of corticosteroids, low (8%)-protein diet, and tetracycline in the drinking water. Heavier degrees of P. carinii infection were most consistently found in C3H/HeN mice; intermediate levels occurred in BALB/c AnN, C57BL/6N, B10.A(2R), AKR/J, and Swiss Webster mice; lighter degrees were found in DBA/2N and DBA/IJ mice. Histopathologically, P. carinii organisms were morphologically indistinguishable from human and rat P. carinii, and elicited a predominantly mononuclear response that was similar among the various mouse strains. The optimal cortisone acetate regimen was 1 mg injected subcutaneously twice weekly. Higher doses shortened the life span of the mice, presumably by inducing overwhelming bacterial infection. This problem occurred not only in different strains of mice, but also in the same strain of mice obtained from different breeders. Thus, cortisonized mice should be useful in the study of experimental P. carinii infection. Success of this model depends on the corticosteroid dose, as well as the strain, source, general health, and preexisting microbial flora of the mice chosen for study.
Cell-mediated immune responses to the hemagglutinin and neuraminidase antigens of influenza A virus after immunization in humans
Authors: Chow T C , Beutner K R , Ogra P L
Published: January 2020

Humoral and cell-mediated immunity (CMI) were evaluated in groups of school children after immunization with inactivated influenza virus vaccines. A conventional biphasic strain (H3ChN2Ch) of Port Chalmers influenza virus (X-41), a recombinant influenza virus specific for the neuraminidase antigen (Heq1N2Ch) of Port Chambers influenza A virus (X-42), and a placebo were employed for immunization. The techniques of hemagglutination inhibition and neuraminidase inhibition were used to determine serum antibody titers. The CMI responses were evaluated by the in vitro lymphocyte transformation assay employing HavN2Ch, Heq1Neq1, H3ChNeq1, and H3ChN2Ch influenza A virus strains as stimulants. Specific HAI antibody and CMI responses to H3Ch were observed in X-41 but not in X-42 vaccinees. Specific anti-neuraminidase antibodies and CMI responses to N2Ch were manifested by both X-41 and X-42 vaccinees. Immunization with the placebo resulted in no influenza-specific immune responses. The CMI response was first detectable 10 days after immunization and then declined. These observations demonstrate the induction of CMI responses to the HA and NA influenza surface antigens after immunization. These responses may be important in antiviral immunity and the recovery from influenza infection.
Myeloperoxidase-Hydrogen Peroxide-Chloride Antimicrobial System: Effect of Exogenous Amines on Antibacterial Action Against
Escherichia coli
Authors: Thomas Edwin L.
Published: January 2020

Exogenous ammonium ions (NH
4
+
) and amine compounds had a profound influence on the antibacterial activity of the myeloperoxidase-hydrogen peroxide-chloride system against
Escherichia coli.
The rate of killing increased in the presence of NH
4
+
and certain guanidino compounds and decreased in the presence of α-amino acids, polylysine, taurine, or tris (hydroxymethyl) aminomethane. Myeloperoxidase catalyzed the oxidation of chloride to hypochlorous acid, which reacted either with bacterial amine or amide components or both or with the exogenous compounds to yield chloramine or chloramide derivatives or both. These nitrogen-chlorine derivatives could oxidize bacterial components. Killing was correlated with oxidation of bacterial components. The rate of oxidation of bacterial sulfhydryls increased in the presence of the compounds that increased the rate of killing and decreased in the presence of the other compounds. The reaction of HOCl with NH
4
+
yielded monochloramine (NH
2
Cl), which could be extracted into organic solvents. The N-Cl derivatives of bacterial components or of polylysine, taurine, or tris(hydroxymethyl)aminomethane could not be extracted. The effect of NH
4
+
on killing is attributed to the ability of NH
2
Cl to penetrate the hydrophobic cell membrane and thus to oxidize intracellular components. Polylysine, taurine, and tris(hydroxymethyl)aminomethane formed high-molecular-weight, charged, or polar N-Cl derivatives that would be unable to penetrate the cell membrane. These results suggest an important role for leukocyte amine components in myeloperoxidase-catalyzed antimicrobial activity in vivo.
Ecological determinants in microbial colonization of the murine gastrointestinal tract: adherence of Torulopsis pintolopesii to epithelial surfaces
Authors: Suegara N , Siegel J E , Savage D C
Published: January 2020

Torulopsis pintolopesii is a yeast indigenous to the gastrointestinal tracts of conventional mice and rats from many colonies. In such natively colonized animals, the organism forms layers on the surface of the epithelium in the secreting portion of the stomach and can be cultured from all areas of the gastrointestinal tract. When given in water or food to germfree mice or specific pathogen-free mice possessing an indigenous microbiota free of yeast, T. pintolopesii also can be cultured from all areas of the tract at population levels ranging from 10(5) to 10(8) cells per g (wet weight). Likewise, as in its native hosts, the organism forms layers on gastric surfaces in the associated animals. The layers form on the secreting surface in both the specific pathogen-free and monoassociated ex-germfree mice. In the latter animal, however, a layer of yeast also forms on the nonsecreting gastric surface. In tests of its capacity to adhere to gastrointestinal surfaces in vitro, the organism adheres to epithelia from all areas of the mouse tract. These findings support an hypothesis that the capacity of T. pintolopesii to adhere to epithelial surfaces may be only one determinant influencing it to form layers on the gastric secreting surface in its native hosts.
Purification and characterization of Clostridium difficile toxin
Authors: Rolfe R D , Finegold S M
Published: January 2020

Recent evidence indicates that toxigenic Clostridium difficile strains are a major cause of antimicrobial-associated ileocecitis in laboratory animals and pseudomembranous colitis in humans. C. difficile ATCC 9689 was cultivated in a synthetic medium to which 3% ultrafiltrated proteose peptone was added. Purification of the toxin from broth filtrate was accomplished through ultrafiltration (100,000 nominal-molecular-weight-limit membrane), precipitation with 75% (NH4)2SO4, and chromatographic separation using Bio-Gel A 5m followed by ion-exchange chromatography on a diethylaminoethyl-Sephadex A-25 column. The purified toxin displayed only one band on polyacrylamide gel electrophoresis, and approximately 170 pg was cytopathic for human amnion cells. The isolated toxin was neutralized by Clostridium sordelli antitoxin, heat labile (56 degrees C for 30 min), and inactivated at pH 4 and 9; it had an isoelectric point of 5.0, increased vascular permeability in rabbits, and caused ileocecitis in hamsters when injected intracecally. Treatment of the toxin with trypsin, chymotrypsin, pronase, amylase, or ethylmercurithiosalicylate caused inactivation, whereas lipase had no effect. By gel filtration, its molecular weight was estimated as 530,000. Upon reduction and denaturation, the toxin dissociated into 185,000- and 50,000-molecular-weight components, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Extensive dissociation yielded only the 50,000-molecular-weight component. The toxin appears to be protoplasmic and is released into the surrounding environment upon autolysis of the cells. Attempts to correlate specific enzymatic activity with the toxin have been unsuccessful. These studies will help delineate the role of C. difficile toxin in antimicrobial-associated colitis and diarrhea.
Opsonization of Cryptococcus neoformans by human immunoglobulin G: masking of immunoglobulin G by cryptococcal polysaccharide
Authors: McGaw T G , Kozel T R
Published: January 2020

Previous studies have shown that attachment of non-encapsulated cryptococci to macrophages is highly dependent on opsonizing immunoglobulin G (IgG) and that cryptococcal polysaccharide inhibits the attachment phase of phagocytosis. We investigated various mechanisms by which cryptococcal polysaccharide might interfere with the opsonizing action of IgG. Cryptococcal polysaccharide did not appreciably prevent binding of opsonizing IgG to the yeast. Furthermore, cryptococcal polysaccharide acted as a noncompetitive inhibitor with respect to the opsonizing action of IgG. These experiments suggested that cell wall-bound IgG is masked in some manner such that it is unable to participate in Fc-mediated phagocytosis. This appeared to be the case, since cryptococcal polysaccharode inhibited agglutination of IgG-opsonized yeast cells by antiserum to IgG. There was good dose-response correlation between the amount of polysaccharide needed to inhibit phagocytosis of non-encapsulated Cryptococcus neoformans and the amount of polysaccharide needed to prevent agglutination of IgG-opsonized cryptococci by antiserum to IgG. The ability of cryptococcal polysaccharide to prevent agglutination of IgG-opsonized cryptococci by antiserum to IgG was lost if dextran, a substance known to enhance agglutination of several particles, was incorporated into the medium.
Enhancement of host resistance against Trypanosoma cruzi infection by the immunoregulatory agent muramyl dipeptide
Authors: Kireszenbaum F , Ferraresi R W
Published: January 2020

N-acetylmuramyl-L-alanyl-D-isoglutamine (muramyl dipeptide [MDP]) enhanced resistance against Trypanosoma cruzi infection in mice. This effect was evidenced by significant reductions in both parasitemias and mortality rates and increased survival time in MDP-treated animals compared with untreated infected mice. MDP effectively augmented host resistance when administered in any one of the following ways: (i) continuous subcutaneous release from an osmotic minipump for a 7-day period starting 2 days before infection; (ii) as a single dose of 0.5 mg injected intraperitoneally 48 h before infection; or (iii) injected intraperitoneally at 48-h intervals during the first 16 days after infection. CBA/J mice, which exhibit very low, insignificant augmentation of reticuloendothelial activity by MDP but are susceptible to its adjuvant effect, failed to manifest enhancement of resistance to T. cruzi infection when treated with MDP under regimens that cause increased resistance in other mouse strains. These results suggest that MDP enhances resistance against T. cruzi infection by stimulating the activity of the phagocytic cells of the host. Adjuvant effect appears to play either a less significant role or no relevant role, except when MDP is administered repeatedly after infection.
Endotoxin toxicity in rats with 6-sulfanilamidoindazole arthritis
Authors: Miller M L , Samuelson C O , Ward J R , Hiramoto R N
Published: January 2020

Seven oral administrations of 6-sulfanilamidoindazole (6-SAI) to 10- to 12-month-old rats sensitized the animals to endotoxin, with dosages as small as 2.5 microgram causing death in 80% of animals. Endotoxin in a dosage of 3,000 microgram was not lethal for nonmedicated control animals. 6-SAI-treated 1-month-old rats were not as sensitive to endotoxin as aged animals. The sulfonamide-induced sensitivity to endotoxin could not be passively transferred and could not be explained by blockade of the reticuloendothelial system or impairment of endotoxin detoxification. 6-SAI administration was associated with both depletion of liver glycogen and lowering of blood glucose concentration without changes in blood lactic acid concentration. Disseminated intravascular coagulation is believed to be involved in the pathogenesis of shock and death as evidenced by: (i) concomitant decreases in plasma fibrinogen concentration and elevations in fibrin degradation products after endotoxin challenge; (ii) protection against lethal actions of endotoxin by pretreatment with heparin. Treatment of 6-SAI-medicated rats with glucocorticoids before endotoxin challenge protected the animals against lethal doses of endotoxin and prevented deposition of fibrin thrombi in the glomerular capillaries.
Immunosuppression and isolation of rubella virus from human lymphocytes after vaccination with two rubella vaccines
Authors: Buimovici-Klein E , Cooper L Z
Published: January 2020

Two groups of young rubella-susceptible women were vaccinated with two rubella vaccines. Heparinized blood samples were taken from all individuals the day of vaccination and 5, 7, 15, 21, 30, 35, and 42 days later. Purified lymphocytes from these samples were cocultivated with AGMK cells for rubella virus isolation. Parallel samples of lymphocytes were stimulated with phytohemagglutinin, and the rate of [14C]thymidine incorporation was determined. Rubella virus was isolated from lymphocytes collected on days 7, 15, and 21 after RA27/3 vaccination in contrast to days 7 to 35 after HPV77 vaccination. The lymphocyte response to phytohemagglutinin was markedly suppressed from day 5 to 15. Normal lymphocyte responses were restored within 1 month after vaccination with RA27/3, but even later (1 week) after HPV77 vaccine. Lymphocytes from rubella-susceptible persons infected invitro with rubella virus vaccines and stimulated with phytohemagglutin displayed a decrease in their responsiveness to the mitogen similar to that observed with lymphocytes from vaccinees. The transient immunosuppression observed in vaccinees is probably due to virus-induced functional damage of the lymphocytes since no direct cytocidal effect of rubella vaccine has been demonstrated on human lymphocytes.
Infection of chicken erythrocytes with influenza and other viruses
Authors: Cook R F , Avery R J , Dimmock N J
Published: January 2020

Chicken erythrocytes can be infected by the fowl plague (Rostock) strain (FP/R) of influenza type A, Newcastle disease virus (NDV), and Semliki Forest virus (SFV). Only NDV and SFV produced infectious progeny, albeit at low levels. Infection by FP/R was monitored by de novo synthesis of viral proteins, and the proteins synthesized could be identified by comparison with infected chicken fibroblast cells. FP/R synthesized far greater amounts of viral protein than did NDV or SFV.
Purification and crystallization of fimbrial hemagglutinin from Bordetella pertussis
Authors: Arai H , Munoz J J
Published: January 2020

A procedure to purify and crystallize fimbrial hemagglutinin from Bordetella pertussis is described. Redissolved crystals had the same specific activity as the original, purified solution of fimbrial hemagglutinin. About 97% of the weight of washed crystals was accounted for by amino acids.
Virulence of Escherichia coli in experimental hematogenous pyelonephritis in mice
Authors: van den Bosch J F , de Graaff J , MacLaren D M
Published: January 2020

Differences in nephropathogenicity between Escherichia coli strains were studied by following the kinetics of the viable count in the mouse kidney during 8 h after intravenous injection. Assuming as a reference point that at zero time 0.1% of the inoculum was lodged in the kidney, we found that strains fell into three main groups with different behavior patterns: in group I, the viable count fell and remained low; in group II, the viable count first fell and then rose after 4 h, reaching the level of the reference point within 8 h; in group III, the viable count rose rapidly and remained high. The kinetics of the viable counts were also studied in blood, spleen, and liver: group I and II strains behaved similarly; only in the kidney did group II strains show higher counts than group I strains. These data suggest that group II strains are specifically virulent for the mouse kidney. Group III strains also gave higher viable counts in blood and spleen but comparable counts in the liver, suggesting that group III strains are more generally virulent. Fifty percent lethal dose measurements confirmed the conclusion that group I strains are avirulent and group III strains are the most virulent. Possible relationships between behavior pattern and serotype are discussed.
Complement components (C1, C2, C3, C4) in bronchial secretions after intranasal infection of guinea pigs with Mycoplasma pneumoniae: dissociation of unspecific and specific defense mechanisms
Authors: Loos M , Brunner H
Published: January 2020

Shortly after intranasal infection of guinea pigs with Mycoplasma pneumoniae, the titers of the complement components increased significantly in bronchial secretions by the folllowing amounts, compared with the titer of a control group: C1, about 2-fold; C2, 1.6-fold; C3, 17-fold; and C4, 942-fold. Histopathological signs of inflammation were not apparent at this time. At 2 weeks after infection, when the titers of complement components in the bronchial secretions were at the level of control values or lower, the serum antibody titer increased, and it reached the highest level at 6 weeks after infection. Therefore, one can distinguish two phases of reaction of the macroorganism to intranasal inoculation. The increase in complement components shortly after infection may represent an earlyunspecific defense mechanism of the host before the specific immune response becomes effective, since the complement system can be activated by M. pneumoniae via the classical as well as the alternative pathway in the absence of antibodies.
Microbial ecological basis of infant botulism as studied with germfree mice
Authors: Moberg L J , Sugiyama H
Published: January 2020

The possible role of the indigenous intestinal microflora in the toxicoinfection of human infant botulism was studied with adult germfree mice. Intraintestinal botulinum monoassociation was consistently produced when mice were fed 10 C. botulinum type A spores. Control germfree mice became enterically infected when placed in the same isolator with, but separated from, animals that had been fed spores. When transferred into a room holding a colony of normal mice, the highly susceptible gnotobiotes became resistant to challenge of 10(5) spores after about 3 days of the conventionalizing exposure. The findings are interpreted as evidence that enteric botulinum infection occurs in human infants whose intestinal tract has not yet been colonized by bacteria which are indigenous to adults and prevent growth of C. botulinum. Intestinal monoassociation could not be developed in germfree infant mice younger than 7 days.
Adherence of
Actinomyces viscosus
T14V and T14AV to Hydroxyapatite Surfaces In Vitro and Human Teeth In Vivo
Authors: Wheeler Timothy T. , Clark William B. , Birdsell Dale C.
Published: January 2020

Adsorption of
Actinomyces viscosus
strains T14V and T14AV to hydroxyapatite (HA) surfaces was studied, using an adsorption model based on the Langmuir adsorption isotherm. Data generally followed the adsorption model as judged by high correlation coefficients obtained for both strains to most of the treated surfaces studied. The number of binding sites for strains T14V and T14AV cells to human saliva-treated HA was similar to that for untreated HA. The affinity of strain T14V for saliva-treated HA was tenfold greater than the affinity of strain T14AV for that surface. To approximate the pellicle of the gingival crevice and margin and to determine whether adherence by strain T14V was to specific saliva or serum receptors, experimental pellicles were formed on HA by saliva/serum mixtures. The number of binding sites on the saliva/serum-treated HA remained the same as for the saliva-treated surface. Although the affinity of strain T14V cells for the saliva/serum HA surface remained generally the same as the affinity for the HA treated with saliva alone, the affinity of strain T14AV cells decreased further as the serum content increased. Strain T14V cell numbers adsorbed to serum-treated HA, and albumin-treated HA were less than those adsorbed to saliva-treated HA, indicating that the adherence by strain T14V was to specific saliva receptors. In vivo results from streptomycin-resistant mutants of both strains T14V and T14AV confirmed in vitro results using saliva-serum pellicles. Pretreatment of strain T14V with proteolytic enzymes and heat inhibited adherence to saliva-treated HA, suggesting that the adherence receptor(s) on the cell surface of strain T14V is protein in nature.
Hormonal and type-dependent adhesion of group B streptococci to human vaginal cells
Authors: Botta G A
Published: January 2020

Adhesion of group B streptococci to epithelial cells of the human vagina proved to be type dependent and to fluctuate during the menstrual cycle with a maximum near the time of ovulation. Oral contraception completely abolished the observed cyclic changes. Reduced serum levels of luteinizing hormones (less than 5 mIU/ml) and of follicle-stimulating hormone (less than 10 mIU/ml) were associated with a 10-fold reduction in adhesion of B streptococci to vaginal cells.
Purification and partial characterization of heat-stable enterotoxin of enterotoxigenic Escherichia coli
Authors: Takeda Y , Takeda T , Yano T , Yamamoto K , Miwatani T
Published: January 2020

Heat-stable enterotoxin was purified from a strain of enterotoxigenic Escherichia coli 53402 A-1 from human intestine. The cells were cultured in Casamino Acids-yeast extract-salts medium, and the purification procedure consisted of protamine sulfate treatment of the culture supernatant, ultrafiltration with an Amicon PM-10 membrane, diethylaminoethyl-cellulose column chromatography, hydroxyapatite column chromatography, Bio-Gel P-10 gel filtration, 90% ethanol extraction, and preparative polyacrylamide gel disc electrophoresis. About 300-fold purification was achieved, with a yield of about 12%. However, the homogeneity of the purified heat-stable enterotoxin was not rigorously demonstrated. The purified heat-stable enterotoxin had an absorption maximum at about 275 nm, and its isoelectric point was about 3.90. The molecular weight of the purified heat-stable enterotoxin was ca. 4,000 by Sephadex G-100 gel filtration. The minimum effective dose of purified heat-stable enterotoxin was about 2.5 ng in the suckling mouse assay. The purified heat-stable enterotoxin gave a positive reaction in not only the suckling mouse assay but also the mouse intestinal loop test and the guinea pig skin permeability test.
Experimental cryptococcosis in normal and B-cell-deficient mice
Authors: Monga D P , Kumar R , Mohapatra L N , Malaviya A N
Published: January 2020

B-cell-deficient mice were prepared by administration of rabbit anti-mouse-mu antiserum to newborn animals within 12 h of birth onwards. Such immunodeficient animals, along with the normal controls, were infected intravenously with Cryptococcus neoformans. There was no difference in the mortality pattern, viable count of cryptococci in different organs, delayed-type hypersensitivity reaction, and antigen level in the sera of control and B-cell-deficient animals. Antibodies were absent in B-cell-deficient animals but were present in low titers in control animals. It is concluded that antibodies are not involved in protection of mice infected with C. neoformans.
Gamma-irradiated scrub typhus immunogens: broad-spectrum immunity with combinations of rickettsial strains
Authors: Eisenberg G H , Osterman J V
Published: January 2020

Scrub typhus immunogens were prepared from Rickettsia tsutsugamushi strains Karp, Kato, Gilliam, Kostival, and Buie by exposing frozen infected yolk sac suspensions to 300 krad of gamma radiation. Mouse protection tests showed that each of the irradiated immunogens protected C3H/HeDub mice against high challenge levels of Karp and Gilliam, but that none of these single-strain immunogens were capable of protecting against all five of the challenge strains. Broad-spectrum protection was achieved by using combinations of three strains of irradiated rickettsiae in a vaccination regimen of three injections at 5-day intervals. A comparison of vaccination efficacy employing three such combinations (Karp-Gilliam-Kato, Karp-Kostival-Kato, and Buie-Kostival-Kato) indicated that both sequential administration of strains on successive vaccination days and multiple injections of trivalent mixtures produced protective responses superior to those obtained with single-strain immunogens. Trivalent mixtures of rickettsiae exhibited a striking synergistic effect on the immune response of C3H/HeDub mice and elicited a protective response against Kato challenge that could not be obtained with any single-strain immunogen. Mice vaccinated with the trivalent Karp-Gilliam-Kato immunogen resisted challenge with more than 10(3) 50% mouse lethal doses of Karp and Gilliam for 12 months, and were resistant to similar levels of challenge with Kato and Buie for 6 months.
Isolation and partial characterization of two different heat-stable enterotoxins produced by bovine and porcine strains of enterotoxigenic Escherichia coli
Authors: Kapitany R A , Forsyth G W , Scoot A , McKenzie S F , Worthington R W
Published: January 2020

Heat-stable enterotoxins (ST-124 and ST-1261) have been isolated from two different enterotoxigenic Escherichia coli of bovine (124) and porcine (1261) origin. The enterotoxin preparations were isolated by ultrafiltration and ion-exchange chromatography and were both active in the suckling mouse test and pig ligated loop test in the nanogram range. The bovine (ST-124) enterotoxin was not stable to heating in its isolated form, and significant differences in amino acid composition were observed between the two enterotoxins. Although both toxins were active at similar levels in the suckling mouse and pig ligated loop tests, ST-124 lacked the ability to cause the profound secretory responses seen with ST-1261 in the weanling pig ligated loop.
Thymosin restoration of cellular immunity to Blastomyces dermatitidis in T-cell-depleted mice
Authors: Longley R E , Cozad G C
Published: January 2020

The immunopotentiating properties of thymosin in thymectomized, lethally irradiated, bone marrow-reconstituted mice (ThyXBM) were characterized, using footpad sensitivity to Blastomyces dermatitidis. Normal mice were shown to exhibit increasing delayed-type hypersensitivity responses to killed yeast cells of B. dermatitidis after injections of the organism on days 0 and 7, as measured by footpad swelling tests. The footpad response of normal thymosin-treated mice was similar to that of normal, non-thymosin-treated mice. ThyXBM mice were unable to elicit a footpad response when similarly injected and footpad tested with B. dermatitidis. Thymosin-treated ThyXBM mice responded to footpad testing at a level that was 62% greater than the response seen in non-thymosin-treated ThyXBM mice. This peak response occurred on day 12. The results indicated that thymosin was unable to enhance immune responses of normal intact mice but could restore immunocompetence in a T-cell-depleted host, as measured by footpad sensitivity to B. dermatitidis.
Interaction of Nocardia asteroides at different phases of growth with in vitro-maintained macrophages obtained from the lungs of normal and immunized rabbits
Authors: Beaman B L
Published: January 2020

The interactions of cells of Nocardia asteroides GUH-2 during different stages of growth with cultured macrophages obtained from the lungs of nonimmunized and immunized rabbits were studied. The nocardial cells from all stages grew intracellularly in "normal" alveolar macrophages; however, log-phase cells increased in numbers more rapidly than did stationary-phase cells. Macrophages obtained from the lungs of specifically immunized rabbits effectively inhibited the growth of stationary-phase cells but only temporarily retarded the growth of log-phase organisms. Specific antiserum added to the nocardial cells before incubation with presensitized macrophages caused enhanced phagocytosis and inactivation of the log-phase cells but had no effect on the fate of the stationary-phase nocardia. In addition, it was fo-nd that log-phase cells were phagocytized less effectively by normal macrophages than were the stationary-phase cells, and log-phase cells were more toxic to the macrophage monolayer. From these data we conclude that secondarily induced macrophages play a major role in host resistance to pulmonary nocardial infections, and antibody may be important for effective host resistance to the filamentous form of N. asteroides. Since the nocardia were able, with time, to overcome these effects, it appears that additional host factors (such as T-lymphocytes) must be involved in an effective host response to N. asteroides.
Susceptibility of inbred mice to chronic central nervous system infection by Theiler's murine encephalomyelitis virus
Authors: Lipton H L , Dal Canto M C
Published: January 2020

The present study demonstrated that the clinicopathological expression of the late demyelinating disease due to chronic central nervous system infection by Theiler's mouse encephalomyelitis virus was dependent, at least in part, on the strain of mouse used as host. A range of involvement was observed, with late disease being most severe in the SJL strain, intermediate in the CBA and C3H/He strains, and least in C57BL/6 mice. The lack of clinical signs in seven other inbred strains of mice indicates that their response to chronic infection was similar to C57BL/6 mice. SJL, CBA, C3H/He, and C57BL/6 mice all generated similar levels of neutralizing antibody. A correlation between the severity of late disease and central nervous system virus content was not demonstrated, which indirectly suggests an immunopathological rather than a cytolytic mechanism of myelin injury during the late disease period. Finally, in addition to being more extensive, SJL demyelinating lesions contained a disproportionately large number of macrophages compared with those of similar lesions in CBA and C3H/He mice.
Polymorphonuclear leukocyte adherence to nylon: effect of oral corticosteroids
Authors: McGillen J , Phair J
Published: January 2020

The effect of orally administered glucocorticoids on polymorphonuclear leukocyte adherence was studied by using the nylon fiber adherence assay. Inhibition of adherence 4 h after administration of the agent was confirmed, and in addition, augmentation of adherence was noted 24 h after ingestion of prednisone. Crossover studies revealed inhibition and augmentation to be cell associated as well as plasma mediated. Suspension of washed, dextran-sedimented polymorphonuclear leukocytes, harvested 4 h after prednisone ingestion in base-line or 24-h plasma failed to reverse inhibition of adherence. Adherence of 24-h polymorphonuclear leukocytes was augmented when suspended in all test plasmas. Plasma-mediated effects were demonstrated by inhibition of base-line adherence of polymorphonuclear leukocytes suspended in 4-h plasma and augmentation of adherence of cells in 24-h plasma. Plasma-mediated effects were reversible by washing.
Biological activity of the slime and endotoxin of the periodontopathic organism Eikenella corrodens
Authors: Behling U H , Pham P H , Nowotny A
Published: January 2020

A partially purified water-soluble slime extract was obtained from two strains of the oral pathogen Eikenella corrodens, designated CS10 A and CS10 B. Endotoxin was also isolated from this organism by the phenol-water extraction procedure. Assays including the local Shwartzman skin reactivity, chicken embryo lethality, Limulus lysate clotting, spleen cell mitogenicity, and immune adjuvancy were used to test the biological properties of these two bacterial extracts. In each of these assay systems the endotoxins of the Eikenella corrodens strains demonstrated the classical endotoxic responses. In contrast, the effect of slime extract in the corresponding assays was either extremely low or absent with the exception of a very strong immunosuppressive effect. Mice treated with slime extract showed a severely reduced immune response to sheep erythrocytes as measured by the hemolytic plaque-forming cell assay.
Comparison of techniques for primary isolation of respiratory Mycoplasma pulmonis from rats
Authors: Lentsch R H , Wagner J E , Owens D R
Published: January 2020

Studies were performed to determine the optimal sites for primary isolation of Mycoplasma pulmonis from the respiratory system of laboratory rats. In a preliminary study, a group of 42 rats was cultured for respiratory M. pulmonis at several sites. Tracheal washes yielded the highest number of positive cultures (61.9%) and ground lung tissue yielded the lowest (19.0%), with the nasopharyngeal culture in the middle (52.38%). In a subsequent study, the tracheal wash was again the optimal method since 76.7% of 103 rats were positive for M. pulmonis, whereas culture of the nasopharyngeal area resulted in 53.9% positive cultures. In a third study, all 45 rats were positive for M. pulmonis when the tracheal wash method was used, whereas only 51% were positive when the nasopharyngeal area was cultured, indicating that the tracheal wash was the most reliable of the commonly used procedures. Other aspects of these experiments demonstrated the tympanic cavity of animals with otitis media to be an excellent source for obtaining material to culture for M. pulmonis.
Demonstration of a new type of immunoglobulin G receptor in Streptococcus zooepidemicus strains
Authors: Myhre E B , Kronvall G
Published: January 2020

Forty-seven bacterial strains representing four different group C streptococcal species were tested for binding of human and bovine immunoglobulin G (IgG) subclasses. Specific binding sites for IgG were found in all bacterial species studied. The four species included differed, however, in their capacities to interact with various IgG subclasses, indicating the existence of different types of IgG receptors. Streptococcus equisimilis and Streptococcus dysgalactiae were found to carry the same type of IgG receptor, one that is identical to the previously described Fc-binding structure type III. A new type of bacterial IgG receptor was detected in Streptococcus zooepidemicus strains. This receptor exhibits a protein A-like subclass specificity, with binding of human IgG1, IgG2, and IgG4 and of bovine IgG2. However, differences in their capacities to interact with other non-human immunoglobulins indicated that these two immunoglobulin-reactive structures were different. All types of IgG receptors in group C streptococci were found to be heat stable but susceptible to proteolytic enzymes. The inability of human serum albumin or fibrinogen to inhibit the uptake of radiolabeled IgG shows that the IgG receptor is separate from binding sites for these two other proteins on the bacterial cell surface. The existence of similar IgG receptors in closely related streptococcal species suggests that these structures have a common origin.
In vitro studies of interaction of rickettsia and macrophages: effect of ultraviolet light on Coxiella burnetii inactivation and macrophage enzymes
Authors: Little J S , Kishimoto R A , Canonico P G
Published: January 2020

The inactivation of Coxiella burnetii in suspension or in cultures of guinea pig peritoneal macrophages by ultraviolet (UV) light was studied. The effect of UV treatment on the activity of macrophage organelle marker enzymes and their subsequent equilibration in linear sucrose gradients was also determined. It was shown that UV treatment of 600 mu W/cm2 for 15 s at a distance of 10 cm inactivated C. burnetti, either in suspension (10(8) organisms per ml) or within guinea pig peritoneal macrophages. Similar UV treatment had little effect on the activity or equilibration of macrophage organelle marker enzymes in linear sucrose gradients. However, longer exposure caused considerable inactivation of these enzymes.