bluuebunny/crossref_metadata_2025 huggingface dataset:
Protective Effect of Immunization with Heat-Labile Enterotoxin in Gnotobiotic Rats Monocontaminated with Enterotoxigenic
Escherichia coli
Authors: Klipstein Frederick A. , Engert Richard F. , Short Helen B.
Published: January 2020

The protective effect of active immunization with a purified preparation of the polymyxin-release form of
Escherichia coli
heat-labile enterotoxin (LT), administered using a parenteral prime and peroral boosts given after ablation of gastric secretion by means of cimetidine, was assessed in gnotobiotic rats which were challenged by monocontamination with enterotoxigenic strains of
E. coli.
Water transport was evaluated by the in vivo marker perfusion technique at weekly intervals over a 3-week period after contamination. Water transport in unimmunized control rats was consistently in absorption in those contaminated by a nontoxigenic strain, in secretion during only week 2 in those contaminated by an LT
+
/− strain, in secretion during weeks 2 and 3 in those contaminated by an LT
+
/ST
+
(heat-stable enterotoxin) strain, and consistently in absorption in those contaminated by an −/ST
+
strain. Rats immunized with a booster dosage of 250 μg had a significant increase (
P
< 0.001) in net water absorption as compared to unimmunized rats, with values in the borderline range of absorption, when challenged with either the LT
+
/− or LT
+
/ST
+
strains. Rats immunized with a 10-fold-higher boosting dosage had a significant increase (
P
< 0.001) in net water absorption as compared to those boosted at the lower dosage; water absorption was within the normal range. There was no difference between the ileal bacterial counts of unimmunized and immunized rats challenged by the various strains. These observations indicate that this immunization program provides complete protection in an animal model against challenge by intestinal contamination with enterotoxigenic strains of
E. coli
which produce LT, either alone or in combination with ST.
Regulation and function of ammonia-assimilating enzymes in Streptococcus mutans
Authors: St Martin E J , Wittenberger C L
Published: January 2020

The ability of Streptococcus mutans to synthesize amino acids was examined. A total of 8 of 12 laboratory strains grew anaerobically on solid-defined medium that contained no amino acids. Several isolates, therefore, assimilated ammonia for the biosynthesis of amino acids. These strains included representatives of five serotypes. One strain, DR0001, was also grown in liquid-defined medium. The enzymes of two pathways by which ammonia can be fixed were detected in this strain DR0001 could use either a reduced nicotinamide adenine dinucleotide phosphate-coupled glutamate dehydrogenase or the combined action of adenosine 5'-triphosphate-driven glutamine synthetase with a reduced nicotinamide adenine dinucleotide-coupled glutamate synthase to assimilate ammonia for the biosynthesis of amino acids. Evidence that both pathways were functional was provided by an analysis of the influence of the nitrogen source on enzyme levels and by the isolation and characterization of glutamate dehydrogenase-negative mutants.
Cytomegalovirus-specific lymphocyte transformations in subjects of different ages with primary immunodeficiency
Authors: Tamura T , Chiba S , Abo W , Chiba Y , Nakao T
Published: January 2020

The role of specific cell-mediated immune responses in human cytomegalovirus (CMV) infections was studied by an in vitro lymphocyte transformation test, using a whole blood culture. CMV-induced in vitro lymphocyte proliferation was mainly dependent on the presence of sensitized T-cells. Three of five seronegative patients with B-cell deficiency showed positive lymphocyte responses to CMV antigen. In contrast, a patient with ataxia-telangiectasia who was shedding the virus in urine did not show a cellular response to either CMV or phytohemagglutinin. Age-related differences were found in the CMV lymphocyte transformation test. The responses were generally low (P less than 0.025) in infants and higher in older children and adults. CMV lymphocyte transformation responses were lower in 15 children who were excreting CMV in urine when tested than in 17 seropositive children who were not excreting the virus.
125I-labeled peptide mapping of some heat-modifiable proteins of the gonococcal outer membrane
Authors: Swanson J
Published: January 2020

Gonococci from opaque colonies have cell wall outer membrane proteins that are lacking from organisms which form transparent colonies. These "colony opacity-associated" proteins are among a group of "minor" proteins that exhibit heat modification of their apparent subunit molecular sizes, are easily extracted by deoxycholate, have apparent subunit molecular weights varying from 24,000 to 29,000 and are exposed on the surfaces of gonococci. Other minor proteins found on gonococci are the "leukocyte association proteins," whose presence correlates with reactivities of gonococci with human neutrophils. Several of the colony opacity-associated proteins and leukocyte association proteins were subjected to 125I-peptide mapping of protein bands separated by polyacrylamide electrophoresis in the presence of sodium dodecyl sulfate. The structural similarities and differences among these heat-modifiable surface proteins were studied, as well as their similarities with the major protein of the gonococcal outer membrane. A relatively high apparent degree of structural homology is found among the heat-modifiable proteins from different strains of opaque colony gonococcal forms. There is also some apparent structural homology for 125I-peptides of heat-modifiable versus major proteins of the gonococcal outer membrane.
Detection of Escherichia coli enterotoxins in stools
Authors: Merson M H , Yolken R H , Sack R B , Froehlich J L , Greenberg H B , Huq I , Black R W
Published: January 2020

We determined whether enterotoxigenic Escherichia coli diarrhea could be diagnosed by direct examination of stools for heat-labile (LT) and heat-stable (ST) enterotoxins. The Y-1 adrenal cell and an enzyme-linked immunosorbent assay (ELISA) detected LT in 85 and 93%, respectively, of stool specimens obtained from adults with acute diarrhea from whom an LT- and ST-producing organism had been isolated. Furthermore, the ELISA assay detected LT in 8 of 35 stool specimens from which no LT-producing E. coli had been isolated. The infant mouse assay was utilized to detect ST in these stool specimens and was found to be an insensitive method, showing positive results in only 36% of the specimens from which an ST-producing organism was isolated. Further studies are warranted to determine the diagnostic value of direct detection of LT in stools, especially by the ELISA method.
Fatty acid binding sites of serum albumin as membrane receptor analogs for streptococcal lipoteichoic acid
Authors: Simpson W A , Ofek I , Beachey E H
Published: January 2020

The ability of bovine serum albumin to inhibit the binding of group A streptococcal lipoteichoic acid (LTA) to human cells was investigated. Albumin blocked the ability of LTA to sensitize erythrocytes to agglutinate in the presence of anti-LTA in a dose-dependent manner. The inhibition of LTA binding to erythrocytes was demonstrated directly with radiolabeled LTA. At an albumin/LTA molar ratio of 1.5:1, albumin binding of the radiolabeled LTA at erythrocytes was inhibited by 45%. Analysis of the binding of radiolabeled LTA to erythrocytes in the presence of albumin indicated that albumin competitively inhibited the binding of LTA to putative cell membrane receptors, indicating that albumin and erythrocytes both bind to the same moiety on the LTA molecule.
Role of Kupffer Cells, Complement, and Specific Antibody in Bactericidal Activities of Perfused Livers
Authors: Friedman Richard L. , Moon Robert J.
Published: January 2020

The relative roles of Kupffer cells, complement, and specific antibody in liver antimicrobial activities were investigated by using a rat liver perfusion model. Normal livers trapped an average of 60% of
Salmonella typhimurium
in a single pass and in the presence of plasma killed more than 60% of these organisms in 30 min. Livers depleted of Kupffer cell function by silica treatment had significantly less bactericidal ability (ca. 15%) in the presence of plasma, showing that viable Kupffer cells are required for optimal antimicrobial activity. To determine the importance of complement in
Salmonella
killing, plasma complement activity was inhibited by heating at 57 and 50°C, zymosan absorption, chelation with disodium ethylenediaminetetraacetate (EDTA) and depletion of rat C3 by using specific immunoabsorbent. All treatments significantly reduced bactericidal activity in the perfused liver. Chelation of plasma with EDTA had no effect, suggesting that the alternate and not the classical pathway for complement activation was involved. Immune plasma alone was bactericidal. When immune plasma was heated, zymosan absorbed, or chelated with EDTA, bactericidal activity was inhibited in the perfused liver, but bacterial trapping increased. These results suggest that complement is required for bactericidal activity in perfused livers and that specific antibody only enhances bacterial trapping.
Surface properties of Chlamydia psittaci
Authors: Vance D W , Hatch T P
Published: January 2020

The surface properties of elementary bodies of Chlamydia psittaci were investigated by diethylaminoethyl-Sephadex chromatography, cytophoresis, partitioning in an aqueous polymer two-phase system, and hydrophobic interaction chromatography of the organism. The surface of C. psittaci was found to be hydrophobic and negatively charged at pH 7 and to have an isoelectric point of about pH 5. Reagents which block free carboxyl groups altered the surface charge of C. psittaci and caused the organism to agglomerate. The possible significance of hydrophobicity and surface charge on the ingestion of C. psittaci by host cells is discussed.
Comparative analysis of plasmids and some metabolic characteristics of Escherichia coli K1 from diseased and healthy individuals
Authors: Silver R P , Aaronson W , Sutton A , Schneerson R
Published: January 2020

All 62 Escherichia coli strains possessing the K1 capsular polysaccharide contained plasmid deoxyribonucleic acid, and most (51 of 62) had multiple plasmid species. The incidence of hemolysins, colicins, hemagglutinins for human erythrocytes, and plasmids did not differ among K1 strains isolated from the cerebrospinal fluids of neonates with meningitis or among those strains isolated from the stools of healthy individuals of all ages. There was an association between E. coli serotype and the distribution of plasmids, hemolysins, and colicins among the K1 strains. A common plasmid of about 65 megadaltons was found in all of the O18 serotypes; the similarity of these plasmids was confirmed by analysis with the restriction endonuclease EcoRI. Plasmids of similar molecular weight were also present in E. coli strains of the O7:K1 and O75:K100 serogroups. These data are consistent with the hypothesis that E. coli strains of the same serotype may be descendents of a single bacterial clone.
Properties of homogeneous heat-labile enterotoxin from Escherichia coli
Authors: Clements J D , Yancey R J , Finkelstein R A
Published: January 2020

Recently, the heat-labile enterotoxin (LT) of Escherichia coli has been purified to homogeneity and partially characterized (Clements and Finkelstein, Infect. Immun. 24:760-769, 1979). This study extends our observations on the physicochemical properties of LT. The toxin has an isoelectric point of pH 8.0, as compared with choleragen and choleragenoid, which have isoelectric points of pH 6.75 and 7.75, respectively. Sedimentation equilibrium measurements established an approximate molecular weight for LT of 91,440. LT had an even more marked affinity than choleragen for agarose-containing matrixes in gel filtration. Of several mono- and disaccharides tested, only galactose and lactose were highly efficient in removing 125I-labeled LT from agarose-containing columns. LT dissociated into subunits (designated A and B) during gel filtration in the presence of 5 M guanidine. These subunits were immunologically distinct and possessed unique and shared antigenic determinants to the corresponding A and B subunits of choleragen. During gel filtration of LT at pH 6.5 and room temperature, a spontaneously occurring toxoid of LT, analogous to choleragenoid, was discovered and designated "coligenoid." This product contains only the B subunits of the toxin. A partial amino acid sequence of the B subunit of LT revealed a remarkable homology to the primary structure of cholera toxin B. Within the first 20 amino acids of the two chains, only 5 differ, and these differences may be attributable to single base substitutions.
Evans blue dye adjuvant enhances delayed hypersensitivity while blocking immunity to Mycobacterium tuberculosis in mice
Authors: Anderson D W , Crowle A J
Published: January 2020

Evans blue dye functions as an adjuvant with protein antigens in saline to induce cell-mediated immunological responses in mice. But when used to help induce cell-mediated tuberculoimmunity, it decreased mouse resistance to tuberculosis instead of helping induce immunity. This paradox was investigated. As could be expected from previous work with other antigens, the dye did promote induction of delayed hypersensitivity in mice to tuberculoprotein when injected in saline with killed tubercle bacilli. Peritoneal macrophages from mice injected with the dye responded normally to migration inhibition factor. Morphologically, these cells were moderately "activated" compared with similar cells taken from untreated mice. However, such cells incubated with tuberculosis growth inhibition lymphokine in an in vitro test for tuberculoimmunity did not express tuberculoimmunity, whereas macrophages from untreated mice did. Therefore, Evans blue dye did promote induction of cell-mediated immunological responses and tuberculoimmunity in lymphocytes, but under the conditions used in these experiments, it also blocked expression of tuberculoimmunity by macrophages.
Adherence of Neisseria meningitidis to human epithelial cells
Authors: Salit I E , Morton G
Published: January 2020

Carrier strains of Neisseria meningitidis are recovered almost solely from the posterior pharynx and they are often nongroupable or rough. Invasive strains can be serogrouped (encapsulated). We studied adherence of both carrier- and patient-derived serogroupable and nongroupable meningococci to buccal epithelial and posterior pharyngeal cells. Fresh meningococcal isolates attached significantly better to pharyngeal than to buccal cells (P = 0.01). Strains that could be serogrouped adhered less than nongroupable strains (P less than 0.05). Meningococci passed in vitro became hemagglutinin negative and nonpiliated. Hemagglutinin-negative meningococci always adhered less to both epithelial cell types than the hemagglutinin-positive variants of the same strain. These results indicate that meningococcal pili probably mediate attachment to oropharyngeal cells, but encapsulation may reduce adherence. Localization of meningococci in the posterior pharynx is in part explained by the receptivity of the epithelial cells in this area for meningococci.
Factors influencing release of type III antigens by group B streptococci
Authors: Doran T I , Straus D C , Mattingly S J
Published: January 2020

The release of serotype III group B streptococcal polysaccharides into the supernatant fluid was examined under a variety of physiological conditions. Release of both high- and low-molecular-weight type III antigens was fairly constant throughout exponential growth, but increased markedly upon entering the stationary phase of growth. Increased glucose and decreased phosphate concentrations both caused a large increase in release of antigens. Inhibition of protein synthesis in exponentially growing cells by chloramphenicol (10 micrograms/ml) caused a condition of unbalanced growth in which antigen release was increased greatly over control values. Strain variability in antigen release was also observed. Strains which are known to be high neuraminidase producers released elevated levels of both low- and high-molecular-weight type III antigens. Non-neuraminidase-producing strains released considerably less high-molecular-weight antigen, but similar levels of the low-molecular-weight antigen compared with the high neuraminidase producers. Strain D136C, a type III non-neuraminidase producer, released negligible quantities of the high-molecular-weight antigen in the supernatant fluid. These results indicate that both the physiological environment and the type III strain are important in determining the quantity of type-specific antigen released into the culture fluid.
Plasmids in Yersinia pestis
Authors: Ferber D M , Brubaker R R
Published: January 2020

Pesticinogenic and Ca2+-dependent strains of Yersinia pestis harbored plasmids of about 6 and 45 megadaltons, respectively. In addition, most isolates examined possessed a cryptic 65-megadalton plasmid.
Immediate hypersensitivity to Cryptococcus neoformans
Authors: Tang Y J , Morelli R
Published: January 2020

The role of the capsular polysaccharide in anaphylactic reactions to Cryptococcus neoformans was investigated. Groups of mice were sensitized with viable cells of either a moderately encapsulated strain of C. neoformans or a non-encapsulated variant. Anaphylactic reactions were observed in both groups of mice to a similar extent when challenged with whole cells. Mice sensitized with the encapsulated strain and challenged with homologous polysaccharide showed only mild hypersensitivity symptoms. Mice sensitized with either the encapsulated or the nonencapsulated strain showed cross-reactivity when challenged with killed cells of the heterologous strain. These data indicate that the capsular polysaccharide plays a minor role in anaphylactic reactions to C. neoformans and that the sensitizing antigen is probably located in the cell wall of the yeast.
Lysis of herpes simplex virus-infected cells early in the infectious cycle by human antiviral antibody and complement
Authors: Cromeans T L , Shore S L
Published: January 2020

Chang liver (CL) cells and human embryonic lung fibroblasts (MRC-5) were infected with type 1 herpes simplex virus (HSV), ant the time postinfection at which these cells became susceptible to lysis by antiviral antibody and complement of human origin was determined in a 51Cr release assay. Using a 1:2 dilution of fresh HSV antibody-positive human serum, we initially detected specific lysis by 4 h postinfection in HSV-infected CL cells and by 3 h postinfection in HSV-infected MRC-5 cells in suspension. MRC-5 cells were more completely lysed than CL cells. Protein inhibition studies with cycloheximide showed that all of the HSV-infected CL cells and most (83%) of the HSV-infected MRC-5 cells injured early in the infectious cycle were attacked because of newly synthesized viral surface antigens rather than because of adherent input virus. Suspension cells early in the infectious cycle were less completely lysed and required higher concentrations of both antiviral antibody and complement for lysis than cells that were in the later stages of infection (18 h postinfection). Guinea pig serum was inferior to human serum as a complement source for lysis of early infectious cycle cells. Lysis early in the infectious cycle was directly proportional to the multiplicity of infection and inversely proportional to the cell concentration. Infected cells in monolayers were lysed less readily and about 1 to 2 h later in the infectious cycle than infected cells in suspension. This difference was pronounced for CL cells, but modest for MRC-5 cells. These studies demonstrate that, despite previously held notions, HSV-infected tissue culture cells can be lysed by antiviral antibody and complement early in the infectious cycle before the initial production of progeny virus particles. The demonstration of lysis was highly dependent on experimental conditions, however, including cell type, suspension versus monolayer culture, cell density, and concentration of antibody and complement as well as the source of complement.
Antibody-producing cell responses to an isolated outer membrane protein and to complexes of this antigen with lipopolysaccharide or with vesicles of phospholipids from Proteus mirabilis
Authors: Karch H , Nixdorff K
Published: January 2020

Antibody-producing cell responses of mice to a protein isolated from the outer membrane of Proteus mirabilis were typical of the responses to a thymus-dependent antigen. The immunoglobulin G antibody-producing cell responses to the protein were increased after administration of the antigen complexed with either lipopolysaccharide or with vesicles of phospholipids extracted from P. mirabilis. The protein in turn significantly increased the immune response to lipopolysaccharide and also converted this response from predominantly immunoglobulin M to predominantly immunoglobulin G.
Extracellular glycoprotein from virulent and avirulent Cryptococcus species
Authors: Ross A , Taylor I E
Published: January 2020

Two virulent strains of Cryptococcus neoformans and two nonvirulent forms (C. albidus and C. laurentii) were grown in liquid culture to produce maximal capsule formation. A glycoprotein was isolated from the culture medium and was homogeneous as determined by cellulose acetate electrophoresis and anion-exchange chromatography. The amino acid, neutral sugar, amino sugar, uronic acid, and O-acetyl compositions and the infrared spectra of the glycoprotein were determined. The product of the C. neoformans strains contained more mannose and uronic acid than did that from the nonpathogenic strains. O-acetyl groups were absent from glycoprotein of the two nonpathogens.
Opsonization of encapsulated Cryptococcus neoformans by specific anticapsular antibody
Authors: Kozel T R , Follette J L
Published: January 2020

Antisera prepared in rabbits against either whole encapsulated cells of Cryptococcus neoformans or purified cryptococcal polysaccharide were opsonic for the encapsulated yeast. The opsonic activity was removed by absorption with whole cryptococci and was inhibited by free polysaccharide. As little as 0.13 microgram of cryptococcal polysaccharide produced a 50% inhibition of opsonization. Various degrees of neutralization by polysaccharides from the four cryptococcal serotypes suggested that the opsonins were type specific. Fractionation of antiserum on Bio-Gel A-5m (Bio-Rad Laboratories) and diethylaminoethyl cellulose showed that the opsonins were antibodies of the immunoglobulin G class. These opsonizing antibodies did not require heat-labile serum components for optimal phagocytosis of the yeast. Inhibition studies using 2-deoxy-D-glucose demonstrated that ingestion of encapsulated cryptococci opsonized with anticapsular antibody was a 2-deoxy-D-glucose-inhibitable process. This result differed from similar studies with non-encapsulated cryptococci which showed that ingestion of non-encapsulated cryptococci opsonized with normal serum was not inhibited by 2-deoxy-D-glucose.
Hyaluronate capsule prevents attachment of group A streptococci to mouse peritoneal macrophages
Authors: Whitnack E , Bisno A L , Beachey E H
Published: January 2020

The antiphagocytic properties of the streptococcal hyaluronic acid capsule were explored in a system in which binding of the organism to the phagocyte, but not ingestion, could occur. The capsule was found to be highly effective in preventing attachment of two strains of group A streptococci to mouse peritoneal macrophages. Variation in attachment with phase of growth in broth culture (low in early log phase, high in late-log phase and thereafter) could be accounted for by production and subsequent loss of capsule. Hyaluronidase treatment removed the capsule and increased adherence; treatment with proteolytic enzymes removed M protein and decreased resistance to phagocytosis in whole human blood but did not remove the capsule or increase adherence to the mouse peritoneal macrophages.
Periodontal bone loss and immune response to ovalbumin in germfree rats fed antigen-free diet with ovalbumin
Authors: Taubman M A , Buckelew J M , Ebersole J L , Smith D J
Published: January 2020

A technique for the characterization of rat gingival lymphocytes has been described. The technique was used to obtain gingival cells from rats maintained on antigen-free diets or such diets with ovalbumin (OVA) added. Increases in gingival lymphocyte numbers in the antigen-fed (AF) animals occurred by 16 to 23 days of OVA feeding. The elevated gingival lymphocyte numbers were predominantly T lymphocytes at the initial intervals of the experiment (to 59 days of OVA feeding). At 128 days of OVA feeding T-lymphocyte numbers diminished but B-lymphocyte numbers increased, and AF animals had more than six times as many gingival B lymphocytes as animals not fed antigen. Also, AF animals showed immunoglobulin A antibody in intestinal perfusates (after 9 days of OVA feeding) and in saliva (within 23 days of OVA initiation). Plasma immunoglobulin G antibodies were not detected until 59 days of feeding. Spleen cells from AF rats showed in vitro blastogenic responses to OVA at 23 to 59 days of feeding. Periodontal bone loss was greater in AF animals after 59 and 128 days of OVA. Germfree animals fed only one antigen experienced more periodontal bone loss than animals fed the same diet not containing antigen. Therefore, immune phenomena can contribute to experimental bone loss in germfree rats.
Virus-specific cytotoxic activity to mammary tumor cells of sera from normal and tumor-bearing mice with inhibition at low dilutions
Authors: Creemers P
Published: January 2020

Sera from normal mice and mice bearing murine mammary tumor virus (MTV)-induced tumors showed cytotoxic reactions to the MTV-producing Mm5mt/c1 cell line. The reaction could be blocked by the addition of MTV, but not of purified gp52 and p28. In sera from tumor bearers, cytotoxic responses ranged from 15 to 66%; reactivity was generally highest when the serum was diluted 32 to 128 times. The cytotoxic sera from the normal animals showed a much lower activity; again, there was a lack of cytotoxic response at lower serum dilutions. Low dilutions (1 to 64) of sera from tumor-bearing and normal mice were found to inhibit the MTV-specific cytotoxic activity of rabbit anti-MTV serum on the Mm5mt/c1 cell line. Specificity of this phenomenon was deduced from the fact that there was less inhibition by the mouse sera of anti-Rauscher leukemia virus-specific cytotoxic activity to Rauscher leukemia virus-infected cells and of anti-vaccinia virus serum to vaccinia virus-infected cells. Absorption of the mouse sera with rabbit anti-gp52 serum almost completely abolished the inhibition; after absorption with MTV, inhibition was somewhat reduced. The effect of free gp52 and MTV/anti-MTV immune complexes on the anti-MTV immune response is discussed.
Influence of Cultural Conditions on Mitomycin C-Mediated Bacteriophage Induction and Release of
Salmonella
Toxin
Authors: Peterson Johnny W. , Houston Clifford W. , Koo Felix C. W.
Published: January 2020

Several isolates of
Salmonella
were examined for the capacity to synthesize and release a cholera toxin-like toxin that exerted a biological effect on Chinese hamster ovary cells. Measurements of this
Salmonella
toxin, which was contained in cell sonic extracts and culture filtrates, were expressed in cholera toxin equivalents (nanograms), since the Chinese hamster ovary cell responses of the cholera toxin and the
Salmonella
toxin were indistinguishable. Comparative titrations of
Salmonella
preparations were also performed by using an enzyme-linked immunosorbent assay specific for cholera toxin antigen. The amount of
Salmonella
toxin synthesized was low (nanogram levels), but the toxin was detectable in cell sonic extracts as early as 6 h after culture inoculation and reached maximal levels by 12 h.
Salmonella
toxin antigen was not detectable in control culture filtrates until 48 h, but the addition of mitomycin C at 8.5 h resulted in the sudden appearance of toxin antigen at 10 to 12 h, and the toxin antigen level reached a maximum at 14 h. A large peak of Chinese hamster ovary cell activity was observed at 48 h in the control culture, but significant Chinese hamster ovary cell activity was detected as early as 14 h. A larger amount of Chinese hamster ovary cell-reactive material was observed as early as 10 h in cultures grown with mitomycin C. The mechanism of the mitomycin-mediated phenomenon that yielded more toxin in culture filtrates was associated with bacteriophage induction. A bacteriophage plaque assay with a susceptible
Salmonella
strain revealed that there were free bacteriophage in mitomycin-treated culture filtrates (but not control culture filtrates) at 12 h. Toxin production was greatest when cultures were grown at 30 to 37°C and lowest when cultures were grown at 25°C. The inoculum size and degree of culture aeration (agitation) had little effect on synthesis of the toxin, and toxin production occurred during anaerobic growth.
Strain differences in lymphocyte responses and in vitro suppressor cell induction between Schistosoma mansoni-infected C57BL/6 and CBA mice
Authors: Lewis F A , Wilson E M
Published: January 2020

Splenic lymphocyte blastogenic responses to mitogens and antigens were compared in Schistosoma mansoni-infected C57BL/6 and CBA mice. At 1 and 2 weeks of infection, elevated responses to phytohemagglutinin (PHA) were noted in C57BL/6, but not in CBA cultures. During the same period, elevated responses to lipopolysaccharide were observed in cultures from CBA, but not from C57BL/6 mice. Responses to both mitogens were depressed in both strains later in infection. The magnitude of antigen-specific responses was greater in CBA than in C57BL/6 cultures. A cercarial extract (CE) induced significant suppressor cell activity in normal C57BL/6 cell cultures as assessed by inhibition of syngeneic cell responsiveness to PHA. CE did not induce suppressive activity in CBA cultures. CE-induced suppression was unaffected by adherent cell removal, but was sensitive to anti-Thy 1.2 plus complement treatment. CE also directly inhibited PHA-stimulated C57BL/6 cell cultures, but enhanced cultures of CBA mice. The significance of these findings is discussed in relation to the relative strain differences seen in antigen-specific lymphocyte proliferation and the levels of protection induced after immunization with irradiated cercariae.
Antigenic and genomic analyses of influenza A(H1N1) viruses from different regions of the world, February 1978 to March 1980
Authors: Nakajima S , Cox N J , Kendal A P
Published: January 2020

Antigenic analysis of influenza A(H1N1) virus isolates by hemagglutination inhibition reactions with postinfection ferret sera and mouse monoclonal antibodies showed that, although the predominant virus in 1978 to 1979 had an A/Brazil/11/78-like hemagglutinin, several new antigenic variants could be detected which differed from those identified in 1977 to 1978. Most of the variants showed very minor changes and did not achieve epidemiological significance. Genome analysis by ribonucleic acid-ribonucleic acid hybridization, and supported by oligonucleotide mapping, indicated that nonrecombinant H1N1 viruses cocirculated in the world with recombinant H1N1 viruses, identified in 1978 to 1979. The results of our antigenic analysis and genomic analysis, in conjunction with genomic analysis by other authors, showed that recombinants with A/USSR/90/77-like and A/Brazil/11/78-like hemagglutinin had different genome compositions, indicating that H3N2 virus recombined separately with these different antigenic variants. Prevalence of the nonrecombinant and recombinant H1N1 viruses varied between regions of the world, and influenza A(H1N1) virus with a genotype almost identical to that of nonrecombinant A/Brazil/11/78 virus reappeared as a cause of local outbreaks in the United States in 1980 despite the predominance of recombinant H1N1 strains in the preceding winter.
Protective effect of low-dose interferon against neonatal murine cytomegalovirus infection
Authors: Cruz J R , Dammin G J , Waner J L
Published: January 2020

Mice were injected with 10 to 5,000 reference units of interferon intraperitoneally or subcutaneously within 24 h of birth and reinoculated intraperitoneally 24 h later with 200 plaque-forming units of murine cytomegalovirus. Mock interferon and virus diluent were the control inocula. Infection of mock interferon-treated mice resulted in significant retardation of growth, accompanied by tissue injury and a depressed blastogenic response of splenic lymphocytes. Prophylactic administration of interferon prevented growth retardation and resulted in lower tissue viral titers and diminished injurious effects of the virus. Intraperitoneal inoculation of interferon was more protective than was subcutaneous, and 10 U of interferon was often as effective as 5,000 U. Accelerated maturation and enhanced activity of lymphoid elements were observed histologically in spleens and lymph nodes of interferon-treated mice; supportive of these findings was the greater incorporation of [3H]thymidine of splenocytes from interferon-treated mice. The protective effect of interferon may, therefore, be due to stimulation or accelerated maturation of cellular immune functions.
Effect of Bacteroides fragilis on the peritoneal clearance of Escherichia coli in mice
Authors: Reznikov M , Finlay-Jones J J , McDonald P J
Published: January 2020

A report that Bacteroides fragilis inhibited the killing of facultative anaerobes by human leukocytes in vitro prompted us to look for such inhibition in the peritoneal cavities of mice. No evidence that this phenomenon was operative could be found.
Immunochemical analysis of intact M protein secreted from cell wall-less streptococci
Authors: van de Rijn I , Fischetti V A
Published: January 2020

M protein is a major virulence factor of group A streptococci, which provides these organisms with protection against phagocytosis in the absence of specific antibody. To gain insight into the nature of the native M-protein molecule, type 12 M protein was isolated and purified from the extracellular supernatants of a group A streptococcal L form and stabilized protoplasts. The intact purified M protein from both sources had a molecular weight of 58,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is in contrast to the 32,0000-dalton molecule isolated from the parent type 12 organism by using a nonionic detergent. The purified secretory M protein removed opsonic antibodies from type 12 rabbit immune serum, as demonstrated by a bactericidal assay. Therefore, it appears that either previous nondestructive methods of M-protein isolation have not removed intact M protein from cell walls or part of the molecule is fragmented during its association with cell walls.
Specificity and reversibility of chemotactic deactivation of human monocytes
Authors: Falk W , Leonard E J
Published: January 2020

The chemotactic deactivation of human monocytes was studied to provide insight into the mechanism of chemotaxis. Deactivation was dependent on the dose of chemoattractant and time of incubation. A concentration in the cell suspension of 10(-8) M N-formylmethionylleucyl phenylalanine (FMLP) for 45 min at 37 degrees C led to 60% suppression of the subsequent specific chemotactic response. Higher concentrations of FMLP led to almost 100% specific suppression. Deactivation was specific under all conditions used. The response to a nonrelated chemoattractant, human serum-derived C5a, was unaffected by incubation in FMLP. Deactivation was also transient. If cells were deactivated at 37 degrees C with FMLP, they recovered within 6 h at 37 degrees C from this deactivation. Both phenomena, deactivation and recovery from deactivation, were temperature dependent. Monocytes could not be deactivated at 0 degrees C, and they did not recover from deactivation when kept at 0 degrees C. Thus, specific deactivation appears to require cellular metabolism, involving loss of receptors or blocking of a step between receptor occupancy and response.
Failure of chlorpromazine to inhibit fluid accumulation caused by Escherichia coli heat-stable enterotoxin in suckling mice
Authors: Takeda T , Honda T , Takeda Y , Miwatani T
Published: January 2020

We studied the effect of chlorpromazine on fluid accumulation caused by purified heat-stable enterotoxin (ST) from enterotoxigenic Escherichia coli in suckling mice. We found that chlorpromazine inactivated ST itself in vitro, but did not inhibit the activity of ST in the intestines.
Effect of siderophores on virulence of Neisseria gonorrhoeae
Authors: Finkelstein R A , Yancey R J
Published: January 2020

The virulence of Neisseria gonorrhoeae for chicken embryos can be modified in a predictable manner by the addition of microbial siderophores to the inoculum. "Meningobactin" and "gonobactin," siderophores isolated from iron-limited cultures of meningococci and gonococci, respectively, enhance the virulence of the relatively avirulent colony type 3 (T3) organisms, but have essentially no effect on the virulence of T1 organisms. Both of these compounds were found previously to stimulate in vitro growth of the pathogenic Neisseria spp. under conditions made iron limiting by the addition of conalbumin, the transferrin counterpart of chickens. Similarly, ferrated schizokinen and arthrobactin, both dihydroxamate siderophores which stimulated growth in iron-limited conditions in vitro, also enhanced virulence of T3 organisms, whereas desferrioxamine B mesylate (Desferal), a trihydroxamate previously shown to be inhibitory in vitro, decreased the virulence of the T1 colony form. This was due to the iron-binding function of the molecule, as the iron-saturated form, ferrioxamine B mesylate, did not affect virulence. An additional trihydroxamate siderophore, ferrichrome A, which was inactive on Neisseria spp. in either the deferri- or ferrated forms in vitro, likewise did not affect virulence in the chicken embryo model. The neisserial siderophores were more effective than the other microbial siderophores in enhancing virulence of T3 gonococci. The results add to the evidence that the ability to acquire iron is an important determinant of virulence.
Comparison of two toxins produced by Clostridium difficile
Authors: Taylor N S , Thorne G M , Bartlett J G
Published: January 2020

Clostridium difficile was shown to produce a toxin which could be biochemically separated from the previously described cytotoxin of the same organism. The two proteins differ in biological activity and physical properties. Antiserum prepared to the second toxin does not neutralize the biological activity of the cytotoxin, and immunological cross-reactivity could not be demonstrated. However, some relationship may exist between the two toxins, since the newly described toxin degrades on polyacrylamide electrophoresis into two molecules, one of which appears to migrate with the band of purified cytotoxin. We suggest that this newly described toxin be designated toxin A until its primary biological activity and physical relationship to cytotoxin is determined. This toxin is active in biological assays of enteric disease and may play an important role in C. difficile-induced colitis.
Analysis of age-dependent resistance to murine coronavirus JHM infection in mice
Authors: Pickel K , Müller M A , ter Meulen V
Published: January 2020

Resistance to intraperitoneal murine coronavirus JHM infection in mice develops with age. C3H mice were found to be fully susceptible up to the age of 20 days and resistant after 23 days of age. Protection of susceptible animals from death due to infection could be achieved by maternal antibodies or by transfer of spleen cells from immunized, but not from nonimmunized, donor mice. Lack of protection by transfer of unprimed adult spleen cells was not related to immunosuppression by the host. Moreover, resistance of adult mice could not be abrogated by application of lymphocytes from suckling mice, although immune suppression by other means did affect the resistance of adult animals. On the other hand, spleen cells from nonimmunized mice could be primed with inactivated JHM virus in suckling mice and protected these mice from death due to a subsequent virus infection. Thus, the outcome of infection with JHM virus in suckling and adult mice can be influenced by immunological events, but is not exclusively due to the different stages of immune competence.
Metabolic and synthetic activities of Pneumocystis carinii in vitro
Authors: Pesanti E L , Cox C
Published: January 2020

Pneumocystic carinii organisms obtained from the lungs of rats with glucocorticoid-induced pneumocystosis retained a number of metabolic activities during in vitro culture for 48 to 72 h. They were able to metabolize [14C]glucose to 14CO2, to synthesize proteins from 3H-amino acids, and to synthesize ribonucleic acid from [3H]uridine. Utilization of [14C]glucose was inhibitable by excess unlabeled glucose, mannose, fructose, 2-deoxy-D-glucose, iodoacetate, and pentamidine, but not glycerol or trimethoprim-sulfamethoxazole. Protein synthesis was almost completely inhibited by incubation with high concentrations of cycloheximide, pentamidine, suramin, and chloroquine, but not by rifampin, tetracycline, or gentamicin. In additional experiments, P. carinii organisms that had been incubated overnight in the presence of potentially lethal agents were tested for their ability to utilize [14C]glucose in inhibitor-free medium as a test of viability. Pentamidine, at concentrations which caused only modest inhibition of glucose metabolism, protein synthesis, amino acid transport, or ribonucleic acid synthesis, was lethal, whereas trimethoprim-sulfamethoxazole was not.
Serology of Neisseria gonorrhoeae: W-antigen serogrouping by coagglutination and protein I serotyping by enzyme-linked immunosorbent assay both detect protein I antigens
Authors: Sandstrom E G , Knapp J S , Buchanan T B
Published: January 2020

A total of 224 strains were serogrouped by coagglutination (COA) and serotyped by protein I enzyme-linked immunosorbent assay (ELISA). Of these strains, 61 were from patients with disseminated gonococcal infection, 21 were from patients with pelvic inflammatory disease, and 115 were from patients with uncomplicated gonococcal infection in Singapore, the Philippines, and Denmark. Twenty-seven were laboratory reference strains. Of the patient strains, 102 belonged to COA serogroup WI, and all of the 100 strains that typed with protein I serotypes 1, 2, or 3 were in this group. Most of the strains of gonococci from the 61 patients with disseminated gonococcal infection were within this group (COA WI, 53 or 87%; protein I serotypes 1, 2, or 3, 51 or 84%). All 46 strains that were protein I serotypes 4 through 7 were also COA serogroup WII. Protein I serotypes 8 and 9 accounted for 49 (25%) of the 197 patient strains. Twenty-eight of these strains typed as COA serogroup WII, 20 typed as serogroup WIII, and 1 typed as serogroups WII and WIII. COA W serogrouping and protein I ELISA both appeared to detect antigens on the protein I molecule of the outer membrane of Neisseria gonorrhoeae. Protein I serotyping, which uses unboiled organisms, may generally recognize more variable and surface-exposed antigenic determinants. In contrast, COA W serogrouping, which uses boiled organisms, may recognize less exposed shared antigenic determinants in addition to variable protein I antigenic determinants. Both methods may prove useful for further studies of the epidemiology and pathogenesis of gonorrhea.
Cultivation and partial characterization of spiroplasmas in cell cultures
Authors: Steiner T , McGarrity G J , Phillips D M
Published: January 2020

Spiroplasmas were propagated in the Drosophila melanogaster cell line Dm-1. Spiroplasma citri and unidentified strains (corn shunt organism, 277F [tick isolate], powder puff, BNR-1, honey bee, and OBMG) grew to 10(8) to 10(9) colony-forming units per ml and could be passaged. Cytopathic effect (CPE) varied with the infecting spiroplasma. The honey bee isolate killed Dm-1 within 2 to 4 days and produced CPE in four mammalian cells tested. At 25 degrees C, suckling mouse cataract agent produced no CPE in Dm-1 cells. Dm-1 cells did not support growth of the spiroplasmal sex ratio organism. Spiroplasmas could be detected in the cell cultures by agar inoculation, dark-field microscopy, scanning electron microscopy, and DNA fluorescent staining. The uridine phosphorylase test showed significant levels of conversion of [14C]uridine to [14C]uracil for all but some plant isolates: S. citri, corn shunt organism, lettuce, cactus, and powder puff strains, the first mycoplasmas to lack the enzyme. Primary isolations of corn shunt organism from infected corn plants were made in Dm-1 and I-XII cultures. The course of corn stunt organism infection of Dm-1 was monitored for three passages. The use of agarose and Dienes staining of the colonies improved growth and colony counting of corn stunt organism. The number of viable infected DM-1 cells decreased from 1.2 x 10(7) at passage 1 to 7.0 x 10(6) at passage 2 and 3 x 10(5) at passage 3.
Effect of nitrogen mustard on natural history of right-sided streptococcal endocarditis in rabbits: role for cellular host defenses
Authors: Yersin B R , Glauser M P , Freedman L R
Published: January 2020

Cellular host defenses are considered to be ineffective in bacterial endocarditis; the microorganisms in infected vegetations are protected from phagocytic cells by dense layers of fibrin. To test this hypothesis, nitrogen mustard-induced agranulocytosis and leukopenia were produced in rabbits with right-sided streptococcal endocarditis. The spontaneous sterilization of tricuspid infection observed in the control animals was not present in the granulocytopenic, leukopenic animals. Since the bacterium Streptococcus intermedius is not sensitive to the complement-mediated bactericidal effect of serum and since the animals were not bacteremic during the time of agranulocytosis, an inhibitory effect of the drug on local cellular host defense mechanisms is postulated. We suggest that the spontaneous sterilization of infective endocarditis in the right side of the heart in rabbits is mediated by cellular host defenses.
In vitro infection of murine macrophages with Junin virus
Authors: González P H , Lampuri J S , Coto C E , Laguens R P
Published: January 2020

Mouse peritoneal macrophages were successfully infected with two strains of Junin virus producing high titers with no apparent cell damage. Infected cultures survived longer than noninfected cultures. The pattern of virus release suggested a persistent infection. Virus replication was delayed in macrophages from mice previously immunized with Junin virus. These results support the opinion that macrophages are targets for virus replication in vivo infections.
In vivo changes in complement induced with peptidoglycan-polysaccharide polymers from streptococcal cell walls
Authors: Lambris J D , Allen J B , Schwab J H
Published: January 2020

In rats injected with an arthropathogenic dose of streptococcal cell wall fragments, serum hemolytic activity decreased over the first 24 h and was then elevated from days 2 through 6 after injection. Hemolytic activity was again elevated at days 16 and 40. Levels of activity of alternative complement pathway, C3, and factor D were also altered.