bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutrophils are critical for host defense against primary infection with the facultative intracellular bacterium Francisella tularensis in mice and participate in defense against reinfection
Authors: Sjöstedt A , Conlan J W , North R J
Published: January 2020

It is generally believed that immunity to experimental infection with the facultative intracellular bacterium Francisella tularensis is an example of T-cell-mediated immunity that is expressed by activated macrophages and mediated by Francisella-specific T cells. According to the results presented herein, neutrophils are also essential for defense against primary infection with this organism. It is shown that mice depleted of neutrophils by treatment with the granulocyte-specific monoclonal antibody RB6-8C5 are rendered defenseless against otherwise sublethal doses of F. tularensis LVS inoculated intravenously or intradermally. In neutrophil-depleted mice, the organism grew progressively in the livers, spleens, and lungs to reach lethal numbers, whereas infection was resolved in normal mice. Although neutrophils were found to resistance to reinfection, their participation was less important. The results suggest that neutrophils are needed for defense against primary infection because they serve to restrict the growth of F. tularensis before it reaches numbers capable of overwhelming a developing specific immune response. The exact way that neutrophils achieve this is not clear at this time, although it is probable that they contribute in ways other than by ingesting and killing the bacterium.
Immune and pathologic responses in mice infected with Brucella abortus 19, RB51, or 2308
Authors: Stevens M G , Olsen S C , Pugh G W , Palmer M V
Published: January 2020

Immune and pathologic responses were measured for 20 weeks after infection of mice with Brucella abortus 19, RB51, or 2308. Live bacteria and bacterial antigens of 19 and RB51 persisted in spleens for 10 and 4 weeks after infection, respectively, whereas 2308 bacteria and bacterial antigens persisted for at least 20 weeks. Small germinal centers and profound lymphoid depletion occurred in spleens of mice during the first 4 weeks of infection with strain 19 or 2308; however, mice infected with strain RB51 had much larger germinal centers but no lymphoid depletion. At 4 weeks, only spleen cells from RB51-infected mice proliferated when incubated with 2308 bacteria. Large germinal centers in the spleen and spleen cell proliferative responses to 2308 did not appear in strain 19-infected mice until 6 weeks or in strain 2308-infected mice until 10 weeks. Similar proliferative responses to 2308 occurred in mice infected with strain 19 or RB51 at 6 weeks and in mice infected with strain 19, RB51, or 2308 at 10 weeks. However, at 20 weeks, spleen cell proliferative responses to 2308 occurred in mice infected with strain 19 or 2308 but not in mice infected with strain RB51. Mice infected with strain RB51 had lower and less persistent antibody titers to 2308 than did mice infected with strain 19 or 2308. Collectively, these results indicate that RB51-infected mice have less persistent immune responses to 2308 than do mice infected with 19 or 2308. The shorter duration of the responses probably resulted because RB51 is considerably less pathogenic and is cleared more rapidly from mice than are 19 and 2308.
Acquisition of iron from transferrin and lactoferrin by the protozoan Leishmania chagasi
Authors: Wilson M E , Vorhies R W , Andersen K A , Britigan B E
Published: January 2020

Leishmania chagasi, the cause of South American visceral leishmaniasis, requires iron for its growth. However, the extent to which different iron sources can be utilized by the parasite is not known. To address this question, we studied acquisition of iron from lactoferrin and transferrin by the extracellular promastigote form of L. chagasi during growth in vitro. A promastigote growth medium based on minimal essential medium supplemented with iron-depleted serum supported promastigote growth only after the addition of exogenous iron. The addition of 8 microM iron chelated to lactoferrin or hemin resulted in normal promastigote growth. Ferritransferrin also supported promastigote growth, but only after a considerable lag. Promastigotes grown in all three iron sources generated similar amounts of hydroxyl radical upon exposure to hydrogen peroxide, indicating that none of these protected parasites against generation of this toxic radical. Promastigotes were able to take up 59Fe chelated to either transferrin or lactoferrin, although uptake from 59Fe-lactoferrin occurred more rapidly. 59Fe uptake from either 59Fe-transferrin or 59Fe-lactoferrin was inhibited by a 10-fold excess of unlabeled ferrilactoferrin, ferritransferrin, apolactoferrin, apotransferrin, or iron nitrilotriacetate but not ferritin or bovine serum albumin. There was no evidence for a role for parasite-derived siderophores or proteolytic cleavage of ferritransferrin or ferrilactoferrin in the acquisition of iron by promastigotes. Thus, L. chagasi promastigotes can acquire iron from hemin, ferrilactoferrin, or ferritransferrin. This capacity to utilize several iron sources may contribute to the organism's ability to survive in the diverse environments it encounters in the insect and mammalian hosts.
A mutant toxin of Vibrio parahaemolyticus thermostable direct hemolysin which has lost hemolytic activity but retains ability to bind to erythrocytes
Authors: Tang G Q , Iida T , Yamamoto K , Honda T
Published: January 2020

A mutant toxin, R7, of thermostable direct hemolysin (TDH) with a single amino acid substitution at glycine 62 was analyzed. The hemolytic activity of R7 decreased to less than 1/1,000 of that of wild-type TDH, and its mouse lethality was undetectable. This mutant toxin, however, showed a marked inhibitory effect on hemolysis by wild-type TDH. Enzyme immunoassay and flow cytometric analysis demonstrated that R7 retained approximately 50% of the ability to bind to erythrocytes compared with that of wild-type TDH, suggesting that its inhibition of hemolysis by wild-type TDH might be due to blocking the binding sites on the erythrocyte membrane. Wild-type TDH affected the erythrocyte membrane by causing an influx of calcium and propidium iodide, while R7 showed no detectable effects of these kinds. These results suggest that hemolysis by TDH consists of at least two steps, binding and postbinding, and that R7 is likely to be a postbinding activity-deficient mutant toxin of TDH.
High-molecular-mass lipopolysaccharides are involved in Actinobacillus pleuropneumoniae adherence to porcine respiratory tract cells
Authors: Paradis S E , Dubreuil D , Rioux S , Gottschalk M , Jacques M
Published: January 2020

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The major adhesin of A. pleuropneumoniae has been identified as the lipopolysaccharides (LPSs) (M. Bélanger, D. Dubreuil, J. Harel, C. Girard, and M. Jacques, Infect. Immun. 58:3523-3530, 1990). Using immunoelectron microscopy and flow cytometry, we showed in the present study that LPSs were well exposed at the surface of this encapsulated microorganism. Immunolocalization with porcine lung and tracheal frozen sections showed that extracted LPS bound to the lung mesenchyme and vascular endothelium and to the tracheal epithelium, respectively. Inhibition of adherence of A. pleuropneumoniae with extracted LPS was also performed with lung and tracheal frozen sections. Acid hydrolysis of LPS revealed that the active component of LPS was not lipid A but the polysaccharides. LPSs from A. pleuropneumoniae serotypes 1 and 2 were separated by chromatography on Sephacryl S-300 SF, in the presence of sodium deoxycholate, according to their molecular masses. The adherence-inhibitory activity was found in the high-molecular-mass fractions. These high-molecular-mass fractions contained 2-keto-3-deoxyoctulosonic acid and neutral sugars, and they were recognized by a monoclonal antibody directed against A. pleuropneumoniae O antigen but not recognized by a monoclonal antibody against capsular antigen.
Evidence that verotoxins (Shiga-like toxins) from Escherichia coli bind to P blood group antigens of human erythrocytes in vitro
Authors: Bitzan M , Richardson S , Huang C , Boyd B , Petric M , Karmali M A
Published: January 2020

The interaction of verotoxins (VTs) with human erythrocytes (RBCs) in vitro was investigated, with particular reference to the role of P blood group glycolipids that are structurally related to the known VT receptors. RBC binding of purified VT1, VT2, VT2c, and VT2e was detected by direct and indirect immunofluorescence. Glycolipids were extracted from defined RBCs, separated by thin-layer chromatography, and assessed for VT binding in an overlay assay by adding toxin and specific antibodies. All VTs bound to P1 phenotype (Pk, P, and P1 antigens) and P2 phenotype (Pk and P antigens) RBCs but not to p phenotype (lacking the Pk, P, and P1 antigens) RBCs. Binding of VT1 and VT2 was approximately 10-fold greater to P1 and the rare Pk2 (Pk antigen but no P1 or P antigen) phenotype cells than to P2 phenotype RBCs, whereas VT2e bound equally well to P1 and P2 phenotype cells. The VT1 and VT2 immunofluorescence results correlated with the detection of P1 and/or increased amounts of Pk (globotriaosylceramide) antigen; VT2e immunofluorescence correlated with the detection of P (globotetraosylceramide) antigen. The Pk band pattern and VT binding observed in the thin-layer chromatogram of human P1 and P phenotype RBC extracts varied from that of human kidney and Pk1 phenotype (Pk and P1 antigens) RBCs. We conclude that each VT binds to human RBCs in vitro by utilizing specific P blood group glycolipids as receptors. On P1 and P phenotype RBCs, the accessibility of the Pk antigen for VTs appeared to be restricted. The occurrence of VT-RBC binding in natural VT-producing Escherichia coli disease and its relevance for the pathophysiology of hemolytic uremic syndrome remain to be established.
Bovine T cells specific for Trypanosoma brucei brucei variant surface glycoprotein recognize nonconserved areas of the molecule
Authors: McKeever D J , Awino E , Kairo A , Gobright E , Nene V
Published: January 2020

The specificity of bovine CD4+ T-cell responses to Trypanosoma brucei variant surface glycoprotein (VSG) has been examined by using a panel of seven T-cell clones and nested deletions of the ILTat 1.3 VSG gene expressed in Escherichia coli. All clones recognized the polymorphic N-terminal domain of the antigen, and the recognition sites of five of the clones were resolved to three areas with lengths of 14, 18, and 21 amino acids. Comparison of these regions with corresponding areas of other VSG molecules, including those derived from the same trypanosomal serodeme, has shown that the sites are not conserved. In the light of recent observations that VSG-specific T-cell responses are induced in mice infected with T. brucei, these results confirm with the belief that immune pressure from T cells may contribute to the generation of antigenic diversity on the surface of African trypanosomes.
Construction of an MR/P fimbrial mutant of Proteus mirabilis: role in virulence in a mouse model of ascending urinary tract infection
Authors: Bahrani F K , Massad G , Lockatell C V , Johnson D E , Russell R G , Warren J W , Mobley H L
Published: January 2020

Proteus mirabilis, a cause of acute pyelonephritis, produces at least four types of fimbriae, including MR/P (mannose-resistant/Proteus-like) fimbriae. To investigate the contribution of MR/P fimbriae to colonization of the urinary tract, we constructed an MR/P fimbrial mutant by allelic exchange. A 4.2-kb BamHI fragment carrying the mrpA gene was subcloned into a mobilizable plasmid, pSUP202. A 1.3-kb Kanr cassette was inserted into the mrpA open reading frame, and the construct was transferred to the parent P. mirabilis strain by conjugation. Following passage on nonselective medium, 1 of 500 transconjugants screened was found to have undergone allelic exchange as demonstrated by Southern blot. Colony immunoblot, Western immunoblot, and immunogold labeling with a monoclonal antibody to MR/P fimbriae revealed that MrpA was not expressed. Complementation with cloned mrpA restored MR/P expression as shown by hemagglutination, Western blot, and immunogold electron microscopy. To assess virulence, we challenged 40 CBA mice transurethrally with 10(7) CFU of wild-type or mutant strains. After 1 week, geometric means of log10 CFU per milliliter of urine or per gram of bladder or kidney for the wild-type and mutant strains were as follows: urine, 7.79 (wild type) versus 7.02 (mutant) (P = 0.035); bladder, 6.22 versus 4.78 (P = 0.019); left kidney, 5.02 versus 3.31 (P = 0.009); and right kidney, 5.28 versus 4.46 (P = 0.039). Mice challenged with the wild-type strain showed significantly more severe renal damage than did mice challenged with the MR/P-negative mutant (P = 0.007). We conclude that MR/P fimbriae contribute significantly to colonization of the urinary tract and increase the risk of development of acute pyelonephritis.
BvgAS-mediated signal transduction: analysis of phase-locked regulatory mutants of Bordetella bronchiseptica in a rabbit model
Authors: Cotter P A , Miller J F
Published: January 2020

Members of the Bordetella genus alternate between two distinct phenotypic phases in response to changes in their environment. This switch, termed phenotypic modulation, is mediated by the BvgAS sensory transduction system. We developed an animal model based on the interaction of Bordetella bronchiseptica with one of its natural hosts, the rabbit. To investigate the importance of BvgAS signal transduction, we constructed constitutive (RB53) and Bvg- (RB54) phase-locked derivatives of a wild-type strain, RB50. RB50 and RB53, but not RB54, established respiratory infections in B. bronchiseptica-free rabbits with an intranasal 50% infective dose of less than 200 organisms, and the course of the infection closely resembled that observed with naturally infected rabbits. Bacteria were recovered from the nasal cavity, larynx, trachea, and lungs in similar numbers from RB50- and RB53-infected rabbits, yet no pathology was detected by histological examination of lung and tracheal sections. The antibody responses in rabbits inoculated with RB50 or RB53 were quantitatively and qualitatively indistinguishable; high titers of antibodies were generated primarily against Bvg(+)-phase-specific antigens. No response against flagella, a Bvg- phase factor, was detected. Assessment of bacteria associated with alveolar macrophages indicated that only a small percentage of bacteria, if any, appear to be residing within lung macrophages. We also tested the ability of these strains to survive in a nutrient poor environment, conditions which may be encountered within certain niches in the host or in an environmental reservoir. The Bvg- phase was advantageous for growth under these conditions. Our results indicate the Bvg+ phase is sufficient for establishment of respiratory tract infection in the rabbit and the normal BvgAS-mediated response to environmental signals is not required during initial colonization. The Bvg- phase may play a role at later stages of infection, including persistence, transmission, or survival in the environment.
Identification of staphylococcal enterotoxin B sequences important for induction of lymphocyte proliferation by using synthetic peptide fragments of the toxin
Authors: Jett M , Neill R , Welch C , Boyle T , Bernton E , Hoover D , Lowell G , Hunt R E , Chatterjee S , Gemski P
Published: January 2020

A series of 13 synthetic peptides, approximately 30 amino acids each, which spanned the entire sequence of staphylococcal enterotoxin B (SEB) were tested to evaluate their effects on T-cell proliferation in a culture system containing elutriated human peripheral blood lymphocytes incubated with a specific ratio of mononuclear cells. Four peptide regions were found to inhibit SEB-induced proliferation; they included sequences 1 to 30 (previously thought to be involved in major histocompatibility complex class II binding), 61 to 92 (sequences which relate to the T-cell receptor site), 93 to 112 (a linear sequence corresponding to the cysteine loop), and 130 to 160 (containing a highly conserved sequence, KKKVTAQEL). Antisera raised to this last peptide were capable of neutralizing SEB-induced proliferation. Antisera raised against the peptides which overlapped this sequence also were somewhat inhibitory. Neutralizing antisera were not produced from any other peptide sequence tested. To determine if any of these effects were nonspecific with regard to SEB-induced proliferation, the peptides were tested for inhibition of phorbol dibutyryl ester-induced proliferation, and only the sequence 93 to 112 (corresponding to the cysteinyl loop region) was consistently inhibitory (40%). Of the regions which displayed inhibition of SEB-induced proliferation, the peptide 130 to 160 inhibited binding of 125I-SEB to lymphocytes. These data suggest that the residues containing and surrounding the sequence KKKVTAQEL may be critical in the SEB-induced proliferation and may be useful for developing neutralizing antisera to SEB.
Platelet microbicidal protein alone and in combination with antibiotics reduces Staphylococcus aureus adherence to platelets in vitro
Authors: Yeaman M R , Sullam P M , Dazin P F , Bayer A S
Published: January 2020

Bacterial adherence to platelets on the cardiac valve surface is believed to be critical in the induction of infective endocarditis. Recent studies have confirmed that thrombin-activated platelets secrete platelet microbicidal protein (PMP), which can both kill and exert nonlethal antiadherence effects against endovascular pathogens. In the present study, we quantified the influence of antibiotic and/or PMP exposures on in vitro platelet adherence of two Staphylococcus aureus strains, identical by DNA restriction and cell wall protein profiles, that differed in their susceptibility to PMP-induced killing (PMPs or PMPr, respectively). Adherence assays were performed by flow cytometry in the presence of sublethal PMP concentrations (1 to 2.5 micrograms/ml) alone or in combination with ampicillin (AMP) alone, sulbactam (SUL) alone, or AMP plus SUL (AMP-SUL), at levels achievable in serum. Exposure of the PMPs and PMPr S. aureus strains to antibiotics (for 2 h at 37 degrees C) prior to flow cytometry resulted in no substantive changes in the percent adherence to platelets compared with that for S. aureus cells not exposed to antibiotics, except for modestly increased adherence of both PMPs and PMPr cells exposed to AMP-SUL (18.5 and 15.8% increases, respectively). Addition of PMP to antibiotic-S. aureus mixtures (final 30 min) caused a significant decrease in S. aureus adherence to platelets, for both the PMPs and PMPr S. aureus strains, compared with antibiotic exposure alone (e.g., reduction in platelet adherence from 57.9 +/- 8.2% to 12.2 +/- 3.6% for PMPs cells exposed to AMP-SUL and PMP [P = 0.01]). Moreover, addition of PMP following exposure of the PMPs and PMPr strains to AMP-SUL reversed the enhanced bacterium-platelet adherence observed with such antibiotic exposures alone (P < or = 0.005). These data demonstrate that PMP exerts a potent antiplatelet adherence effect which is independent of its microbicidal capacity, rendering S. aureus cells less adherent to platelets in the presence or absence of antibiotics. Reduction of microbial adherence to platelets by PMP alone or with antibiotics provides further insight into the mechanism(s) that may be involved in host defense and antibiotic prophylaxis of infective endocarditis and other endovascular infections.
Mice immunized with a chlamydial extract have no increase in early protective immunity despite increased inflammation following genital infection by the mouse pneumonitis agent of Chlamydia trachomatis
Authors: Blander S J , Amortegui A J
Published: January 2020

We have determined that immunization with a detergent extract of the mouse pneumonitis agent of Chlamydia trachomatis fails to induce a protective inflammatory immune response following genital infection by C. trachomatis. We demonstrated that mice immunized with the detergent extract have increased cutaneous delayed-type hypersensitivity and increased splenic T-cell proliferation in response to the chlamydial extract. After genital infection by C. trachomatis, extract-sensitized mice had significantly increased genital inflammation (P = 0.044) compared with controls. The inflammation was characterized by significantly increased eosinophils in the genitalia (P < 0.0005) and increased genital edema (P < 0.0005). However, the increased genital inflammation of extract-sensitized mice provided no increase in protection against infection (P = 0.92).
Cytokine gene expression in mice at an early stage of infection with various strains of Listeria spp. differing in virulence
Authors: Xiong H , Kawamura I , Nishibori T , Mitsuyama M
Published: January 2020

By using reverse transcription-PCR, cytokine gene expression was examined in mice 24 h after infection with various strains of Listeria spp. differing in virulence as determined by in vivo growth and 50% lethal dose values. All the virulent strains of Listeria monocytogenes induced the expression of mRNAs specific for interleukin-1 alpha (IL-1 alpha), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) in the spleen of mice, while an L. monocytogenes strain incapable of producing listeriolysin O and strains of Listeria innocua induced the expression of TNF-alpha mRNA only. The levels of expression of IL-1 alpha and IFN-gamma mRNAs were proportional to the levels of listeriolysin O produced by each strain. Those strains which induced the expression of IFN-gamma were capable of generating protective immunity in the infected host, suggesting that the virulence-related induction of some cytokine at the initial stage of infection plays a role in the induction of acquired cellular resistance to L. monocytogenes.
Tryptophan depletion as a mechanism of gamma interferon-mediated chlamydial persistence
Authors: Beatty W L , Belanger T A , Desai A A , Morrison R P , Byrne G I
Published: January 2020

Previous studies have shown that the immune-regulated cytokine gamma interferon (IFN-gamma) activates host cells to restrict intracellular growth of the bacterial pathogen Chlamydia trachomatis by induction of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO). Recently, subinhibitory levels of IFN-gamma were used to generate an in vitro persistent chlamydial infection characterized by large aberrant, noninfectious reticulate bodies from which infectious progeny could be recovered following the removal of IFN-gamma. Studies were done to determine if the mechanism functioning to induce chlamydiae to enter a persistent state in the presence of low levels of IFN-gamma was similar to that reported to inhibit chlamydial growth. Host cells treated with levels of IFN-gamma required to induce persistence were assessed for IDO activity by high-performance liquid chromatography analysis of tryptophan and its catabolic products. Substantial tryptophan catabolism was detected in acid-soluble cellular pools, indicating that the intracellular availability of this essential amino acid was limited under these conditions. In addition, a mutant cell line responsive to IFN-gamma but deficient in IDO activity was shown to support C. trachomatis growth, but aberrant organisms were not induced in response to IFN-gamma treatment. Analyses of infected cells cultured in medium with incremental levels of exogenous tryptophan indicated that persistent growth was induced by reducing the amount of this essential amino acid. These studies confirmed that nutrient deprivation by IDO-mediated tryptophan catabolism was the mechanism by which IFN-gamma mediates persistent growth of C. trachomatis.
Identification and characterization of a Salmonella typhimurium oxygen-regulated gene required for bacterial internalization
Authors: Jones B D , Falkow S
Published: January 2020

Growth of Salmonella typhimurium in a low-oxygen environment induces the ability of these bacteria to enter mammalian cells. We have carried out a search for invasion genes that are expressed under low-oxygen conditions by using Tn5lacZY transcriptional fusions. Several noninvasive oxygen-regulated lacZY insertion strains have been identified. The invasion defect in one of these noninvasive S. typhimurium strains, BJ66, has been complemented by introduction of a cosmid (pBDJ125) from an S. typhimurium SL1344 gene bank. A 1.9-kb EcoRV DNA fragment subcloned from this cosmid, containing a single open reading frame (orgA), restores the ability of BJ66 to invade mammalian cells. Comparative searches of the GenBank and EMBL sequence data banks with the nucleotide sequence of the gene and deduced amino acid sequence of the protein reveal no significant similarities. Interestingly, hybridization of an orgA gene probe with a P22 chromosomal mapping library demonstrated that the orgA gene maps to a region on the chromosome between 57.5 and 60 min where other Salmonella invasion genes have been mapped. Other enteroinvasive bacteria (Shigella flexneri, Escherichia coli, Yersinia spp., and Listeria monocytogenes) lack sequences which cross hybridize to the probe. We have compared the virulence of S. typhimurium SL1344 and an isogenic orgA mutant in a mouse model of typhoid fever. The orgA mutant was as virulent as the wild-type strain was when inoculated intraperitoneally but is significantly reduced (> 60-fold) in its ability to cause disease by an oral route of infection.
Human immune response to Pseudomonas aeruginosa mucoid exopolysaccharide (alginate) vaccine
Authors: Pier G B , DesJardin D , Grout M , Garner C , Bennett S E , Pekoe G , Fuller S A , Thornton M O , Harkonen W S , Miller H C
Published: January 2020

Chronic lung infection with mucoid Pseudomonas aeruginosa is the major pathologic feature of cystic fibrosis. Previous studies suggested that a failure to produce opsonic antibody to the mucoid exopolysaccharide (MEP; also called alginate) capsule is associated with the maintenance of chronic bacterial infection. Provision of MEP-specific opsonic antibodies has therapeutic potential. To evaluate the ability of MEP to elicit opsonic antibodies, humans were immunized with two lots of MEP vaccine that differed principally in molecular size. Lot 2 had a larger average MEP polymer size. Both vaccines were well tolerated, but lot 1 was poorly immunogenic, inducing long-lived opsonic antibodies in only 2 of 28 vaccinates given doses of 10 to 150 micrograms. In contrast, at the optimal dose of 100 micrograms, lot 2 elicited long-lived opsonic antibodies in 80 to 90% of the vaccinates. The antibodies elicited by both lots enhanced deposition of C3 onto mucoid P. aeruginosa cells and mediated opsonic killing of heterologous mucoid strains expressing distinct MEP antigens. These results indicate that the polymers of MEP with the largest molecular sizes safely elicit opsonic antibodies in a sufficiently large proportion of vaccinates to permit studies of active and passive immunization of cystic fibrosis patients against infection with mucoid P. aeruginosa.
Immunodepression by Rowson-Parr Virus in Mice. I. Growth Curves of Rowson-Parr Virus and Immunological Relationships with Friend Virus
Authors: Bendinelli M. , Nardini L.
Published: January 2020

The growth curve of Rowson-Parr virus (RPV) was studied in the spleen of mice infected with RPV only and of mice infected with Friend virus (FV) preparations, which consist of a mixture of RPV and FV. In mice infected with FV preparations, RPV replicated to a higher titer than FV and attained higher levels than in singly infected mice. The chronic viremia of RPV-infected mice was found to coexist with circulating anti-RPV antibodies. These antibodies also neutralize FV and are probably responsible for the resistance against FV conferred to mice by prior infection with RPV.
Effects of Promethazine-Hydrochloride on Human Polymorphonuclear Leukocytes
Authors: DeChatelet Lawrence R. , Qualliotine-Mann Diane , Caldwell Ronald , McCall Charles E. , Gusdon John P.
Published: January 2020

Promethazine hydrochloride at a concentration of 0.033 mg/ml has pronounced effects on leukocyte metabolism and function. The drug inhibits the phagocytosis-induced increases in O
2
consumption and hexose monophosphate shunt activity. Associated with these effects is an inhibition of the iodination of zymosan particles and an inhibition of bacterial killing by the cell. At least two mechanisms appear to be involved. Many of the effects can be explained by an inhibition of phagocytosis, but promethazine also inhibits the decarboxylation of amino acids and iodide fixation in a cell-free system, indicating a specific effect on metabolism. These results may partially account for the action of the drug in ameliorating the effects of erythroblastosis.
Iron-Binding Catechols and Virulence in
Escherichia coli
Authors: Rogers Henry J.
Published: January 2020

Previous work suggested that virulent bacteria, which can grow rapidly in serum, must possess a specific mechanism for removing iron from its transferrin complex. Two strains of
Escherichia coli
were examined with this in mind. Strain O141, which showed inoculum-dependent growth in serum and multiplied in the mouse peritoneum, secreted iron-binding catechols into both synthetic medium and serum. One of these compounds has an association constant for iron similar to that of transferrin. Both transferrin and ethylenediamine-di-
o
-hydroxyphenyl acetic acid (EDDA), which have very high affinities for ferric iron, induced catechol synthesis in growing cultures of strain O111. This organism was inhibited by normal horse serum. Further work showed that traces of specific antibody inhibited catechol synthesis by O111 exposed to EDDA; therefore, the existence of this inhibitory process means that the organism can no longer obtain Fe
3+
, which all remains bound to transferrin in serum. In vivo, the inhibition of O111 is similar to that produced by serum in vitro. Neither phagocytosis nor killing by complement appeared to be of any significance during the first 4 h of the infections. Significantly, the purified catechol was capable of abolishing bacteriostasis in vivo. Since these results show that the production of iron-binding catechols is essential for rapid bacterial growth both in vitro and in vivo, these compounds should therefore be considered as true virulence factors. Conversely, any interference by the host with the production or activity of these compounds would constitute an important aspect of antibacterial defense.
Isolation of Streptolysin O by Preparative Polyacrylamide Gel Electrophoresis
Authors: Van Epps Dennis E. , Andersen Burton R.
Published: January 2020

Streptolysin O giving a single band by Ouchterlony and acrylamide gel analysis has been isolated by ammonium sulfate precipitation, Sephadex gel filtration chromatography, and preparative polyacrylamide gel electrophoresis.
Reduction of Antibody Plaque-Forming Cells by Allogeneic Antilymphocyte Serum
Authors: Morgan G. W. , Esposito V. M. , Jarboe William
Published: January 2020

Allogeneic mouse antilymphocyte serum effectively reduced the number of antibody plaque-forming cells after the natural antilytic property had been eliminated by dilution.
Interaction of
Mycoplasma arthritidis
and Other Mycoplasmas with Murine Peritoneal Macrophages
Authors: Cole B. C. , Ward J. R.
Published: January 2020

Neither mouse nor rat peritoneal macrophages were able to kill
Mycoplasma arthritidis
to any observable degree in the absence of specific hyperimmune rabbit antiserum. Although convalescent mouse and rat serum were somewhat inhibitory to
M. arthritidis
in the absence of macrophages, these sera did not promote active phagocytosis by peritoneal macrophages. In fact, the macrophages appeared to protect the mycoplasmas against the inhibitory effects of the antisera by stimulating their growth. Hyperimmune rabbit antiserum against
M. arthritidis
initiated phagocytic action and resulted in a 50-fold decrease in numbers of viable mycoplasmas by 6 h. In contrast with
M. arthritidis, M. pulmonis
rapidly adsorbed to the surface of peritoneal macrophages. Upon addition of specific rabbit antiserum, a rapid decrease in viable organisms occurred, and a more complete destruction of organisms ensued in comparison with
M. arthritidis. M. gallinarum
, as with
M. arthritidis
, did not adsorb to the macrophages to any great extent. Phagocytic action was observed only in the presence of homologous rabbit antiserum and was not marked until after 6 h of incubation.
Relationship of Some
Cryptococcus neoformans
Hypha-Forming Strains to Standard Strains and to Other Species of Yeasts as Determined by Deoxyribonucleic Acid Base Ratios and Homologies
Authors: Erke Keith H. , Schneidau J. D.
Published: January 2020

The taxonomic relationship between some hypha-forming
Cryptococcus neoformans
strains and those that morphologically fit the standard description of this species was determined on the basis of DNA base ratios and DNA-DNA duplex formation. The average guanosine plus cytosine content, as estimated from melting temperature profiles, varied between 43.0 and 45.9% for all
C. neoformans
strains examined. The relative homology was at least 60% for all
C. neoformans
strains when the labeled DNA was from either a hyphal variant or a standard strain. The nonpathogenic cryptococci,
C. laurentii
and
C. uniguttulatus
, showed less than 10% relative homology with either the hyphal or standard
C. neoformans
strains. Thus, hyphal and standard strains of
C. neoformans
were sufficiently related to be considered members of the same species.
Ontogeny of the Bovine Immune Response
Authors: Schultz R. D. , Dunne H. W. , Heist C. E.
Published: January 2020

The ontogenesis of the bovine immune response was studied in three embryos (<40 days) and 106 fetuses of various ages. In the absence of overt antigenic stimulation, fetuses had lymphoid development of the thymus at 42 days of gestation, the spleen was structurally present at 55 days, and certain peripheral lymph nodes were present at 60 days. Mesenteric lymph nodes were structurally present by 100 days of gestation, and lymphoid tissue of the gastrointestinal tract, particularly the lower ileum, was observed in histologic sections of a 175-day fetus with a bacterial infection. Pyroninophilic cells, plasma cells, and germinal centers were present in lymph node sections of antigenically stimulated fetuses. Lymphoid tissue developed more rapidly in fetuses with bacteria, viral antigens, or apparent maternal red-blood-cell antigens than in the normal fetus. Thymic and splenic indices reached maximal values in the 205- to 220-day fetal age group. Immunoglobulin M (IgM)-containing cells were first observed, by immunofluorescence, in a single fetus at 59 days of gestation. Immunoglobulin G (IgG)-containing cells were observed at 145 days of gestation in one fetus with a bacterial and viral infection. IgM-containing cells were observed in 36 fetuses and IgM and IgG cells were present in seven fetuses. Spleen, lymph nodes, thymus, bone marrow, and liver of one fetus from a dam with lymphosarcoma had immunoglobulin-containing cells. Hemal lymph nodes, blood (buffy coat), Peyer patches, and heart and lung sections from fetuses with immunoglobulin-containing cells in spleen or lymph node did not have immunoglobulin-containing cells.

Antigens of the virus of bovine virus diarrhea-mucosal disease (BVD) were detected in one fetus, and antigens of infectious bovine rhinotracheitis (IBR) virus were detected in three fetuses; however, viruses were not isolated in primary bovine embryonic kidney cells. Two of the three fetuses with IBR virus antigens had neutralizing serum antibody titers to IBR virus. Bacteria including
Escherichia coli, Lactobacillus
sp. and
Mima polymorpha
var.
oxidans
were isolated from four fetuses. Antibodies that caused the agglutination of maternal red blood cells were present in 8 of 20 bovine fetal serum samples. The antibodies were 2-mercaptoethanol sensitive and partially heat resistant (56 C for 30 min). The ontogeny of the bovine immune response and human immune response were compared, and it was suggested that the similarities were primarily due to the two species having the same approximate gestation period of 280 days.
Altered Immune Functions in Hypercholesterolemic Monkeys
Authors: Fiser R. H. , Denniston J. C. , McGann V. G. , Kaplan J. , Adler W. H. , Kastello M. D. , Beisel W. R.
Published: January 2020

Humoral and cellular immune responses to several antigens were compared in control and hypercholesterolemic groups of monkeys. Chronic hypercholesterolemia, with concomitant hyperphospholipidemia and hypotriglyceridemia, was produced experimentally by feeding monkeys a high-fat, high-cholesterol diet. When studied prior to infection, hypercholesterolemic monkeys exhibited impaired development of precipitating antibodies against ovalbumin, enhanced sensitivity to tuberculin antigen (stimulated apparently by mycobacterial components in complete Freund adjuvant), and an increased rate of clearance of colloidal carbon from blood. During pneumococcal infection the ability of neutrophiles from hypercholesterolemic monkeys to reduce nitroblue tetrazolium dye showed an increase greater than that of control monkeys; both groups exhibited increased but comparable final clearance rates of colloidal carbon, although the increment of increase was smaller in hypercholesterolemic monkeys.
Effect of Influenza Anti-Neuraminidase Antibody on Virus Neutralization
Authors: Kasel Julius A. , Couch Robert B. , Gerin John L. , Schulman Jerome L.
Published: January 2020

Antibody to influenza virus neuraminidase participates in tissue culture neutralization tests in which inhibition of hemadsorption is the end point. Presumably, by inhibiting virus release it functions additively with anti-hemagglutinin in reducing total virus replication.
Metabolism of
Rickettsia tsutsugamushi
and
Rickettsia rickettsi
in Irradiated Host Cells
Authors: Weiss E. , Green A. E. , Grays R. , Newman L. M.
Published: January 2020

The metabolism of
Rickettsia tsutsugamushi
(Gilliam strain) multiplying in irradiated L cells was investigated by methods involving the use of
14
C-labeled substrates and cycloheximide, an inhibitor of eukaryotic metabolism. Cycloheximide-resistant amino acid and adenine incorporations were appreciably higher in infected than in uninfected cultures during the period from 3 to 5 or 6 days postinoculation. The metabolism of
R. rickettsi
was similarly studied in primary duck embryo cells, which are more susceptible to infection with this rickettsia than are L cells. A difference in cycloheximide-resistant activity between infected and uninfected cultures was also noted, but was small. This finding is attributed to the more limited growth of
R. rickettsi.
Interactions Between Macrophages of Guinea Pigs and Salmonellae III. Bactericidal Action and Cytophilic Antibodies of Macrophages of Infected Guinea Pigs
Authors: Hsu H. S. , Mayo Donald R.
Published: January 2020

The fate of virulent
Salmonella typhimurium
within macrophages of guinea pigs was assessed by a suspended cell culture procedure. The present study confirmed that macrophages of normal guinea pigs were capable of inactivating the ingested salmonellae. Macrophages of previously infected guinea pigs were not endowed with any significant increase in their ability to eliminate the ingested pathogen. However, the immune macrophages were observed to clump together tightly when they were exposed to salmonellae. This phenomenon was attributed to the presence of specific cytophilic antibodies on the immune macrophages. When immune macrophages were inactivated with Merthiolate, they agglutinated with both the H and the O antigens of
S. typhimurium
, but not with the O antigens of other species of
Salmonella
nor with the O antigens of
Escherichia coli.
Cytophilic antibodies could be eluted from immune macrophages by incubation in the absence of immune serum. Conversely, cytophilic antibodies could be passively transferred onto normal macrophages by incubation in the presence of immune serum. Furthermore, using immune serum previously adsorbed with the O antigens of
S. typhimurium
, cytophilic antibodies against the H antigens alone could be transferred onto normal macrophages, or those against the O antigens alone could be eluted from immune macrophages. These data suggest that immune macrophages possess specific cytophilic antibodies against both the H and the O antigens of
S. typhimurium.
It is proposed that the presence of cytophilic antibodies on immune macrophages represents an expression of antibacterial cellular immunity by enhanced clumping and phagocytic activities of the macrophages.
Extraction, Purification, and Chemical and Immunological Properties of the
Streptococcus mutans
Group “a” Polysaccharide Cell Wall Antigen
Authors: Mukasa Hidehiko , Slade Hutton D.
Published: January 2020

An antigen of
Streptococcus mutans
has been extracted from HS6 (group “a”) whole cells and repeatedly fractionated by Sephadex chromatography. The antigen is shown to be a polysaccharide and contains the
S. mutans
group “a” antigenic site and also a second antigenic site which is common to “a” strains and 2 of 3 group “d” strains. Immunological electrophoretic and chromatographic data indicate that the two sites exist in a single molecule. The polysaccharide has a molecular weight of 107,000 and is composed of glucose, galactose, glucosamine, and galactosamine. No significant quantities of lipid, phosphorus, glycerol, or ribitol are present. Immunological specificity of the group “a” polysaccharide site depends primarily on a
d
-glucose ·
d
-glucose sequence, the “a-d” site on a terminal
d
-galactose. Water at 100 C and pepsin (pH 2.5) at room temperature are very effective in extracting the polysaccharide from lyophilized
S. mutans
cells. Trypsin and lysozyme are less effective. The antigen-antibody combining site appears to be located at the cell wall surface. A small quantity of enzyme-resistant protein (5%) is firmly linked to the antigen and is considered to be a remnant of a protein to which the polysaccharide is attached in the cell wall. The composition of the protein does not identify it as a part of the peptidoglycan. No reaction to the purified polysaccharide is obtained with antisera specific for teichoic acid glycerophosphate polymers from streptococci, staphylococci, or lactobacilli.
Occurrence of Neuraminidase and Acylneuraminate Pyruvate Lyase in a Strain of Vibrio Falling into Heiberg's Group II Isolated from a Patient with Diarrhea
Authors: Müller H. E.
Published: January 2020

The enzymes neuraminidase (EC 3.2.1.18) and acylneuraminate pyruvate lyase (EC 4.1.3.3) were found in a strain of vibrio falling into Heiberg's group II isolated from a patient with diarrhea. The neuraminidase of this strain resembles the neuraminidase of Vibrio cholerae. The pH-optimum, activation by Ca-ions and heat inactivation were studied. There is also some indication of an immunologically common antigenicity. The occurrence of this neuraminidase in the Heiberg's group II vibrio stain is discussed especially with reference to the relationship with the well known enzyme of
Vibrio cholerae.
Chemical Characterization of a Cell Wall Antigen from
Streptococcus mutans
FA1
Authors: Burgess Thomas E. , Edwards John R.
Published: January 2020

The cell wall antigen from
Streptococcus mutans
(FA1) was extracted from cell walls and whole cells and was found to contain rhamnose, galactose, and glucosamine in a ratio of approximately 5:2:1.
Transformation of Lymphocytes in Gonorrhea Before and After Therapy
Authors: Esquenazi Violet , Streitfeld Murray M.
Published: January 2020

Patients were studied for lymphocyte transformation responses to a variety of
Neisseria gonorrhoeae
antigens and to a
Neisseria catarrhalis
sonicate. Cells from infected patients manifested significant uptake of tritiated thymidine in response to one or more gonococcal antigens. In some cases, deoxyribonucleic acid synthesis was so marked in lymphocytes not challenged by antigens in vitro that added blastogenesis was either obscured or inhibited. At five weeks posttherapy, lymphocytes were relatively nonreactive to gonococcal antigenic stimulation. Blastogenesis in response to
N. catarrhalis
was also seen for a few gonorrhea patients and normal controls. Cross-antigenicity of catarrhalis organisms and gonococci was indicated by the disappearance of reactivity to catarrhalis sonicate by the lymphocytes of almost all convalescent gonorrhea patients.
Role of Cell-Mediated Immunity in the Recovery of Cattle from Primary and Recurrent Infections with Infectious Bovine Rhinotracheitis Virus
Authors: Davies D. H. , Carmichael L. E.
Published: January 2020

When cattle infected with infectious bovine rhinotracheitis virus (IBRV) were treated 3 months later with a synthetic corticosteroid, consistent recrudescence of the infection was observed. Suppression of cell-mediated immunity, as measured by lymphocyte transformation responses, could be demonstrated at the time of recrudescence. Treatment with adrenocorticotropic hormone and trigeminal neurotomy also resulted in recrudescence of IBRV, but immunosuppression was not detected in these animals. The detection of specific, antigen-induced, lymphocyte transformation responses at the time of recovery from both primary and recurrent infections suggests that cell-mediated immunity may be important in determining the duration and severity of the recurrent infection. However, immunosuppression may not be the direct mechanism of recrudescence.

Lesions were not observed in untreated animals, and virus could not be detected in either tissues or secretions. However, both lesions and virus were found consistently after corticosteroid treatment.
Immunological Quantitation of Hepatic Tryptophan Oxygenase in Endotoxin-Poisoned Mice
Authors: Rippe Delfin F. , Berry L. Joe
Published: January 2020

An apparent inhibition of induction of mouse hepatic tryptophan oxygenase by endotoxin has been reported previously, as evidenced by low catalytic activity. This could be due either to decreased tryptophan oxygenase levels or to inactivation of existing enzyme molecules. To resolve this question, the enzyme was quantitated immunologically in control and endotoxin-poisoned mice. Tryptophan oxygenase was purified and used as an antigen to prepare antienzyme antibodies. The antiserum was shown to be monospecific by immuno-electrophoresis. Addition of the antiserum to high-speed supernatant fluids of liver homogenates of control or endotoxin-poisoned mice resulted in precipitation of the enzyme. Radial immunodiffusion assays revealed that there was less enzyme in livers of mice that received 1 mean lethal dose of endotoxin. It was concluded that endotoxin interfered with the synthetic process that results in enhanced levels of tryptophan oxygenase.
Coupling of Peroxidase to Poliovirus Antibody: Characteristics of the Conjugates and Their Use in Virus Detection
Authors: Herrmann John E. , Morse Stephen A.
Published: January 2020

Antibody to poliovirus type 1 (Po-1) was coupled to peroxidase by use of glutaraldehyde or 4, 4′ -difluoro,3, 3′ -dinitro diphenyl sulfone. Glutaraldehyde was found to be the superior coupling agent, yielding conjugates that had up to 2.8 × 10
4
enzyme units/ml (75% of total enzyme input). Conjugates migrated as a single band when centrifuged in sucrose density gradients, demonstrating that the purification procedure used was effective in removing both noncoupled enzyme and heterogeneous antibody components. Conjugates were specific for Po-1 and did not adsorb to cells infected with unrelated enterovirus types. Adsorption of conjugates to Po-1-infected cells was demonstrable within 6 h postinfection.