bluuebunny/crossref_metadata_2025 huggingface dataset:
Restriction fragment length polymorphisms and sequence variation within the spaP gene of Streptococcus mutans serotype c isolates
Authors: Brady L J , Crowley P J , Ma J K , Kelly C , Lee S F , Lehner T , Bleiweis A S
Published: January 2020

A restriction fragment length polymorphism study was undertaken to determine the extent and location of heterogeneity within spaP encoding the Mr 185,000 cell surface protein P1 (antigen I/II) of Streptococcus mutans serotype c isolates. The gene was found to be highly conserved except for a central variable (V) region predicted to encode less than 150 amino acids. Sequence analysis identified two V-region variants. These differences were independent of the geographic source of the isolates. Southern analysis using synthetic oligonucleotide probes indicated that nonretention of P1 (I/II) by some isolates is not due to a deletion of the 3'-terminal DNA necessary to encode an intact carboxy terminus.
Iron-dependent regulation of diphtheria toxin and siderophore expression by the cloned Corynebacterium diphtheriae repressor gene dtxR in C. diphtheriae C7 strains
Authors: Schmitt M P , Holmes R K
Published: January 2020

A regulatory gene (dtxR) responsible for iron-dependent repression of the toxin (tox) and siderophore genes in Corynebacterium diphtheriae was cloned and characterized. A DNA fragment carrying dtxR repressed expression of a tox-lacZ gene fusion in Escherichia coli DH5 alpha in a high-iron environment but not under low-iron conditions. A protein with mobility corresponding to approximately 28 to 29 kDa was identified as the product of the dtxR gene by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A shuttle vector designated pCM2.6 was constructed which carries the origin of replication from C. diphtheriae plasmid pNG2 and confers resistance to chloramphenicol in E. coli and C. diphtheriae. DNA fragments carrying dtxR were cloned into pCM2.6, and the hybrid shuttle plasmids were transformed by electroporation into wild-type C. diphtheriae C7(beta) and the regulatory mutant C7(beta)hm723, which produces toxin and siderophore constitutively under high-iron conditions. Expression of the cloned dtxR determinant did not affect the phenotype of C. diphtheriae C7(beta). In C. diphtheriae C7(beta)hm723, expression of cloned dtxR restored full repression of siderophore production and partial repression of diphtheria toxin production during growth in a high-iron environment.
Protection against anthrax with recombinant virus-expressed protective antigen in experimental animals
Authors: Iacono-Connors L C , Welkos S L , Ivins B E , Dalrymple J M
Published: January 2020

We previously described the cloning and expression of the protective antigen (PA) gene of Bacillus anthracis in both vaccinia virus and a baculovirus. The antigenicity of the PA products was characterized. PA expressed by the recombinant vaccinia viruses elicited a partial protective immune response against a lethal B. anthracis spore challenge in guinea pigs and mice. The WR strain vaccinia virus recombinant (WR-PA) protected 60% of male mice and 50% of guinea pigs. WR-PA elicited high anti-PA antibody titers in mice but not in guinea pigs. Connaught strain vaccinia virus recombinants failed to protect any immunized animals. PA purified from baculovirus recombinant-infected cultures plus adjuvant partially protected male CBA/J mice and completely protected female Hartley guinea pigs from challenge. Both the recombinant and nonrecombinant PA preparations combined with adjuvant elicited high anti-PA antibody titers in Hartley guinea pigs and CBA/J mice. These data demonstrate that the recombinant baculovirus- and vaccinia virus-produced PAs were immunogenic in both guinea pigs and mice, that the baculovirus-PA recombinant was a useful source of immunogenic PA, and that vaccinia virus-PA recombinants may be feasible live anthrax vaccine candidates worthy of consideration for further development as live vaccines.
Correlation between molecular size of the surface array protein and morphology and antigenicity of the Campylobacter fetus S layer
Authors: Fujimoto S , Takade A , Amako K , Blaser M J
Published: January 2020

The correlation between the molecular size of the surface layer protein (S protein) and both structure and antigenicity of the Campylobacter fetus surface layer (S layer) was investigated in several clinical strains and their spontaneous variants which produce S proteins of molecular weights (MW) different from those of the parents. Only three molecular sizes of the S proteins were observed (98, 127, and 149 kDa) in the parental and variant strains. Immunologically, the 98-kDa protein and the 149-kDa protein but not the 127-kDa protein were cross-reactive. Freeze-etching analysis showed that the 98-kDa S protein formed a hexagonal arrangement with a 24-nm center-to-center space and that the S proteins with larger MW (127 or 149 kDa) formed tetragonal ones with an 8-nm center-to-center space. Thus, the MW changes of the S proteins seen in the variant strains were associated with both morphological and antigenic changes in S layer. These observations support the hypothesis that the pattern and antigenicity of the C. fetus S layer is determined by the particular type of S protein. Furthermore, the presence of the two different S layer patterns on a single bacterial cell indicates that multiple S proteins can be produced and expressed in a single cell.
Further characterization of a potent immunogen and the chromosomal gene encoding it in the Lyme disease agent, Borrelia burgdorferi
Authors: Perng G C , LeFebvre R B , Johnson R C
Published: January 2020

Further characterization of a previously reported 83-kDa antigen of Borrelia burgdorferi and the gene encoding it is reported. The DNA sequence of the gene and the amino acid sequence of the protein were determined. On the basis of the amino acid content, the actual size of the antigen was determined to be 79.8 kDa, rather than 83 kDa as previously reported. The expression of the antigen in several representative North American and European B. burgdorferi isolates was demonstrated. The conservation of the gene within the species was demonstrated by DNA hybridization of a labeled gene probe to several North American and European B. burgdorferi isolates. Of other Borrelia spp. assayed (B. hermsii, B. coriaceae, B. duttonii, and B. anserina), only B. anserina, a poultry pathogen, hybridized to the gene probe and expressed the 79.8-kDa antigen.
Gastrointestinal candidiasis in a murine model of severe combined immunodeficiency syndrome
Authors: Narayanan R , Joyce W A , Greenfield R A
Published: January 2020

A murine model of severe combined immunodeficiency syndrome (scid mice) affords an opportunity to study the interaction of Candida albicans with a host lacking functional B- and T-cell mechanisms. We have previously reported no significant difference in yeast recovery after intravenous challenge of BALB/c mice and scid mice with C. albicans (S. Mahanty, R.A. Greenfield, W.A. Joyce, and P.W. Kincade, Infect. Immun. 56:3162-3166, 1988). In this study, we evaluate the course of gastrointestinal candidiasis after a single oral challenge with C. albicans. BALB/c and scid mice received H2O containing 10(6) C. albicans per ml for 16 h. Half the mice of each strain continuously received H2O containing 1 mg of tetracycline per ml. Stool samples were cultured for yeast twice weekly until they were negative three consecutive times or positive for 8 weeks. Mice were then sacrificed for quantitative cultures of liver, spleen, and kidneys. At eight weeks postinoculation, 2 of 13 BALB/c mice, 0 of 14 BALB/c mice receiving tetracycline, 6 of 12 scid mice, and 8 of 13 scid mice receiving tetracycline had positive stool cultures (P less than 0.05, likelihood ratio chi-square). Quantitative recovery of yeasts from stools was also higher in the scid mice. Cultures of liver, spleen, and kidneys wer negative in all BALB/c mice and essentially all negative in scid mice; a single colony was isolated from the kidney of one scid mouse and the liver of another scid mouse. We conclude that B cells and/or T cells and their products are important in gastrointestinal colonization with C. albicans but that even in their absence, dissemination of infection from the gastrointestinal tract does not consistently occur. Thus, other aspects of host defense must be critical in containing gastrointestinal Candida colonization.
Rosette formation of Plasmodium falciparum-infected erythrocytes from patients with acute malaria
Authors: Ho M , Davis T M , Silamut K , Bunnag D , White N J
Published: January 2020

Noninfected erythrocytes form rosettes around those infected with trophozoites and schizonts of Plasmodium falciparum in vitro. These rosettes are thought to contribute to the microvascular obstruction which underlies the pathophysiology of severe falciparum malaria. To determine whether the percentage of infected erythrocytes forming rosettes for a parasite isolates in vitro correlates with the in vivo severity of disease, we studied the rosette formation behavior of 35 isolates of P. falciparum from patients with uncomplicated, severe, and cerebral malaria. There was a wide variation in the degree of rosette formation (0 to 53%). Four parasite isolates formed rosettes well (30 to 53%), and seven isolates formed rosettes poorly or not at all (0 to 5%), while the majority of the isolates formed rosettes to various degrees between these two extremes. In this relatively small sample of patients, we were unable to demonstrate a significant association between in vitro rosette formation and patients with cerebral malaria or conscious patients with significant renal (serum creatinine greater than 200 mumol/liter) or hepatic dysfunction (serum bilirubin greater than 50 mumol/liter and aspartate aminotransferase greater than 50 Reitman-Frankel units). However, there was an inverse relationship between rosette formation and cytoadherence (r = -0.575, P less than 0.01) which could not be explained on the basis of steric hindrance. This finding suggests that cytoadherence and rosette formation properties are intrinsic to the parasites, with isolates having a greater propensity for one or the other but not both. Further studies are required to establish the occurrence and pathophysiological role of rosette formation in vivo.
Purification and characterization of a new heat-stable enterotoxin produced by Vibrio cholerae non-O1 serogroup Hakata
Authors: Arita M , Honda T , Miwatani T , Ohmori K , Takao T , Shimonishi Y
Published: January 2020

The possible production of a heat-stable enterotoxin (Vc-H-ST) by Vibrio cholerae non-O1 serogroup Hakata was investigated, and the purified Vc-H-ST was characterized. It has a unique amino acid sequence, LIDCCEICCNPACFGCLN. This sequence is quite similar to that of the heat-stable enterotoxin (NAG-ST) produced by V. cholerae non-O1 except for one amino acid (leucine) residue excess at the N terminus. Other characteristics, including biological activity, are compatible with those of NAG-ST.
Shift of excretory-secretory immunogens of Trypanosoma cruzi during human Chagas' disease
Authors: Jazín E E , Luquetti A O , Rassi A , Frasch A C
Published: January 2020

We studied secreted-excreted immunogens in human patients infected with Trypanosoma cruzi. A pair of 45- to 55-kDa antigens and a family of shed acute-phase antigens characterized the acute phase, while antibodies against a 160- to 170-kDa immunogen appeared at the chronic phase of the disease.
A 23-kilodalton protein, distinct from BvgA, expressed by virulent Bordetella pertussis binds to the promoter region of vir-regulated toxin genes
Authors: Huh Y J , Weiss A A
Published: January 2020

Bordetella pertussis coordinately regulates expression of its virulence factors in response to changing environmental conditions. These factors include pertussis toxin, adenylate cyclase toxin, and the filamentous hemagglutinin (FHA). The vir (or bvg) locus has been shown genetically to be required for this coordinate regulation. We have attempted to study the biochemical basis for coordinate regulation. DNA promoter deletion studies from other laboratories have shown that two tandem 20-bp repeats -157 to -117 bp upstream from the pertussis toxin promoter are essential for transcription. A similar 20-bp tandem repeat was found at the same site in the upstream region of the adenylate cyclase toxin promoter but is not present in the FHA or vir promoter region. Gel retardation revealed protein from virulent strains (able to express the virulence genes) but not from avirulent strains (unable to express the virulence genes) bound to the promoter region of the pertussis toxin gene, and this binding could be abolished by competition with an excess of oligonucleotides corresponding to either tandem repeat. The protein was determined to be 23 kDa by Southwestern (DNA-protein) analysis and could bind to either 20-bp oligonucleotide from the pertussis toxin promoter and either 20-bp oligonucleotide from the adenylate cyclase toxin promoter. BvgA, a 23-kDa protein encoded in the vir locus, has been reported to bind to a 14-bp inverted repeat in the FHA promoter which is not present in the pertussis toxin or adenylate cyclase promoter. We could not demonstrate binding of BvgA to the pertussis toxin promoter region. These data suggest that we have identified a second 23-kDa protein, distinct from BvgA but regulated by the vir operon, that binds to DNA sequences required for transcription of some, but not all, vir-regulated genes.
Proteolysis of bacterial membrane proteins by Neisseria gonorrhoeae type 2 immunoglobulin A1 protease
Authors: Shoberg R J , Mulks M H
Published: January 2020

The immunoglobulin A1 (IgA1) proteases of Neisseria gonorrhoeae have been defined as having human IgA1 as their single permissive substrate. However, in recent years there have been reports of other proteins which are susceptible to the proteolytic activity of these enzymes. To examine the possibility that gonococcal membrane proteins are potential substrates for these enzymes, isolated outer and cytoplasmic membranes of N. gonorrhoeae were treated in vitro with exogenous pure IgA1 protease. Analysis of silver-stained sodium dodecyl sulfate-polyacrylamide gels of outer membranes indicated that there were two outer membrane proteins of 78 and 68 kDa which were cleaved by IgA1 protease in vitro in GCM 740 (a wild-type strain) and in two isogenic IgA1 protease-negative variants. Similar results were observed with a second gonococcal strain, F62, and its isogenic IgA1 protease-negative derivative. When GCM 740 cytoplasmic membranes were treated with protease, three minor proteins of 24.5, 23.5, and 21.5 kDa were cleaved. In addition, when outer membranes of Escherichia coli DH1 were treated with IgA1 protease, several proteins were hydrolyzed. While the identities of all of these proteolyzed proteins are unknown, the data presented indicate that there are several proteins found in the isolated membranes of gram-negative bacteria which are permissive in vitro substrates for gonococcal IgA1 protease.
Human Mycobacterium tuberculosis-reactive CD4+ T-cell clones: heterogeneity in antigen recognition, cytokine production, and cytotoxicity for mononuclear phagocytes
Authors: Boom W H , Wallis R S , Chervenak K A
Published: January 2020

CD4+ T cells regulate the protective immune response which follows exposure to Mycobacterium tuberculosis by activating macrophages through the cytokines the CD4+ T cells secrete. In addition CD4+ T cells have been shown to be directly cytotoxic for antigen-pulsed mononuclear phagocytes (monocytes-macrophages). To explore the functional interaction between mycobacterial antigen-specific CD4+ T cells and mononuclear phagocytes further, CD4+ T-cell clones were derived from healthy purified protein derivative-positive individuals. Five T-cell clones were selected for detailed analysis. None responded to the purified recombinant or native mycobacterial antigens of 14, 19, 65, 71, and 30 (alpha-antigen/Ag6) kDa. However, the T-cell clones demonstrated heterogeneity in antigen recognition as measured by their Western blot (immunoblot) responses. Some T-cell clones made only interleukin 2, while others made only interleukin 4; all produced gamma interferon, although in differing amounts. Four of five T-cells clones were cytotoxic for purified protein derivative-pulsed monocytes at 1:1 and 10:1 effector-target cell ratios. When monocytes infected with live M. tuberculosis were used as targets, comparable levels of cytotoxicity were observed. The cytotoxicity was major histocompatibility complex class II restricted and inhibited by antibodies to ICAM-1 and LFA-1 and not by antibodies to tumor necrosis factor alpha, lymphotoxin, and gamma interferon. Cytotoxicity by CD4+ T cells for monocytes pulsed with mycobacterial antigens or infected with live M. tuberculosis is a common property of these cells and appears to be independent of the repertoire of lymphokines produced and not limited to recognition of defined mycobacterial heat shock proteins. Lysis of heavily infected mononuclear phagocytes may be one manner in which CD4+ T cells regulate host immune response to M. tuberculosis.
Antibody response of humans to the circumsporozoite protein of Plasmodium vivax
Authors: Franke E D , Lucas C M , San Roman E
Published: January 2020

We studied the interaction of sera from residents of an area in northern Peru where vivax malaria is endemic with four recombinant DNA-derived circumsporozoite (CS) proteins of Plasmodium vivax. The antigens used in the enzyme-linked immunosorbent assay included one Escherichia coli-produced and three Saccharomyces cerevisiae-produced recombinant proteins. Three of the proteins (NS1(81)V20, Vivax-1, and Vivax-2) contain the entire central repeat region of the P. vivax CS protein, and one protein (Vivax-3) contains only two repeat sequences. Vivax-1, Vivax-2, and Vivax-3 contain different lengths of sequences flanking the repeats. A higher percentage of the sera had antibodies to Vivax-2 and Vivax-3, the two proteins containing the longest nonrepeat sequences, than to NS1(81)V20 or Vivax-1. Children less than 5 years of age did not have immunoglobulin G antibodies to NS1(81)V20; however, they had antibodies to Vivax-1, Vivax-2, and Vivax-3. The finding that individuals living in a malaria-endemic area produce antibodies to peptides containing nonrepeat regions of the CS protein emphasizes the need to characterize the immune response to these regions in naturally exposed and experimentally immunized humans.
Cloning and sequence analysis of the major outer membrane protein gene of Chlamydia psittaci 6BC
Authors: Everett K D , Andersen A A , Plaunt M , Hatch T P
Published: January 2020

The gene encoding the major outer membrane protein (MOMP) of the psittacine Chlamydia psittaci strain 6BC was cloned and sequenced. N-terminal protein sequencing of the mature MOMP indicated that it is posttranslationally processed at a site identical to the site previously identified in the MOMP of Chlamydia trachomatis L2. The nucleotide sequence of the C. psittaci 6BC MOMP gene was found to be 67 to 68% identical to those of human C. trachomatis strains, 73% identical to that of Chlamydia pneumoniae IOL-207, 79% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, GPIC, and 83% identical to that of the C. psittaci ovine abortion strain S26/3. In contrast, the 6BC sequence was found to be greater than 99% identical to the sequences reported for two strains of C. psittaci, A22/M and Cal-10 meningopneumonitis, believed to be of nonpsittacine avian origin. Monoclonal antibody analysis confirmed the nonpsittacine avian origin of A22/M but identified the Cal-10 strain from which the MOMP gene was previously sequenced as a psittacine strain. These results confirm that psittacine and nonpsittacine avian strains of C. psittaci are closely related and distinct from the mammalian guinea pig inclusion conjunctivitis and ovine abortion strains of C. psittaci.
Endocytic mechanisms utilized by chlamydiae and their influence on induction of productive infection
Authors: Reynolds D J , Pearce J H
Published: January 2020

The microfilament-disrupting drug cytochalasin D and, initially, inoculation at 20 degrees C were used to differentiate between phagocytosis (sensitive to both treatments) and pinocytosis (resistant to both treatments) to assess whether chlamydial uptake into McCoy cells occurred by one or both mechanisms and whether each could contribute to productive infection. Both treatments suppressed the infectivity of Chlamydia trachomatis L2/434/Bu and C. psittaci GPIC (the guinea pig inclusion conjunctivitis strain) following static inoculation by only 50%, indicating that there was simultaneous operation of both phagocytosis and pinocytosis during uptake that led to productive infection. Measurement of the entry of organisms by two separate assays established that both strains predominantly used a cytochalasin D-resistant (pinocytic) mechanism, implying that phagocytic uptake was coupled to a higher frequency of productive infection. Integration of the data on infectivity and entry allowed the potential for an organism to infect a host cell to be quantified. This synthesis revealed that for both strains the infectivity potential following phagocytic entry was ca. 10-fold greater than that following pinocytic entry. However, both entry mechanisms were exploited more efficiently by strain L2/434/Bu than by strain GPIC (unless the latter was inoculated with centrifugation), indicating that intrinsic strain properties are more important for infectivity potential than the endocytic mechanism utilized.
Increase of T-cell receptor gamma/delta-bearing T cells in cord blood of newborn babies obtained by in vitro stimulation with mycobacterial cord factor
Authors: Tsuyuguchi I , Kawasumi H , Ueta C , Yano I , Kishimoto S
Published: January 2020

Cord blood T lymphocytes proliferated in vitro in response to mycobacterial organisms but did not proliferate in the presence of tuberculin purified protein derivative. Components recognized by cord blood T cells were resistant to protease digestion. In contrast, T lymphocytes derived from tuberculin-positive adult peripheral blood proliferated when stimulated by the protease-sensitive component of mycobacterial organisms or purified protein derivative, confirming that adult T cells respond to protein components whereas cord blood T cells respond to the nonpeptide component of mycobacteria. In vitro culture of cord blood lymphocytes stimulated by either mycobacterial lysates or the lipid fraction showed increases in the numbers of T-cell receptor (TcR) gamma/delta T lymphocytes with no changes in the numbers of TcR alpha/beta T lymphocytes in contrast to the in vitro cultures of adult blood lymphocytes stimulated with mycobacterial ligands in which no increase of TcR gamma/delta cells was observed. Interleukin-2 receptor (CD25) and Ia antigen (HLA-DR) analyses evidenced the activation of a large proportion of cord blood gamma/delta T cells which had increased after stimulation with mycobacteria in vitro. Further characterization of mycobacterial ligand suggested that the lipid fraction of mycobacterial lysate or trehalose dimycolate-cord factor was the most plausible cause for T-cell proliferation in cord blood. These results suggest that when the gamma/delta T cells in a newborn infant not yet sensitized to any pathogenic organisms are confronted by a mycobacterium, they respond nonspecifically to the mycobacterial organism or its lipid component (cord factor). gamma/delta T cells may therefore play a distinct role in forming the first line of the host defense system against certain microorganisms.
Differential effect of aging on B-cell immune responses to cholera toxin in the inductive and effector sites of the mucosal immune system
Authors: Haq J A , Szewczuk M R
Published: January 2020

The age-associated primary immune response of B cells from the Peyer's patches (PP), the lamina propria (LP), the mesenteric lymph nodes (MLN), and the spleen of mice following oral immunization with cholera toxin (CTx) was investigated. The induction of immune responses was assessed in 4-, 11-, and 24-month-old, individual C57BL/6J male mice by determining the number and isotype of anti-CTx ELISPOT-forming cells (SFC) in the PP, LPL, MLN, and spleen and the titer and isotype of serum anti-CTx antibody. The data indicate a significant age-associated decline in immunoglobulin G (IgG) and IgA anti-CTx SFC in the LP B cells but only in IgA anti-CTx SFC in the PP. No decline was seen in the anti-CTx SFC response in the MLN and spleen. Peroral immunization of mice with CTx resulted in a serum anti-CTx antibody response which was predominantly of the IgG class in all three age groups of mice tested. There was no age-associated decline in anti-CTx IgM, IgG, or IgA titers in serum. Isoelectric focusing and affinity immunoblotting revealed several distinct new antibody clonotypes in the immune serum of old mice following oral immunization with CTx. The results indicate a loss of immune responsiveness to CTx following oral immunization in senescent PP and LP B cells. The MLN and spleen B-cell responses were found to be refractory to the loss of immune function with aging. These findings suggest a differential effect of aging in the inductive and effector sites of the mucosal immune system, and the loss of antigen-specific IgA responses at mucosal sites may have adverse effects on the host's defense against potential pathogens.
Early events in initiation of alternative complement pathway activation by the capsule of Cryptococcus neoformans
Authors: Kozel T R , Wilson M A , Murphy J W
Published: January 2020

The capsule of Cryptococcus neoformans is a powerful activator of the alternative complement pathway. This study examined the manner in which the cryptococcal capsule influences initiation of and early events in complement activation by C. neoformans. These studies examined the effects of the classical and alternative pathways on the kinetics and early sites for deposition of C3 fragments on encapsulated cryptococci, nonencapsulated cryptococci, and zymosan. The results showed that nonencapsulated cryptococci and zymosan are qualitatively and quantitatively similar in the manner in which they initiate complement activation. Both utilize the classical and alternative pathways. Initiation via the classical pathway occurs suddenly and simultaneously at sites distributed over the entire cell surface. Initiation of the alternative pathway by zymosan and nonencapsulated cryptococci is characterized by a lag of 6 to 8 min before appreciable amounts of C3 accumulate on the cells. Alternative pathway initiation by zymosan and nonencapsulated cryptococci occurs at a limited number of focal initiation sites that expand with alternative pathway amplification to cover the cell surface. Presence of the cryptococcal capsule blocks classical pathway initiation, which would normally occur at the cryptococcal cell wall, and produces an initiation that is dependent solely on the alternative pathway. Initiation of the alternative pathway by the cryptococcal capsule is characterized by a lag in C3 accumulation and the appearance of a limited number of focal initiation sites which resemble those observed when the alternative pathway is activated by zymosan and nonencapsulated cryptococci.
Identification of two proteins associated with virulence of Streptococcus suis type 2
Authors: Vecht U , Wisselink H J , Jellema M L , Smith H E
Published: January 2020

The protein profiles of various cell fractions of 180 strains of Streptococcus suis type 2, which were isolated from diseased pigs, from healthy pigs when they were slaughtered, and from human patients, were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The isolates from diseased pigs contained two proteins that were absent in most of the isolates from healthy pigs. One of these proteins was a 136-kDa protein that was previously identified as the muramidase-released protein (MRP). This protein was predominantly detected in protoplast supernatants and culture supernatants. The second protein was a 110-kDa protein that was detected only in culture supernatants and therefore was provisionally called extracellular factor (EF). Three phenotypes of S. suis type 2 strains were recognized. Isolates from organs of diseased pigs mainly belonged to the MRP+ EF+ phenotype (77%), while isolates from tonsils of healthy pigs mainly had the MRP- EF- phenotype (86%). Most of the isolates from human patients contained MRP (89%); 74% had the MRP+ EF- phenotype. These findings confirm the results of previous investigations which demonstrated that S. suis type 2 strains differ in virulence. Monoclonal antibodies raised against the 110-kDa EF recognized proteins with higher molecular weights in culture supernatants of all of the strains with the MRP+ EF- phenotype. However, none of the strains with the MRP+ EF+ phenotype produced these high-molecular-weight proteins. Our results demonstrate that MRP and EF are associated with virulence. This suggests that one or both of these proteins are virulence factors that play a role in the pathogenesis of S. suis type 2 infections in pigs and human patients.
Relative availability of transferrin-bound iron and cell-derived iron to aerobactin-producing and enterochelin-producing strains of Escherichia coli and to other microorganisms
Authors: Brock J H , Williams P H , Licéaga J , Wooldridge K G
Published: January 2020

A method is described for determination of the relative availability of transferrin-bound iron and cell-derived iron to microbial iron-scavenging mechanisms. This involved incubation of parallel cultures of microorganisms in dialysis tubes placed in RPMI 1640 tissue culture medium containing 30%-iron-saturated transferrin and K562 erythroleukemia cells. In one culture the transferrin was labelled with 59Fe and in the other the cells were labelled, and the relative uptake of radioiron by the microorganisms determined. The results showed that Staphylococcus epidermidis and Staphylococcus aureus acquired iron predominantly from cells, while Candida albicans and the enteropathogenic Escherichia coli NCTC 8623 tended to acquire iron from transferrin. E. coli K-12 strains W3110 and LG1705, which (like NCTC 8623) produce the siderophore enterochelin but not aerobactin, acquired predominantly transferrin-bound iron, whereas the related E. coli strains LG1315 and LG1628, which produce aerobactin but not enterochelin, showed a preference for cell-derived iron. When the cells were incubated in the presence of 59Fe-labelled transferrin and 55Fe-labelled ferritin, no difference in relative availability of iron to E. coli was observed, suggesting that differences in the ability of aerobactin and enterochelin to remove iron from intracellular ferritin were not responsible for this preference. These results may help to explain why production of aerobactin, despite its relatively low affinity for iron, is more closely associated with invasiveness in E. coli than is enterochelin production. Reduced availability of cell-bound iron during inflammation may contribute to antimicrobial defenses.
Protein and antigen heterogeneity among strains of Mycoplasma fermentans
Authors: Städtlander C T , Zuhua C , Watson H L , Cassell G H
Published: January 2020

The proteins and antigens of three strains of Mycoplasma fermentans were compared with those of a mycoplasma, designated "Mycoplasma incognitus," recently identified in tissues of AIDS patients. Previous studies have shown that "M. incognitus" is most likely not a new species but rather a strain of M. fermentans. In the present study, one- and two-dimensional electrophoretic analysis demonstrated the expected similarity between these mycoplasmas, but it also demonstrated several distinct protein differences. Nine proteins were identified as strain variable by two-dimensional gel electrophoresis. Also, immunoblot analysis using rabbit antiserum against the type strain of M. fermentans (strain PG 18) documented the occurrence of size heterogeneity in at least one and possibly two other antigens.
Functional evidence that the Ser-195 residue of staphylococcal exfoliative toxin A is essential for biological activity
Authors: Prévost G , Rifai S , Chaix M L , Piémont Y
Published: January 2020

The substitution of the serine 195 residue of staphylococcal exfoliative toxin A by a cysteine residue led to a biologically inactive protein. This result is consistent with the hypothesis that exfoliative toxin A could be a protease or a lipase. However, no protease or lipase activity was detected with the native toxin.
Uptake and Killing of
Mima polymorpha
and
Herellea vaginicola
by the Reticuloendothelial System of Neonatally Thymectomized Nonwasted Mice
Authors: McCloskey Richard V.
Published: January 2020

Phagocytosis and killing of
Mima polymorpha
and
Herellea vaginicola
by the liver, lungs, spleen, and kidneys from neonatally thymectomized nonwasted mice and their sham-thymectomized litter mates were compared. The removal of
M. polymorpha
from blood by these organs, measured 2 and 4 hr after intravenous injection of bacteria, was not affected by thymectomy. Because significantly fewer viable organisms persisted in the liver, spleen, and kidneys, it is concluded that bacterial killing increased after thymectomy. Phagocytosis of
M. polymorpha
by peritoneal macrophages increased in thymectomized mice. Removal of
H. vaginicola
from the blood by the lungs was greater after thymectomy. Thymectomy did not affect the killing of
H. vaginicola
by the liver, spleen, lungs, or kidneys. Killing of
H. vaginicola
by the kidney was less than that by other organs, although this was not affected by thymectomy. Chronic reticuloendothelial stimulation associated with infection was not an adequate explanation for these findings because no wasting syndrome was encountered.
Serological Diagnosis of Tropical Canine Pancytopenia by Indirect Immunofluorescence
Authors: Ristic Miodrag , Huxsoll David L. , Weisiger Rita M. , Hildebrandt Paul K. , Nyindo M. B. A.
Published: January 2020

An indirect fluorescent-antibody test for detection and titration of antibodies to
Ehrlichia canis
, the causative agent of tropical canine pancytopenia, has been described. The organism propagated by an in vitro technique in canine blood monocytes served as an antigen in the test. The specificity of the test was revealed by absence of cross-reactivity between the antigen and sera from dogs infected with various common pathogens and specific sera against eight rickettsial species. The accuracy of the test was ascertained by isolation of the organism from reactor dogs located in and outside the United States. Histopathological examination of nine reactor dogs revealed plasmacytosis of meninges and kidneys in eight of them.
Delayed Hypersensitivity Reactions Provoked by Ribosomes from Acid-Fast Bacilli I. Ribosomal Isolation, Characterization, Delayed Hypersensitivity, and Specificity
Authors: Baker R. E. , Hill W. E. , Larson C. L.
Published: January 2020

Ribosomes and ribosomal subunits of
Mycobacterium bovis
(strain BCG) and
M. smegmatis
have been isolated and employed as skin test antigens in guinea pigs sensitized with homologous or heterologous organisms. Ribosomes and ribosomal subunits were found to be potent antigens for skin test purposes, and the 30
S
subunits were found to be more specific and active than the 50
S
subunits.
Growth of Newcastle Disease Virus and Rubella Virus in Rheumatoid and Nonrheumatoid Synovial Cell Cultures
Authors: Spruance Spotswood L. , Smith Charles B. , Krall Judith , Ward John R.
Published: January 2020

Rheumatoid and nonrheumatoid synovial cell cultures were challenged with Newcastle disease virus and rubella virus in an attempt to confirm reports that rheumatoid synovial cells are relatively resistant to infection with these viruses. Newcastle disease virus caused complete cell destruction by day 7 in both rheumatoid and nonrheumatoid cultures, and peak virus titers were similar. Rubella virus replicated in both rheumatoid and nonrheumatoid synovial cell cultures, and no consistent differences in virus titers were detected. Rubella-infected cell lines were observed for up to 28 days and no virus-specific cytopathic effect was seen.
Response of Mice to Injection of Ribosomal Fraction from Group B
Neisseria meningitidis
Authors: Thomas David W. , Weiss Emilio
Published: January 2020

Ribosomes of strain NOR-7 of group B
Neisseria meningitidis
were isolated by a procedure that included treatment of the cells with sodium dodecyl sulfate, disruption in a French pressure cell, and differential centrifugation. These preparations consisted of 66% ribonucleic acid and 24% protein and sedimented as a single component with a constant of approximately 66
S.
When used in immunodiffusion tests with homologous rabbit antiserum, untreated ribosomes formed two precipitin lines, when treated with ribonuclease three lines, and when Pronase-digested only one distinct line. Qualitatively indistinguishable reactions were obtained with the same antiserum and ribosomes from group A meningococci, but no precipitation occurred with those of
Escherichia coli.
When injected into mice, group B ribosomes elicited an increase in the number of antibody-producing spleen cells demonstrable by the hemolytic plaque technique using unsensitized sheep erythrocytes. Sensitization of the erythrocytes with increasing amounts of supernatant fluid of meningococcal cultures progressively reduced the number of demonstrable plaque-forming cells. Neuraminidase treatment of the erythrocytes increased immune hemolysis, whereas Pronase digestion reduced it. Injected mice were protected against homologous and heterologous meningococcal challenge. Both hemolysis and protection-inducing activities of the ribosomes were unimpaired by ribonuclease, but were reduced by Pronase. It is concluded that the immunological response elicited by the meningococcal ribosomes does not involve the group-specific carbohydrate antigen. The immunological mechanism by which the mice are protected against meningococcal challenge remains unknown.
Ribonucleic Acid-Protein Fractions of Virulent
Salmonella typhimurium
as Protective Immunogens
Authors: Smith Randall A. , Bigley Nancy J.
Published: January 2020

Mice were injected with virulent
Salmonella typhimurium
SR-11 subfractions containing varied amounts of ribonucleic acid (RNA) and protein or with living attenuated
S. typhimurium
RIA. In these mice, maximal resistance to lethal infection by 1,000 or 5,000 median lethal doses of
S. typhimurium
SR-11 was seen 2 to 3 weeks after immunization. The
S. typhimurium
RIA vaccine and a crude ethanol-precipitated RNA fraction (E-RNA) prepared from lysates of
S. typhimurium
SR-11 were the most efficient immunogens inducing protection against salmonellosis. The contribution of the components present in the E-RNA fractions to host protection against lethal salmonella infection was also examined. RNA-rich fractions (P-RNA) prepared from lysates of the virulent salmonellae contained several bands of protein when examined by disc electrophoresis. P-RNA fractions stimulated protective immunity in mice to infection with
S. typhimurium
SR-11 but to a much lesser degree than did the E-RNA fractions or strain RIA vaccine. Protein-rich fractions (NP), separated from E-RNA by salt precipitation, exhibited the same number and distribution of protein bands by disc electrophoresis as did the parent E-RNA fractions. Mixtures of either bovine liver soluble RNA or various synthetic polynucleotides and NP were examined, as was NP fraction alone, for the ability to confer protection in mice to challenge infections by the virulent strain of salmonella. Polyadenylic-uridylic acid plus NP conferred significant protective immunity to challenge infections in mice immunized with this mixture, being nearly as effective an immunogen as were the E-RNA fractions of
S. typhimurium
SR-11 or the attenuated
S. typhimurium
RIA.
Cytophilic Macroglobulin Reactive with Bacterial Protein in Mice Immunized with Ribonucleic Acid-Protein Fractions of Virulent
Salmonella typhimurium
Authors: Margolis Jeffrey M. , Bigley Nancy J.
Published: January 2020

Cytophilic macroglobulin was eluted (by heating at 56 C for 60 min) from lymphoid cells of mice immunized with subfractions of virulent
Salmonella typhimurium
SR-11 or vaccinated with an attenuated strain of
S. typhimurium
(RIA). No such macroglobulin was present on comparable cell populations from normal or adjuvant-injected mice. Cytophilic macroglobulin was also present in the sera of immunized mice. In mice immunized with RNA and protein-containing subfractions extracted from lysates of
S. typhimurium
SR-11, the cytophilic macroglobulin was present by 14 days after immunization, whereas it was present by 10 days in mice injected with living attenuated
S. typhimurium
RIA. This macroglobulin reacts specifically with protein-rich components present in the immunogenic subfractions of the whole bacterial cells and has been demonstrated to facilitate phagocytic uptake of virulent
S. typhimurium
SR-11. Moreover, a similar protein material was present in broth culture media in which the salmonellae were cultivated. Greater amounts were detectable in older (4 day) cultures.
Demonstration of Antigenic Identity Between Purified Equine Infectious Anemia Virus and an Antigen Extracted from Infected Horse Spleen
Authors: Nakajima Hideo , Norcross Neil L. , Coggins Leroy
Published: January 2020

Antigenic relationship between purified equine infectious anemia (EIA) virus and spleen-derived antigen from EIA-infected horses was examined by immunodiffusion. Identical antigenicity of these two antigens has been proven because precipitation lines formed between the two antigens and EIA antiserum connected with each other. The results indicate that the antigenic substance derived from infected spleen is a component of EIA virus.
Immunological Response of Mice to Members of the Autochthonous Intestinal Microflora
Authors: Foo M. C. , Lee Adrian
Published: January 2020

Based on agglutination, complement fixation, bactericidal, and opsonization tests, it is evident that suspensions of a
Bacteroides
sp. isolated from the mouse intestine and given by parenteral routes do not initiate antibody formation in mice. Rats also respond poorly to the antigenic stimulus. In contrast, suspensions of other bacterial species isolated from the rodent intestine are highly immunogenic. Furthermore, high titers of antibody are produced in rabbits, guinea pigs, and sheep after parenteral injection of the
Bacteroides
suspensions. Marked differences in the absolute and relative numbers of
Bacteroides
in the intestinal contents of rodents and the latter three animal species have been demonstrated. It is proposed that the immunological unresponsiveness of rodents to this organism is related to its existence as a member of the autochthonous microflora in these animals.
Biological and Chemical Characterization of Toxic Substances from
Candida albicans
Authors: Cutler Jim E. , Friedman Lorraine , Milner Kelsey C.
Published: January 2020

Whole cells, morphological components, and various extracts of
Candida albicans
were tested for toxicity by methods involving biological activities ordinarily used to characterize bacterial endotoxin. Fungal preparations exerted several of these activities, but only at much higher dose levels than those required for bacterial products. Both fungal cell walls and intact cells were pyrogenic in rabbits and lethal to actinomycin D-treated mice, but only the former were also lethal to chicken embryos; neither coagulated a hemolysate of horseshoe crabs. Wallfree fungal protoplasm was minimally pyrogenic but negative in the other assays. Bacterial endotoxin was strongly active in all four systems. The toxicity of fungous cell walls was undiminished after exposure to strong alkali, a treatment which destroyed bacterial endotoxin. Extracts obtained with hot phenol-water or potassium hydroxide killed mice but were nonpyrogenic. A defatted and enzyme-digested ethylenediamine extract was both lethal and pyrogenic. Particulate fungal materials but not bacterial endotoxin induced a granulomatous response in prepared mice. These data indicate that contaminating bacterial endotoxin was not responsible for the biological effects of fungal products and suggest that
C. albicans
may contain at least two different toxic components. Chemical analyses were performed on soluble fractions, but a role in toxicity could not be assigned to any identified component.
Interferon System in Mice Infected with the Scrapie Agent
Authors: Worthington Michael
Published: January 2020

Therapy with polyinosinic-polycytidylic acid did not protect scrapie-infected mice; scrapie infection did not affect the interferon response to polyinosinic · polycytidyl acid or Newcastle disease virus.
Bacterial Lipopolysaccharide: Oral Route for Interferon Production in Mice
Authors: Youngner Julius S.
Published: January 2020

Bacterial lipopolysaccharide given orally to mice in relatively small amounts produces significant amounts of circulating interferon.
Production and Degradation of Serogroup B
Neisseria meningitidis
Polysaccharide
Authors: Maloney Peter C. , Schneider Herman , Brandt Brenda L.
Published: January 2020

Polysaccharide produced from cultures of serogroups A, B, and C
Neisseria meningitidis
was assayed by the serogroup-specific hemagglutination inhibition (HAI) test. The polysaccharide produced by all serogroups was found to increase during the exponential phase of growth. For serogroups A and C, the HAI activity was stable during the stationary phase; for serogroup B, however, the HAI decayed rapidly. The degradation of the serogroup B polysaccharide was not caused by enzymatic degradation, but was due to acid accumulation in the culture medium. The large-molecular-size serogroup B polysaccharide was stabilized by increasing the buffering capacity of the medium, which also increased the yield of this antigen.
Association of Lactoferrin with Lysozyme in Granules of Human Polymorphonuclear Leukocytes
Authors: Leffell Mary S. , Spitznagel John K.
Published: January 2020

Lactoferrin is contained in cytoplasmic granules of human polymorphonuclear leukocytes. Upon centrifugation, it sediments in a band of granules that also contain 50% of the lysozyme activity. This granule class is distinct from others associated with alkaline phosphatase and peroxidase. The granules are latent for lactoferrin as only lysed granules have the capacity specifically to inhibit antigen binding by anti-lactoferrin serum.