bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intranasal Immunization with Pneumococcal Polysaccharide Conjugate Vaccines with Nontoxic Mutants ofEscherichia coliHeat-Labile Enterotoxins as Adjuvants Protects Mice against Invasive Pneumococcal Infections
Authors: Jakobsen Håvard , Schulz Dominique , Pizza Mariagrazia , Rappuoli Rino , Jónsdóttir Ingileif 
Published: December 2019

ABSTRACTHost defenses againstStreptococcus pneumoniaedepend largely on phagocytosis following opsonization by polysaccharide-specific immunoglobulin G (IgG) antibodies and complement. Since colonization of the respiratory mucosa is the first step in pneumococcal pathogenesis, mucosal immune responses may play a significant role. In addition to inducing systemic immune responses, mucosal vaccination with an effective adjuvant has the advantage of inducing mucosal IgA antibodies. The heat-labile enterotoxin (LT) ofEscherichia coliis a well-studied mucosal adjuvant, and adjuvant activity of nontoxic LT mutants has been demonstrated for several protein antigens. We investigated the immunogenicity of pneumococcal polysaccharide conjugate vaccines (PNC) of serotypes 1 and 3 in mice after intranasal (i.n.) immunization by using as an adjuvant the nontoxic LT mutant LT-K63 or LT-R72, which has minimal residual toxicity. Pneumococcal serotype-specific antibodies were measured in serum (IgM, IgG, and IgA) and saliva (IgA), and vaccine-induced protection was evaluated by i.n. challenge with virulent pneumococci of the homologous serotype. When administered with LT mutants, i.n. immunization with both conjugates induced systemic and mucosal immune responses, and serum IgG antibody levels were significantly higher than after subcutaneous immunization. All mice immunized i.n. with PNC-1 and LT mutants were protected against bacteremia and cleared the pneumococci from the lung 24 h after i.n. challenge; pneumococcal density correlated significantly with serum IgG antibody levels. Similarly, the survival of mice immunized i.n. with PNC-3 and LT mutants was significantly prolonged. These results demonstrate that i.n. vaccination with PNC and potent adjuvants can protect mice against invasive and lethal pneumococcal infections, indicating that mucosal vaccination with PNC may be an alternative vaccination strategy for humans.
Molecular Characterization of the Locus Encoding Biosynthesis of the Lipopolysaccharide O Antigen of
Escherichia coli
Serotype O113
Authors: Paton Adrienne W. , Paton James C. 
Published: December 2019

ABSTRACT

Shiga toxigenic
Escherichia coli
(STEC) strains are a diverse group of organisms capable of causing severe gastrointestinal disease in humans. Within the STEC family,
eae
-positive STEC strains, particularly those belonging to serogroups O157 and O111, appear to have greater virulence for humans. However, in spite of being
eae
negative, STEC strains belonging to serogroup O113 have frequently been associated with cases of severe STEC disease, including hemolytic-uremic syndrome (HUS). Western blot analysis with convalescent-phase serum from a patient with HUS caused by an O113:H21 STEC strain indicated that human immune responses were directed principally against lipopolysaccharide O antigen. Accordingly, the serum was used to isolate a clone expressing O113 O antigen from a cosmid library of O113:H21 DNA constructed in
E. coli
K-12. Sequence analysis indicated that the O113 O-antigen biosynthesis (
rfb
) locus contains a cluster of nine genes which may be cotranscribed. Comparison with sequence databases identified candidate genes for four glycosyl transferases, an
O
-acetyl transferase, an O-unit flippase, and an O-antigen polymerase, as well as copies of
galE
and
gnd
. Two additional, separately transcribed genes downstream of the O113
rfb
region were predicted to encode enzymes involved in synthesis of activated sugar precursors, one of which (designated
wbnF
) was essential for O113 O-antigen synthesis, and so is clearly a part of the O113
rfb
locus. Interestingly, expression of O113 O antigen by
E. coli
K-12 significantly increased in vitro adherence to both HEp-2 and Henle 407 cells.
T-Cell Recognition ofMycobacterium tuberculosisCulture Filtrate Fractions in Tuberculosis Patients and Their Household Contacts
Authors: Demissie Abebech , Ravn Pernille , Olobo Joseph , Doherty T. Mark , Eguale Tewodros , Geletu Mulu , Hailu Wondewossen , Andersen Peter , Britton Sven 
Published: December 2019

ABSTRACTWe examined the immune responses of patients with active pulmonary tuberculosis (TB) and their healthy household contacts to short-term culture filtrate (ST-CF) ofMycobacterium tuberculosisor molecular mass fractions derived from it. Our goal was to identify fractions strongly recognized by donors and differences among the donor groups of possible relevance for vaccine development. The study population consisted of 65 human immunodeficiency virus-negative donors from the Hossana Regional Hospital, Hossana, Ethiopia. Peripheral blood leukocytes from the donors were stimulated with different antigens and immune responses were determined. Household contacts produced significantly higher levels of gamma interferon (IFN-γ) than the TB patients in response to antigens present in ST-CF and the 10 narrow-molecular-mass fractions. A similar difference in leukocyte proliferative responses to the antigens between the two groups was also found. In general, while all fractions stimulated immune responses, the highest activity was seen with the low-molecular-mass fractions, which include well-defined TB antigens such as ESAT-6. Leukocytes from contacts of TB patients with severe disease produced higher levels of antigen-specific IFN-γ than those from contacts of patients with minimal disease. Both groups of contacts exhibited higher cell-mediated responses than the patients themselves. The enhanced immune response of healthy contacts, especially those of patients with severe disease, to secreted mycobacterial antigens is suggestive of an early stage of infection byM. tuberculosis, which could in time result in overt disease or containment of the infection. This possibility is currently being investigated by follow-up studies of the household contacts.
Shiga Toxins Stimulate Secretion of Interleukin-8 from Intestinal Epithelial Cells
Authors: Thorpe C. M. , Hurley Bryan P. , Lincicome Lisa L. , Jacewicz Mary S. , Keusch Gerald T. , Acheson David W. K. 
Published: December 2019

ABSTRACT

In the 1980s, Shiga toxin (Stx)-producing
Escherichia coli
O157:H7 (STEC) was identified as a cause of hemorrhagic colitis in the United States and was found to be associated with hemolytic uremic syndrome (HUS), a microangiopathic hemolytic anemia characterized by thrombocytopenia and renal failure. The precise way that Stxs cause hemorrhagic colitis and HUS is unclear. Stxs have been thought to cause disease by killing or irreversibly harming sensitive cells through a nonspecific blockade of mRNA translation, eventually resulting in cytotoxicity by preventing synthesis of critical molecules needed to maintain cell integrity. Because STEC is noninvasive, we have been exploring the host-toxin response at the level of the gastrointestinal mucosa, where STEC infection begins. We have found that Stx is capable of interleukin-8 (IL-8) superinduction in a human colonic epithelial cell line. Despite a general blockade of mRNA translation, Stx treatment results in increased IL-8 mRNA as well as increased synthesis and secretion of IL-8 protein. Our data suggest that an active Stx A subunit is required for this activity. Ricin, which has the same enzymatic activity and trafficking pathway as Stx, has similar effects. Exploration of the effects of other protein synthesis inhibitors (cycloheximide, anisomycin) suggests a mechanism of gene regulation that is distinct from a general translational blockade. Use of the specific p38/RK inhibitor SB202190 showed that blocking of this pathway results in decreased Stx-mediated IL-8 secretion. Furthermore, Stxs induced mRNA of the primary response gene c-
jun
, which was subsequently partially blocked by SB202190. These data suggest a novel model of how Stxs contribute to disease, namely that Stxs may alter regulation of host cell processes in sensitive cells via activation of at least one member of the mitogen-activated protein kinase family in the p38/RK cascade and induction of c-
jun
mRNA. Stx-induced increases in chemokine synthesis from intestinal epithelial cells could be important in augmenting the host mucosal inflammatory response to STEC infection.
A Genomic Island, Termed High-Pathogenicity Island, Is Present in Certain Non-O157 Shiga Toxin-Producing
Escherichia coli
Clonal Lineages
Authors: Karch H. , Schubert S. , Zhang D. , Zhang W. , Schmidt H. , Ölschläger T. , Hacker J. 
Published: December 2019

ABSTRACT

Shiga toxin-producing
Escherichia coli
(STEC) strains cause a wide spectrum of diseases in humans. In this study, we tested 206 STEC strains isolated from patients for potential virulence genes including
stx
,
eae
, and enterohemorrhagic
E. coli hly
. In addition, all strains were examined for the presence of another genetic element, the high-pathogenicity island (HPI). The HPI was first described in pathogenic
Yersinia
species and encodes the pesticin receptor FyuA and the siderophore yersiniabactin. The HPI was found in the genome of distinct clonal lineages of STEC, including all 31
eae
-positive O26:H11/H
−
strains and 7 of 12
eae
-negative O128:H2/H
−
strains. In total, the HPI was found in 56 (27.2%) of 206 STEC strains. However, it was absent from the genome of all 37 O157:H7/H
−
, 14 O111:H
−
, 13 O103:H2, and 13 O145:H
−
STEC isolates, all of which were positive for
eae
. Polypeptides encoded by the
fyuA
gene located on the HPI could be detected by using immunoblot analysis in most of the HPI-positive STEC strains, suggesting the presence of a functional yersiniabactin system. The HPI in STEC was located next to the tRNA gene
asnT
. In contrast to the HPI of other pathogenic enterobacteria, the HPI of O26 STEC strains shows a deletion at its left junction, leading to a truncated integrase gene
int
. We conclude from this study that the
Yersinia
HPI is disseminated among certain clonal subgroups of STEC strains. The hypothesis that the HPI in STEC contributes to the fitness of the strains in certain ecological niches rather than to their pathogenic potential is discussed.
Identification, Characterization, and Expression of Three New Members of the
Borrelia burgdorferi
Mlp (2.9) Lipoprotein Gene Family
Authors: Yang Xiaofeng , Popova Taissia G. , Hagman Kayla E. , Wikel Stephen K. , Schoeler George B. , Caimano Melissa J. , Radolf Justin D. , Norgard Michael V. 
Published: December 2019

ABSTRACT

We previously reported on the existence of a family of lipoprotein genes, designated 2.9 lipoprotein genes, encoded in at least seven versions on the circular (supercoiled) cp32 and cp18 plasmids of
Borrelia burgdorferi
297. A distinguishing feature of the 2.9 lipoproteins were highly similar signal sequences but variable mature polypeptides that segregated into two antigenic classes. Further screenings of
B. burgdorferi
297 genomic libraries led to the identification of three additional 2.9 lipoprotein genes, renamed herein
mlp
, for multicopy lipoprotein genes. Computer analyses and immunoblotting revealed that Mlp-9 segregated with the antigenic class I lipoproteins, whereas Mlp-8 and Mlp-10 were members of class II. Northern blotting showed that all three of the
mlp
genes were expressed when
B. burgdorferi
was cultivated in vitro at 34°C, although
mlp-9
and
mlp-10
transcripts were expressed at very low levels. Additional combined immunoblotting and comparative reverse transcription-PCR analyses performed on borreliae cultivated in vitro at 23, 34, or 37°C indicated that although Mlp-8 was substantially more abundant than Mlp-9 or Mlp-10, all three of the
mlp
genes were upregulated during
B. burgdorferi
replication at 37°C. Expression of the same three lipoproteins was further enhanced upon growth of the spirochetes within dialysis membrane chambers (DMCs) implanted intraperitoneally in rats (i.e., spirochetes in a mammalian host-adapted state), suggesting that temperature alone did not account for maximal upregulation of the
mlp
genes. That certain
mlp
genes are likely expressed during the growth of
B. burgdorferi
in mammalian tissues was supported by findings of antibodies against all three Mlp lipoproteins in mice after challenge with
Ixodes scapularis
nymphs harboring
B. burgdorferi
297. The combined data suggest that as opposed to being differentially expressed in any reciprocal fashion (e.g., OspA/OspC), at least three
mlp
genes are simultaneously upregulated by temperature (37°C) and some other mammalian host factor(s). The findings have importance not only for understanding alternative modes of differential antigen expression by
B. burgdorferi
but also for assessing whether one or more of the Mlp lipoproteins represent new candidate vaccinogens for Lyme disease.
CD4 T Cells and Major Histocompatibility Complex Class II Expression Influence Worm Expulsion and Increased Intestinal Muscle Contraction duringTrichinella spiralisInfection
Authors: Vallance Bruce A. , Galeazzi Francesca , Collins Stephen M. , Snider Denis P. 
Published: December 2019

ABSTRACTExpulsion of intestinal nematode parasites and the associated increased contraction by intestinal muscle are T cell dependent, since both are attenuated in athymic rodents. The CD4 T-cell subset has been strongly associated with worm expulsion; however, the relationship between these cells, antigen presentation, and worm expulsion is not definitive and the role of these factors in intestinal muscle hypercontractility has not been defined. We infected C57BL/6, athymic, CD4-deficient, CD8α-deficient, and major histocompatibility complex class II (MHC II)-deficient (C2d) mice withTrichinella spiralislarvae. We examined intestinal worm numbers, longitudinal muscle contraction, and MHC II expression. Numerous MHC II-positive cells were identified within the muscularis externa of infected but not uninfected C57BL/6 mice. C57BL/6 and CD8α-deficient mice developed large increases in muscle contraction, expelling the parasite by day 21. Athymic and C2d mice exhibited much smaller increases in muscle contraction and delayed parasite expulsion. CD4-deficient mice exhibited intermediate levels of muscle contraction and delayed parasite expulsion. To further examine the role of MHC II and CD4 T cells, we irradiated C2d mice and reconstituted them with C57BL/6 bone marrow alone or with C57BL/6 CD4 T cells. C57BL/6 bone marrow alone did not affect muscle function or worm expulsion in recipient C2d mice. Partial CD4 T-cell reconstitution was sufficient to restore increased muscle contraction but not worm expulsion. Thus, hematopoietic MHC II expression alone is insufficient for the development of muscle hypercontractility and worm expulsion, but the addition of even small numbers of CD4 T cells was sufficient to induce intestinal muscle pathophysiology.
Cell Death of Human Polymorphonuclear Neutrophils Induced by a
Pseudomonas aeruginosa
Cystic Fibrosis Isolate Requires a Functional Type III Secretion System
Authors: Dacheux D. , Attree I. , Schneider C. , Toussaint B. 
Published: December 2019

ABSTRACT

With a coincubation model incorporating
Pseudomonas aeruginosa
and human polymorphonuclear neutrophils (PMNs), a cystic fibrosis (CF)
P. aeruginosa
isolate has been shown to resist the bactericidal action of PMNs and to induce their cellular death. An isogenic mutant of this CF isolate in which the type III secretion system was rendered nonfunctional was unable to induce cellular death of PMNs.
Modulation of B-Lymphocyte and NK Cell Activities by Glycoinositolphospholipid Purified fromTrypanosoma cruzi
Authors: de Arruda Hinds Luciana B. , Previato Lucia Mendonça , Previato José Osvaldo , Vos Quirijn , Mond James J. , Peçanha Ligia M. T. 
Published: December 2019

ABSTRACTGlycoinositolphospholipids (GIPLs) are some of the major glycolipids of theTrypanosoma cruzisurface that were previously shown to activate B cells. In the present study, we investigated whether (i)T. cruziGIPLs could induce immunoglobulin secretion from B cells in the absence of T cells and NK cells and whether (ii) NK cells are also stimulated by the GIPLs. B cells purified from mice deficient in both T and NK cells (CD3ɛ transgenic mice) secreted immunoglobulin in response to the GIPL. This response was increased by coculture with a murine NK cell line. TheT. cruziGIPL also increased the NK cell (interleukin-2 induced) proliferative response. Our data indicate that theT. cruziGIPL has a direct stimulatory effect on NK cells and induces immunoglobulin secretion in the absence of T lymphocytes and NK cells. These findings suggest that thisT. cruzi-derived molecule may be one of the stimulators that lead to NK cell activation duringT. cruziinfection.
Identification of Genes Coding for Exported Proteins of
Actinobacillus actinomycetemcomitans
Authors: Mintz Keith P. , Fives-Taylor Paula M. 
Published: December 2019

ABSTRACT

Random fusions of genomic DNA fragments to a partial gene encoding a signal sequence-deficient bacterial alkaline phosphatase were utilized to screen for exported proteins of
Actinobacillus actinomycetemcomitans
in
Escherichia coli
. Twenty-four PhoA
+
clones were isolated and sequenced. Membrane localization signals in the form of signal sequences were deduced from most of these sequences. Several of the deduced amino acid sequences were found to be homologous to known exported or membrane-associated proteins. The complete genes corresponding to two of these sequences were isolated from an
A. actinomycetemcomitans
lambda phage library. One gene was found to be homologous to the outer membrane lipoprotein LolB. The second gene product had homology with a
Haemophilus influenzae
protein and was localized to the inner membrane of
A. actinomycetemcomitans
.
Differential Expression of Caprine β-Defensins in Digestive and Respiratory Tissues
Authors: Zhao Chengquan , Nguyen Tung , Liu Lide , Shamova Olga , Brogden Kim , Lehrer Robert I. 
Published: December 2019

ABSTRACT
We identified two novel β-defensin precursors, preproGBD-1 and preproGBD-2, in the tissues of a goat. Although the precursors were identical in 96.8% of their bases and 88.2% (60 of 68) of their amino acids, preproGBD-1 was expressed principally in the tongue and respiratory tract, whereas preproGBD-2 expression predominated throughout the intestine. These findings exemplify the phenomenon of tissue-specific expression in a family of host defense peptides that arose before the avian and mammalian lineages diverged.
The Mannose Receptor Mediates Uptake of Pathogenic and Nonpathogenic Mycobacteria and Bypasses Bactericidal Responses in Human Macrophages
Authors: Astarie-Dequeker Catherine , N’Diaye Elsa-Noah , Le Cabec Veronique , Rittig Michael G. , Prandi Jacques , Maridonneau-Parini Isabelle 
Published: December 2019

ABSTRACTThe mannose receptor (MR) is involved in the phagocytosis of pathogenic microorganisms. Here we investigated its role in the bactericidal functions of human monocyte-derived macrophages (MDMs), using (i) trimannoside-bovine serum albumin (BSA)-coated latex beads and zymosan as particulate ligands of the MR, and (ii) mannan and mannose-BSA as soluble ligands. We show that phagocytosis of mannosylated latex beads did not elicit the production of O2−. Zymosan, which is composed of α-mannan and β-glucan, was internalized by the MR and a β-glucan receptor, but the production of O2−was triggered only by phagocytosis through the β-glucan receptor. Activation and translocation of Hck, a Src family tyrosine kinase located on lysosomes, has previously been used as a marker of fusion between lysosomes and phagosomes in human neutrophils. In MDMs, Hck was activated and recruited to phagosomes containing zymosan later than LAMP-1 and CD63. Phagosomes containing mannosylated latex beads fused with LAMP-1 and CD63 vesicles but not with the Hck compartment, and the kinase was not activated. We also demonstrate that the MR was unable to distinguish between nonpathogenic and pathogenic mycobacteria, as they were internalized at similar rates by this receptor, indicating that this route of entry cannot be considered as a differential determinant of the intracellular fate of mycobacteria. In conclusion, MR-dependent phagocytosis is coupled neither to the activation of NADPH oxidase nor to the maturation of phagosomes until fusion with the Hck compartment and therefore constitutes a safe portal of entry for microorganisms.
Inhibition ofStaphylococcus aureusAdherence to Collagen under Dynamic Conditions
Authors: Mohamed Nehal , Teeters Mark A. , Patti Joseph M. , Höök Magnus , Ross Julia M. 
Published: December 2019

ABSTRACTStaphylococcus aureusis the most common etiological agent of bacterial arthritis and acute osteomyelitis and has been shown to bind to type II collagen under static and dynamic conditions. We have previously reported the effect of shear on the adhesion ofS. aureusPhillips to collagen and found that this process is shear dependent (Z. Li, M. Höök, J. M. Patti, and J. M. Ross, Ann. Biomed. Eng. 24[Suppl. 1]:S–55). In this study, we used recombinant collagen adhesin fragments as well as polyclonal antibodies generated against adhesin fragments in attempts to inhibit bacterial adhesion. A parallel-plate flow chamber was used in a dynamic adhesion assay, and quantification of adhesion was accomplished by phase contrast video microscopy coupled with digital image processing. We report that both recombinant fragments studied, M19 and M55, and both polyclonal antibodies studied, α-M17 and α-M55, inhibit adhesion to varying degrees and that these processes are shear dependent. The M55 peptide and α-M55 cause much higher levels of inhibition than M19 and α-M17, respectively, at all wall shear rates studied. Our results demonstrate the importance of using a dynamic system in the assessment of inhibitory strategies and suggest the possible use of M55 and α-M55 in clinical applications to prevent infections caused byS. aureusadhesion to collagen.
Neisseria gonorrhoeae
Mutants Altered in Toxicity to Human Fallopian Tubes and Molecular Characterization of the Genetic Locus Involved
Authors: Arvidson Cindy Grove , Kirkpatrick Risa , Witkamp Manon T. , Larson Jason A. , Schipper Christel A. , Waldbeser Lillian S. , O’Gaora Peadar , Cooper Morris , So Magdalene 
Published: December 2019

ABSTRACT

In an effort to identify potential cytotoxins expressed by
Neisseria gonorrhoeae
, we have identified a locus that, when mutated in the gonococcus, results in a significant increase in toxicity of the strain to human fallopian tube organ cultures (HFTOC). This locus,
gly1
, contains two open reading frames (ORFs) which are likely cotranscribed. ORF1 encodes a polypeptide of 17.8 kDa with a signal sequence that is recognized and processed in
Escherichia coli
and
N. gonorrhoeae
. The 15.6-kDa processed polypeptide has been observed in membrane fractions and filtered spent media from cultures of
E. coli
expressing
gly1
and in outer membrane preparations of wild-type
N. gonorrhoeae
. The
gly1
locus is not essential for bacterial survival, and it does not play a detectable role in epithelial cell adhesion, invasion, or intracellular survival. However, a
gly1
null mutant causes much more damage to fallopian tube tissues than its isogenic wild-type parent. A strain complemented in
trans
for the
gly1
mutation showed a level of toxicity to HFTOC similar to the level elicited by the wild-type parent. Taken together, these results indicate an involvement of the
gly1
locus in the toxicity of
N. gonorrhoeae
to human fallopian tubes.