bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a Recombinant Vaccine against Diphtheria Toxin
Authors: Lobeck Karin , Drevet Pascal , Léonetti Michel , Fromen-Romano Cécile , Ducancel Frédéric , Lajeunesse Evelyne , Lemaire Caroline , Ménez André 
Published: December 2019

ABSTRACT

Two recombinant fragments of diphtheria toxin (DT) were fused to an engineered tandem repeat of the immunoglobulin (Ig) binding domain of protein A, called ZZ. These fragments are (i) the receptor binding domain (DTR), which comprises amino acids 382 to 535 of DT, and (ii) a linear peptide (DT
168–220
) which comprises residues 168 to 220 of the loop between fragment A and fragment B of DT. The fusion proteins were produced in
Escherichia coli
and purified by affinity chromatography. In vitro experiments showed that the DTR domain is responsible for the capacity of ZZ-DTR to bind to Vero cells and is capable of inhibiting the cytotoxicity of DT for these cells. These findings suggest that DTR binds to the cell surface receptors of DT and hence adopts a conformation that is similar to that of the receptor binding domain of DT. We compared the capacities of ZZ-DTR, ZZ-DT
168–220
, and a chemically detoxified form of DT currently used for vaccination to elicit antibodies in rabbits. The toxoid was more immunogenic than ZZ-DT
168–220
, which in turn was more immunogenic than ZZ-DTR. However, ZZ-DT
168–220
antiserum was poorly efficient at neutralizing DT cytotoxicity on Vero cells, whereas ZZ-DTR antiserum was only 15-fold less potent than anti-DT antisera.
Neutrophil-Activating Protein Mediates Adhesion of
Helicobacter pylori
to Sulfated Carbohydrates on High-Molecular-Weight Salivary Mucin
Authors: Namavar Ferry , Sparrius Marion , Veerman Enno C. I. , Appelmelk Ben J. , Vandenbroucke-Grauls Christina M. J. E. 
Published: December 2019

ABSTRACT

The in vitro binding of surface-exposed material and outer membrane proteins of
Helicobacter pylori
to high-molecular-weight salivary mucin was studied. We identified a 16-kDa surface protein which adhered to high-molecular-weight salivary mucin. This protein binds specifically to sulfated oligosaccharide structures such as sulfo-Lewis a, sulfogalactose and sulfo-
N
-acetyl-glucosamine on mucin. Sequence analysis of the protein proved that it was identical to the N-terminal amino acid sequence of neutrophil-activating protein. Moreover, this adhesin was able to bind to Lewis x blood group antigen.
Differential Effects of Infection with aBabesia-Like Piroplasm, WA1, in Inbred Mice
Authors: Moro Manuel H. , David Chella S. , Magera Jenifer M. , Wettstein Peter J. , Barthold Stephen W. , Persing David H. 
Published: December 2019

ABSTRACTA newly identified intraerythrocyticBabesia-like organism, WA1, and its relatives were recently shown to be infectious for humans in the western United States. The purpose of the present study was to determine the susceptibilities of selected mouse genotypes to WA1 infection in an attempt to develop a murine model of the human disease. Several mouse strains were inoculated intraperitoneally with various passages of WA1-parasitized erythrocytes. Parasitemia was evaluated by blood smears and by PCR with blood samples collected at various intervals after inoculation. Hematologic parameters were monitored in blood samples at all intervals. C57BL/6 and C57BL/10 mice exhibited mortality rates of <10%. BALB/cJ, CBAJ, and 129/J mice had higher peak parasitemias than did C57BL mice, with mortality rates of 40, 50, and 50%, respectively. A/J, AKR/N, C3H, and DBA/1J mice also had higher peak parasitemia and mortality rates (>95%). An F1cross of C57BL/6 (resistant) and C3H.RKK (susceptible) mice had a mortality rate similar to that of the resistant parental strain. Histopathology of BALB/cJ and C3H mice at 9 and 14 days after inoculation revealed erythrophagocytosis and deposition of an iron-negative pigment in multiple organs. Morbidly ill C3H mice at 14 days had severe pulmonary edema, hemoglobinuria, and glomerulonephritis.
Mice Are Protected fromHelicobacter pyloriInfection by Nasal Immunization with AttenuatedSalmonella typhimurium phoPcExpressing Urease A and B Subunits
Authors: Corthésy-Theulaz Irène E. , Hopkins Sally , Bachmann Daniel , Saldinger Pierre F. , Porta Nadine , Haas Rainer , Zheng-Xin Yan , Meyer Thomas , Bouzourène Hanifa , Blum André L. , Kraehenbuhl Jean-Pierre 
Published: December 2019

ABSTRACTLiveSalmonella typhimurium phoPcbacteria were tested as mucosal vaccine vectors to deliverHelicobacter pyloriantigens. The genes encoding the A and B subunits ofH. pyloriurease were introduced intoS. typhimurium phoPcand expressed under the control of a constitutive tac promoter (tac-ureAB) or a two-phase T7 expression system (cT7-ureAB). Both recombinantSalmonellastrains expressed the two urease subunits in vitro and were used to nasally immunize BALB/c mice. The plasmid carrying cT7-ureABwas stably inherited by bacteria growing or persisting in the spleen, lungs, mesenteric or cervical lymph nodes, and Peyer’s patches of immunized mice, while the plasmid carrying tac-ureABwas rapidly lost. Spleen and Peyer’s patch CD4+lymphocytes from mice immunized withS. typhimurium phoPccT7-ureABproliferated in vitro in response to urease, whereas cells from mice givenS. typhimurium phoPcalone did not. Splenic CD4+cells from mice immunized withphoPccT7-ureABsecreted gamma interferon and interleukin 10, while Peyer’s patch CD4+cells did not secrete either cytokine. SpecificH. pylorianti-urease immunoglobulin G1 (IgG1) and IgG2A antibodies were detected following immunization, confirming that both Th1- and Th2-type immune responses were generated by the live vaccine. Sixty percent of the mice (9 of 15) immunized withS. typhimurium phoPccT7-ureABwere found to be resistant to infection byH. pylori, while all mice immunized withphoPctac-ureAB(15 of 15) orphoPc(15 of 15) were infected. Our data demonstrate thatH. pyloriurease delivered nasally by using a vaccine strain ofS. typhimuriumcan trigger Th1- and Th2-type responses and induce protective immunity againstHelicobacterinfection.
Requirement for CD40-CD40 Ligand Interaction for Elimination ofCryptosporidium parvumfrom Mice
Authors: Cosyns Mary , Tsirkin Svetlana , Jones Michelle , Flavell Richard , Kikutani Hitoshi , Hayward Anthony R. 
Published: December 2019

ABSTRACTMice with disrupted genes for CD40 and CD40 ligand (CD40L) are unable to clear infection withCryptosporidium parvumand develop cholangitis. Parasites are present in the gut, gall bladder, and biliary tree, and biliary epithelial cells express CD40 on the cell surface. SCID mice infected withC. parvumfor >1 month can clear the infection after reconstitution with spleen cells from CD40, but not CD40L, knockout mice. In an in vitro model,C. parvum-infected HepG2 cells were triggered to apoptosis when incubated with a CD40L-CD8 fusion protein. The requirement for CD40-CD40L interactions for immunity toC. parvumindicated by our results may entail the triggering of apoptosis in infected cells, in addition to the known role of CD40L-CD40 interactions in stimulating cytokine production and promoting T-cell responses.
Anthrax Toxin-Mediated Delivery In Vivo and In Vitro of a Cytotoxic T-Lymphocyte Epitope from Ovalbumin
Authors: Ballard Jimmy D. , Doling Amy M. , Beauregard Kathryn , Collier R. John , Starnbach Michael N. 
Published: December 2019

ABSTRACTWe reported earlier that a nontoxic form of anthrax toxin was capable of delivering a cytotoxic T-lymphocyte (CTL) epitope in vivo, such that a specific CTL response was primed against the epitope. The epitope, of bacterial origin, was fused to an N-terminal fragment (LFn) from the lethal-factor component of the toxin, and the fusion protein was injected, together with the protective antigen (PA) component, into BALB/c mice. Here we report that PA plus LFn is capable of delivering a different epitope—OVA257–264from ovalbumin. Delivery was accomplished in a different mouse haplotype,H-2Kband occurred in vitro as well as in vivo. An OVA257–264-specific CTL clone, GA-4, recognized EL-4 cells treated in vitro with PA plus as little as 30 fmol of the LFn-OVA257–264fusion protein. PA mutants attenuated in toxin self-assembly or translocation were inactive, implying that the role of PA in epitope delivery is the same as that in toxin action. Also, we showed that OVA257–264-specific CTL could be induced to proliferate by incubation with splenocytes treated with PA plus LFn-OVA257–264. These findings imply that PA-LFn may serve as a general delivery vehicle for CTL epitopes in vivo and as a safe, efficient tool for the ex vivo expansion of patient-derived CTL for use in adoptive immunotherapy.
Occurrence of Virulence-Associated Properties inEnterobacter cloacae
Authors: Keller Rogéria , Pedroso Margareth Z. , Ritchmann Rosana , Silva Rosa M. 
Published: December 2019

ABSTRACTEnterobacter cloacaeis not a primary human pathogen but has been considered to be an important cause of nosocomial infections. Even so, there are almost no reports on its ability to produce recognized virulence-associated properties. In this study, we show that most of theE. cloacaestrains examined were resistant to serum bactericidal activity and were able to produce aerobactin and mannose-sensitive hemagglutinin, and all of them could adhere to and invade HEp-2 cells. SinceE. cloacaeis part of the normal intestinal floras of many individuals, we believe that infectious disease due to endogenousE. cloacaemight be a result of both host predisposing factors and the bacterial virulence determinants that we have detected in this survey.
Comparative Analysis of
Haemophilus influenzae hifA
(Pilin) Genes
Authors: Clemans Daniel L. , Marrs Carl F. , Patel Mayuri , Duncan Michelle , Gilsdorf Janet R. 
Published: December 2019

ABSTRACT

Adherence of
Haemophilus influenzae
to epithelial cells plays a central role in colonization and is the first step in infection with this organism. Pili, which are large polymorphic surface proteins, have been shown to mediate the binding of
H. influenzae
to cells of the human respiratory tract. Earlier experiments have demonstrated that the major epitopes of
H. influenzae
pili are highly conformational and immunologically heterogenous; their subunit pilins are, however, immunologically homogenous. To define the extent of structural variation in pilins, which polymerize to form pili, the pilin genes (
hifA
) of 26 type a to f and 16 nontypeable strains of
H. influenzae
were amplified by PCR and subjected to restriction fragment length polymorphism (RFLP) analysis with
Alu
I and
Rsa
I. Six different RFLP patterns were identified. Four further RFLP patterns were identified from published
hifA
sequences from five nontypeable
H. influenzae
strains. Two patterns contained only nontypeable isolates; one of these contained
H. influenzae
biotype aegyptius strains F3031 and F3037. Another pattern contained predominantly
H. influenzae
type f strains. All other patterns were displayed by a variety of capsular and noncapsular types. Sequence analysis of selected
hifA
genes confirmed the 10 RFLP patterns and showed strong identity among representatives displaying the same RFLP patterns. In addition, the immunologic reactivity of pili with antipilus antisera correlated with the groupings of strains based on
hifA
RFLP patterns. Those strains that show greater reactivity with antiserum directed against
H. influenzae
type b strain M43 pili tend to fall into one RFLP pattern (pattern 3); while those strains that show equal or greater reactivity with antiserum directed against
H. influenzae
type b strain Eagan pili tend to fall in a different RFLP pattern (pattern 1). Sequence analysis of representative HifA pilins from typeable and nontypeable
H. influenzae
identified several highly conserved regions that play a role in bacterial pilus assembly and other regions with considerable amino acid heterogeneity. These regions of HifA amino acid sequence heterogeneity may explain the immunologic diversity seen in intact pili.
Encapsulation ofCryptococcus neoformanswith Glucuronoxylomannan Inhibits the Antigen-Presenting Capacity of Monocytes
Authors: Retini Cinzia , Vecchiarelli Anna , Monari Claudia , Bistoni Francesco , Kozel Thomas R. 
Published: December 2019

ABSTRACTThis report examines the effect of the major capsular polysaccharide ofCryptococcus neoformans, glucuronoxylomannan (GXM), on the antigen-presenting capability of human monocytes treated with acapsular cells ofC. neoformans. We found that pretreatment of acapsular cryptococci with GXM downregulates, in a dose-dependent manner, the antigen-presenting capacity of monocytes, leading to reduced proliferative T-lymphocyte responses. Similar levels of suppression occurred when monocytes were exposed to encapsulated cryptococci or acapsular cryptococci that were pretreated with GXM. The magnitude of the T-cell response correlated with the ability of monocytes to ingest the yeast. Supernatant fluids from cocultures of monocytes and T cells cultured with encapsulated cryptococci contained higher levels of interleukin-10 (IL-10) than supernatant fluids of cells with acapsular cryptococci. Addition of anti-IL-10 monoclonal antibodies to the incubation medium of monocytes and T cells cultured with encapsulated cryptococci restored proliferative T-cell responses to levels observed during culture with acapsular cryptococci. Finally, treatment of monocytes with encapsulated cryptococci or GXM-treated acapsular cryptococci suppressed expression of class II major histocompatibility complex (MHC) molecules in a manner consistent with previous reports of IL-10-mediated suppression of class II MHC molecules and suppression of proliferative T-cell responses. These results suggest a link between GXM encapsulation, increased IL-10 synthesis by monocytes, decreased expression of class II MHC molecules on monocytes, and reduced proliferative T-cell responses.
Proteolytic Activation of the Interleukin-1β Precursor byCandida albicans
Authors: Beauséjour Annie , Grenier Daniel , Goulet Jean-Paul , Deslauriers Noëlla 
Published: December 2019

ABSTRACTChronic inflammation rather than invasion is characteristic of some forms of superficial candidiasis such as denture stomatitis. We hypothesized thatCandida albicansmay play a critical role in the pathogenesis of inflammatory lesions observed in chronic candidiasis by activating the proinflammatory cytokine interleukin-1β (IL-1β) from epithelial stores of the precursor. The aim of this study was therefore to demonstrate the proteolytic cleavage and activation of the inactive precursor of IL-1β (pro-IL-1β) byC. albicans. After incubation of either blastospores or hyphae with the inactive precursor, proteolytic cleavage was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis Western immunoblotting analysis, and the biological activity of the cleavage products was tested in a bioassay. We report here that late-stationary-growth-phase blastospores as well as hyphae ofC. albicans, but not exponentially growing cells, can efficiently cleave pro-IL-1β to yield fragments of molecular masses compatible with mature biologically active IL-1β (17 to 19 kDa). Assays conducted in the presence of selected proteinase inhibitors suggest that the cleavage of pro-IL-1β involves the participation of one or more aspartyl proteinases. Cleavage products showed a dose-dependent IL-1β-like activity in a thymocyte proliferation bioassay, which was inhibited by anti-IL-1β neutralizing antibodies. The present data thus suggest a role forC. albicansproteinases in the activation and maintenance of the inflammatory response at epithelial surfaces.
Environmental Regulation of
Salmonella typhi
Invasion-Defective Mutants
Authors: Leclerc Guy J. , Tartera Carmen , Metcalf Eleanor S. 
Published: December 2019

ABSTRACT

Salmonella typhi
is the etiologic agent of human typhoid. During infection,
S. typhi
adheres to and invades epithelial and M cells that line the distal ileum. To survive in the human host,
S. typhi
must overcome numerous complex extracellular and intracellular environments. Since relatively little is known about
S. typhi
pathogenesis, studies were initiated to identify
S. typhi
genes involved in the early steps of interaction with the host and to evaluate the environmental regulation of these genes. In the present study, Tn
phoA
mutagenesis was used to study these early steps. We isolated 16
Salmonella typhi
Tn
phoA
mutants that were defective for both adherence and invasion of the human small intestinal epithelial cell line Int407. Twelve of sixteen mutations were identified in genes homologous to the
S. typhimurium invG
and
prgH
genes, which are known to be involved in the type III secretion pathway of virulence proteins. Two additional insertions were identified in genes sharing homology with the
cpxA
and
damX
genes from
Escherichia coli
K-12, and two uncharacterized invasion-deficient mutants were nonmotile. Gene expression of Tn
phoA
fusions was examined in response to environmental stimuli. We found that the
cpxA
,
invG
, and
prgH
genes were induced when grown under conditions of high osmolarity (0.3 M NaCl). Expression of
invG
and
prgH
genes was optimal at pH 6.5 and strongly reduced at low pH (5.0). Transcription of both
invG
and
prgH
Tn
phoA
gene fusions was initiated during the late logarithmic growth phase and was induced under anaerobic conditions. Finally, we show that both
invG
and
prgH
genes appear to be regulated by DNA supercoiling, a mechanism influenced by environmental factors. These results are the first to demonstrate that in
S. typhi
, (i) the
prgH
and
cpxA
genes are osmoregulated, (ii) the
invG
gene is induced under low oxygen conditions, (iii) the
invG
gene is pH regulated and growth phase dependent, and (iv) the
prgH
gene appears to be regulated by DNA supercoiling. Since our experimental conditions were designed to mimic the in vivo environmental milieu, our results suggest that specific environmental conditions act as signals to induce the expression of
S. typhi
invasion genes.
Investigation of the Roles of Toxin-Coregulated Pili and Mannose-Sensitive Hemagglutinin Pili in the Pathogenesis of
Vibrio cholerae
O139 Infection
Authors: Tacket Carol O. , Taylor Ronald K. , Losonsky Genevieve , Lim Yu , Nataro James P. , Kaper James B. , Levine Myron M. 
Published: December 2019

ABSTRACT

In this study, adult volunteers were fed
tcpA
and
mshA
deletion mutants of
V. cholerae
O139 strain CVD 112 to determine the role of toxin-coregulated pili (TCP) and mannose-sensitive hemagglutinin (MSHA) in intestinal colonization. Eight of 10 volunteers who received CVD 112 or CVD 112 Δ
mshA
shed the vaccine strains in their stools; the geometric mean peak excretion for both groups was 1.4 × 10
5
CFU/g of stool. In contrast, only one of nine recipients of CVD 112 Δ
tcpA
shed vibrios in his stool (
P
< 0.01); during the first 24 h after inoculation, 3 × 10
2
CFU/g was recovered from this volunteer. All recipients of CVD 112 and 8 (80%) of the recipients of CVD 112 Δ
mshA
developed at least a fourfold rise in vibriocidal titer after immunization. In contrast, only one (11%) of the nine recipients of CVD 112 Δ
tcpA
developed a fourfold rise in vibriocidal titer (
P
< 0.01). We conclude that TCP are an important colonization factor of
V. cholerae
O139 and probably of El Tor
V. cholerae
O1. In contrast, MSHA does not appear to promote intestinal colonization in humans.
Induction of a Gradual, Reversible Morphogenesis of Its Host’s Epithelial Brush Border by
Vibrio fischeri
Authors: Lamarcq Laurence H. , McFall-Ngai Margaret J. 
Published: December 2019

ABSTRACT

Bacteria exert a variety of influences on the morphology and physiology of animal cells whether they are pathogens or cooperative partners. The association between the luminous bacterium
Vibrio fischeri
and the sepiolid squid
Euprymna scolopes
provides an experimental model for the study of the influence of extracellular bacteria on the development of host epithelia. In this study, we analyzed bacterium-induced changes in the brush borders of the light organ crypt epithelia during the initial hours following colonization of this tissue. Transmission electron microscopy of the brush border morphology in colonized and uncolonized hosts revealed that the bacteria effect a fourfold increase in microvillar density over the first 4 days of the association. Estimates of the proportions of bacterial cells in contact with host microvilli showed that the intimacy of the bacterial cells with animal cell surfaces increases significantly during this time. Antibiotic curing of the organ following colonization showed that sustained interaction with bacteria is essential for the retention of the induced morphological changes. Bacteria that are defective in either light production or colonization efficiency produced changes similar to those by the parent strain. Conventional fluorescence and confocal scanning laser microscopy revealed that the brush border is supported by abundant filamentous actin. However, in situ hybridization with β-actin probes did not show marked bacterium-induced increases in β-actin gene expression. These experiments demonstrate that the
E. scolopes-V. fischeri
system is a viable model for the experimental study of bacterium-induced changes in host brush border morphology.
Analysis of the Immune Responses of Mice to Infection withLeishmania braziliensis
Authors: DeKrey Gregory K. , Lima Hermenio C. , Titus Richard G. 
Published: December 2019

ABSTRACTLeishmania majorandLeishmania braziliensisboth cause cutaneous leishmaniasis, but the former kills BALB/c mice while the latter is killed by the mice. This killing ofL. braziliensisoccurred by a gamma interferon-dependent mechanism, potentially made possible by the observed lack of high interleukin-4 production.
Role of Tumor Necrosis Factor Alpha in the Host Response of Mice to Bacteremia Caused by Pneumolysin-DeficientStreptococcus pneumoniae
Authors: Benton Kimberly A. , VanCott John L. , Briles David E. 
Published: December 2019

ABSTRACTPneumolysin-deficient mutant strains ofStreptococcus pneumoniaeare known to cause less-severe sepsis than wild-type pneumococcal strains that produce pneumolysin. This difference is associated with greater host resistance in mice infected with the pneumolysin-deficient strains. These studies show that the host resistance developed during the first 1 to 2 days after infection with a pneumolysin-deficient mutant strain is dependent on tumor necrosis factor alpha but is apparently independent of interleukin 1β (IL-1β) or IL-6. Survival beyond 5 days appeared to depend on the ability of the mice to produce IL-1β.