bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comprehensive Genetic Study of Streptococcal Immunoglobulin A1 Proteases: Evidence for Recombination within and between Species
Authors: Poulsen Knud , Reinholdt Jesper , Jespersgaard Christina , Boye Kit , Brown Thomas A. , Hauge Majbritt , Kilian Mogens 
Published: December 2019

ABSTRACTAn analysis of 13 immunoglobulin A1 (IgA1) protease genes (iga) of strains ofStreptococcus pneumoniae,Streptococcus oralis,Streptococcus mitis, andStreptococcus sanguiswas carried out to obtain information on the structure, polymorphism, and phylogeny of this specific protease, which enables bacteria to evade functions of the predominant Ig isotype on mucosal surfaces. The analysis included cloning and sequencing ofigagenes fromS. oralisandS. mitisbiovar 1, sequencing of an additional sevenigagenes fromS. sanguisbiovars 1 through 4, and restriction fragment length polymorphism (RFLP) analyses ofigagenes of another 10 strains ofS. mitisbiovar 1 and 6 strains ofS. oralis. All 13 genes sequenced had the potential of encoding proteins with molecular masses of approximately 200 kDa containing the sequence motif HEMTH and an E residue 20 amino acids downstream, which are characteristic of Zn metalloproteinases. In addition, all had a typical gram-positive cell wall anchor motif, LPNTG, which, in contrast to such motifs in other known streptococcal and staphylococcal proteins, was located in their N-terminal parts. Repeat structures showing variation in number and sequence were present in all strains and may be of relevance to the immunogenicities of the enzymes. Protease activities in cultures of the streptococcal strains were associated with species of different molecular masses ranging from 130 to 200 kDa, suggesting posttranslational processing possibly as a result of autoproteolysis at post-proline peptide bonds in the N-terminal parts of the molecules. Comparison of deduced amino acid sequences revealed a 94% similarity betweenS. oralisandS. mitisIgA1 proteases and a 75 to 79% similarity between IgA1 proteases of these species and those ofS. pneumoniaeandS. sanguis, respectively. Combined with the results of RFLP analyses using differentigagene fragments as probes, the results of nucleotide sequence comparisons provide evidence of horizontal transfer ofigagene sequences among individual strains ofS. sanguisas well as amongS. mitisand the two speciesS. pneumoniaeandS. oralis. Whileigagenes ofS. sanguisandS. oraliswere highly homogeneous, the genes ofS. pneumoniaeandS. mitisshowed extensive polymorphism reflected in different degrees of antigenic diversity.
Mycoplasma pulmonis
Inhibits Electrogenic Ion Transport across Murine Tracheal Epithelial Cell Monolayers
Authors: Lambert Linda C. , Trummell Hoa Q. , Singh Ashvani , Cassell Gail H. , Bridges Robert J. 
Published: December 2019

ABSTRACT

Murine chronic respiratory disease is characterized by persistent colonization of tracheal and bronchial epithelial cell surfaces by
Mycoplasma pulmonis
, submucosal and intraluminal immune and inflammatory cells, and altered airway activity. To determine the direct effect of
M. pulmonis
upon transepithelial ion transport in the absence of immune and inflammatory cell responses, primary mouse tracheal epithelial cell monolayers (MTEs) were apically infected and assayed in Ussing chambers.
M. pulmonis
-infected MTEs, but not those infected with a nonmurine mycoplasma, demonstrated reductions in amiloride-sensitive Na
+
absorption, cyclic AMP, and cholinergic-stimulated Cl
−
secretion and transepithelial resistance. These effects were shown to require interaction of viable organisms with the apical surface of the monolayer and to be dependent upon organism number and duration of infection. Altered transport due to
M. pulmonis
was not merely a result of epithelial cell death as evidenced by the following: (i) active transport of Na
+
and Cl
−
, albeit at reduced rates; (ii) normal cell morphology, including intact tight junctions, as demonstrated by electron microscopy; (iii) maintenance of a mean transepithelial resistance of 440 Ω/cm
2
; and (iv) lack of leakage of fluid from the basolateral to the apical surface of the monolayer. Alteration in epithelial ion transport in vitro is consistent with impaired pulmonary clearance and altered airway function in
M. pulmonis
-infected animals. Furthermore, the ability of
M. pulmonis
to alter transport without killing the host cell may explain its successful parasitism and long-term persistence in the host. Further study of the MTE-
M. pulmonis
model should elucidate the molecular mechanisms which mediate this reduction in transepithelial ion transport.
MPB70 and MPB83 as Indicators of Protein Localization in Mycobacterial Cells
Authors: Harboe Morten , Wiker Harald G. , Ulvund Gunni , Lund-Pedersen Bent , Andersen Åse Bengård , Hewinson R. Glyn , Nagai Sadamu 
Published: December 2019

ABSTRACTCulture fluids after growth ofMycobacterium bovisBCG on Sauton medium contain actively secreted proteins and proteins released by bacterial lysis. BCG culture fluids and sonicates ofMycobacterium tuberculosisandMycobacterium paratuberculosiswere tested after separation by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The localization of marker proteins was determined by enzyme-linked immunosorbent assay and Western blotting with selected monoclonal antibodies of known specificities. Soluble secreted proteins (MPB64 and proteins of the antigen 85 complex) and three heat shock proteins (DnaK, GroEL, and GroES) were recovered in a single peak after gel filtration, indicating their occurrence as a free monomer in the culture fluid and cytosol, respectively. Other constituents eluted in two distinct peaks during gel filtration. The first peak corresponded to the void volume, indicating complex formation between several proteins or attachment to lipids in the surface layer or the cytoplasmic membrane; the second peak corresponded to the expected monomer size indicated by SDS-PAGE under conditions that separate proteins from each other during sample preparation. The two-peak group contained constituents with known lipid contents, the 19- and 38-kDa lipoproteins and lipoarabinomannan. The 26-kDa form of MPB83 behaved similarly. After extraction with Triton X-114, these constituents entered into the detergent phase, confirming the lipoprotein nature of 26-kDa MPB83. The MPB83 molecule was shown to be available on the surface of BCG Tokyo bacilli for reaction with monoclonal antibody MBS43 by flow cytometry.
Immunization of the Female Genital Tract with a DNA-Based Vaccine
Authors: Livingston Julie B. , Lu Shan , Robinson Harriet , Anderson Deborah J. 
Published: December 2019

ABSTRACTVaccines are being sought for contraception and the prevention of sexually transmitted diseases. However, progress is slow in this area largely because of lack of information on induction of protective immune responses in genital tract mucosa. In this study, we investigated whether in vivo transfection with a model DNA-based antigen delivered by gene gun technology would induce an antibody response detectable in vaginal secretions. Female rats were immunized with plasmids encoding human growth hormone (HGH) under the control of a cytomegalovirus promoter (pCMV/HGH) via vaginal mucosa (V), Peyer’s patch (PP), and/or abdominal skin (S) routes. Localization of HGH in the target tissues demonstrated that all three sites can be transfected in vivo with pCMV/HGH. Vaginal tissues expressed roughly the same level of plasmid as skin. Antibodies to HGH were detectable in serum and vaginal secretions in rats immunized with pCMV/HGH. In the rats primed and boosted vaginally, vaginal immunoglobulin A (IgA) and IgG antibody titers to HGH were sustained for at least 14 weeks, whereas rats immunized via other routes and protocols (S/V, S/S, PP/PP, or PP/V) did not consistently sustain significant vaginal antibody titers beyond week 6. DNA-based immunizations administered by the gene gun may be an effective method of inducing local immunity in the female genital tract.
Characterization of the Immunostimulatory Properties ofLeishmania infantumHSP70 by Fusion to theEscherichia coliMaltose-Binding Protein in Normal andnu/nuBALB/c Mice
Authors: Rico Ana I. , Del Real Gustavo , Soto Manuel , Quijada Luis , Martinez-A. Carlos , Alonso Carlos , Requena Jose M. 
Published: December 2019

ABSTRACTLeishmania infantumHSP70 has been described as an immunodominant antigen in both humans and dogs suffering from visceral leishmaniasis. In this study, we usedL. infantumHSP70 fused toEscherichia colimaltose-binding protein (MBP), as the reporter protein, to analyze the influence of HSP70 on the immunogenicity of MBP in BALB/c mice. Plasmids were constructed to produce the three recombinant proteins used in this study, namely, MBP,L. infantumHSP70, and MBP-HSP70, which consists of MBP fused to theL. infantumHSP70 amino terminus. Immunization of BALB/c mice with the MBP-HSP70 fusion protein elicited humoral and cellular responses against MBP that were higher by an order of magnitude than those elicited by immunization with MBP alone or with a mixture of MBP and HSP70. Covalent linkage of MBP to HSP70 was essential for eliciting a strong anti-MBP immune response. Cytokine secretion and immunoglobulin G isotype analyses indicated that immunization with the MBP-HSP70 fusion protein preferentially induces a Th1 immune response. Immunization of athymicnu/numice with the MBP-HSP70 fusion protein unexpectedly gave rise to an anti-MBP humoral response showing features of a T-cell-dependent response. Thus, we present evidence thatL. infantumHSP70 demonstrates an adjuvant effect in the immune response against a covalently linked reporter protein.
Extensive Immunoglobulin Binding of
Plasmodium falciparum
-Infected Erythrocytes in a Group of Children with Moderate Anemia
Authors: Scholander Carin , Carlson Johan , Kremsner Peter G. , Wahlgren Mats 
Published: December 2019

ABSTRACT

Immunoglobulins (Ig) from healthy, nonimmune individuals bind to the surfaces of
Plasmodium falciparum
-infected erythrocytes (RBC). In order to investigate the presence of this parasite phenotype in wild isolates and its potential association with malarial anemia, we conducted a study of 207 anemic or nonanemic children with malaria in Gabon. Surface Ig binding to infected RBC was detected for 83% of the isolates. No difference in Ig binding between the groups was observed, but all isolates which exhibited extensive Ig binding were found in a group of moderately anemic children.
Prevalence and Distribution of the
hmw
and
hia
Genes and the HMW and Hia Adhesins among Genetically Diverse Strains of Nontypeable
Haemophilus influenzae
Authors: St. Geme Joseph W. , Kumar Vini V. , Cutter David , Barenkamp Stephen J. 
Published: December 2019

ABSTRACT

Nontypeable
Haemophilus influenzae
is a common cause of human disease and initiates infection by colonizing the upper respiratory tract. In previous work we identified high-molecular-weight adhesins referred to as HMW1 and HMW2, expressed by nontypeable strain 12, and determined that most strains of nontypeable
H. influenzae
express one or two antigenically related proteins. More recently, we determined that some strains lack HMW1- and HMW2-like proteins and instead express an adhesin called Hia. In the present study, we determined the prevalence and distribution of the
hmw
and
hia
genes in a collection of 59 nontypeable strains previously characterized in terms of genetic relatedness. Based on Southern analysis, 47 strains contained sequences homologous to the
hmw1
and
hmw2
genes and nine strains contained homologs to
hia
. No strain harbored both
hmw
and
hia
, and three strains harbored neither. Although the
hmw
and
hia
genes failed to define distinct genetic divisions, the
hmw
-deficient strains formed small clusters or lineages within the larger population structure. Additional analysis established that the IS
1016
insertion element was uniformly absent from strains containing
hmw
sequences but was present in two-thirds of the
hmw
-deficient strains. As IS
1016
is associated with the capsule locus (
cap
) in most encapsulated strains of
H. influenzae
, we speculate that
hmw
-deficient nontypeable strains evolved more recently from an encapsulated ancestor.
Molecular Characterization of an Outer Membrane Protein of
Actinobacillus actinomycetemcomitans
Belonging to the OmpA Family
Authors: White Peter A. , Nair Sean P. , Kim Mi-Jurng , Wilson Michael , Henderson Brian 
Published: December 2019

ABSTRACT

The major outer membrane protein (OMP) of
Actinobacillus actinomycetemcomitans
is an OmpA homolog that demonstrates electrophoretic heat modifiability. The gene encoding this protein was isolated from a genomic library of
A. actinomycetemcomitans
NCTC 9710 by immunoscreening with serum from a patient with localized juvenile periodontitis. Expression of the cloned gene in
Escherichia coli
and subsequent Western blot analysis revealed a protein with an approximate molecular mass of 34 kDa. The amino acid sequence predicted from the cloned gene demonstrated that the mature protein had a molecular mass of 34,911 Da and significant identity to members of the OmpA family of proteins. We have named the major OMP of
A. actinomycetemcomitans
Omp34, and its corresponding gene has been named
omp34.
Analysis of Inhibitory Epitopes in thePlasmodium falciparumRhoptry Protein RAP-1 Including Identification of a Second Inhibitory Epitope
Authors: Howard Randall F. , Jacobson Kym C. , Rickel Erika , Thurman Joyce 
Published: December 2019

ABSTRACTImmune responses toPlasmodium falciparumrhoptry-associated protein 1 (RAP-1), RAP-2, and RAP-3 appear to contribute to protection against infection by this human malarial parasite. This conclusion is suggested by results of monkey immunization trials and of cell culture studies showing antibody-dependent inhibition of erythrocyte invasion. In the present study, splenectomized owl monkeys were infected withP. falciparumin order to monitor anti-RAP-1 antibody production as antiparasite immunity developed. The monkeys responded to a primary infection with the production of antibodies to a fragment of RAP-1 containing amino acids 1 to 294 (RAP-11–294). After drug cure and reinfection, the monkeys had a prolonged prepatent period, indicating they had already developed partial immunity to the parasite. Sera from these animals showed major increases in anti-RAP-11–294antibodies. In contrast, only low levels of antibodies to inhibitory B-cell epitope 1 (iB-1), an inhibitory epitope in RAP-11–294with the sequence N200TLTPLEELYPT211, was observed after the initial parasite infection, and the anti-iB-1 antibodies were not readily boosted upon reinfection. These results suggest that iB-1 is an immunogenic but not immunodominant epitope and that anti-iB-1 antibodies do not substantially contribute to early stages of naturally acquired immunity in the owl monkey model. To identify additional epitopes bound by inhibitory antibodies, mouse monoclonal antibodies were produced with a recombinant fusion protein containing RAP-11–294. Monoclonal antibody 1D6 inhibited parasite invasion of erythrocytes in vitro. 1D6 did not bind peptide iB-1 but rather bound a second inhibitory epitope called iB-2. iB-2, like iB-1, is found near the amino terminus of p67, a RAP-1 processing product thought to be involved in merozoite invasion of erythrocytes. Since anti-iB-1 antibodies were not readily produced during parasite infection, it may be desirable to direct antibody responses to particular epitopes in RAP-1, such as iB-1 and iB-2.
Virulence of aSalmonella typhimuriumOmpD Mutant
Authors: Meyer Paul N. , Wilmes-Riesenberg Mary R. , Stathopoulos Christos , Curtiss Roy 
Published: December 2019

ABSTRACTAnompDmutation caused by a Tn10insertion was transduced intoSalmonella typhimuriumSL1344 and UK-1. The adherence and invasion capabilities of the resultantompDmutants were examined by tissue culture analysis. The virulence of theS. typhimurium ompDmutants was ascertained by a 50% lethal dose (LD50) study and by determining colonization ability with BALB/c mice. We found no statistically significant difference in adherence and invasion capacities between theS. typhimuriumwild type strains and their correspondingompDmutants. Furthermore, the LD50and colonization studies revealed that there is no statistically significant difference in virulence between theS. typhimuriumwild type strains and their correspondingompDmutants. These results differ from those reported previously (C. J. Dorman, S. Chatfield, C. F. Higgins, C. Hayward, and G. Dougan, Infect. Immun. 57:2136–2140, 1989).
Capsular Polysaccharide-Fimbrial Protein Conjugate Vaccine Protects againstPorphyromonas gingivalisInfection in SCID Mice Reconstituted with Human Peripheral Blood Lymphocytes
Authors: Choi Jeom-Il , Schifferle Robert E. , Yoshimura Fuminobu , Kim Byung-Woo 
Published: December 2019

ABSTRACTThe effect of immunization with either aPorphyromonas gingivalisfimbrial protein, a capsular polysaccharide, or a capsular polysaccharide-fimbrial protein conjugate vaccine were compared in hu-PBL-SCID mice. A significantly higher human immunoglobulin G antibody response and the highest degree of in vivo protection against bacterial challenge was observed in the group immunized with the conjugate vaccine. It was concluded that capsular polysaccharide-fimbrial protein conjugate fromP. gingivaliscould potentially be developed as a vaccine against periodontal infection byP. gingivalis.
Microevolution of a Standard Strain ofCryptococcus neoformansResulting in Differences in Virulence and Other Phenotypes
Authors: Franzot Sarah P. , Mukherjee Jean , Cherniak Robert , Chen Lin-Chi , Hamdan Junia S. , Casadevall Arturo 
Published: December 2019

ABSTRACTCryptococcus neoformansis a major fungal pathogen for patients with debilitated immune systems. However, no information is available on the stability of virulence or of phenotypes associated with virulence forC. neoformanslaboratory strains. A serendipitous observation in our laboratory that one isolate ofC. neoformansATCC 24067 (strain 52D) became attenuated after continuous in vitro culture prompted us to perform a comparative study of nine strain 24067 isolates obtained from six different research laboratories. Each isolate was characterized by DNA typing, virulence for mice, proteinase production, extracellular protein synthesis, melanin synthesis, carbon assimilation pattern, antifungal drug susceptibility, colony morphology, growth rate, agglutination titers, phagocytosis by murine macrophages, capsule size, and capsular polysaccharide structure. All isolates had similar DNA typing patterns consistent with their assignment to the same strain, although minor chromosome size polymorphisms were observed in the electrophoretic karyotypes of two isolates. Several isolates had major differences in phenotypes that may be associated with virulence, including growth rate, capsule size, proteinase production, and melanization. These findings imply thatC. neoformansis able to undergo rapid changes in vitro, probably as a result of adaptation to laboratory conditions, and suggest the need for careful attention to storage and maintenance conditions. In summary, our results indicate thatC. neoformans(i) can become attenuated by in vitro culture and (ii) is capable of microevolution in vitro with the emergence of variants exhibiting new genotypic and phenotypic characteristics.
Streptococcus pyogenes
Serotype M1 Encodes Multiple Pathways for Entry into Human Epithelial Cells
Authors: Cue D. , Dombek P. E. , Lam H. , Cleary P. P. 
Published: December 2019

ABSTRACT

The ability of a serotype M1 strain of
Streptococcus pyogenes
to efficiently invade A549 human lung epithelial cells was previously shown to be dependent on bacterial exposure to human or bovine serum proteins or synthetic peptides containing the sequence RGD. In this study, stimulation by invasion agonists was determined to be dependent on expression of the streptococcal cell surface protein, M1. Fetal bovine serum (FBS), fibronectin (Fn), the extracellular matrix protein laminin (Lm), and RGD-containing peptides were tested for their abilities to promote epithelial cell invasion and adherence by isogenic M1
+
and M1
−
strains of
S. pyogenes
. In the absence of an agonist, invasion and adherence were comparable for the two bacterial strains. FBS, Fn, and Lm stimulated invasion of the M1
+
strain as much as 70-fold but failed to significantly affect invasion by the M1
−
mutant. Adherence of the wild-type strain was stimulated by these same agonists. Epithelial cell adherence by the M1
−
strain, however, was unaffected by the presence of Fn or Lm. Several RGD-containing peptides were found to promote invasion independently of M1 expression. Binding of
125
I-Fn was reduced 88% by the M1
−
mutation and Fn was found to bind purified M1 protein, suggesting that Fn mediates invasion by direct binding to M1. To determine if host integrins might be involved in internalization of streptococci, several anti-integrin monoclonal antibodies (MAbs) were tested for their abilities to inhibit invasion. Antibody directed against integrin β1 inhibited FBS-, Fn-, and Lm-mediated invasion but did not abrogate RGD-peptide-stimulated invasion. MAb directed against the epithelial cell Fn receptor, integrin α5β1, inhibited Fn and FBS-mediated invasion but did not specifically inhibit Lm-mediated invasion. These results indicate that
S. pyogenes
has evolved multiple mechanisms for invasion of eukaryotic cells, at least two of which involve interactions between M1 protein, host integrins, and integrin ligands.
Surface-Associated Hsp60 Chaperonin of
Legionella pneumophila
Mediates Invasion in a HeLa Cell Model
Authors: Garduño Rafael A. , Garduño Elizabeth , Hoffman Paul S. 
Published: December 2019

ABSTRACT

HeLa cells have been previously used to demonstrate that virulent strains of
Legionella pneumophila
(but not salt-tolerant avirulent strains) efficiently invade nonphagocytic cells. Hsp60, a member of the GroEL family of chaperonins, is displayed on the surface of virulent
L. pneumophila
(R. A. Garduño et al., J. Bacteriol. 180:505–513, 1988). Because Hsp60 is largely involved in protein-protein interactions, we investigated its role in adherence-invasion in the HeLa cell model. Hsp60-specific antibodies inhibited the adherence and invasiveness of two virulent
L. pneumophila
strains in a dose-dependent manner but had no effect on the association of their salt-tolerant avirulent derivatives with HeLa cells. A monospecific anti-OmpS (major outer membrane protein) serum inhibited the association of both virulent and avirulent strains of
L. pneumophila
to HeLa cells, suggesting that while both Hsp60 and OmpS may mediate bacterial association to HeLa cells, only virulent strains selectively displayed Hsp60 on their surfaces. Furthermore, the surface-associated Hsp60 of virulent bacterial cells was susceptible to the action of trypsin, which rendered the bacteria noninvasive. Additionally, pretreatment of HeLa cells with purified Hsp60 or precoating of the plastic surface where HeLa cells attached with Hsp60 reduced the adherence and invasiveness of the two virulent strains. Finally, recombinant Hsp60 covalently bound to latex beads promoted the early association of beads with HeLa cells by a factor of 20 over bovine serum albumin (BSA)-coated beads and competed with virulent strains for association with HeLa cells. Hsp60-coated beads were internalized in large numbers by HeLa cells and remained in tight endosomes that did not fuse with other vesicles, whereas internalized BSA-coated beads, for which endocytic trafficking is well established, resided in more loose or elongated endosomes. Mature intracellular forms of
L. pneumophila
, which were up to 100-fold more efficient than agar-grown bacteria at associating with HeLa cells, were enriched for Hsp60 on the bacterial surface, as determined by immunolocalization techniques. Collectively, these results establish a role for surface-exposed Hsp60 in invasion of HeLa cells by
L. pneumophila
.