bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sulfolipid Deficiency Does Not Affect the Virulence ofMycobacterium tuberculosisH37Rv in Mice and Guinea Pigs
Authors: Rousseau Cécile , Turner Oliver C. , Rush Erik , Bordat Yann , Sirakova Tatiana D. , Kolattukudy Pappachan E. , Ritter Shannon , Orme Ian M. , Gicquel Brigitte , Jackson Mary 
Published: July 2003

ABSTRACTLipids that are found only in the cell envelope of pathogenic mycobacteria, such as those containing multiple methyl-branched fatty acids, have long been thought to play a role in pathogenesis. Among these complex lipids, sulfolipids have been the most extensively studied over the last 50 years. The numerous biological effects exhibited by purified sulfolipids on phagocytic cells led to the idea that these molecules are probably important virulence factors facilitating the intracellular survival ofMycobacterium tuberculosis. However, definitive evidence to support this concept has been lacking. The recent construction of an isogenic sulfolipid-deficient mutant ofM. tuberculosisH37Rv (Sirakova et al., J. Biol. Chem.276:16833-16839, 2001) has for the first time provided the opportunity to directly assess the contribution of these complex lipids to pathogenesis. In the present study, we show that against all expectations, sulfolipid deficiency does not significantly affect the replication, persistence, and pathogenicity ofM. tuberculosisH37Rv in mice and guinea pigs or in cultured macrophages.
Efficacy of the 26-Kilodalton Outer Membrane Protein and Two P5 Fimbrin-Derived Immunogens To Induce Clearance of Nontypeable
Haemophilus influenzae
from the Rat Middle Ear and Lungs as Well as from the Chinchilla Middle Ear and Nasopharynx
Authors: Kyd Jennelle M. , Cripps Allan W. , Novotny Laura A. , Bakaletz Lauren O. 
Published: July 2003

ABSTRACT

The rat middle ear and lung clearance model has been used to show that the nontypeable
Haemophilus influenzae
26-kDa outer membrane protein OMP26 is highly efficacious as a mucosal immunogen, inducing significantly enhanced clearance in immunized rats upon direct challenge of these two anatomic sites. Similarly, the chinchilla model of middle ear and nasopharyngeal clearance has been used to show that two P5 fimbrin adhesin-derived immunogens, LB1 and lipoprotein D (LPD)-LB1(f)
2,1,3
, are highly efficacious as parenteral immunogens. Both induced significantly augmented clearance of nontypeable
H. influenzae
upon challenge of these sites. Here, these three nontypeable
H. influenzae
immunogens in addition to six bovine serum albumin and keyhole limpet hemocyanin conjugates of the synthetic peptide LB1(f) were assayed for relative efficacy in the reciprocal rodent model system. OMP26 was assayed in the chinchilla host by a parenteral immunization route, with clearance of the middle ear and nasopharynx used as outcome measures. Both LB1 and LPD-LB1(f)
2,1,3
were assayed in the rat host with a mucosal immunization route and clearance of nontypeable
H. influenzae
from the lungs and middle ears as outcome measures. Both of the immunogens were found to induce a high-titered and specific immune responses in the heterologous host system. Moreover, each was found to be highly efficacious in the reciprocal host system, providing strong support for the continued development and inclusion of both OMP26 and P5 fimbrin-derived peptides as candidate vaccine antigens directed at otitis media caused by nontypeable
H. influenzae
.
Primary Cultures of Female Swine Genital Epithelial Cells In Vitro: a New Approach for the Study of Hormonal Modulation of Chlamydia Infection
Authors: Guseva Natalia V. , Knight Stephen T. , Whittimore Judy D. , Wyrick Priscilla B. 
Published: July 2003

ABSTRACTPrevious studies have demonstrated that female reproductive hormones influence chlamydial infection both in vivo and in vitro. Due to the reduced availability of human genital tissues for research purposes, an alternative hormone-responsive model system was sought to study chlamydial pathogenesis. Mature female swine eliminated from breeding programs were selected as the animals of choice because of the similarity of a sexually transmitted disease syndrome and sequelae in swine to a disease syndrome and sequelae found in humans, because of the near identity of a natural infectious chlamydial isolate from swine toChlamydia trachomatisserovar D from humans, and because a pig's epithelial cell physiology and the mean length of its estrous cycle are similar to those in humans. Epithelial cells from the cervix, uterus, and horns of the uterus were isolated, cultivated in vitro in Dulbecco's minimum essential medium-Hanks' F-12 (DMEM-F-12) medium with and without exogenous hormone supplementation, and analyzed forChlamydia suisS-45 infectivity. The distribution of chlamydial inclusions in swine epithelial cells was uneven and was influenced by the genital tract site and hormone status. This study confirmed that, like primary human endometrial epithelial cells, estrogen-dominant swine epithelial cells are more susceptible to chlamydial infection than are progesterone-dominant cells. Further, the more differentiated luminal epithelial cells were more susceptible to infection than were glandular epithelial cells. Interestingly, chlamydial growth in mature luminal epithelia was morphologically more active than in glandular epithelia, where persistent chlamydial forms predominated. Attempts to reprogram epithelial cell physiology and thereby susceptibility to chlamydial infection by reverse-stage, exogenous hormonal supplementation were unsuccessful. Freshly isolated primary pig epithelial cells frozen at −80°C in DMEM-F-12 medium with 10% dimethyl sulfoxide for several weeks can, after thawing, reform characteristic polarized monolayers in 3 to 5 days. Thus, primary swine genital epithelia cultured ex vivo appear to be an excellent cell model for dissecting the hormonal modulation of several aspects of chlamydial pathogenesis and infection.
Calprotectin, an Abundant Cytosolic Protein from Human Polymorphonuclear Leukocytes, Inhibits the Growth ofBorrelia burgdorferi
Authors: Lusitani Denise , Malawista Stephen E. , Montgomery Ruth R. 
Published: July 2003

ABSTRACTWe previously showed that numerous polymorphonuclear leukocyte (PMN) granule components efficiently killBorrelia burgdorferi, the agent of Lyme disease. In addition, motile, granule-poor cytoplasts (U-Cyt) from human blood PMN can exert anti-Borreliaactivity against opsonizedB. burgdorferiindependently of oxidative mechanisms. Here we show that lysates of U-Cyt also possess anti-Borreliaactivity, a portion of which comes from the abundant cytosolic protein calprotectin. The anti-Borreliaactivity of U-Cyt lysates and recombinant calprotectin was partially or completely reversed by specific antibody to calprotectin and by Zn2+, a cation essential for the growth ofB. burgdorferiand known to inhibit the antimicrobial activity of calprotectin. Quantitative microscopic and regrowth assays revealed that calprotectin acted in a bacteriostatic fashion againstB. burgdorferi. We conclude that calprotectin, a potent bacteriostatic agent from a cell primarily recognized for its oxidative and granular antibacterial mechanisms, may play a modulatory role in infection by the Lyme spirochete, particularly at sites of acute inflammation.
SCID Mouse Model for Lethal Q Fever
Authors: Andoh Masako , Naganawa Takashi , Hotta Akitoyo , Yamaguchi Tsuyoshi , Fukushi Hideto , Masegi Toshiaki , Hirai Katsuya 
Published: July 2003

ABSTRACTQ fever, a worldwide zoonosis caused byCoxiella burnetii, has many manifestations in humans. Endocarditis is the most serious complication of Q fever. Animal models are limited to acute pulmonary or hepatic disease and reproductive disorders. An appropriate experimental animal model for Q fever endocarditis does not yet exist. In this study, severe combined immunodeficient (SCID) mice infected withC. burnetiishowed persistent clinical symptoms and died, whereas immunocompetent mice similarly infected became asymptomatic and survived. The SCID mice examined in this study had severe chronic lesions in their primary organs: the heart, lung, spleen, liver, and kidney. The heart lesions of the SCID mice were similar to those in humans with chronic Q fever endocarditis: they had focal calcification and expanded macrophages containingC. burnetii. The 50% lethal dose ofC. burnetiiin SCID mice was at least 108times less than that in immunocompetent mice. The SCID mouse is highly susceptible toC. burnetii, and the immunodeficiency of the host enhances the severity of Q fever. This animal model could provide a new tool for the study of chronic Q fever and Q fever in immunodeficient hosts.
Correlation of Acetate Catabolism and Growth Yield inStaphylococcus aureus: Implications for Host-Pathogen Interactions
Authors: Somerville Greg A. , Saïd-Salim Battouli , Wickman Jaala M. , Raffel Sandra J. , Kreiswirth Barry N. , Musser James M. 
Published: July 2003

ABSTRACTRecently, we reported that the prototypicalStaphylococcus aureusstrain RN6390 (a derivative of NCTC 8325) had significantly reduced aconitase activity relative to a diverse group ofS. aureusisolates, leading to the hypothesis that strain RN6390 has impaired tricarboxylic acid (TCA) cycle-mediated acetate catabolism. Analysis of the culture supernatant from RN6390 confirmed that acetate was incompletely catabolized, suggesting that the ability to catabolize acetate can be lost byS. aureus. To test this hypothesis, we examined the carbon catabolism of theS. aureusstrains whose genome sequences are publicly available. All strains catabolized glucose and excreted acetate into the culture medium. However, strains NCTC 8325 and N315 failed to catabolize acetate during the postexponential growth phase, resulting in significantly lower growth yields relative to strains that catabolized acetate. Strains NCTC 8325 and RN6390 contained an 11-bp deletion inrsbU, the gene encoding a positive regulator of the alternative sigma factor σBencoded bysigB. An isogenic derivative strain of RN6390 containing the wild-typersbUgene had significantly increased acetate catabolism, demonstrating that σBis required for acetate catabolism. Taken together, the data suggest that naturally occurring mutations can alter the ability ofS. aureusto catabolize acetate, a surprising discovery, as TCA cycle function has been demonstrated to be involved in the virulence, survival, and persistence of several pathogenic organisms. Additionally, these mutations decrease the fitness ofS. aureusby reducing the number of progeny placed into subsequent generations, suggesting that in certain situations a decreased growth yield is advantageous.
Induction of Antimicrobial Pathways during Early-Phase Immune Response toSalmonellaspp. in Murine Macrophages: Gamma Interferon (IFN-γ) and Upregulation of IFN-γ Receptor Alpha Expression Are Required for NADPH Phagocytic Oxidase gp91-Stimulated Oxidative Burst and Control of VirulentSalmonellaspp
Authors: Foster N. , Hulme S. D. , Barrow P. A. 
Published: July 2003

ABSTRACTThe effect of gamma interferon (IFN-γ) on elevation of reactive oxygen species and the viability of virulent wild-type and avirulent mutants ofSalmonella entericaserovar Typhimurium andS. entericaserovar Infantis was studied in a murine macrophage cell line (J774.2 cells).S. entericaserovar Typhimurium 14028phoPand a rough lipopolysaccharide mutant ofS. entericaserovar Infantis 1326/28 (φr) (avirulent mutants) induced NADPH phagocytic oxidase gp91 (gp91phox) activity and a significant (P< 0.05) elevation of reactive oxygen species within 12 h without coculture with IFN-γ. This coincided with reduced survival ofS. entericaserovar Typhimurium14028phoPor stasis ofS. entericaserovar Infantis φr. Fluorometric studies indicated that expression of IFN-γ on infected J774.2 cells was not significantly (P> 0.05) elevated. However, studies with the virulentS. entericaserovar Typhimurium strains showed that a comparable level of control of bacterial numbers could only be achieved by coculture with IFN-γ. This coincided with significant upregulation of IFN-γ receptor alpha expression on the surface of J774.2 cells and was completely abolished byN-acetyl-l-cysteine captopril (an inhibitor of reactive oxygen species). Delay in reactive oxygen species induction due to a requirement for IFN-γ and upregulation of IFN-γ receptor alpha in macrophages infected with virulent salmonellae may result in greater dissemination of virulent salmonellae in host tissue.
Effect of Inactivation of the Arg- and/or Lys-Gingipain Gene on Selected Virulence and Physiological Properties of
Porphyromonas gingivalis
Authors: Grenier Daniel , Roy Sophie , Chandad Fatiha , Plamondon Pascale , Yoshioka Masami , Nakayama Koji , Mayrand Denis 
Published: July 2003

ABSTRACT

Proteolytic enzymes produced by
Porphyromonas gingivalis
are thought to play critical roles in the pathogenesis of periodontitis. The aim of this study was to investigate the effect of gingipain cysteine proteinase gene inactivation on selected pathological and physiological functions of
P. gingivalis
. Our results showed that Arg- and Lys-gingipain activities are critical components for the efficient growth of
P. gingivalis
in human serum. However, when the serum was supplemented with peptides provided as pancreatic casein hydrolysate, the gingipains did not appear to be essential for growth. The effect of gingipain gene inactivation on the susceptibility of
P. gingivalis
to serum bactericidal activity was investigated using standardized human serum. The wild-type strain,
P. gingivalis
ATCC 33277, was largely unaffected by the bactericidal activity of human serum complement. On the other hand, mutants lacking Arg-gingipain A, Arg-gingipain B, or Lys-gingipain activity were susceptible to complement. Since gingipains are mostly located on the outer membrane of
P. gingivalis
, inactivation of the genes for these enzymes may modify cell surface properties. We showed that gingipain-deficient mutants differed in their capacities to assimilate radiolabeled amino acids, cause hemolysis, express adhesins, hemagglutinate, and form biofilms. Lastly, the gingipains, more specifically Arg-gingipains, were responsible for causing major cell damage to human gingival fibroblasts. In conclusion, our study indicated that, in addition to being critical in the pathogenic process, gingipains may play a variety of physiological roles in
P. gingivalis
, including controlling the expression and/or processing of virulence factors. Mutations in gingipain genes thus give rise to pleiotropic effects.
Induction of Parasite Growth-Inhibitory Antibodies by a Virosomal Formulation of a Peptidomimetic of Loop I from Domain III of
Plasmodium falciparum
Apical Membrane Antigen 1
Authors: Mueller Markus S. , Renard Annabelle , Boato Francesca , Vogel Denise , Naegeli Martin , Zurbriggen Rinaldo , Robinson John A. , Pluschke Gerd 
Published: July 2003

ABSTRACT

Apical membrane antigen 1 (AMA-1) of
Plasmodium falciparum
is a leading candidate antigen for inclusion in a malaria subunit vaccine. Its ectodomain can be divided into three subdomains, each with disulfide bond-stabilized structures. Since the majority of antibodies raised against the ectodomain appear to recognize strain-specific epitopes in domain I, we attempted to develop a vaccine formulation which directs the immune response to a region that contains more conserved epitopes. Here we demonstrate that a virosomal formulation of a peptide that mimics the semiconserved loop I of domain III elicits parasite growth-inhibitory antibodies. A synthetic peptide comprising residues 446 to 490 of AMA-1 (AMA-1
446-490
) was conjugated through the N terminus to a derivative of phosphatidylethanolamine and the phosphatidylethanolamine-peptide conjugate was incorporated into immunopotentiating reconstituted influenza virosomes as a human-compatible antigen delivery system. Both cyclized and linear versions of the peptide antigen elicited antibodies which specifically bound to parasite-expressed AMA-1 in Western blotting with parasite lysates as well as in immunofluorescence assays with blood stage parasites. All 11 peptidomimetic-specific monoclonal antibodies generated were cross-reactive with parasite-expressed AMA-1. Antigen binding assays with a library of overlapping cyclic peptides covering the target sequence revealed differences in the fine specificity of these monoclonal antibodies and provided evidence that at least some of them recognized discontinuous epitopes. The two immunodominant epitopes comprised the conserved linear sequences K
459
RIKLN
464
and D
467
DEGNKKII
475
. A key feature of the synthetic vaccine formulation proposed here is the display of the peptide antigen in a native-like state on the surface of the virosome.
Growth, Development, and Gene Expression in a Persistent
Streptococcus gordonii
Biofilm
Authors: Gilmore Keeta S. , Srinivas Pravina , Akins Darrin R. , Hatter Kenneth L. , Gilmore Michael S. 
Published: July 2003

ABSTRACT

A model for the protracted (30-day) colonization of smooth surfaces by
Streptococcus gordonii
that incorporates the nutrient flux that occurs in the oral cavity was developed. This model was used to characterize the biphasic expansion of the adherent bacterial population, which corresponded with the emergence of higher-order architectures characteristic of biofilms. Biofilm formation by
S. gordonii
was observed to be influenced by the presence of simple sugars including sucrose, glucose, and fructose. Real-time PCR was used to quantify changes in expression of
S. gordonii
genes known or thought to be involved in biofilm formation. Morphological changes were accompanied by a significant shift in gene expression patterns. The majority of
S. gordonii
genes examined were observed to be downregulated in the biofilm phase. Genes found to be upregulated in the biofilm state were observed to encode products related to environmental sensing and signaling.
Nonspecific Immunoglobulin M Binding and Chondroitin Sulfate A Binding Are Linked Phenotypes of
Plasmodium falciparum
Isolates Implicated in Malaria during Pregnancy
Authors: Creasey Alison M. , Staalsoe Trine , Raza Ahmed , Arnot David E. , Rowe J. Alexandra 
Published: July 2003

ABSTRACT

Binding of immunoglobulin M (IgM) antibodies from normal human serum to the surface of
Plasmodium falciparum
-infected red blood cells (iRBC) has previously been demonstrated only in parasites that form rosettes with uninfected red cells. We show that natural, nonspecific IgM but not IgG, IgA, IgD, or IgE also binds to the surface of iRBC selected for adhesion to chondroitin sulfate A (CSA), a placental receptor for parasites associated with malaria in pregnancy. The protease sensitivity of IgM-binding appears to match that of CSA binding, suggesting that the two phenotypes may be mediated by the same parasite molecule. We also show that a wide range of mouse monoclonal antibodies of the IgM class bind nonspecifically to CSA-selected iRBC, an important consideration in the interpretation of immunological assays performed on these parasite lines.
Recombinant 56-Kilodalton Major Outer Membrane Protein Antigen of
Orientia tsutsugamushi
Shanxi and Its Antigenicity
Authors: Chen Wei-Jun , Niu Dong-Sheng , Zhang Xue-Ying , Chen Mei-Ling , Cui Hong , Wei Wen-Jin , Wen Bo-Hai , Chen Xiang-Rui 
Published: July 2003

ABSTRACT

The gene encoding the 56-kDa protein of
Orientia tsutsugamushi
Shanxi was amplified by a nested PCR and cloned into the expression vector pQE30. The 56-kDa protein of
O. tsutsugamushi
Shanxi (Sxh56) was expressed as a fusion protein with the His
6
-binding protein of
Escherichia coli
by deleting the signal peptide-encoding sequence from the 5′ end of the open reading frame. The recombinant protein formed inclusion bodies when expressed in
E. coli
M15. The recombinant protein was examined for reactivity with mouse sera against three antigenic prototypes of
O. tsutsugamushi
by an immunoblot assay. The recombinant Sxh56 reacted only to polyclonal antiserum to
O. tsutsugamushi
Gilliam in an enzyme-linked immunosorbent assay (ELISA) and in an immunoblot assay. Recombinant Sxh56 was purified by Ni-nitrilotriacetic acid affinity chromatography and injected into mice to evaluate its ability to stimulate immune responses. High levels of immunoglobulin G and T-cell proliferation appeared in mice immunized with the recombinant protein. The recombinant Sxh56 was used in an ELISA to evaluate the ability of the method to detect antibodies to
O. tsutsugamushi
in human and animal sera. Thirty sera from mice infected with
O. tsutsugamushi
Gilliam or Shanxi and 55 sera from normal mice were detected in the ELISA with recombinant Sxh56, and the sensitivity and specificity were 96.67 and 100%, respectively. One hundred fifty-one positive sera and 412 negative sera to
O. tsutsugamushi
Gilliam were detected in an indirect immunofluorescence assay with the recombinant protein, and the sensitivity and specificity were 96.36 and 88.08%, respectively. These results strongly suggest that the recombinant Sxh56 is a suitable type-specific immunodiagnostic antigen and vaccine candidate.
Increased Protection against Pneumococcal Disease by Mucosal Administration of Conjugate Vaccine plus Interleukin-12
Authors: Lynch Joyce M. , Briles David E. , Metzger Dennis W. 
Published: July 2003

ABSTRACTStreptococcus pneumoniaeis a common cause of respiratory tract infections, its main entry route being the nasal mucosa. The recent development of pneumococcal polysaccharide conjugate vaccines has led to a dramatic improvement in protection against invasive disease in infants and children, but these vaccines have been found to be only 50 to 60% protective against bacterial carriage. In this study, we investigated the efficacy of intranasal (i.n.) conjugate vaccine delivery using interleukin-12 (IL-12) as a mucosal adjuvant. Immunized mice treated with IL-12 demonstrated increased expression of lung and splenic gamma interferon and IL-10 mRNAs; high levels of antibody, particularly serum immunoglobulin G2a (IgG2a) and respiratory IgA; and significantly increased opsonic activity. After intraperitoneal challenge with type 3 pneumococci, there was 75% survival of i.n. vaccinated mice compared to 0% survival of unvaccinated mice. In addition, after i.n. challenge with type 14 pneumococci, vaccinated mice possessed fewer bacterial colonies in the upper respiratory tract than unvaccinated mice. However, no significant difference in type 14 carriage was observed between vaccinated and unvaccinated groups following intramuscular vaccination, the typical route of vaccination in humans. Using mice with a genetic disruption in IgA expression, it was found that pneumococcus-specific IgA played a significant role in the clearance of bacteria from the upper respiratory tract. We conclude that i.n vaccination in the presence of IL-12 is able to enhance systemic and mucosal immune responses to pneumococci and efficiently protect against both invasive infection and bacterial carriage.