Publications

localization of haemophilus ducreyi at the pustular stage of disease in the human model of infection.	to localize haemophilus ducreyi in vivo, human subjects were experimentally infected with h. ducreyi until they developed a painful pustule or for 14 days. lesions were biopsied, and biopsy samples were fixed in 4% paraformaldehyde, and cryosectioned. sections were stained with polyclonal anti-h. ducreyi antiserum or h. ducreyi-specific monoclonal antibodies (mabs) and fluorescently tagged secondary antibodies and examined by confocal microscopy. we identified h. ducreyi in 16 of 18 pustules but ...	2000	10722634
cloning and characterization of the lipooligosaccharide galactosyltransferase ii gene of haemophilus ducreyi.	haemophilus ducreyi is the etiologic agent of chancroid, a genital ulcer disease. the lipooligosaccharide (los) is considered to be a major virulence determinant and has been implicated in the adherence of h. ducreyi to keratinocytes. strain a77, an isolate from the paris collection, is serum sensitive, poorly adherent to fibroblasts, and deficient in microcolony formation. structural analysis indicates that the los of strain a77 lacks the galactose residue found in the n-acetyllactosamine porti ...	2000	10735874
development of a serological test for haemophilus ducreyi for seroprevalence studies.	we developed a new enzyme immunoassay (rpeia) for use in determining the seroprevalence of chancroid. three highly conserved outer membrane proteins from haemophilus ducreyi strain 35000 were cloned, overexpressed, and purified from escherichia coli for use as antigens in the rpeia. serum specimens from patients with and without chancroid were assayed to determine optimum sensitivity and specificity and to establish cutoff values. on the basis of these data, rpeia was found to be both sensitive ...	2000	10747137
evaluation of an isogenic major outer membrane protein-deficient mutant in the human model of haemophilus ducreyi infection.	haemophilus ducreyi expresses 2 ompa homologs, designated momp and ompa2, whose genes are arranged in tandem on the chromosome. northern blot analysis indicated that momp and ompa2 are transcribed independently. sequences of the momp open reading frame (orf) lacking the transcriptional start site were amplified by pcr, and an omega-km2 cassette was ligated into the orf. a plasmid containing this construction was electroporated into h. ducreyi 35000hp, and an isogenic momp-deficient mutant (35000 ...	2000	10768950
treatment of sexually transmitted bacterial diseases in pregnant women.	testing for and treating sexually transmitted diseases (stds) in pregnant women deserves special attention. treatment possibilities are limited because of potential risks for the developing fetus, and because effects can differ in pregnant compared with non-pregnant women, re-infection may be missed because of the intrinsic delicacy of contact-tracing during pregnancy and because pregnant women are more reluctant to take the prescribed medication in its full dose, if at all. however, the devasta ...	2000	10776830
construction and characterization of haemophilus ducreyi lipooligosaccharide (los) mutants defective in expression of heptosyltransferase iii and beta1,4-glucosyltransferase: identification of los glycoforms containing lactosamine repeats.	to begin to understand the role of the lipooligosaccharide (los) molecule in chancroid infections, we constructed mutants defective in expression of glycosyltransferase genes. pyocin lysis and immunoscreening was used to identify a los mutant of haemophilus ducreyi 35000. this mutant, hd35000r, produced a los molecule that lacked the monoclonal antibody 3f11 epitope and migrated with an increased mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page). structural studies ...	2000	10816485
identification of cdtb homologues and cytolethal distending toxin activity in enterohepatic helicobacter spp.	a bacterial toxin that causes progressive distension and death of chinese hamster ovary (cho) cells and hela cells, termed cytolethal distending toxin (cdt), has been identified in several diarrhoeagenic bacteria, including campylobacter spp. (c. jejuni and cq coli), some pathogenic strains of escherichia coli and shigella spp. genes encoding this toxin were identified as a cluster of three adjacent genes cdta, cdtb and cdtc. homologues of cdtb from five species of enterohepatic helicobacters (h ...	2000	10847206
chancroid in the united kingdom.		2000	10858704
diagnostic tests for chancroid.		2000	10858718
expression of the cytolethal distending toxin (cdt) operon in actinobacillus actinomycetemcomitans: evidence that the cdtb protein is responsible for g2 arrest of the cell cycle in human t cells.	we have previously shown that actinobacillus actinomycetemcomitans produces an immunosuppressive factor that is encoded by the cdtb gene, which is homologous to a family of cytolethal distending toxins (cdt) expressed by several gram-negative bacteria. in this study, we report that the cdt locus in a. actinomycetemcomitans is composed of five open reading frames, designated orf1, orf2, cdta, cdtb, and cdtc. the deduced amino acid sequences of the five open reading frames are highly conserved amo ...	2000	10946289
quality of sexually transmitted disease treatments in the formal and informal sectors of bangui, central african republic.	interventions for upgrading sexually transmitted disease (std) management in sub-saharan africa have focused on the public sector, and to a much lower extent on private medical practitioners and pharmacies. however, in most african cities there is a large informal sector that provides care to many patients with std symptoms.	2000	10987452
characterization and expression of hmur, a tonb-dependent hemoglobin receptor of porphyromonas gingivalis.	the gram-negative pathogen porphyromonas gingivalis requires hemin for growth. hemoglobin bound to haptoglobin and hemin complexed to hemopexin can be used as heme sources, indicating that p. gingivalis must have a means to remove the hemin from these host iron-binding proteins. however, the specific mechanisms utilized by p. gingivalis for the extraction of heme from heme-binding proteins and for iron transport are poorly understood. in this study we have determined that a newly identified tonb ...	2000	11004172
episome profiles and mobilizable beta-lactamase plasmid in haemophilus ducreyi.	chancroid caused by haemophilus ducreyi has been described as a significantly predisposing factor of hiv heterosexual transmission in an endemic region of both diseases. the fastidious, h. ducreyi has been reported world wide with various antimicrobial susceptibility patterns. a high tendency of drug resistances has generally been found among isolates derived in thailand. in this study, the plasmids of h. ducreyi were isolated and analysed from 63 clinically derived organisms. twenty-nine out of ...	2000	11023070
expression of peptidoglycan-associated lipoprotein is required for virulence in the human model of haemophilus ducreyi infection.	haemophilus ducreyi expresses a peptidoglycan-associated lipoprotein (pal) that exhibits extensive homology to haemophilus influenzae protein 6. we constructed an isogenic pal mutant (35000hp-sms4) by the use of a suicide vector that contains lacz as a counterselectable marker. h. ducreyi 35000hp-sms4 and its parent, 35000hp, had similar growth rates in broth and similar lipooligosaccharide profiles. 35000hp-sms4 formed smaller, more transparent colonies than 35000hp and, unlike its parent, was ...	2000	11035757
effect of a cellulose acetate phthalate topical cream on vaginal transmission of simian immunodeficiency virus in rhesus monkeys.	human immunodeficiency virus type 1 (hiv-1) infection continues to spread in developing countries, mostly through heterosexual transmission. the development of a safe and cost-effective topical microbicide, effective against a range of stds including hiv-1, would greatly impact the ongoing epidemic. when formulated in a vehicle, a micronized form of cellulose acetate phthalate (cap), which is an inactive pharmaceutical excipient, has been shown to inactivate hiv-1, herpes simplex virus types 1 a ...	2000	11036053
etiology of genital ulcer disease in dakar, senegal, and comparison of pcr and serologic assays for detection of haemophilus ducreyi.	we used pcr assays to determine the etiology of genital ulcers in patients presenting to a sexually transmitted disease clinic in dakar, senegal, and evaluated the ability of two pcr tests (groel and recd) and two serological tests (adsorption enzyme immunoassay [eia] and lipooligosaccharide [los] eia) to detect current haemophilus ducreyi infection. we found that in this population, h. ducreyi, t. pallidum, and herpes simplex virus hsv dna were detected in 56, 15, and 13% of 39 genital ulcer sp ...	2000	10618099
human immunodeficiency virus infection and genital ulcer disease in south africa: the herpetic connection.	while genital ulcers are a risk factor in hiv infection, the association of specific agents of genital ulcer disease (gud) with hiv infection may vary.	2000	10654864
update on the experimental human model for chancroid infection.		2000	10667906
cumulative experience with haemophilus ducreyi 35000 in the human model of experimental infection.	to study haemophilus ducreyi pathogenesis, the authors developed an experimental model of infection in human volunteers. the authors analyze their cumulative experience with strain 35000 in the model and calculate the papule and pustule formation rates for estimated delivered doses (edds) ranging from 1 cfu to 100 cfu.	2000	10676978
serum resistance in haemophilus ducreyi requires outer membrane protein dsra.	haemophilus ducreyi is resistant to killing by normal serum antibody and complement. we discovered an h. ducreyi outer membrane protein required for expression of serum resistance and termed it dsra (for "ducreyi serum resistance a"). the dsra locus was cloned, sequenced, and mutagenized. an isogenic mutant (fx517) of parent strain 35000 was constructed and characterized, and it was found to no longer express dsra. fx517 was at least 10-fold more serum susceptible than 35000. dsra was expressed ...	2000	10678980
stable shuttle vectors for neisseria gonorrhoeae, haemophilus spp. and other bacteria based on a single origin of replication.	an origin of replication (ori) was obtained from a naturally occurring beta-lactamase-producing plasmid isolated from neisseria gonorrhoeae and used to construct shuttle vectors capable of replicating in n. gonorrhoeae, haemophilus ducreyi, haemophilus influenzae and escherichia coli. using the gonococcal proab genes, we complemented proline-requiring n. gonorrhoeae f62 and e. coli hb101 in trans. the first demonstration of the expression of the green fluorescent protein (gfp) in either n. gonor ...	2000	10689182
cellular internalization of cytolethal distending toxin from haemophilus ducreyi.	the chancroid bacterium haemophilus ducreyi produces a toxin (hdcdt) which is a member of the recently discovered family of cytolethal distending toxins (cdts). these protein toxins prevent the cyclin-dependent kinase cdc2 from being activated, thus blocking the transition of cells from the g(2) phase into mitosis, with the consequent arrest of intoxicated cells in g(2). it is not known whether these toxins act by signaling from the cell surface or intracellularly only. here we report that hdcdt ...	2000	11083812
the use of molecular techniques for the diagnosis and epidemiologic study of sexually transmitted infections.	molecular diagnostic tests are more sensitive and, in many cases, more specific than conventional laboratory methods for the detection of sexually transmitted infections. here, we review recently developed molecular methods for the diagnosis and subtyping of the most common sexually transmitted infections: infections caused by chlamydia trachomatis, neisseria gonorrhoeae, human papillomavirus, trichomonas vaginalis, and the agents of genital ulcer disease (haemophilus ducreyi, herpes simplex vir ...	2000	11095835
chancroid: from clinical practice to basic science.	chancroid is a sexually transmitted disease caused by the bacterium haemophilus ducreyi. it usually presents as a genital ulcer and may be associated with regional lymphadenopathy and bubo formation. h. ducreyi infection is predominantly seen in tropical resource-poor regions of the world where it is frequently the most common etiological cause of genital ulceration. genital ulcer disease has been shown to be an extremely important co-factor in hiv transmission. with the advent of the aids epide ...	2000	12240879
trichomonas vaginalis-an indicator for other sexually transmitted infecting agents.	the present study is based on 350 women having sexually transmitted diseases (std) and 68 male counterparts. trichomonas vaginalis was a significant contributor in 216 (61.7%) out of 350 female std cases and 56 (82.3%) out of 68 male counterparts. further, out of 126 (58.3%) out of 216 cases of t. vaginalis, 41 cases (32.5%) were associated with candida species; 29 cases (23%) were associated with neisseria gonorrhoeae (n gonorrhoeae); haemophilus ducreyi (h. ducreyi) 18 cases (14.3%) and chlamy ...	2000	20877088
identification of a plasmid-encoded gene from haemophilus ducreyi which confers nad independence.	members of the family pasteurellaceae are classified in part by whether or not they require an nad supplement for growth on laboratory media. in this study, we demonstrate that this phenotype can be determined by a single gene, nadv, whose presence allows nad-independent growth of haemophilus influenzae and actinobacillus pleuropneumoniae. this gene was cloned from a 5.2-kb plasmid which was previously shown to be responsible for nad independence in haemophilus ducreyi. when transformed into a. ...	2001	11157928
diagnosing genital ulcer disease in a clinic for sexually transmitted diseases in amsterdam, the netherlands.	the most common etiologic agents of genital ulcer disease (gud) are herpes simplex virus type 1 (hsv-1), hsv-2, treponema pallidum, and haemophilus ducreyi. in an outpatient clinic for sexually transmitted diseases in amsterdam, the netherlands, specimens from 372 patients with gud were collected from february to november 1996. sera were collected at the time of the symptoms and, for most patients, also during follow-up visits. swabs in viral transport medium were used for hsv culture and for de ...	2001	11158114
transcription of candidate virulence genes of haemophilus ducreyi during infection of human volunteers.	haemophilus ducreyi expresses several putative virulence factors in vitro. isogenic mutant-to-parent comparisons have been performed in a human model of experimental infection to examine whether specific gene products are involved in pathogenesis. several mutants (momp, ftpa, losb, lst, cdtc, and hhdb) were as virulent as the parent in the human model, suggesting that their gene products did not play a major role in pustule formation. however, we could not exclude the possibility that the gene o ...	2001	11179316
dsra-deficient mutant of haemophilus ducreyi is impaired in its ability to infect human volunteers.	haemophilus ducreyi produces an outer membrane protein called dsra, which is required for serum resistance. an isogenic dsra mutant, fx517, was constructed previously in h. ducreyi 35000. compared to its parent, fx517 cannot survive in normal human serum. when complemented in trans with a plasmid containing dsra, fx517 is converted to a serum-resistant phenotype (c. elkins, k. j. morrow, jr., and b. olsen, infect. immun. 68:1608-1619, 2000). to test whether dsra was transcribed in vivo, we succe ...	2001	11179317
expression of cytolethal distending toxin and hemolysin is not required for pustule formation by haemophilus ducreyi in human volunteers.	haemophilus ducreyi makes cytolethal distending toxin (cdt) and hemolysin. in a previous human challenge trial, an isogenic hemolysin-deficient mutant caused pustules with a rate similar to that of its parent. to test whether cdt was required for pustule formation, six human subjects were inoculated with a cdt mutant and parent at multiple sites. the pustule formation rates were similar at both parent and mutant sites. a cdt and hemolysin double mutant was constructed and tested in five addition ...	2001	11179379
haemophilus ducreyi associates with phagocytes, collagen, and fibrin and remains extracellular throughout infection of human volunteers.	in a previous study, haemophilus ducreyi was found in the pustule and dermis of samples obtained at the clinical end point in the human model of infection. to understand the kinetics of localization, we examined infected sites at 0, 24, and 48 h after inoculation and at the clinical end point. immediately after inoculation, bacteria were found predominantly in the dermis but also in the epidermis. few bacteria were detectable at 24 h; however, by 48 h, bacteria were readily seen in the pustule a ...	2001	11254619
the impact of haemophilus ducreyi cytolethal distending toxin on cells involved in immune response.	the haemophilus ducreyi cytolethal distending toxin (hdcdt) induces cell cycle arrest and thereby inhibits cell proliferation of many cultured mammalian cell-lines. we investigated the effect of hdcdt on circulating human hematopoietic cells, including t- and b-cells, monocytes and polymorphonuclear cells (pmn). lymphocytes were stimulated with t- and b-cell specific mitogens, whereas monocytes and pmn with endotoxin. hdcdt inhibited the mitogen-induced proliferation of t-cells in a dose-depende ...	2001	11273741
vitamin a and risk of hiv-1 seroconversion among kenyan men with genital ulcers.	vitamin a is involved in normal immune function and the maintenance of mucosal integrity through complex effects on cellular differentiation.	2001	11317002
new tests for syphilis: rational design of a pcr method for detection of treponema pallidum in clinical specimens using unique regions of the dna polymerase i gene.	a sensitive and specific pcr method to detect treponema pallidum in clinical specimens was developed. pcr primers were designed based on two unique features of the dna polymerase i gene (pola). the first distinctive characteristic is that the region codes for a high cysteine content and has low homology with similar regions of dna polymerase i gene from known microorganisms. the second unique feature is the presence of four insertions in the gene. pcr tests using primers designed on the basis th ...	2001	11326018
the effect of temperature on the interaction of haemophilus ducreyi with human epithelial cells.	to investigate if temperature affects the interaction of haemophilus ducreyi with human epithelial cells, nine strains were used to evaluate the adhesion kinetics of the organism at 33 degrees c and 37 degrees c. the effect of the free toxin on the epithelial cells at those temperatures was also assessed. the cyto-adherence kinetics of h. ducreyi to the epithelial cells was significantly greater at 33 degrees c (10 times more) than at 37 degrees c in all seven clinical isolates tested. there was ...	2001	11339253
haemophilus ducreyi lipooligosaccharide mutant defective in expression of beta-1,4-glucosyltransferase is virulent in humans.	the lipooligosaccharide (los) of haemophilus ducreyi contains a major glycoform that is immunochemically identical to paragloboside, a glycosphingolipid precursor of major human blood group antigens. we recently identified the gene responsible for the glucosyltransferase activity and constructed an isogenic mutant (35000glu-) deficient in this activity. 35000glu- makes an los that consists only of the heptose trisaccharide core and 2-keto-deoxyoctulosonic acid (kdo). for this study, the mutant w ...	2001	11349097
a novel heme protein, the cu,zn-superoxide dismutase from haemophilus ducreyi.	haemophilus ducreyi, the causative agent of the genital ulcerative disease known as chancroid, is unable to synthesize heme, which it acquires from humans, its only known host. here we provide evidence that the periplasmic cu,zn-superoxide dismutase from this organism is a heme-binding protein, unlike all the other known cu,zn-superoxide dismutases from bacterial and eukaryotic species. when the h. ducreyi enzyme was expressed in escherichia coli cells grown in standard lb medium, it contained o ...	2001	11369755
a histidine-rich metal binding domain at the n terminus of cu,zn-superoxide dismutases from pathogenic bacteria: a novel strategy for metal chaperoning.	a group of cu,zn-superoxide dismutases from pathogenic bacteria is characterized by histidine-rich n-terminal extensions that are in a highly exposed and mobile conformation. this feature allows these proteins to be readily purified in a single step by immobilized metal affinity chromatography. the cu,zn-superoxide dismutases from both haemophilus ducreyi and haemophilus parainfluenzae display anomalous absorption spectra in the visible region due to copper binding at the n-terminal region. reco ...	2001	11369756
detection of the lst gene in different serogroups and los immunotypes of neisseria meningitidis.	the sialylation of the lipooligosaccharide (los) of neisseria meningitidis is mediated by the los sialyltransferase enzyme encoded by the lst gene. pcr using four sets of primers that targeted to different regions of the lst gene was used to survey the distribution of lst in different serogroups and los immunotypes of n. meningitidis as well as other neisseria species. while the lst gene was found in n. meningitidis strains regardless of their capsular serogroup and los structures, the gene is a ...	2001	11377868
vaccine candidates in std.	sexually transmitted diseases (stds) are caused by organisms that infect the mucosal surfaces of the genitourinary tract. in spite of its public health importance, particular scientific problems have delayed the development of an std vaccine, such as incomplete attenuation (human herpes simplex virus type 2), accentuated immunopathology (chlamydia trachomatis), poor immunogenicity (treponema pallidum), and broad antigenic heterogeneity (neisseria gonorrhoeae). nevertheless, efforts continue with ...	2001	11394975
the role of different protein components from the haemophilus ducreyi cytolethal distending toxin in the generation of cell toxicity.	cytolethal distending toxin of haemophilus ducreyi (hdcdt) is a multicomponent toxin, encoded by an operon consisting of three genes, cdtabc. to investigate the role of the individual products in generation of toxicity, recombinant plasmids were constructed allowing expression of each of the genes individually or in different combinations in escherichia coli and vibrio cholerae. expression of all three genes (cdtabc) was necessary to generate toxicity on cells, and no activity was obtained using ...	2001	11399138
characterization of haemophilus ducreyi-specific t-cell lines from lesions of experimentally infected human subjects.	haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmitted genital ulcer disease that facilitates the transmission of human immunodeficiency virus. in the human model of infection, the histopathology of infected sites in part resembles a delayed-type hypersensitivity (dth) response. in this study, t cells were isolated from skin biopsy specimens obtained from 24 subjects who were infected for 7 to 14 days. one clone and 12 lines that responded to h. ducreyi antigens were obt ...	2001	11401958
cloning, overexpression, purification, and immunobiology of an 85-kilodalton outer membrane protein from haemophilus ducreyi.	we have identified an 85-kda outer membrane protein that is expressed by all tested strains of haemophilus ducreyi. studies of related proteins from other pathogenic bacteria, including haemophilus influenzae, pasteurella multocida, neisseria gonorrhoeae, neisseria meningitidis, and shigella dysenteriae, suggested a role for these proteins in pathogenesis and immunity. in keeping with the first such described protein from haemophilus influenzae type b, we termed the h. ducreyi protein d15. the g ...	2001	11401984
haemophilus ducreyi inhibits phagocytosis by u-937 cells, a human macrophage-like cell line.	haemophilus ducreyi is a gram-negative obligate human pathogen that causes the genital ulcer disease chancroid. chancroid lesions are deep necrotic ulcers with an immune cell infiltrate that includes macrophages. despite the presence of these phagocytic cells, chancroid ulcers can persist for months and live h. ducreyi can be isolated from these lesions. to analyze the interaction of h. ducreyi with macrophages, we investigated the ability of h. ducreyi strain 35000 to adhere to, invade, and sur ...	2001	11447144
investigation of the interaction among the components of the cytolethal distending toxin of haemophilus ducreyi.	the cytolethal distending toxin (cdt) of haemophilus ducreyi is encoded by the cdtabc genes, but the composition of active cdt is not known. both immunoaffinity and metal affinity chromatographic methods were used to purify h. ducreyi cdt from recombinant escherichia coli strains bearing wild-type or mutated h. ducreyi cdtabc genes. both affinity-purified preparations contained cdta, cdtb, and cdtc proteins. these purification efforts also revealed that the formation of a noncovalent cdtb-cdtc c ...	2001	11453636
characterization of haemophilus ducreyi cdta, cdtb, and cdtc mutants in in vitro and in vivo systems.	haemophilus ducreyi expresses a soluble cytolethal distending toxin (cdt) that is encoded by the cdtabc gene cluster and can be detected in culture supernatant fluid by its ability to kill hela cells. the cdta, cdtb, and cdtc genes of h. ducreyi were cloned independently into plasmid vectors, and their encoded proteins expressed singly or in various combinations in an escherichia coli background. all three gene products had to be expressed in order for e. coli-derived culture supernatant fluids ...	2001	11500438
neutrophil degranulation induced by haemophilus ducreyi.	haemophilus ducreyi is the causative bacterium of genital ulcers, which are collectively known as chancroid. little is known about the cytotoxicity of h. ducreyi. the virulent strains are relatively resistant to phagocytosis and apoptosis by neutrophils. therefore, experiments were designed to examine whether neutrophil degranulation caused by h. ducrey would provide insights into the virulence mechanisms through which cellular damage is affected by the organism. clinical isolates of eight strai ...	2001	11517937
calorimetric analysis of cephalosporins using an immobilized tem-1 beta-lactamase on ni2+ chelating sepharose fast flow.	two beta-lactamases, penicillinase type i from bacillus cereus and tem-1 beta-lactamase from haemophilus ducreyi, were immobilized on a chelating sepharose fast flow column loaded with ni2+ in an active form. flow-injection analysis of beta-lactams was performed by using an enzyme column reactor fitted into the enzyme thermistor. with both enzymes it was possible to monitor both penicillins and cephalosporins. moreover, michaelis constants of the tem-1 beta-lactamase were markedly increased upon ...	2001	11520032
multiple origins and replication proteins influence biological properties of beta-lactamase-producing plasmids from neisseria gonorrhoeae.	the beta-lactamase-producing asia-type plasmid pjd4 of neisseria gonorrhoeae is a 7.4-kb, broad-host-range plasmid. it is part of a family of plasmids which are structurally related yet vary in size, found in both n. gonorrhoeae and haemophilus ducreyi. branch-point analysis by electron microscopy indicates that pjd4 carries three clustered but distinguishable origins of replication, which we named ori1, ori2, and ori3. although pjd4 belongs to incompatibility (inc) group w, it also carries a si ...	2001	11544207
genetic analysis of a pyocin-resistant lipooligosaccharide (los) mutant of haemophilus ducreyi: restoration of full-length los restores pyocin sensitivity.	dna sequence and southern blot analyses were used to determine the genetic defect of a haemophilus ducreyi pyocin-resistant lipooligosaccharide (los) mutant, hd35000r. the region of the hd35000r chromosome containing the suspected mutation was amplified, and sequence analysis detected a 3,189-bp deletion. this deletion resulted in the loss of the entire waaq gene, another open reading frame that encodes a putative homolog to a hypothetical protein (hi0461) of h. influenzae, the gene encoding an ...	2001	11544241
purification and characterization of a beta-lactamase from haemophilus ducreyi in escherichia coli.	a pcb plasmid encoding a beta-lactamase from haemophilus ducreyi was transferred to escherichia coli, purified, and characterized. the beta-lactamase could be isolated from a culture filtrate and further purified by ammonium sulfate and chelating sepharose fast flow loaded with zn(2+). the purified enzyme resulted in a major band at approximately 30-kda on sds-page and its pi was determined to be 5.4. the beta-lactamase could hydrolyze both penicillin antibiotics including ampicillin, benzylpeni ...	2001	11570857
eradicating chancroid.	genital ulcers are important cofactors of hiv transmission in the countries most severely affected by hiv/aids. chancroid is a common cause of genital ulcer in all 18 countries where adult hiv prevalence surpasses 8% and is rare in countries with low-level hiv epidemics. haemophilus ducreyi, the causative organism of chancroid, is biologically vulnerable and occupies a precarious epidemiological niche. both simple, topical hygiene and male circumcision greatly reduce risk of infection and severa ...	2001	11584729
prevalence of cdtabc genes encoding cytolethal distending toxin among haemophilus ducreyi and actinobacillus actinomycetemcomitans strains.	the aim of this study was to investigate the presence of the three cdtabc genes responsible for production of cytolethal distending toxin (cdt) in haemophilus ducreyi and actinobacillus actinomycetemcomitans strains. of 100 h. ducreyi strains from the culture collection of the university of göteborg (ccug), 27 strains with low or intermediate cytotoxic titre (< 1 in 10(4)) and 23 of the remaining isolates with a high cytotoxic titre (> or = 1 in 10(4)) were selected. twenty-nine strains of h. du ...	2001	11599734
biosynthesis of sialylated lipooligosaccharides in haemophilus ducreyi is dependent on exogenous sialic acid and not mannosamine. incorporation studies using n-acylmannosamine analogues, n-glycolylneuraminic acid, and 13c-labeled n-acetylneuraminic acid.	haemophilus ducreyi is a gram-negative bacterium that causes chancroid, a sexually transmitted disease. cell surface lipooligosaccharides (los) of h. ducreyi are thought to play important biological roles in host infection. the vast majority of h. ducreyi strains contain high levels of sialic acid (n-acetylneuraminic acid, neuac) in their los. here we investigate the biosynthetic origin of h. ducreyi sialosides by metabolic incorporation studies using a panel of n-acylmannosamine and sialic acid ...	2001	11601991
nonimmune binding of human immunoglobulin a (iga) and igg fc by distinct sequence segments of the eibf cell surface protein of escherichia coli.	the eib genes of escherichia coli encode surface-exposed proteins which bind immunoglobulins (ig) such as the fc fragment of human igg (igg fc) in a nonimmune manner. the eib proteins belong to a family which includes yada of yersinia, uspa2 of moraxella, and dsra of haemophilus ducreyi. this family of surface-exposed proteins shares several features, such as the ability to impart resistance to human serum complement and a tendency to exist as stable multimers. four genes, eiba, eibc, eibd and e ...	2001	11705900
development of a heminested polymerase chain reaction assay for the detection of haemophilus ducreyi in clinical specimens.	detection of haemophilus ducreyi in genital ulcer specimens by culture lacks sensitivity. to enhance detection, a heminested polymerase chain reaction (pcr) assay was developed targeting the nucleotide sequence of a gene, designated p27, which encodes for a 27 kda h. ducreyi-specific protein. the p27 pcr assay detected all (37/37) h. ducreyi strains tested and gave no amplified product from dna extracts of any of 31 other microorganisms, from 30 non-genital ulcer specimens, or from 29 urethral a ...	2001	11779370
the haemophilus ducreyi cytolethal distending toxin induces cell cycle arrest and apoptosis via the dna damage checkpoint pathways.	the cytolethal distending toxins (cdts) induce cell cycle arrest by a mechanism still not well characterized. we demonstrate that the effect of the haemophilus ducreyi cdt (hdcdt) is cell type-specific: b cell lines underwent apoptosis, epithelial cells and keratinocytes arrested exclusively in g(2), whereas normal fibroblasts arrested both in g(1) and g(2). we studied normal keratinocytes and fibroblasts, which are relevant for understanding the pathogenicity of h. ducreyi. the response to hdcd ...	2001	11076947
molecular mimicry of host structures by lipooligosaccharides of neisseria meningitidis: characterization of sialylated and nonsialylated lacto-n-neotetraose (galbeta1-4glcnacbeta1-3galbeta1-4glc) structures in lipooligosaccharides using monoclonal antibodies and specific lectins.	neisseria meningitidis lipooligosaccharides (loss) are classified into 12 immunotypes. most loss are heterogeneous in having a few components by sds-page analysis that differ antigenically and chemically. we have utilized a monoclonal antibody that recognizes lacto-n-neotetraose (lnnt) and the lectin, maackia amurensis leukoagglutinin (mal), which is specific for neunacalpha2-3galbeta1-4glcnac trisacchride sequence to characterize the 12 n. meningitidis loss. using the combination of elisa, sds- ...	2001	14533820
development of a rapid immunodiagnostic test for haemophilus ducreyi.	haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmitted disease that increases the rate of transmission of human immunodeficiency virus. chancroid ulcerations are difficult to distinguish from those produced by syphilis and herpes. diagnosis based solely on clinical grounds is inaccurate, and culture is insensitive. highly sensitive pcr has largely superseded culture as the preferred method of laboratory diagnosis; however, neither culture nor pcr is feasible where chancr ...	2002	12354868
haemophilus ducreyi: clinical features, epidemiology, and prospects for disease control.	haemophilus ducreyi is the causative agent of the genital ulcer disease chancroid. chancroid is common in developing countries and facilitates human immunodeficiency virus transmission. in this review, the clinical features, epidemiology, and prospects for disease control are discussed in the context of experimental and natural infection of humans.	2002	12361914
vaccine candidates in std.	sexually transmitted diseases (stds) are caused by organisms that infect the mucosal surfaces of the genitourinary tract. in spite of its public health importance, current std vaccine research lags behind work against pathogens that target another mucosal region, the respiratory tract. in the latter case, live-attenuated viral vaccines, killed whole-cell bacterial vaccines, subunit/protein bacterial vaccines, and bacterial polysaccharide vaccines have been enormously successful. to move std vacc ...	2002	12537725
pre-b-cell colony-enhancing factor, whose expression is up-regulated in activated lymphocytes, is a nicotinamide phosphoribosyltransferase, a cytosolic enzyme involved in nad biosynthesis.	the murine homologue of the previously identified human "pre-b-cell colony-enhancing factor" (pbef) gene coding for a putative cytokine has been identified by screening a subtractive library enriched in genes expressed in activated t lymphocytes. unlike most cytokine genes known to date, the pbef gene is ubiquitously expressed in lymphoid and non-lymphoid tissues and displays significant homology with genes from primitive metazoans (marine sponges) and prokaryotic organisms. recently, a bacteria ...	2002	12555668
the haemophilus ducreyi serum resistance antigen dsra confers attachment to human keratinocytes.	haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. h. ducreyi serum resistance protein a (dsra) is a member of a family of multifunctional outer membrane proteins that are involved in resistance to killing by human serum complement. the members of this family include yada of yersinia species, the uspa proteins of moraxella catarrhalis, and the eib proteins of escherichia coli. the role of yada, uspa1, and uspa2h as eukaryotic cell adhesins and ...	2002	12379693
evolution of the cutaneous immune response to experimental haemophilus ducreyi infection and its relevance to hiv-1 acquisition.	haemophilus ducreyi causes the sexually transmitted disease chancroid, which facilitates hiv-1 transmission. skin biopsies were obtained from subjects experimentally infected with h. ducreyi to study the evolution of the immune response and immunophenotypes relevant to transmission of hiv-1. compared with peripheral blood, there was an enrichment of t cells and macrophages after 48 h of infection in the skin. neutrophils became the predominant cell type by 7-9 days. by immunohistochemistry, macr ...	2002	12444138
chancroid: an update.	chancroid, an important sexually transmissible genital ulcer disease of the developing world, has gained new importance with the onset of hiv era. though common, it poses diagnostic problem because of the difficulties in demonstrating haemophilus ducreyi itself or indirect evidence of its presence. in the present discussion, various aspects of this challenging disease along with recent aspects of its pathogenesis, diagnosis and treatment have been focussed.	2002	17656857
in vitro and in vivo interactions of haemophilus ducreyi with host phagocytes.	we investigated the phagocytosis of haemophilus ducreyi both in vitro and in vivo. human granulocyte and monocyte phagocytosis of opsonized and nonopsonized, fluorescence-labeled h. ducreyi was assessed by flow cytometry. both escherichia coli and noncapsulated h. influenzae were included as controls. the maximal percentage of granulocytes taken up by h. ducreyi was 35% after 90 min. in contrast, 95% of h. influenzae bacteria were phagocytosed by granulocytes after 30 min. these results indicate ...	2002	11796625
men are more susceptible than women to pustule formation in the experimental model of haemophilus ducreyi infection.	naturally occurring chancroid is usually more prevalent in men than in women.	2002	11818898
[characteristics of genes identified in the 120 mda plasmid dna in a mutant of azospirillum brasilense sp245 bacteria, defective in polar flagellation and swarming].	the sequencing data were analyzed for two regions of the 120-mda plasmid (p120) of azospirillum brasilense sp245. the 2420-bp region i, which flanks the omegon insertion in the sk048 mutant defective in production of the polar flagellum (fla-) and swarming (swa-), was shown to contain a cluster of two open reading frames (orf) that possess properties of coding sequences (cdss). the ntra (sigma 54) boxes were found in their upstream regions. the products of orf1 and orf2 are 16.5 and 15.5 kda in ...	2002	11852790
a superoxide dismutase c mutant of haemophilus ducreyi is virulent in human volunteers.	haemophilus ducreyi produces a periplasmic copper-zinc superoxide dismutase (cu-zn sod), which is thought to protect the organism from exogenous reactive oxygen species generated by neutrophils during an inflammatory response. we had previously identified the gene, sodc, responsible for the production and secretion of cu-zn sod and constructed an isogenic h. ducreyi strain with a mutation in the sodc gene (35000hp-sodc-cat). compared to the parent, the mutant does not survive in the presence of ...	2002	11854222
cytolethal distending toxins and activation of dna damage-dependent checkpoint responses.	cytolethal distending toxins (cdts) are unique among bacterial protein toxins in their ability to cause dna damage, due to their functional similarity to the mammalian deoxyribonuclease i (dnase i). the cellular response to cdt intoxication is characterised by activation of dna damage-induced checkpoint responses, and the final outcome is cell type dependent. cells of epithelial origin and normal keratinocytes are arrested in the g2 phase of the cell cycle, normal fibroblasts are also arrested i ...	2002	11890549
immunopathogenesis of haemophilus ducreyi infection (chancroid).		2002	11895928
the haemophilus ducreyi cytolethal distending toxin activates sensors of dna damage and repair complexes in proliferating and non-proliferating cells.	cytolethal distending toxins (cdts) block proliferation of mammalian cells by activating dna damage-induced checkpoint responses. we demonstrate that the haemophilus ducreyi cdt (hdcdt) induces phosphorylation of the histone h2ax as early as 1 h after intoxication and re-localization of the dna repair complex mre11 in hela cells with kinetics similar to those observed upon ionizing radiation. early phosphorylation of h2ax was dependent on a functional ataxia telangiectasia mutated (atm) kinase. ...	2002	11896765
the cytolethal distending toxin of haemophilus ducreyi inhibits endothelial cell proliferation.	haemophilus ducreyi, the etiologic agent of the sexually transmitted disease chancroid, produces a cytolethal distending toxin (hdcdt) that inhibits mammalian cell proliferation. we investigated the effects of hdcdt on normal human endothelial cells and on tubule formation in an in vitro model of angiogenesis. endothelial cells were arrested in the g2 phase of the cell cycle, and tubule formation was inhibited in a dose-dependent manner. the antiproliferative activities of hdcdt on endothelial c ...	2002	11953409
haemophilus ducreyi: clinical disease and pathogenesis.	haemophilus ducreyi causes the sexually transmitted disease chancroid, which facilitates the transmission of hiv infection. this review focuses on recent advances in the epidemiology, diagnosis, treatment and pathogenesis of this disease.	2002	11964905
epidemic lymphogranuloma venereum during epidemics of crack cocaine use and hiv infection in the bahamas.	since the early 1980s, the bahamas has experienced sequential epidemics of freebase/crack cocaine use, genital ulcer-inguinal adenopathy disease (gud), and heterosexual hiv infection.	2002	11984440
the lbgab gene cluster of haemophilus ducreyi encodes a beta-1,4-galactosyltransferase and an alpha-1,6-dd-heptosyltransferase involved in lipooligosaccharide biosynthesis.	all haemophilus ducreyi strains examined contain a lipooligosaccharide (los) consisting of a single but variable branch oligosaccharide that emanates off the first heptose (hep-i) of a conserved hep(3)-phosphorylated 3-deoxy-d-manno-octulosonic acid-lipid a core. in a previous report, identification of tandem genes, lbga and lbgb, that are involved in los biosynthesis was described (stevens et al., infect. immun. 65:651-660, 1997). in a separate study, the same gene cluster was identified and th ...	2002	12010972
haemophilus ducreyi requires the flp gene cluster for microcolony formation in vitro.	haemophilus ducreyi, the etiologic agent of chancroid, has been shown to form microcolonies when cultured in the presence of human foreskin fibroblasts. we identified a 15-gene cluster in h. ducreyi that encoded predicted protein products with significant homology to those encoded by the tad (for tight adhesion) locus in actinobacillus actinomycetemcomitans that is involved in the production of fimbriae by this periodontal pathogen. the first three open reading frames in this h. ducreyi gene clu ...	2002	12010986
characterization of lipooligosaccharides from haemophilus ducreyi containing polylactosamine repeats.	haemophilus ducreyi, a gram-negative human mucosal pathogen, is one of the principal causes of genital ulcer disease. the lipooligosaccharides (los) of these bacteria are considered to be a major virulence factor and have been implicated in the adherence and invasion of h. ducreyi to several human cell types. an isogenic heptosyltransferase-iii knockout strain (waaq) was recently constructed from h. ducreyi 35000 wild-type strain and immunochemical and molecular weight data of the isolated los s ...	2002	12056572
cpsk of streptococcus agalactiae exhibits alpha2,3-sialyltransferase activity in haemophilus ducreyi.	streptococcus agalactiae (gbs) is a major cause of serious newborn bacterial infections. crucial to gbs evasion of host immunity is the production of a capsular polysaccharide (cps) decorated with sialic acid, which inactivates the alternative complement pathway. the cps operons of serotypes ia and iii gbs have been described, but the cps sialyltransferase gene was not identified. we identified cpsk, an open reading frame in the cps operon of most serotypes, which was homologous to the lipooligo ...	2002	12100552
the activity of p-methoxybenzylisothiocyanate against neisseria gonorrhoeae, haemophilus ducreyi, and other microorganisms.	p-methoxybenzylisothiocyanate was isolated from lepidium bonariense and found to be responsible for the plants antimicrobial and std activity. mic determinations were conducted for p-methoxybenzylisothiocyanate on haemophilus ducreyi, neisseria gonorrheae, candida albicans, bacillus subtilus, micrococcus luteus, staphylococcus aureus, enterobacter sp., escherichia coli, klebsiella pneumoniae, and psuedomanas aeruginosa. an in vitro cellular toxicity assay showed that at 100 microm (17,9 microg/m ...	2002	12161151
validation of syndromic algorithm for the management of genital ulcer diseases in china.	1. to determine the aetiologies of genital ulcers in china. 2. to evaluate a modified who syndromic management algorithm for genital ulcer disease (gud).	2002	12171666
community prevalence of sexually transmitted diseases and human immunodeficiency virus infection in tamil nadu, india: a probability proportional to size cluster survey.	human immunodeficiency virus (hiv) infection and aids is threatening the survival of many nations. to evaluate ongoing interventional strategies and burden of illness estimates, valid data on the prevalence of hiv are required. often, in the absence of community prevalence data, estimates are based on surrogate markers such as prevalence of hiv in antenatal clinics. even though the antenatal prevalence of hiv is easier to measure and can be repeated for evaluation, it is important to establish t ...	2002	12186325
toxicity and immunogenicity of purified haemophilus ducreyi cytolethal distending toxin in a rabbit model.	the cytolethal distending toxin of haemophilus ducreyi (hdcdt) is a three-component toxin that induces the arrest of the mammalian cell cycle in the g2 phase. all of the individual gene products, cdta, cdtb and cdtc, are required for toxic activity on cultured mammalian cells. the cdtb component alone exerts nuclease activity. the individual hdcdt components were purified by affinity chromatography or ion-exchange chromatography followed by gel-filtration. hdcdt was reconstituted and purified by ...	2002	12202104
identification and characterization of the n-acetylglucosamine glycosyltransferase gene of haemophilus ducreyi.	haemophilus ducreyi is the causative agent of chancroid, a sexually transmitted ulcerative disease. in the present study, the neisseria gonorrhoeae lgta lipooligosaccharide glycosyltransferase gene was used to identify a homologue in the genome of h. ducreyi. the putative h. ducreyi glycosyltransferase gene (designated lgta) was cloned and insertionally inactivated, and an isogenic mutant was constructed. structural studies demonstrated that the lipooligosaccharide isolated from the mutant strai ...	2002	12228324
cloning and characterisation of type 4 fimbrial genes from actinobacillus pleuropneumoniae.	actinobacillus pleuropneumoniae is the cause of porcine pleuropneumoniae. little is known about the mechanisms by which a. pleuropneumoniae colonises the respiratory tract. fimbriae are common mediators of bacterial adherence to mucosal epithelia and have been observed on the surface of a. pleuropneumoniae cells. here we report the identification and characterisation of the type 4 fimbrial structural gene (apfa) from a. pleuropneumoniae. in addition a number of open reading frames were identifie ...	2003	12488076
etiology of genital ulcer disease and association with human immunodeficiency virus infection in two tanzanian cities.	the etiological agent is usually not established in cases of genital ulcer disease (gud) in tanzania, since diagnosis and treatment of this disease are based mainly on clinical rather than microbiologic parameters. gud increases the risk of infection with hiv. however, the association between specific gud infections and hiv infection has not been fully investigated.	2003	12567167
chancroid: clinical manifestations, diagnosis, and management.	chancroid is a sexually transmitted disease (std) caused by the gram negative bacterium haemophilus ducreyi and is characterised by necrotising genital ulceration which may be accompanied by inguinal lymphadenitis or bubo formation. h ducreyi is a fastidious organism which is difficult to culture from genital ulcer material. dna amplification techniques have shown improved diagnostic sensitivity but are only performed in a few laboratories. the management of chancroid in the tropics tends to be ...	2003	12576620
metabolic incorporation of unnatural sialic acids into haemophilus ducreyi lipooligosaccharides.	the lipooligosaccharides (los) of haemophilus ducreyi are highly sialylated, a modification that has been implicated in resistance to host defense and in virulence. in previous work, we demonstrated that h. ducreyi scavenges sialic acid from the extracellular milieu and incorporates those residues into los. here we report that h. ducreyi can use unnatural sialic acids bearing elongated n-acyl groups from three to seven carbon atoms in length, resulting in outer membrane presentation of unnatural ...	2003	12615992
association between hiv-1 infection, the etiology of genital ulcer disease, and response to syndromic management.	reports on the effect of hiv-1 infection on healing rates of ulcers are conflicting.	2003	12616144
mutations in the lspa1 and lspa2 genes of haemophilus ducreyi affect the virulence of this pathogen in an animal model system.	haemophilus ducreyi 35000hp contains two genes, lspa1 and lspa2, whose predicted protein products have molecular weights of 456,000 and 543,000, respectively (c. k. ward, s. r. lumbley, j. l. latimer, l. d. cope, and e. j. hansen, j. bacteriol. 180:6013-6022, 1998). we have constructed three h. ducreyi 35000hp mutants containing antibiotic resistance cartridges in one or both of the lspa1 and lspa2 open reading frames. western blot analysis using lspa1- and lspa2-specific monoclonal antibodies i ...	2003	12704119
increasing relative prevalence of hsv-2 infection among men with genital ulcers from a mining community in south africa.	to determine the aetiology of genital ulcer disease (gud) and its association with hiv infection in the mining community of carletonville, south africa, from two cross sectional surveys of consecutive men presenting with genital lesions during october 1993 to january 1994 and july to november 1998.	2003	12794202
expression of the cytolethal distending toxin in a geographically diverse collection of haemophilus ducreyi clinical isolates.	to screen a collection of isolates of haemophilus ducreyi for expression of the cytolethal distending toxin (cdt).	2003	12902578
specificity of antibodies directed against the cytolethal distending toxin of haemophilus ducreyi in patients with chancroid.	antibodies specific for the cytolethal-distending toxin of haemophilus ducreyi (hdcdt) complex and for the cdta, cdtb, and cdtc components were measured by elisa in the sera of 50 patients with culture and/or pcr proven chancroid, 42 patients with periodontitis, 50 blood donors from tanzania, 50 blood donors from sweden. in addition, the biological activity e.g. neutralization capacity of the sera were tested. our results demonstrate that majority of chancroid patients and healthy individuals ha ...	2003	12927521
nicotinamide ribosyl uptake mutants in haemophilus influenzae.	the gene for the nicotinamide riboside (nr) transporter (pnuc) was identified in haemophilus influenzae. a pnuc mutant had only residual nr uptake and could survive in vitro with high concentrations of nr, but could not survive in vivo. pnuc may represent a target for the development of inhibitors for preventing h. influenzae disease.	2003	12933892
the haemophilus ducreyi cytolethal distending toxin induces dna double-strand breaks and promotes atm-dependent activation of rhoa.	among bacterial protein toxins, the cytolethal distending toxins (cdts) are unique in their ability to activate the dna damage checkpoint responses, causing cell cycle arrest or apoptosis in intoxicated cells. we provide direct evidence that natural intoxication of cells with the haemophilus ducreyi cdt (hdcdt) holotoxin induces dna double-strand breaks similarly to ionizing radiation. upon dna damage, epithelial cells and fibroblasts promote the formation of actin stress fibres via activation o ...	2003	12969375
inhibition of phagocytosis by haemophilus ducreyi requires expression of the lspa1 and lspa2 proteins.	haemophilus ducreyi previously has been shown to inhibit the phagocytosis of both secondary targets and itself by certain cells in vitro. wild-type h. ducreyi strain 35000hp contains two genes, lspa1 and lspa2, whose encoded protein products are predicted to be 456 and 543 kda, respectively. an isogenic mutant of h. ducreyi 35000hp with inactivated lspa1 and lspa2 genes has been shown to exhibit substantially decreased virulence in the temperature-dependent rabbit model for chancroid. this lspa1 ...	2003	14500520
a cdta-cdtc complex can block killing of hela cells by haemophilus ducreyi cytolethal distending toxin.	the cytolethal distending toxin (cdt) of haemophilus ducreyi is comprised of the cdta, cdtb, and cdtc proteins, with the cdtb protein having demonstrated enzymatic (i.e., dnase) activity. using a single recombinant escherichia coli strain with two plasmids individually containing the h. ducreyi cdta and cdtc genes, we purified a noncovalent cdta-cdtc complex. incubation of this cdta-cdtc complex with hela cells blocked killing of these cells by cdt holotoxin. furthermore, the addition of purifie ...	2003	14573688
differences in host susceptibility to disease progression in the human challenge model of haemophilus ducreyi infection.	with human volunteers inoculated at two sites with haemophilus ducreyi, outcomes for a subject were not independent. in a reinfection trial, 2 of 11 previous pustule formers and 6 of 10 previous resolvers resolved all sites of infection. there was no correlation between serum bactericidal or phagocytic activity and outcome in the trial. these data indicate that different hosts are differentially susceptible to disease progression versus resolution in the model.	2003	14573692
proteome of haemophilus ducreyi by 2-d sds-page and mass spectrometry: strain variation, virulence, and carbohydrate expression.	we have analyzed the proteome of several strains of haemophilus ducreyi by two-dimensional gel electrophoresis (2-de) and mass spectrometry. over 100 spots were analyzed from the soluble and insoluble protein fractions from the prototype strain 35000hp and 122 distinct proteins were identified. functions of approximately 80% of the 122 proteins were deduced by identification with close homologues of haemophilus influenzae. four additional wild type and three mutant strains were also analyzed tha ...	2003	14582649
a humoral immune response confers protection against haemophilus ducreyi infection.	haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. neither naturally occurring chancroid nor experimental infection with h. ducreyi results in protective immunity. likewise, a single inoculation of h. ducreyi does not protect pigs against subsequent infection. accordingly, we used the swine model of chancroid infection to examine the impact of multiple inoculations on a host's immune response. after three successive inoculations with h. ducrey ...	2003	14638786