SEARCH · PubMed Health

Results for “Pathogen”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

PubMed2003

Bacterial pathogens modulate an apoptosis differentiation program in human neutrophils.

Human polymorphonuclear leukocytes (PMNs or neutrophils) are essential to the innate immune response against bacterial pathogens. Recent evidence suggests that PMN apoptosis facilitates resolution of inflammation during bacterial infection. Although progress has been made toward understanding apoptosis in neutrophils, very little is known about transcriptional regulation of this process during bacterial infection. To gain insight into the molecular processes that facilitate resolution of infection, we measured global changes in PMN gene expression during phagocytosis of a diverse group of bacterial pathogens. Genes encoding key effectors of apoptosis were up-regulated, and receptors critical to innate immune function were down-regulated during apoptosis induced by phagocytosis of Burkholderia cepacia, Borrelia hermsii, Listeria monocytogenes, Staphylococcus aureus, and Streptococcus pyogenes. Importantly, we identified genes that comprise a common apoptosis differentiation program in human PMNs after phagocytosis of pathogenic bacteria. Unexpectedly, phagocytosis of Str. pyogenes induced changes in neutrophil gene expression not observed with other pathogens tested, including down-regulation of 21 genes involved in responses to IFN. Compared with other bacteria, PMN apoptosis was significantly accelerated by Str. pyogenes and was followed by necrosis. Thus, we hypothesize that there are two fundamental outcomes for the interaction of bacterial pathogens with neutrophils: (i) phagocytosis of bacteria induces an apoptosis differentiation program in human PMNs that contributes to resolution of bacterial infection, or (ii) phagocytosis of microorganisms such as Str. pyogenes alters the apoptosis differentiation program in neutrophils, resulting in pathogen survival and disease.

Apoptosis↗

PubMed2002

HecA, a member of a class of adhesins produced by diverse pathogenic bacteria, contributes to the attachment, aggregation, epidermal cell killing, and virulence phenotypes of Erwinia chrysanthemi EC16 on Nicotiana clevelandii seedlings.

Erwinia chrysanthemi is representative of a broad class of bacterial pathogens that are capable of inducing necrosis in plants. The E. chrysanthemi EC16 hecA gene predicts a 3,850-aa member of the Bordetella pertussis filamentous hemagglutinin family of adhesins. A hecATn7 mutant was reduced in virulence on Nicotiana clevelandii seedlings after inoculation without wounding. Epifluorescence and confocal laser-scanning microscopy observations of hecA and wild-type cells expressing the green fluorescent protein revealed that the mutant is reduced in its ability to attach and then form aggregates on leaves and to cause an aggregate-associated killing of epidermal cells. Cell killing also depended on production of the major pectate lyase isozymes and the type II, but not the type III, secretion pathway in E. chrysanthemi. HecA homologs were found in bacterial pathogens of plants and animals and appear to be unique to pathogens and universal in necrogenic plant pathogens. Phylogenetic comparison of the conserved two-partner secretion domains in the proteins and the 16S rRNA sequences in respective bacteria revealed the two datasets to be fundamentally incongruent, suggesting horizontal acquisition of these genes. Furthermore, hecA and its two homologs in Yersinia pestis had a G+C content that was 10% higher than that of their genomes and similar to that of plant pathogenic Ralstonia, Xylella, and Pseudomonas spp. Our data suggest that filamentous hemagglutinin-like adhesins are broadly important virulence factors in both plant and animal pathogens.

Adhesins, Bacterial↗

PubMed1989

Genomic DNA differences between pathogenic and nonpathogenic Entamoeba histolytica.

cDNA libraries were constructed from pathogenic (HM-1:IMSS) and nonpathogenic (SAW 1734) isolates of Entamoeba histolytica. A cDNA clone (cEH-P1) specific for pathogenic amoebae was identified by screening with a pool of sera from patients with invasive amoebiasis that had been absorbed with nonpathogenic amoebae. This clone was used for the identification of a homologous clone (cEH-NP1) in the cDNA from nonpathogenic amoebae. Sequence analysis and comparison of the predicted amino acid sequences for both clones disclosed 12% evolutionary divergence in structure. Hybridization of both cDNA probes to genomic DNA from four pathogenic and five nonpathogenic E. histolytica isolates revealed two distinct Southern blot patterns, one characteristic for pathogenic amoebae and the other for nonpathogenic amoebae. Further, the complex pattern of restriction fragments hybridizing to an actin cDNA probe was also different between pathogenic and nonpathogenic isolates but was conserved within each group of amoebae. The results indicate that pathogenic isolates of E. histolytica are genetically distinct from nonpathogenic isolates.

Amino Acid Sequence↗

PubMed1997

A secreted Salmonella protein with homology to an avirulence determinant of plant pathogenic bacteria.

Bacterial pathogens have evolved sophisticated mechanisms to interact with their hosts. A specialized type III protein secretion system capable of translocating bacterial proteins into host cells has emerged as a central factor in the interaction between a variety of mammalian and plant pathogenic bacteria with their hosts. Here we describe AvrA, a novel target of the centisome 63 type III protein secretion system of Salmonella enterica. AvrA shares sequence similarity with YopJ of the animal pathogen Yersinia pseudotuberculosis and AvrRxv of the plant pathogen Xanthomonas campestris pv. vesicatoria. These proteins are the first examples of putative targets of type III secretion systems in animal and plant pathogenic bacteria that share sequence similarity. They may therefore constitute a novel family of effector proteins with related functions in the cross-talk of these pathogens with their hosts.

Amino Acid Sequence↗

PubMed1998

Separate jasmonate-dependent and salicylate-dependent defense-response pathways in Arabidopsis are essential for resistance to distinct microbial pathogens.

The endogenous plant hormones salicylic acid (SA) and jasmonic acid (JA), whose levels increase on pathogen infection, activate separate sets of genes encoding antimicrobial proteins in Arabidopsis thaliana. The pathogen-inducible genes PR-1, PR-2, and PR-5 require SA signaling for activation, whereas the plant defensin gene PDF1.2, along with a PR-3 and PR-4 gene, are induced by pathogens via an SA-independent and JA-dependent pathway. An Arabidopsis mutant, coi1, that is affected in the JA-response pathway shows enhanced susceptibility to infection by the fungal pathogens Alternaria brassicicola and Botrytis cinerea but not to Peronospora parasitica, and vice versa for two Arabidopsis genotypes (npr1 and NahG) with a defect in their SA response. Resistance to P. parasitica was boosted by external application of the SA-mimicking compound 2, 6-dichloroisonicotinic acid [Delaney, T., et al. (1994) Science 266, 1247-1250] but not by methyl jasmonate (MeJA), whereas treatment with MeJA but not 2,6-dichloroisonicotinic acid elevated resistance to Alternaria brassicicola. The protective effect of MeJA against A. brassicicola was the result of an endogenous defense response activated in planta and not a direct effect of MeJA on the pathogen, as no protection to A. brassicicola was observed in the coi1 mutant treated with MeJA. These data point to the existence of at least two separate hormone-dependent defense pathways in Arabidopsis that contribute to resistance against distinct microbial pathogens.

Journal Article↗

PubMed1999

The Xanthomonas Hrp type III system secretes proteins from plant and mammalian bacterial pathogens.

Studies of essential pathogenicity determinants in Gram-negative bacteria have revealed the conservation of type III protein secretion systems that allow delivery of virulence factors into host cells from plant and animal pathogens. Ten of 21 Hrp proteins of the plant pathogen Xanthomonas campestris pv. vesicatoria have been suggested to be part of a type III machinery. Here, we report the hrp-dependent secretion of two avirulence proteins, AvrBs3 and AvrRxv, by X. campestris pv. vesicatoria strains that constitutively express hrp genes. Secretion occurred without leakage of a cytoplasmic marker in minimal medium containing BSA, at pH 5.4. Secretion was strictly hrp-dependent because a mutant carrying a deletion in hrcV, a conserved hrp gene, did not secrete AvrBs3 and AvrRxv. Moreover, the Hrp system of X. campestris pv. vesicatoria was able to secrete proteins from two other plant pathogens: PopA, a protein secreted via the Hrp system in Ralstonia solanacearum, and AvrB, an avirulence protein from Pseudomonas syringae pv. glycinea. Interestingly, X. campestris pv. vesicatoria also secreted YopE, a type III-secreted cytotoxin of the mammalian pathogen Yersinia pseudotuberculosis in a hrp-dependent manner. YerA, a YopE-specific chaperone, was required for YopE stability but not for secretion in X. campestris pv. vesicatoria. Our results demonstrate the functional conservation of the type III system of X. campestris for secretion of proteins from both plant and mammalian pathogens and imply recognition of their respective secretion signals.

Animals↗

PubMed2003

Targeted gene disruption of glycerol-3-phosphate dehydrogenase in Colletotrichum gloeosporioides reveals evidence that glycerol is a significant transferred nutrient from host plant to fungal pathogen.

Unidirectional transfer of nutrients from plant host to pathogen represents a most revealing aspect of the parasitic lifestyle of plant pathogens. Whereas much effort has been focused on sugars and amino acids, the identification of other significant metabolites is equally important for comprehensive characterization of metabolic interactions between plants and biotrophic fungal pathogens. Employing a strategy of targeted gene disruption, we generated a mutant strain (gpdhDelta) defective in glycerol-3-phosphate dehydrogenase in a hemibiotrophic plant pathogen, Colletotrichum gloeosporioides f.sp. malvae. The gpdhDelta strain had severe defects in carbon utilization as it could use neither glucose nor amino acids for sustained growth. Although the mutant mycelia were able to grow on potato dextrose agar medium, they displayed arrhythmicity in growth and failure to conidiate. The metabolic defect of gpdhDelta could be entirely ameliorated by glycerol in chemically defined minimal medium. Furthermore, glycerol was the one and only metabolite that could restore rhythmic growth and conidiation of gpdhDelta. Despite the profound defects in carbon source utilization, in planta the gpdhDelta strain exhibited normal pathogenicity, proceeded normally in its life cycle, and produced abundant conidia. Analysis of plant tissues at the peripheral zone of fungal infection sites revealed a time-dependent reduction in glycerol content. This study provides strong evidence for a role of glycerol as a significant transferred metabolite from plant to fungal pathogen.

Althaea↗

PubMed1998

The ability of enteric diarrhoeal pathogens to ferment starch to short-chain fatty acids in vitro.

BACKGROUND: Short-chain fatty acids (SCFA), produced in the normal colon by bacterial fermentation, are decreased in acute diarrhoea. This may have deleterious effects on epithelial function in the colon. METHODS: The ability of several diarrhoeal pathogens to produce SCFA when incubated with starch in vitro was studied. Isolated pathogens were incubated for 24 h with either no added substrate, glucose, or starch under anaerobic conditions, and SCFA were quantitated by gas-liquid chromatography. RESULTS: Unlike the normal colonic flora, the pathogens produced acetate but not propionate or butyrate. D-Lactate was also produced by all the pathogens studied. When the pathogens were incubated in anaerobic medium containing starch, significantly greater amounts of acetate and significantly lesser amounts of lactate were produced. CONCLUSIONS: The inability of enteric pathogens to produce butyrate may impair epithelial cell function, whereas production of D-lactate may enhance mucosal damage in diarrhoeal disease. The presence of luminal starch may be helpful in shifting the fermentation profile to a more favourable pattern.

Butyrates↗

PubMed2003

Pathogens and manure management systems: a review.

There has been an increasing concern about the effects of pathogens that are present in animal manure on humanand animal health. In recent years, outbreaks of food-borne diseases associated with the consumption of animal products havereceived much attention from the media in North America and Europe, leading to increased consumer concerns about the safety of their food supply. The health risks associated with animal operations depend on various factors. The most important ones appear to be related to the animal species being reared and the concentration of pathogenic microorganisms in animal manure. The ability of the pathogens to survive for long periods and through treatment to remain infective in the environment until ingested by human or animal host is an added concern. On the other hand, the role of livestock in most waterborne bacterial outbreaks has often been difficult to clarify since both humans and various wildlife species can shed the same microorganisms and thereby serve as sources of infection. This paper summarizes existing information on the main microbial pathogens present in livestock wastes, and discusses the impact of livestock wastes and agricultural drainage on microbiological quality of water, as well as available management and treatment technologies to minimize the prevalence of pathogens in animal wastes. Despite the fact that most disease outbreaks have been associated with food poisoning by cross-contamination during meat or milk processing and during finished product storage this review shows that a number of best management practices and technical solutions have been developed in the last few years that can be effective tools in minimizing the spread of pathogens from livestock operations in the environment.

Agriculture↗

PubMed2001

Host-pathogen interactions: the attributes of virulence.

Virulence is one of a number of possible outcomes of host-microbe interaction. As such, microbial virulence is dependent on host factors, as exemplified by the pathogenicity of avirulent microbes in immunocompromised hosts and the lack of pathogenicity of virulent pathogens in immune hosts. Pathogen-centered views of virulence assert that pathogens are distinguished from nonpathogens by their expression of virulence factors. Although this concept appears to apply to certain microbes that cause disease in normal hosts, it does not apply to most microbes that cause disease primarily in immunocompromised hosts. The study of virulence is fraught with the paradox that virulence, despite being a microbial characteristic, can only be expressed in a susceptible host. Thus, the question "What is a pathogen?" begs the question, "What is the outcome of the host-microbe interaction?" We propose that host damage provides a common denominator that translates into the different outcomes of host-microbe interaction.

Animals↗

PubMed2004

The role of the intestinal tract as a reservoir and source for transmission of nosocomial pathogens.

The intestinal tract provides an important reservoir for many nosocomial pathogens, including Enterococcus species, Enterobacteriaciae, Clostridium difficile, and Candida species. These organisms share several common risk factors and often coexist in the intestinal tract. Disruption of normal barriers, such as gastric acidity and the indigenous microflora of the colon, facilitates overgrowth of pathogens. Factors such as fecal incontinence and diarrhea contribute to the subsequent dissemination of pathogens into the health care environment. Selective pressure exerted by antibiotics plays a particularly important role in pathogen colonization, and adverse effects associated with these agents often persist beyond the period of treatment. Infection-control measures that are implemented to control individual pathogens may have a positive or negative impact on efforts to control other pathogens that colonize the intestinal tract.

Animals↗

PubMed2000

Pathogenic organisms associated with artificial fingernails worn by healthcare workers.

OBJECTIVE: To determine differences in the identity and quantity of microbial flora from healthcare workers (HCWs) wearing artificial nails compared with control HCWs with native nails. DESIGN: Two separate studies were undertaken. In study 1, 12 HCWs who did not normally wear artificial nails wore polished artificial nails on their nondominant hand for 15 days. Identity and quantity of microflora were compared between the artificial nails and the polished native nails of the other hand. In study 2, the microbial flora of the nails of 30 HCWs who wore permanent acrylic artificial nails were compared with that of control HCWs who had native nails. In both studies, nail surfaces were swabbed and subungual debris was collected to obtain material for culture. Staphylococcus aureus, gram-negative bacilli, enterococci, and yeasts were considered to be potential pathogens. All organisms were identified and quantified. RESULTS: In study 1, potential pathogens were isolated from more samples obtained from artificial nails than native nails (92% vs. 62%; P<.001). Colonization of artificial nails increased over time; by day 15, 71% of cultures yielded a pathogen compared with 21% on day 1 (P=.004). A significantly greater quantity of organisms (expressed as mean log10 colony-forming units +/- standard deviation) was isolated from the subungual area than the nail surface; this was noted for both artificial (5.0+/-1.4 vs. 4.1+/-1.0; P<.001) and native nails (4.9+/-1.3 vs. 3.7+/-0.8; P<.001). More organisms were found on the surface of artificial nails than native nails (P=.008), but there were no differences noted in the quantities of organisms isolated from the subungual areas. In study 2, HCWs wearing artificial nails were more likely to have a pathogen isolated than controls (87% vs. 43%; P=.001). More HCWs with artificial nails had gram-negative bacilli (47% vs. 17%; P=.03) and yeasts (50% vs. 13%; P=.006) than control HCWs. However, the quantities of organisms isolated from HCWs wearing artificial nails and controls did not differ. CONCLUSIONS: Artificial fingernails were more likely to harbor pathogens, especially gram-negative bacilli and yeasts, than native nails. The longer artificial nails were worn, the more likely that a pathogen was isolated. Current recommendations restricting artificial fingernails in certain healthcare settings appear justified.

Adult↗

PubMed2025

Missense variants pathogenicity annotation from homologous proteins.

MOTIVATION: High-throughput DNA sequencing has revealed millions of single nucleotide variants (SNVs) in the human genome, with a small fraction linked to disease. The effect of missense variants, which alter the protein sequence, is particularly challenging to interpret due to the scarcity of clinical annotations and experimental information. While using conservation and structural information, current prediction tools still struggle to predict variant pathogenicity. In this study, we explored the pathogenicity of homologous missense variants-variants in equivalent positions across homologous proteins-focusing on proteins involved in autosomal dominant diseases. RESULTS: Our analysis of 2976 pathogenic and 17 555 non-pathogenic homologous variants demonstrated that pathogenicity can be extrapolated with 95% accuracy within a family, or up to 98% for closer homologs. Remarkably, the evaluation of 27 commonly used mutation predictor methods revealed that they were not fully capturing this biological feature. To facilitate the exploration of homologous variants, we created HomolVar, a web server that computationally predicts the pathogenesis of missense variants using annotations from homologous variants, freely available at https://rarevariants.org/HomolVar. Overall, these findings and the accompanying tool offer a robust method for predicting the pathogenicity of unannotated variants, enhancing genotype-phenotype correlations, and contributing to diagnosing rare genetic disorders. AVAILABILITY AND IMPLEMENTATION: HomolVar is freely available at https://rarevariants.org/HomolVar.

Mutation, Missense↗

PubMed2026

VisPan: real-time visualisation of multiplex amplicon-based sequencing panels for rapid syndromic surveillance and pathogen detection.

MOTIVATION: Infectious diseases persist as a major global public health challenge. Diverse factors, including climate change, globalization, deforestation, human-animal interactions, lifestyle choices, and various biological factors, can contribute to their emergence and reemergence. Rapid detection and characterization of (re)emerging pathogens are therefore critical for effective outbreak management and for enhancing our understanding of epidemics by monitoring the transmission, spread, evolution, and genomics of pathogens. In this context, next-generation sequencing technologies (NGS), particularly long-read platforms such as Oxford Nanopore Technologies (ONT), have opened new avenues for real-time pathogen monitoring. However, the bioinformatics bottleneck remains a challenge, emphasizing the need for efficient, accessible, and user-friendly analysis tools. RESULTS: Here, we present a tool adapted from the RAMPART software that enables real-time data visualisation of multiplex PCR syndromic panels combined with Oxford Nanopore sequencing. This real-time analysis enables rapid pathogen detection, from raw data acquisition to taxonomic assignment, within minutes. The interface offers dynamic visual tracking of the sequencing run and amplicon coverage, facilitating immediate insights during diagnostic workflows. Validation experiments confirmed the system's reliability, accurately identifying all pathogens present in complex clinical or environmental samples. This tool provides an integrated, user-friendly solution for genomic pathogen surveillance in field or clinical settings.

Software↗

PubMed2026

ECLIPSE: exploring the dark proteome of ESKAPE pathogens through the sequence similarity network of the Protein Universe Atlas.

MOTIVATION: The accelerating crisis of antimicrobial resistance among the critical so-called ESKAPE pathogens demands the urgent identification of novel molecular targets. However, a substantial fraction of ESKAPE proteomes remains functionally uncharacterized, with many genes annotated as encoding hypothetical proteins. These protein sequences often lack significant similarity to known protein families when conventional homology-based annotation methods are used and thus remain "dark". This limits our ability to explore their roles in pathogenicity, and it is thus crucial to bridge this substantial gap in pathogen biology by developing new strategies to illuminate these "dark" regions of the ESKAPE pan-proteome. RESULTS: We introduce ECLIPSE (ESKAPE Connectome Linkage and Inference for Proteome Sequence Exploration), a network-based computational framework that systematically identifies and prioritizes functionally dark protein families in ESKAPE pan-proteomes. ECLIPSE embeds target ESKAPE pathogen proteomes within the global sequence similarity network of the Protein Universe Atlas. It detects connected components composed entirely of unannotated proteins, called the "dark proteome." As a case study, we applied ECLIPSE to a pan-proteome of 3 460 657 protein sequences from 635 strains of Pseudomonas aeruginosa (PA). ECLIPSE identified 120 985 proteins (4%) residing in completely dark connected components. Furthermore, we have performed a taxonomic diversity analysis using normalized Shannon indices to characterize each dark component by its enrichment in ESKAPE pathogens. The analysis utilized the evenness (E) value (see Methods 2.1), which distinguishes Pseudomonas-specific (target-specific) from ESKAPE-enriched dark components. We then developed the Dark Proteome Prioritization Score (DPPS), a composite multidimensional scoring framework (see Methods 2.5). It ranks these dark components by biological relevance across four orthogonal axes: (i) functional darkness, (ii) P. aeruginosa proportion in the Atlas, (iii) AMR-clade taxonomic restriction, and (iv) conservation across the 635 P. aeruginosa strains. This framework outputs a robust four-tier scoring system; the prioritized Tier I components were validated by weight sensitivity analysis and remained stable across 500 Monte Carlo weight perturbations. Structural characterization of one of the top-ranked ESKAPE-enriched dark components revealed that it belongs to the beta-barrel fold DUF1302 (PF06980) family, for which no experimentally solved three-dimensional structure exists in the PDB. The genomic context analysis indicates that it is co-localized with a LuxR-type transcriptional regulator. Collectively, ECLIPSE identifies evolutionarily conserved, structurally defined, and functionally dark proteins enriched across ESKAPE pathogens; these dark proteins can further be utilized as alternative antimicrobial targets for experimental characterization. AVAILABILITY AND IMPLEMENTATION: The source code and dataset are available for free at: Github: https://github.com/surabhilata/ECLIPSE.git, Zenodo: DOI: 10.5281/zenodo.21064323.

Proteome↗

PubMed2005

The pathogenic agent in Drosophila models of 'polyglutamine' diseases.

A substantial body of evidence supports the identity of polyglutamine as the pathogenic agent in a variety of human neurodegenerative disorders where the mutation is an expanded CAG repeat. However, in apparent contradiction to this, there are several human neurodegenerative diseases (some of which are clinically indistinguishable from the 'polyglutamine' diseases) that are due to expanded repeats that cannot encode polyglutamine. As polyglutamine cannot be the pathogenic agent in these diseases, either the different disorders have distinct pathogenic pathways or some other common agent is toxic in all of the expanded repeat diseases. Recently, evidence has been presented in support of RNA as the pathogenic agent in Fragile X-associated tremor/ataxia syndrome (FXTAS), caused by expanded CGG repeats at the FRAXA locus. A Drosophila model of FXTAS, in which 90 copies of the CGG repeat are expressed in an untranslated region of RNA, exhibits both neurodegeneration and similar molecular pathology to the 'polyglutamine' diseases. We have, therefore, explored the identity of the pathogenic agent, and specifically the role of RNA, in a Drosophila model of the polyglutamine diseases by the expression of various repeat constructs. These include expanded CAA and CAG repeats and an untranslated CAG repeat. Our data support the identity of polyglutamine as the pathogenic agent in the Drosophila models of expanded CAG repeat neurodegenerative diseases.

Animals↗

PubMed1993

Diagnosis of pathogenic Entamoeba histolytica infection using a stool ELISA based on monoclonal antibodies to the galactose-specific adhesin.

Monoclonal antibodies (MAbs) directed against pathogen-specific epitopes of the galactose adhesin of Entamoeba histolytica were used in an ELISA to detect antigen from pathogenic E. histolytica. Single stool specimens from 74 patients in Bangladesh were used. The ELISA for pathogenic E. histolytica was positive in all 12 stool specimens with pathogenic amebae subsequently cultured, in no stool specimens with nonpathogenic E. histolytica and in 2 of 40 stools with other or no intestinal parasites detected. Specificity and sensitivity of the assay for pathogenic E. histolytica were 97% and 100%, respectively. These preliminary data offer promise for an ELISA using MAbs to the galactose adhesin as a rapid and sensitive means to detect the presence of pathogenic E. histolytica infection in stool specimens.

Animals↗

PubMed2002

Pathogen-induced expression of cyclo-oxygenase homologue in hot pepper (Capsicum annuum cv. Pukang).

The hypersensitive reaction (HR) in plants is typified by a rapid and localized cell death at the site of pathogen infection. To understand better the molecular and cellular defence mechanism controlling HR, hot pepper leaves (Capsicum annuum cv. Pukang) were inoculated with the soybean pustule pathogen Xanthomonas campestris pv. glycine 8ra. By using the DD-PCR technique, a cDNA fragment was identified that exhibited a sequence similarity to the recently identified tobacco pathogen-induced oxygenase (PIOX) with homology to animal cyclo-oxygenase (COX). Subsequently, the full-length cDNA clone, pCa-COX1, encoding the COX homologue from the pathogen-inoculated hot pepper leaf cDNA library was isolated. The deduced amino acid sequence of Ca-COX1 shares 85.8% identity with tobacco PIOX and displays a significant degree of sequence identity (21.7-23.7%) with mammalian COXs. The expression of Ca-COX1 was markedly induced at 4-12 h after pathogen infection, while HR cell death on pepper leaves appeared at approximately 15 h post-inoculation. These results are consistent with the notion that the lipid-derived signalling pathway is involved in the initial response of hot pepper plants to pathogen infection.

Amino Acid Sequence↗