Identification and virulence test of a new pathogen that causes verticillium striping on rapeseed in northwestern China

Five stems of rapeseed with abundant black microsclerotia were collected from Huangyuan County of Qinghai Province,China,and fungal isolates were obtained from the stems.They were identified based on morphology,molecular features and specific PCR detection.The results showed that the 10 fungal isolates belonged to Verticillium longisporum lineage A1/D3.One of the 10 isolates(HW7-1)was tested for virulence on three species of rapeseed,including B.napus Zhongshuang 9,B.rapa Qingyou 9 and B.juncea Tayou 2 by conidia inoculation of HW7-1 on roots of young seedlings.Control seedlings were inoculated with V.dahliae conidia or water alone.The seedlings of these treatments were transplanted in culture mix and incubated in a growth chamber(20℃).Results suggested that the control seedlings of three cultivars appeared quite healthy,while the seedlings inoculated with HW7-1 turned yellowing leaves,seedling stunting or even death after 22 days post-inoculation.V.longisporum was re-isolated from he yellow leaves,thus fulfilling Koch's postulates.Moreover,compared to the control treatments,inoculation with HW7-1 caused flowering delay and seed yield reduction on Tayou 2 with production of microsclerotia on the stems.To our knowledge,this is the first report of V.longisporum lineage A1/D3 on rapeseed in northwestern China.

Isolation,identification,and virulence gene analysis of pathogenic Aeromonas dhakensis in Macrobrachium rosenbergii and histopathological observation

To identify the cause of mass mortality of adult Macrobrachium rosenbergii in a farm in Gaoyou City,Jiangsu Province,China,a dominant strain named DKQ-1 was isolated from the hepatopancreas of dying M.rosenbergii and identified as Aeromonas dhakensis by purification culture,biochemical characterization,and 16S rRNA and gyrB gene sequence analysis.The results of the challenge test revealed that the strain was highly pathogenic and the 50%lethal dose(LD_(50))in 72 h to M.rosenbergii was 1.54×10^(5)CFU/mL.The amplification results of virulence genes show that strain DKQ-1 carried 9 virulence genes,including ascV,aexT,aer,act,lip,ompAI,gcaT,acg,and exu,supporting the strong virulence of strain DKQ-1 to M.rosenbergii.Histopathological observation of the hepatopancreas,gills,and intestines indicated that DKQ-1 injection into M.rosenbergii could cause serious tissue damage,which further supported the strong virulence of this strain.In addition,a drug susceptibility test revealed that strain DKQ-1 was sensitive to 16 kinds of antibiotics,resistant to 9 kinds of antibiotics,and had intermediate resistance to spectinomycin and kanamycin.This study is the first report of A.dhakensis isolated from M.rosenbergii and provided a reference for the pathogen identification of bacterial diseases in M.rosenbergii,and for the prevention and treatment caused by A.dhakensis.

A potential hyphal fusion protein complex with an important role in development and virulence interacts with autophagy-related proteins in Fusarium pseudograminearum

Hyphal fusion(anastomosis)is a common process serving many important functions at various developmental stages in the life cycle of ascomycetous fungi.However,the biological roles and molecular mechanisms in plant pathogenic fungi were widely unknown.In this study,a hyphal fusion protein FpHam-2 was screened from a T-DNA insertion mutant library of Fusarium pseudograminearum,and FpHam-2 interacts with another 2 hyphal fusion protein homologues FpHam-3 and FpHam-4.Each of these 3 genes deletion mutant revealed in similar defective phenotypes compared with the WT and complemented strains,including reduction in growth rate,defects in hyphal fusion and conidiation,more sensitive for cell membrane,cell wall and oxidative stress responses,and decreased in virulence.The yeast two-hybrid assay was used to identify that FpHam-2 interacts with 3 autophagy-related proteins,including FpAtg3,FpAtg28 and FpAtg33.Furthermore,FpHam-2-deletion mutant showed decreased accumulation of autophagic bodies in hypha.In conclusion,FpHam-2,FpHam-3 and FpHam-4 have an essential role for hyphal fusion and regulating the growth,conidiation and virulence in F.pseudograminearum.

Mechanistic research:Selenium regulates virulence factors,reducing adhesion ability and inflammatory damage of Helicobacter pylori

BACKGROUND The pathogenicity of Helicobacter pylori is dependent on factors including the environment and the host.Although selenium is closely related to pathogenicity as an environmental factor,the specific correlation between them remains unclear.AIM To investigate how selenium acts on virulence factors and reduces their toxicity.METHODS H.pylori strains were induced by sodium selenite.The expression of cytotoxin-associated protein A(CagA)and vacuolating cytotoxin gene A(VacA)was determined by quantitative PCR and Western blotting.Transcriptomics was used to analyze CagA,CagM,CagE,Cag1,Cag3,and CagT.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction,and H.pylori colonization,inflammatory reactions,and the cell adhesion ability of H.pylori were assessed.RESULTS CagA and VacA expression was upregulated at first and then downregulated in the H.pylori strains after sodium selenite treatment.Their expression was significantly and steadily downregulated after the 5th cycle(10 d).Transcriptome analysis revealed that sodium selenite altered the levels affect H.pylori virulence factors such as CagA,CagM,CagE,Cag1,Cag3,and CagT.Of these factors,CagM and CagE expression was continuously downregulated and further downregulated after 2 h of induction with sodium selenite.Moreover,CagT expression was upregulated before the 3rd cycle(6 d)and significantly downregulated after the 5th cycle.Cag1 and Cag3 expression was upregulated and downregulated,respectively,but no significant change was observed by the 5th cycle.C57BL/6A mice were infected with the attenuated strains subjected to sodium selenite induction.The extent of H.pylori colonization in the stomach increased;however,sodium selenite also induced a mild inflammatory reaction in the gastric mucosa of H.pylori-infected mice,and the cell adhesion ability of H.pylori was significantly weakened.CONCLUSION These results demonstrate that H.pylori displayed virulence attenuation after the 10th d of sodium selenite treatment.Sodium selenite is a low toxicity compound with strong stability that can reduce the cell adhesion ability of H.pylori,thus mitigating the inflammatory damage to the gastric mucosa.

psk1 virulence gene-induced pulmonary and systemic tuberculosis in a young woman with normal immune function:A case report

BACKGROUND Tuberculosis is a chronic infectious disease and an important public health pro-blem.Despite progress in controlling tuberculosis,the incidence of tuberculosis in China is still very high,with 895000 new cases annually.This case report des-cribes the investigation of a case of severe disseminated tuberculosis in a young adult with normal immune function,conducted to ascertain why a Mycobacterium tuberculosis(M.tuberculosis)strain caused such severe disease.CASE SUMMARY A previously healthy 28-year-old woman presented to our hospital with a 1-mo-nth history of fever and fatigue.She was diagnosed with severe disseminated pulmonary tuberculosis,spinal tuberculosis with paravertebral abscesses,and tuberculous meningitis.M.tuberculosis was isolated from bronchoal-veolar lavage fluid.She was treated with standard antituberculous therapy and underwent debridement,bone graft,and internal fixation surgery for spinal tuberculosis.She responded to therapy and regained her ability to walk following the surgery.We analysed the whole-genome sequence of the strain and designated it BLM-A21.Additional M.tuberculosis genomes were selected from the Virulence Factor Database(http://www.mgc.ac.cn/cgi-bin/VFs/genus.cgi?Genus=Mycobacterium)for comparison.An evolutionary tree of the BLM-A21 strain was built using PhyML maximum likelihood software.Further gene analysis revealed that,except for the pks1 gene,BLM-A21 had similar virulence genes to the CDC 1551 and H37Rv strains,which have lower dissemination.CONCLUSION We speculate that the pks1 virulence gene in BLM-A21 may be the key virulence gene responsible for the wide-spread dissemination of M.tuberculosis infection in this previously healthy adult with normal immune function.

Molecular investigation of exoU and exoY virulence genes in Pseudomonas aeruginosa collected from hospitalized patients in North of Iran:A descriptive-analytical study

Objective:To investigate the frequency of exoU and exoY genes in patients with Pseudomonas aeruginosa infection.Methods:In this study,100 clinical isolates of Pseudomonas aeruginosa were collected from patients hospitalized in educational-therapeutic hospitals and were identified using standard microbiological tests.Then,the antibiotic resistance pattern of the isolates was determined by the disk agar diffusion method.The bacterial DNAs were extracted by the alkaline lysis method.Finally,the presence of exoU and exoY genes was evaluated by the PCR test.Results:In this study,47%,72%,29%,39%,40%,and 44%of the isolates were non-susceptible to piperacillin,aztreonam,ceftazidime,imipenem,tobramycin,and ciprofloxacin,respectively.In addition,95%and 93%of the clinical isolates carried the exoU and exoY genes.Blood and fecal isolates had both virulence genes,while only one wound isolate had neither genes.Meanwhile,all urinary isolates contained the exoY gene and only one isolate lacked the exoU gene.Also,88 isolates simultaneously had both exoU and exoY genes.Conclusions:High prevalence of exoU and exoY genes in this region indicates a significant role of typeⅢsecretion system in pathogenesis of Pseudomonas aeruginosa.The typeⅢsecretion system may be a suitable target to reduce the pathogenicity of this bacterium.

Molecular Detection of Resistance and Virulence Genes in Coagulase Negative Staphylococci Isolated from Blood Cultures at the University Teaching Hospital of Bouake

Introduction: Coagulase-negative staphylococci (CoNS) are currently recognized as genuine pathogens. However, little is known about the resistance and virulence genes that explain their pathogenicity in hospitals in Cte d'Ivoire. The aim of this study was to contribute to the genotypic identification of resistance and virulence genes in CoNS isolated from blood cultures at the University Teaching Hospital (CHU) of Bouak, in order to improve patient management. Material and Methods: This was a descriptive study conducted from September to December 2023. The CoNS isolates studied came from the collection of strains isolated from blood cultures of febrile patients hospitalized or attending consultations at the CHU of Bouak. The strains were analyzed using conventional simplex PCR. Results: Of the 45 isolates analyzed, 46.7% carried both the aacA-aphD and tetK genes and 40% carried the mecA gene. With regard to virulence genes, only the LukS-PV gene was observed in S. epidermidis and S. haemolyticus isolates. Conclusion: The high prevalence of CoNS isolates carrying the mecA gene and the presence of virulence genes observed in this study give cause for concern in hospitals. It is important to develop comprehensive surveillance strategies against nosocomial and multi-resistant infections at the CHU of Bouak.

PCR Detection of Virulence Genes Colv,Stxs and HlyE of Escherichia coli

[Objective] This study aimed to explore the presence of three causative genes Colv,Stxs and HlyE of the pathogenic E.coli from chickens,pigs and food.[Method] By using 44 E.coli strains from chickens,24 from pigs and 26 from food as the experimental materials,virulence genes Colv,Stxs（stx2,stx2e） and HlyE were detected with polymerase chain reaction（PCR） method.[Result] Among all the E.coli strains,the detection rate of Colv was 25% from chickens,4.2% from pigs,and 0 from food;the detection rate of Stx2（Stx2e） from all E.coli strains was 0;the detection rate of HlyE was 2.27% from chickens,0 from pigs,and 11.5% from food.[Conclusion] Virulence gene Colv shows relatively high carrying rate in E.coli from chickens and pigs;HlyE also shows a certain degree of presence in E.coli from chickens and food.

Virulence Types of Magnaporthe oryzae to Hybrid Rice in Sichuan,China

A total of 638 isolates of rice blast （Magnaporthe oryzae） were isolated in 2002-2009 from different rice varieties in different regions of Sichuan, China and inoculated onto seven rice varieties （Lijiangxintuanheigu, IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1） to differentiate the virulence types of the fungus and trace the changes. The virulence to the seven varieties was respectively scored at 1, 2, 4, 8, 16, 32 and 64. The total scores of individual M. grisea isolates which were the sum of scores infecting differential varieties could, in turn, be used for the nomenclature of the virulence types due to their accordance to the special virulence patterns. The 638 tested isolates were then differentiated into 56 different virulence types. Type 15 virulent to Lijiangxintuanheigu, IR24 and Minghui 63, and Type 127 virulent to all of the seven varieties were the most dominant virulence types respectively with the occurrence frequencies of 15.99% and 15.83%. Type 19 and other seven virulence types were not monitored during 2002-2009. Type 15 was the predominant virulence type in 2002, 2003, 2004 and 2007, whereas Type 127 had been the most dominant virulence type after 2005 except for the year 2007 when the province underwent severe drought. Five hundred and seven out of the 638 tested isolates were virulent to Minghui 63, and 89.58% of the 384 isolates virulent to either Duohui 1, Chenghui 448 or Neihui 99-14 were virulent to Minghui 63, which indicated the impact of the extensive plantation of hybrid rice Minghui 63 as the restorer line on the virulence evolution of M. oryzae in Sichuan. The virulence pattern of the dominant virulence types suggested that the acquiring of virulence to all the major resistant restorer lines was the main routes of the evolution in virulence of M. oryzae to hybrid rice in Sichuan. The virulence frequencies of the 638 tested isolates to IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1 were respectively 74.6%, 79.5%, 73.8%, 37.0%, 39.0% and 40.4%. The analysis for the sources of the different virulence type isolates indicated the pathogen on the newly released resistant varieties were stronger than conventional rice varieties which had become susceptible in the field since 1980s.

Stress Physiology and Virulence Characterization of Phomopsis asparagi (Sacc.) Bubák isolated from Asparagus in Jiangxi Province of China

Fungal pathogen of asparagus stem blight was isolated. No significant genetic difference was detected among the three strains with 492 bp long ITS1-5.8S-ITS2 sequence. It was then identified through colony growth, conidia morphology, and molecular characterization. The physiological response to oxidation and osmosis stress, and virulence to Asparagus officinalis L. were analyzed. The results showed that the pathogen causing asparagus stem blight for A. officinalis L. in Jiangxi Province is Phomopsis asparagri (Sacc.) Bubák. Under pure culture conditions, the conidia were oval-shaped (α-type), with colorless single spore and single nucleus, containing 0-2 oil balls. Its vegetative growth rate was higher when cultured on 0.2 × potato dextrose agar (0.2 × PDA) medium than that on oatmeal agar (OA) medium. However, the pycnidia appeared earlier on OA medium than on 0.2 earlier PDA medium. The vegetative growth rate was depressed under oxidation (H2O2) or osmosis (NaCl) stress conditions, and totally inhibited under 7 mmol/L H2O2 or 2.4 mol/L NaCl. All the strains caused typical pathogenic symptoms to Asparagus officinalis L. at 7 days-post-inoculation (dpi) with conidia.

Helicobacter pylori virulence genes

Helicobacter pylori(H.pylori)is one of the most important human pathogens,infecting approximately half of the global population.Despite its high prevalence,only a subset of H.pylori infected individuals develop serious gastroduodenal pathology.The pathogenesis of H.pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host,environmental and bacterial virulence factors.H.pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment,movement towards the gastric epithelium,and attachment to gastric epithelial cells.These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H.pylori infection,causing chronic inflammation and tissue damage,which may eventually lead to the development of peptic ulcers and gastric cancer.Numerous studies have focused on the prevalence and role of putative H.pylori virulence genes in disease pathogenesis.While several virulence factors with various functions have been identified,disease associations appear to be less evident,especially among different study populations.This review presents key findings on the most important H.pylori virulence genes,including several bacterial adhesins and toxins,in children and adults,and focuses on their prevalence,clinical significance and potential relationships.

New insights of Helicobacter pylori host-pathogen interactions: The triangle of virulence factors, epigenetic modifications and non-coding RNAs

Helicobacter pylori(H. pylori) is a model organism for understanding host-pathogen interactions and infection-mediated carcinogenesis. Gastric cancer and H. pylori colonization indicates the strong correlation. The progression and exacerbation of H. pylori infection are influenced by some factors of pathogen and host. Several virulence factors involved in the proper adherence and attenuation of immune defense to contribute the risk of emerging gastric cancer, therefore analysis of them is very important. H. pylori also modulates inflammatory and autophagy process to intensify its pathogenicity. From the host regard, different genetic factors particularly affect the development of gastric cancer. Indeed, epigenetic modifications, Micro RNA and long non-coding RNA received more attention. Generally, various factors related to pathogen and host that modulate gastric cancer development in response to H. pylori need more attention due to develop an efficacious therapeutic intervention. Therefore, this paper will present a brief overview of host-pathogen interaction especially emphases on bacterial virulence factors, interruption of host cellular signaling, the role of epigenetic modifications and non-coding RNAs.

Virulence factors of Enterococcus strains isolated from patients with inflammatory bowel disease

AIM: To determine the features of Enterococcus that contribute to the development and maintenance of the inflammatory process in patients with inflammatory bowel disease (IBD). METHODS: Multiplex polymerase chain reaction (PCR) was applied to assess the presence of genes that encode virulence factors [surface aggregating protein (asa1), gelatinase (gelE), cytolysin (cylA), extracellular surface protein (esp) and hyaluronidase (hyl)] in the genomic DNA of 28 strains of Enterococcus isolated from the intestinal tissues of children with IBD (n =16) and of children without IBD (controls; n = 12). Additionally, strains with confirmed presence of the gelE gene were tested by PCR for the presence of quorum sensing genes (fsrA, fsrB, fsrC) that control the gelatinase production. Gelatinase activity was tested on agar plates containing 1.6% gelatin. We also analysed the ability of Enterococcus strains to release and decompose hydrogen peroxide (using Analytical Merckoquant peroxide test strips) and tested their ability to adhere to Caco-2 human gut epithelium cells and form biofilms in vitro. RESULTS: A comparison of the genomes of Enterococcus strains isolated from the inflamed mucosa of patients with IBD with those of the control group showed statistically significant differences in the frequency of theasa1 gene and thegelE gene. Furthermore, the cumulative occurrence of different virulence genes in the genome of a single strain ofEnterococcus isolated from the IBD patient group is greater than in a strain from the control group, although no significant difference was found. Statistically significant differences in the decomposition of hydrogen peroxide and adherence to the Caco-2 epithelial cell line between the strains from the patient group and control group were demonstrated. The results also showed that profuse biofilm production was more frequent amongEnterococcus strains isolated from children with IBD than in control strains. CONCLUSION: Enterococcus strains that adhere strongly to the intestinal epithelium, form biofilms and possess antioxidant defence mechanisms seem to have the greatest influence on the inflammatory process.

Virulence and potential pathogenicity of coccoid Helicobacter pylori induced by antibiotics

AIM: To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic. METHODS: Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole. Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot. The mutation of the genes including ureA, ureB,hpaA, vacA and cagA, related with virulence, was detected by means of PCR and PCR-SSCP. RESULTS: In the coccoid H. pylori,the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells all decreased. In strain F44, the rate and index of adherence reduced from 70.0% +/- 5.3% to 33% +/- 5.1% and from 2.6 +/- 0.4 to 0.96 +/- 0.3 (P 【 0.01), respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr 74000 decreased, and the hybriditional signal in band M(r) 125000 weakened, while the band M(r)110000 and M(r)63000 strengthened in coccoid H.pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA. CONCLUSION: The virulence and the proteins with molecular weight over M(r)74000 in coccoid H.pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA, vacA and cagA genes, suggesting that coccoid H.pylori may have potential pathogenicity.

Helicobacter pylori's virulence and infection persistence define pre-eclampsia complicated by fetal growth retardation

AIM: To better understand the pathogenic role of Helicobacter pylori (H. pylori) in pre-eclampsia (PE), and whether it is associated or not with fetal growth retardation (FGR). METHODS: Maternal blood samples were collected from 62 consecutive pregnant women with a diagnosis of PE and/or FGR, and from 49 women with uneventful pregnancies (controls). Serum samples were evaluated by immunoblot assay for presence of specific antibodies against H. pylori antigens [virulence: cytotoxin-associated antigen A (CagA); ureases; heat shock protein B; flagellin A; persistence: vacuolating cytotoxin A (VacA)]. Maternal complete blood count and liver enzymes levels were assessed at delivery by an automated analyzer. RESULTS: A significantly higher percentage of H. pyloriseropositive women were found among PE cases (85.7%) compared to controls (42.9%, P < 0.001). There were no differences between pregnancies complicated by FGR without maternal hypertension (46.2%) and controls. Importantly, persistent and virulent infections (VacA/ CagA seropositive patients, intermediate leukocyte blood count and aspartate aminotransferase levels) were exclusively associated with pre-eclampsia complicated by FGR, while virulent but acute infections (CagA positive/ VacA negative patients, highest leukocyte blood count and aspartate aminotransferase levels) specifically correlated with PE without FGR. CONCLUSION: Our data strongly indicate that persistent and virulent H. pylori infections cause or contribute to PE complicated by FGR, but not to PE without feto-placental compromise.

Role of polymorphisms in genes that encode cytokines and Helicobacter pylori virulence factors in gastric carcinogenesis

The Helicobacter pylori(H. pylori) infection is a determinant factor in gastric cancer(GC) development. However, the infection outcomes are variable and depend on both host and bacterial characteristics. Some host cytokines such as interleukin(IL)-1β, IL-1 Ra, IL-8, IL-10 and tumor necrosis factor-α play important roles in the host immune system response to the pathogen, in the development of gastric mucosal lesions and in cell malignant transformation. Therefore, these host factors are crucial in neoplastic processes. Certain polymorphisms in genes that encode these cytokines have been associated with an increased risk of GC. On the other hand, various virulence factors found in distinct H. pylori bacterial strains, including cytotoxinassociated antigen A, vacuolating cytotoxin, duodenal ulcer promoting gene A protein, outer inflammatory protein and blood group antigen binding adhesin, have been associated with the pathogenesis of different gastric diseases. The virulent factors mentioned above allow the successful infection by the bacterium and play crucial roles in gastric mucosa lesions, including malignant transformation. Moreover, the role of host polymorphisms and bacterial virulence factors in gastric carcinogenesis seems to vary among different countries and populations. The identification of host and bacterium factors that are associated with an increased risk of GC development may be useful in determining the prognosis of infection in patients, what could help in clinical decision-making and in providing of an optimized clinical approach.

Virulence and Diversity of Blumeria graminis f.sp.tritici Populations in China

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important disease in China. To characterize the virulence and diversity of the pathogen, 1 082 isolates were obtained from 8 major wheat-growing regions during the spring growing season in 2011. The virulence test was performed by inoculation on detached leaves of 22 differential lines with known Pm genes. Frequencies of virulence on these genotypes ranged from 0 to 97.4%. None of the 1 082 isolates was compatible to Pm21 and less than 20.0%were virulent to the genotype carrying Pm13. In contrast, the virulence frequencies of each population was more than 50.0%to differentials carrying Pm1a, Pm3b, Pm3c, Pm3f, Pm5a, Pm6 and Pm8. In total, 1 028 pathotypes were detected, of which 984 were unique. Phenotypic diversity indices revealed a high level of diversity within populations. Genetic distance between different populations correlated signiifcantly with geographical distance （R2=0.494, P 0.001）. In addition, isolates from Xinjiang appear to form a separate group. Signiifcant positive or negative associations between alleles at pairs of virulence loci were detected in 57 allele pairs to Pm genes. Virulence and diversity of the 8 populations suggested that varieties with effective resistance gene combinations should be developed at a regional level.

H pylori iceA alleles are disease-specific virulence factors

AIM： To characterize and compare genotype profiles of H pylori strains isolated from patients with chronic gastritis and duodenal ulcer in western part of Turkey. METHODS： A total of 46 patients [30 chronic gastritis （CG） and 16 duodenal ulcer （DU）] who had undergone endoscopy because of dyspeptic complaints were studied. The antral biopsy specimens were evaluated for the presence of Hpylori by rapid urease test and culture, and the genotype profiles were determined by real-time PCR. RESULTS： The cagA gene was observed in 43 （93.5%） isolates. The vacA s1m2 genotype was the predominant subtype, found in 63.3% and 68.7% of isolates in patients with CG and DU, respectively. Twenty （66.6%） isolates from patients with CG were iceA2 positive while the iceA1 was predominant in those with DU （68.8%）. In terms of the association of the ice,4 alleles to other genes, both alleles were significantly associated with the cagA vacA slm2 genotype. CONCLUSION： The prevalent circulating genotypes in CG and DU were cagA vacA slm2 iceA2 and cagA vacA slm2 iceA1 genotype, respectively. It was found that cagA vacA slm2 genotype seems to be common virulence factors in both CG and DU while iceA alleles show specificity for gastroduodenal pathologies in this study.

Distribution and Virulence Diversity of Phytophthora sojae in China

By investigating occurrence of Phytophthora root rot in fields and isolating P.sojae fromdiseased plants and soils, the distribution of P.sojae in China was surveyed. In addition tonortheast region, P.sojae existed in Huanghe-Huaihe basin and Yangtze basin too. Eighty- threeisolates of P.sojae isolated from different areas were identified on virulence using 13differential soybean cultivars, abundant virulence diversity was found in P.sojae. The greaterdiversity in virulence of P.sojae was in isolates from soil than from plants. And the greatestvirulence diversity of P.sojae was found in Yangtze basin.

Can bacterial virulence factors predict antibiotic resistant Helicobacter pylori infection?

AIM To evaluate the association between virulence factor status and antibiotic resistance in Helicobacter pylori(H. pylori)-infected patients in Ireland. METHODS DNA was extracted from antral and corpus biopsies obtained from 165 H. pylori-infected patients. Genotyping for clarithromycin and fluoroquinolone-mediating mutations was performed using the Genotype Helico DR assay. cag A and vac A genotypes were investigated using PCR. RESULTS Primary, secondary and overall resistance rates for clarithromycin were 50.5%(n = 53/105), 78.3%(n = 47/60) and 60.6%(n = 100/165), respectively. Primary, secondary and overall resistance rates for fluoroquinolones were 15.2%(n = 16/105) and 28.3%(n = 17/60) and 20%(n = 33/165), respectively. Resistance to both antibiotics was 12.4%(n = 13/105) in treatment-na?ve patients, 25%(n = 15/60) in those previously treated and 17%(n = 28/165) overall. A cag A-positive genotype was detected in 22.4%(n = 37/165) of patient samples. The dominant vac A genotype was S1/M2 at 44.8%(n = 74/165), followed by S2/M2 at 26.7%(n = 44/165), S1/M1 at 23.6%(n = 39/165) and S2/M1 at 4.8%(n = 8/165). Primary clarithromycin resistance was significantly lower in cag A-positive strains than in cag A-negative strains [32%(n = 8/25) vs 56.3%(n = 45/80); P = 0.03]. Similarly, in patients infected with more virulent H. pylori strains bearing the vac A s1 genotype, primary clarithromycin resistance was significantly lower than in those infected with less virulent strains bearing the vac A s2 genotype, [41%(n = 32/78) vs 77.8%(n = 21/27); P = 0.0001]. No statistically significant association was found between primary fluoroquinolone resistance and virulence factor status.CONCLUSION Genotypic H. pylori clarithromycin resistance is high and cag A-negative strains are dominant in our population. Less virulent(cag A-negative and vac A S2-containing) strains of H. pylori are associated with primary clarithromycin resistance.