The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Heterogeneity of cag Genotypes in Helicobacter pylori Isolates from Human Biopsy Specimens

The Helicobacter pylori chromosomal cluster of genes known as the cytotoxin-associated gene (cag) island may have different compositions in infecting strains. In this study, we analyzed 150 single colonies obtained from gastric biopsy specimens from 10 patients infected with cagA-positive H. pylori strains and sweep isolates (isolates harvested with sweep in different points of the plate) from 6 patients infected with cagA-negative strains. Three loci in the cag island (cagA, cagE, and virB11) and the conserved gene glmM (ureC) were investigated by PCR. The levels of anti-H. pylori and anti-CagA antibodies in patient sera were also measured. For subjects infected with cagA-negative strains, all sweep isolates were also negative for cagE and virB11, suggesting the complete absence of the cag island. For subjects infected with cagA-positive strains, most of the isolates were positive for all three genes studied, whereas 24.7% of the isolates had a partial or total deletion of the cag island. cagA, cagE, and virB11 were, respectively, present in 87.3, 77.3, and 90% of the colonies. The deletion of virB11 was always associated with the deletion of cagA and/or cagE. H. pylori colonies with different cag genotypes were isolated within a single gastric biopsy specimen from 3 of the 10 patients and were further characterized by random amplified polymorphic DNA (RAPD) analysis and by sequencing of an arbitrarily selected gene segment. Although the colonies had different cag genotypes, their RAPD profiles were highly similar within each patient, and the nucleotide sequences of the selected gene segment were identical. All of the patients had detectable antibodies against H. pylori, and 9 of 10 had anti-CagA antibodies. In conclusion, we show that a single infecting H. pylori strain may include variable proportions of colony subtypes with different cag genotypes. The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between cag genotypes and clinical outcomes of H. pylori infections

Protein signature characterizing Helicobacter pylori strains of patients with autoimmune atrophic gastritis, duodenal ulcer and gastric cancer

Abstract Background Helicobacter pylori (H. pylori) represents a key factor in the etiology of autoimmune atrophic gastritis (AAG), duodenal ulcer (DU) and gastric cancer (GC). The aim of this study was to characterize the differential protein expression of H. pylori isolated from gastric biopsies of patients affected by either AAG, DU or GC. Methods The H. pylori strains were isolated from endoscopic biopsies from the stomach of patients with gastric disease. Protein profiles of H. pylori were compared by two-dimensional difference in gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS) for the identification of significantly different spots (Student t-test, p 1.5). These spots corresponded to 35 unique proteins. The identity of 7 protein spots was validated after one-dimensional electrophoresis and MS/MS analyses of excised gel portions. In H. pylori isolated from DU-patients a significant increase in proteins with antioxidant activity emerged (AroQ, AspA, FldA, Icd, OorA and ScoB), together with a higher content of proteins counteracting the high acid environment (KatA and NapA). In H. pylori isolated from AAG-patients proteins neutralizing hydrogen concentrations through organic substance metabolic processes decreased (GroL, TrxB and Tuf). In addition, a reduction of bacterial motility (FlhA) was found to be associated with AAG-H. pylori isolates. In GC-H. pylori strains it was found an increase in nucleic acid-binding proteins (e.g. DnaG, Tuf, RpoA, RplU) which may be involved in a higher demand of DNA- and protein-related processes. Conclusion Our data suggest the presence of specific protein signatures discriminating among H. pylori isolated from either AAG, DU or GC. Changes in protein expression profiles evaluated by DIGE succeeded in deciphering part of the molecular scenarios associated with the different H. pylori-related gastric diseases

Differential <i>Helicobacter pylori</i> Plasticity in the Gastric Niche of Subjects at Increased Gastric Cancer Risk

Helicobacter pylori (H. pylori) represents an independent risk factor for Gastric Cancer (GC). First Degree Relatives (FDR) of GC subjects and Autoimmune Gastritis (AG) patients are both at increased risk for GC. H. pylori genetic heterogeneity within the gastric niche of FDR and AG individuals has been little explored. To understand whether they exploit an increased H. pylori stability and virulence, 14 AG, 25 FDR, 39 GC and 13 dyspeptic patients (D) were investigated by a cultural PCR-based approach characterizing single colonies-forming-units. We chose three loci within the Cytotoxin-associated gene-A Pathogenicity Island (CagPAI) (cagA,cagE,virB11), vacA, homA and homB as markers of virulence with reported association to GC. Inflammatory/precancerous lesions were staged according to Sydney System. When compared to D, FDR, similarly to GC patients, were associated to higher atrophy (OR = 6.29; 95% CI:1.23&#8722;31.96 in FDR; OR = 7.50; 95% CI:1.67&#8722;33.72 in GC) and a lower frequency of mixed infections (OR = 0.16; 95% CI:0.03&#8722;0.81 in FDR; OR = 0.10; 95% CI:0.02&#8722;0.48 in GC). FDR presented also an increased neutrophil infiltration (OR = 7.19; 95% CI:1.16&#8722;44.65). Both FDR and GC carried a higher proportion of CagPAI+vacAs1i1mx+homB+ profiles (OR = 2.71; 95% CI: 1.66&#8722;4.41 and OR = 3.43; 95% CI: 2.16&#8722;5.44, respectively). Conversely, AG patients presented a lower frequency of subtypes carrying a stable CagPAI and vacAs1i1mx. These results underline different H. pylori plasticity in FDR and AG individuals, and thus, a different host-bacterium interaction capacity that should be considered in the context of eradication therapies

Quantification of Hepatitis C Virus (HCV) in Liver Specimens and Sera from Patients with Human Immunodeficiency Virus Coinfection by Using the Versant HCV RNA 3.0 (Branched DNA-Based) DNA Assay

The new generation assay Versant HCV RNA 3.0v (Bayer Diagnostics) was evaluated to quantify hepatitis C virus (HCV) RNA levels in liver biopsy specimens from patients with HCV and human immunodeficiency virus (HIV) coinfection. A total of 25 liver biopsies and sera collected at the time of liver biopsy were used. The efficiency of HCV RNA recovery from spiked samples was between 38.6 and 50.7%, and reproducible measurements of viral load were observed (the intra- and interrun coefficients of variation were 0.5 to 13% and 3.5 to 24.7%, respectively), with good specificity and sensitivity. Linearity was evaluated in the range of 96,154 to 769 IU/μg by using a serially diluted high-titer sample. Coinfected patients had high HCV RNA viral loads in serum and liver (498,471 IU/ml and 231,495 IU/μg, respectively), and both levels were correlated (r = 0.63; P < 0.01). The amount of hepatic HCV RNA was significantly higher among patients with genotype 1 than among patients with genotype 3 (P < 0.01). The virological end-of-treatment response in the serum was associated with a lower pretreatment intrahepatic HCV viral load (P = 0.03). The new version of b-DNA is a sensitive, specific, and reproducible method for quantitating HCV RNA in the liver. Given its positive analytical performance, the assay will be used to evaluate the HCV RNA levels in the serum and liver during follow-up of patients treated with an anti-HCV therapeutic regimen

The role of HIV-1 DNA levels in HIV-related lymphoma patients treated with autologous stem cell transplantation (ASCT)

Objective. Aim of our study was to evaluate the kinetics of HIV-1 DNA levels (HIV DNA) and its clinical role in HIV-related lymphoma patients undergoing autologous stem cell transplantation (ASCT). Materials and methods. HIV DNA was measured by real-time PCR in the peripheral blood mononuclear cells (PBMCs) of 22 patients, 16 with non-Hodgkin’s lymphoma and 6 with Hodgkin’s disease. Results: Baseline HIV DNA levels were associated with HIV-1 RNA levels (HIV RNA) (r = 0.56, p = 0.02), but not with CD4 counts (r = - 0.10, p = 0.68).The viremia was undetectable for all the follow-up time post-ASCT, while HIV DNA could be evaluated in a high percentage of patients before ASCT and during the entire follow-up (median, 89.5%). At 3 months and at 1 year from transplantation, the median HIV DNA levels were 113 copies/106 PBMCs (baseline vs. 3 months, p &gt; 0.05) and 66 copies/106 PBMCs (baseline vs. 1 year, p &gt; 0.05), respectively. Moreover, baseline HIV DNA levels were significantly different between alive and deceased patients (p = 0.03), and the overall survival (OS) analysis showed that patients with higher HIV DNA levels at baseline had an increased and nearly significant risk of dying if compared to patients with lower levels (HR, 8.33, 95% CI, 0.99-70.06, p = 0.05). Conclusions: Our study demonstrated the association between increased HIV DNA levels at baseline and overall survival after ASCT, in one of the largest cohorts of HIV-lymphoma patients, treated with salvage therapy

Identification and characterization of CDH1 germline variants in sporadic gastric cancer patients and in individuals at risk of gastric cancer.

ObjectiveTo screen and characterize germline variants for E-cadherin (CDH1) in non-hereditary gastric cancer (GC) patients and in subjects at risk of GC.Methods59 GCs, 59 first degree relatives (FDRs) of GC, 20 autoimmune metaplastic atrophic gastritis (AMAGs) and 52 blood donors (BDs) were analyzed for CDH1 by direct sequencing, structural modelling and bioinformatics. Functional impact on splicing was assessed for intronic mutations. E-cadherin/β-catenin immunohistochemical staining and E-cadherin mRNA quantification using RT-PCR were performed.ResultsIn GCs, 4 missense variants (p.G274S; p.A298T; p.T470I; p.A592T), 1 mutation in the 5'UTR (-71C>G) and 1 mutation in the intronic IVS12 (c.1937-13T>C) region were found. First pathogenic effect of p.A298T mutation was predicted by protein 3D modelling. The novel p.G274S mutation showed a no clear functional significance. Moreover, first, intronic IVS12 (c.1937-13T>C) mutation was demonstrated to lead to an aberrant CDH1 transcript with exon 11 deletion. This mutation was found in 2 GCs and in 1 BD. In FDRs, we identified 4 variants: the polymorphic (p.A592T) and 3 mutations in untranslated regions with unidentified functional role except for the 5'UTR (-54G>C) that had been found to decrease CDH1 transcription. In AMAGs, we detected 2 alterations: 1 missense (p.A592T) and 1 novel variant (IVS1 (c.48+7C>T)) without effect on CDH1 splicing. Several silent and polymorphic substitutions were found in all the groups studied.ConclusionsOverall our study improves upon the current characterization of CDH1 mutations and their functional role in GC and in individuals at risk of GC. Mutations found in untranslated regions and data on splicing effects deserve a particular attention like associated with a reduced E-cadherin amount. The utility of CDH1 screening, in addition to the identification of other risk factors, could be useful for the early detection of GC in subjects at risk (i.e. FDRs and AMAGs), and warrants further study