Whole Genome Sequencing Reveals Virulence Potentials of Helicobacter pylori Strain KE21 Isolated from a Kenyan Patient with Gastric Signet Ring Cell Carcinoma

Immunoinformatics-Based Designing of Novel and Potent Multi-Epitope PSA D15 and Cag11 Immunogens for Helicobacter pylori Immunodiagnostic Assay Development

Helicobacter pylori (H. pylori) strain is the most genetically diverse pathogenic bacterium and now alarming serious human health concern ranging from chronic gastritis to gastric cancer and human death all over the world. Currently, the majority of commercially available diagnostic assays for H. pylori is a challenging task due to the heterogeneity of virulence factors in various geographical regions. In this concern, designing of universal multi-epitope immunogenic biomarker targeted for all H. pylori strains would be crucial to successfully immunodiagnosis assay and vaccine development for H. pylori infection. Hence, the present study aimed to explore the potential immunogenic epitopes of PSA D15 and Cag11 proteins of H. pylori, using immunoinformatics web tools in order to design novel immune-reactive multi-epitope antigens for enhanced immunodiagnosis in humans. Through an in silico immunoinformatics approach, high-ranked B-cell, MHC-I, and MHC-II epitopes of PSA D15 and Cag11 proteins were predicted, screened, and selected. Subsequently, a novel multi-epitope PSA D15 and Cag11 antigens were designed by fused the high-ranked B-cell, MHC-I, and MHC-II epitopes and 50S ribosomal protein L7/L12 adjuvant using linkers. The antigenicity, solubility, physicochemical properties, secondary and tertiary structures, 3D model refinement, and validations were carried. Furthermore, the designed multi-epitope antigens were subjected to codon adaptation and in silico cloning, immune response simulation, and molecular docking with receptor molecules. A novel, stable multi-epitope PSA D15 and Cag11 H. pylori antigens were developed and immune simulation of the designed antigens showed desirable levels of immunological response. Molecular docking of designed antigens with immune receptors (B-cell, MHC-I, MHC-II, and TLR-2/4) revealed robust interactions and stable binding affinity to the receptors. The codon optimized and in silico cloned showed that the designed antigens were successfully expressed (CAI value of 0.95 for PSA D15 and 1.0 for Cag11) after inserted into pET-32ba (+) plasmid of the E. coli K12 strain. In conclusion, this study revealed that the designed multi-epitope antigens have a huge immunological potential candidate biomarker and useful in developing immunodiagnostic assays and vaccines for H. pylori infection.

Pangenome Analysis of Helicobacter pylori Isolates from Selected Areas of Africa Indicated Diverse Antibiotic Resistance and Virulence Genes

The challenge facing Helicobacter pylori (H. pylori) infection management in some parts of Africa is the evolution of drug-resistant species, the lack of gold standard in diagnostic methods, and the ineffectiveness of current vaccines against the bacteria. It is being established that even though clinical consequences linked to the bacteria vary geographically, there is rather a generic approach to treatment. This situation has remained problematic in the successful fight against the bacteria in parts of Africa. As a result, this study compared the genomes of selected H. pylori isolates from selected areas of Africa and evaluated their virulence and antibiotic drug resistance, those that are highly pathogenic and are associated with specific clinical outcomes and those that are less virulent and rarely associated with clinical outcomes. 146 genomes of H. pylori isolated from selected locations of Africa were sampled, and bioinformatic tools such as Abricate, CARD RGI, MLST, Prokka, Roary, Phandango, Google Sheets, and iTOLS were used to compare the isolates and their antibiotic resistance or susceptibility. Over 20 k virulence and AMR genes were observed. About 95% of the isolates were genetically diverse, 90% of the isolates harbored shell genes, and 50% harbored cloud and core genes. Some isolates did not retain the cagA and vacA genes. Clarithromycin, metronidazole, amoxicillin, and tinidazole were resistant to most AMR genes (vacA, cagA, oip, and bab). Conclusion. This study found both virulence and AMR genes in all H. pylori strains in all the selected geographies around Africa with differing quantities. MLST, Pangenome, and ORF analyses showed disparities among the isolates. This in general could imply diversities in terms of genetics, evolution, and protein production. Therefore, generic administration of antibiotics such as clarithromycin, amoxicillin, and erythromycin as treatment methods in the African subregion could be contributing to the spread of the bacterium's antibiotic resistance.

A Review of Helicobacter pylori Diagnostics in Africa : From the Bedside to the Laboratory

Helicobacter pylori (H. pylori) is endemic in Africa with a prevalence estimate of 79.1%. In addition, there is a significant community burden of dyspepsia in Africa, similar to other western countries. However, the majority of infected persons do not manifest the disease. In Africa, for instance, peptic ulcer disease is prevalent, whereas gastric cancer has reportedly low incidence. Therefore, it is important that testing is focused, targeting individuals most likely to benefit from treatment. In Africa, there are currently no guidelines for H. pylori testing and treatment. Empirical treatment is common due to variable access to diagnostics and health care. To assess the spectrum of H. pylori testing in Africa, we performed a literature search in PubMed over the past 10 years, 2013 to 2023. Histology was the most widely used modality in 16 out of 18 countries. Capacity for culture was shown in 11 studies, importantly across regions of Africa. H. pylori serology was demonstrated in 8 countries, although it has limited sensitivity in identifying active infection. H. pylori test-and-treat strategy has been shown to be cost-effective. Particularly in a region with high antibiotic resistance, adopting this strategy ensures that only confirmed positive patients are treated. Furthermore, test-of-cure ought to be mandatory to guide future therapies. Health authorities can leverage polymerase chain reaction facilities, left behind by the coronavirus disease 2019 pandemic, to make molecular susceptibility testing available in the near future. A systematic approach to testing incorporating indication for endoscopy and medication use is recommended.

Updated Epidemiology of Gastric Cancer in Asia: Decreased Incidence but Still a Big Challenge

Despite the decline in incidence and mortality rates, gastric cancer (GC) is the fifth leading cause of cancer deaths worldwide. The incidence and mortality of GC are exceptionally high in Asia due to high H. pylori infection, dietary habits, smoking behaviors, and heavy alcohol consumption. In Asia, males are more susceptible to developing GC than females. Variations in H. pylori strains and prevalence rates may contribute to the differences in incidence and mortality rates across Asian countries. Large-scale H. pylori eradication was one of the effective ways to reduce GC incidences. Treatment methods and clinical trials have evolved, but the 5-year survival rate of advanced GC is still low. Efforts should be put towards large-scale screening and early diagnosis, precision medicine, and deep mechanism studies on the interplay of GC cells and microenvironments for dealing with peritoneal metastasis and prolonging patients' survival.

Lacticaseibacillus casei T1 attenuates Helicobacter pylori-induced inflammation and gut microbiota disorders in mice

Probiotics are defined as live microbial food elements that are beneficial to human health. Lacticaseibacillus casei T1 was considered to have potential as a bioactive ingredient in functional foods, which was isolated from kurut. Previous research by our group proved that L. casei T1 could prevent inflammatory responses caused by Helicobacter pylori. This study aimed to investigate whether treatment with L. casei T1 resulted in a suppressive effect on H. pylori-induced oxidative stress and inflammatory responses. The results showed that treatment with L. casei T1 could relieve H. pylori-induced overexpression of inflammatory cytokines in GES-1 cells. Experiments in animals suggested that taking long-term L. casei T1 could reduce oxidative stress and inflammatory cytokines and improve H. pylori-induced gastric mucosal damage. Furthermore, taking L. casei T1 could increase the relative abundance of beneficial intestinal bacterium (Lachnospiraceae and Odoribacter) of H. pylori-infected mice and help in maintaining the balance of intestinal microflora.Collectively, L. casei T1 had certain degrees of therapeutic effect against H. pylori. In the future, it combined with antibiotics for H. pylori eradication deserves further study.

Pattern and trends of Helicobacter pylori genotypes in gastric cancer: A Kenyan 8-year study

Background

Notable geographic and temporal variations in the prevalence and genotypes of Helicobacter pylori, in relation to gastric pathologies, have been observed; however, their significance and trends in African populations is scarcely described. The aim of this study, was to investigate the association of H. pylori and its respective CagA and vacuolating cytotoxin A (VacA) genotypes with gastric adenocarcinoma, and to describe the trends of H. pylori genotypes over an 8-year period (2012-2019).

Materials and methods

A total of 286 samples of gastric cancer cases and benign controls (one-to-one matching), from three main cities in Kenya, between 2012 and 2019 were included. Histologic evaluation, and CagA and VacA genotyping using PCR, was performed. Distribution of H. pylori genotypes was presented in proportions. To determine association, a univariate analysis was conducted using a Wilcoxon rank sum test for continuous variables, and a Chi-squared test or Fisher's exact test for categorical data.

Results

The VacA s1m1 genotype was associated with gastric adenocarcinoma, {odds ratio (OR) = 2.68 [confidence interval (CI) of 95%: 0.83-8.65]; p = 0.108}, whilst VacA s2m2 was associated with a reduced probability of gastric adenocarcinoma [OR = 0.23 (CI 95%: 0.07-0.78); p = 0.031]. No association between cytotoxin associated gene A (CagA) and gastric adenocarcinoma was observed.

Conclusion

Over the study period, an increase in all genotypes of H. pylori was seen, and although no predominant genotype was noted, there was significant year-to-year variation, with VacA s1 and VacA s2 showing the greatest variation. VacA s1m1 and VacA s2m2 were associated with increased, and reduced risk of gastric cancer, respectively. Intestinal metaplasia and atrophic gastritis did not appear to be significant in this population.

The role of infections in the causation of cancer in Kenya

Cancer constitutes a major health care burden in the world today with the situation worsening in resource poor settings as seen in most Sub-Saharan African (SSA) countries. Infections constitute by far the most common risk factors for cancer in SSA and being a typical country in this region, Kenya has experienced an upsurge in the incidence of various types of cancers in the last few decades. Although there is limited population-based data in Kenya of infections-associated cancers, this review provides an up-to-date literature-based discussion on infections-associated cancers, their pathogenesis, and preventive approaches in the country. The primary infectious agents identified are largely viral (human immunodeficiency virus, human papillomavirus (HPV), Kaposi's sarcoma-associated herpes virus, Epstein-Barr virus, hepatitis B virus (HBV), hepatitis C virus), and also bacterial: Helicobacter pylori and parasitic: Schistosomiasis haematobium. Cancers associated with infections in Kenya are varied but the predominant ones are Non-Hodgkin lymphoma, Kaposi's sarcoma, Hodgkin lymphoma, Burkitt's lymphoma, cervical, liver, and gastric cancers. The mechanisms of infections-induced carcinogenesis are varied but they mainly seem to stem from disruption of signaling, chronic inflammation, and immunosuppression. Based on our findings, actionable cancer-preventive measures that are economically feasible and aligned with existing infrastructure in Kenya include screening and treatment of infections, implementation of cancer awareness and screening, and vaccination against infections primarily HBV and HPV. The development of vaccines against other infectious agents associated with causation of cancer remains also as an important goal in cancer prevention.

Biomarker Characterization and Prediction of Virulence and Antibiotic Resistance from Helicobacter pylori Next Generation Sequencing Data

The Gram-negative bacterium Helicobacter pylori colonizes c.a. 50% of human stomachs worldwide and is the major risk factor for gastric adenocarcinoma. Its high genetic variability makes it difficult to identify biomarkers of early stages of infection that can reliably predict its outcome. Moreover, the increasing antibiotic resistance found in H. pylori defies therapy, constituting a major human health problem. Here, we review H. pylori virulence factors and genes involved in antibiotic resistance, as well as the technologies currently used for their detection. Furthermore, we show that next generation sequencing may lead to faster characterization of virulence factors and prediction of the antibiotic resistance profile, thus contributing to personalized treatment and management of H. pylori-associated infections. With this new approach, more and permanent data will be generated at a lower cost, opening the future to new applications for H. pylori biomarker identification and antibiotic resistance prediction.

Assessment of the diagnostic accuracy and relevance of a novel ELISA system developed for seroepidemiologic surveys of Helicobacter pylori infection in African settings

Beside diagnostic uncertainties due to the lack of a perfect gold standard test for Helicobacter pylori infection, the diagnosis and the prevalence estimation for this infection encounter particular challenges in Africa including limited diagnostic tools and specific genetic background. We developed and evaluated the accuracy of an enzyme-linked immunosorbent assay (ELISA) system tailored for H. pylori genetics in Africa (HpAfr-ELISA). Strains belonging to main genetic populations infecting Africans were exploited as sources for whole-cell antigens to establish in-house the ELISA system. A phase II unmatched case-control study explored the diagnostic accuracy of the HpAfr-ELISA using a training set of samples collected from dyspeptic patients from Kinshasa, the Democratic Republic of Congo (DRC) who had been tested with invasive standard tests (i.e., histology, culture, and rapid urease test) in 2017. Then the assay was cross-validated through a community-based survey assessing the prevalence of H. pylori and associated factors in 425 adults from Mbujimayi, DRC in 2018. Bayesian inferences were used to deal with statistical uncertainties of estimates (true prevalence, sensitivity, and specificity) in the study population. At its optimal cut-off-value 20.2 U/mL, the assay achieved an estimated sensitivity of 97.6% (95% credible interval [95%CrI]: 89.2; 99.9%) and specificity of 90.5% (95%CrI: 78.6; 98.5). Consistent outcomes obtained at repeated tests attested the robustness of the assay (negative and positive agreements always > 70%). The true prevalence of H. pylori was estimated 53.8% [95%CrI: 42.8; 62.7%]. Increasing age (adjusted odds ratio [aOR] > 1.0 [95% confidence interval (CI): > 1.0; 1.1]; p<0.001), overcrowding households (aOR = 3.2 [95%CI: 2.0; 5.1]; p<0.001), and non-optimal hand hygiene (aOR = 4.5 [95%CI: 2.0; 11.4]; p = 0.001) were independently associated with the H. pylori-seropositivity. The novel ELISA system has demonstrated good diagnostic accuracy and potential usefulness for management and mitigation strategies for H. pylori infection in African settings.

Helicobacter pylori Infection in Africa: Update of the Current Situation and Challenges

BACKGROUND

The burden of Helicobacter pylori infection (HPI) in Africa remains high with varying levels of prevalence among children and adults reported in different regions of the continent. Persistent and uneradicated HPI could result in gastric cancer, although less severe pathological outcomes have been reported among Africans - the so-called "African enigma."

SUMMARY

Analysis of endoscopic findings of the upper gastrointestinal tract demonstrates similarities with that of patients from the West. Thus, it could be asserted that the true picture of HPI in Africa is yet to be unveiled due to several challenges including inadequate health-care system, lack of treatment guidelines and standardized protocol for diagnosis, and lack of data. This review explores the prevalence, diagnosis, treatment, and health-care system in Africa as it relates to HPI, thus providing an update and highlighting the need for an African HPI guideline.

KEY MESSAGES

There is high prevalence of Helicobacter pylori infection (HPI) in Africa with an increasing burden of antibiotic resistance. Various methods including invasive and noninvasive methods are deployed in the diagnosis of HPI in Africa. There is a need for consensus on diagnosis and treatment of HPI in Africa.