Browsing by Author "Dharmendra Kumar Soni"

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ATP-binding cassette (ABC) import systems of Mycobacterium tuberculosis: target for drug and vaccine development
(Taylor and Francis Ltd., 2020) Dharmendra Kumar Soni; Suresh Kumar Dubey; Rakesh Bhatnagar
Nutrient procurement specifically from nutrient-limiting environment is essential for pathogenic bacteria to survive and/or persist within the host. Long-term survival or persistent infection is one of the main reasons for the overuse of antibiotics, and contributes to the development and spread of antibiotic resistance. Mycobacterium tuberculosis is known for long-term survival within the host, and develops multidrug resistance. Before and during infection, the pathogen encounters various harsh environmental conditions. To cope up with such nutrient-limiting conditions, it is crucial to uptake essential nutrients such as ions, sugars, amino acids, peptides, and metals, necessary for numerous vital biological activities. Among the various types of transporters, ATP-binding cassette (ABC) importers are essentially unique to bacteria, accessible as drug targets without penetrating the cytoplasmic membrane, and offer an ATP-dependent gateway into the cell by mimicking substrates of the importer and designing inhibitors against substrate-binding proteins, ABC importers endeavour for the development of successful drug candidates and antibiotics. Alternatively, the production of antibodies against substrate-binding proteins could lead to vaccine development. In this review, we will emphasize the role of M. tuberculosis ABC importers for survival and virulence within the host. Furthermore, we will elucidate their unique characteristics to discover emerging therapies to combat tuberculosis. © 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd.
Biosensor for the detection of Listeria monocytogenes: emerging trends
(Taylor and Francis Ltd, 2018) Dharmendra Kumar Soni; Rafiq Ahmad; Suresh Kumar Dubey
The early detection of Listeria monocytogenes (L. monocytogenes) and understanding the disease burden is of paramount interest. The failure to detect pathogenic bacteria in the food industry may have terrible consequences, and poses deleterious effects on human health. Therefore, integration of methods to detect and trace the route of pathogens along the entire food supply network might facilitate elucidation of the main contamination sources. Recent research interest has been oriented towards the development of rapid and affordable pathogen detection tools/techniques. An innovative and new approach like biosensors has been quite promising in revealing the foodborne pathogens. In spite of the existing knowledge, advanced research is still needed to substantiate the expeditious nature and sensitivity of biosensors for rapid and in situ analysis of foodborne pathogens. This review summarizes recent developments in optical, piezoelectric, cell-based, and electrochemical biosensors for Listeria sp. detection in clinical diagnostics, food analysis, and environmental monitoring, and also lists their drawbacks and advantages. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.
Evaluation and use of in silico structure based epitope prediction for listeriolysin O of Listeria monocytogenes
(National Institute of Science Communication and Information Resources (NISCAIR), 2015) Dharmendra Kumar Soni; Abhigyan Nath; Suresh Kumar Dubey
Listeria infection is major health problem causing listeriosis that manifests as abortion, stillbirth, septicemia, meningitis and meningoencephalitis. Listeriolysin O is the cholesterol-dependent cytolysin toxin involved in the escape of L. monocytogenes from primary and secondary intracellular vacuoles and, therefore, can serve as the vital target for vaccine development. Consequently, the present study was aimed to design epitope-based vaccine against Listeria. LLO, ILO, and SLO proteins from L. monocytogenes, L. ivanovii and L. seeligeri, respectively were analyzed using various bioinformatics and immuonoinformatics tools, including sequence and structure-based ones. A total of 11 antigenic B-cell epitopes, and 4 and 3 allelic classes for MHC class I and MHC class II binding peptides, respectively were predicted for LLO protein. The unique peptide 363LGDLRD368 was identified in the LLO protein. Further, we also observed that IgG class of B-cells were predominant in these proteins. The study revealed potential B-cell and T-cell epitope that can raise the desired immune response against these proteins. The present study would, therefore, be helpful in designing and predicting novel vaccine candidates, which in near future might offer the source for eradicating listeriosis.
Label-free impedimetric detection of Listeria monocytogenes based on poly-5-carboxy indole modified ssDNA probe
(Elsevier, 2015) Kashish; Dharmendra Kumar Soni; Sunil Kumar Mishra; Rajiv Prakash; Suresh Kumar Dubey
Listeria monocytogenes is a life threatening pathogenic bacteria concerned with human health. The accurate and rapid detection of L. monocytogenes is required for preventing of listeriosis. In this study, DNA sensing probe based on conducting polymer poly-5-carboxy indole (5C Pin) was developed for the detection of L. monocytogenes hlyA gene responsible for pathogenicity. The probe sequences (24 mer ssDNA) were covalently immobilized on 5C Pin via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimidehydrochloride (EDC) and N-hydroxysuccinimide (NHS). The probe having ssDNA was further hybridized with the target DNA sequence. Electrochemical impedance spectroscopic study was carried out to determine the extent of DNA hybridization over the probe. Significant change was observed in the impedance spectra before and after hybridization of ssDNA immobilized over the probe with the target DNA. RCT (charge transfer resistance) was estimated from the Nyquist plot (impedance plot) for target DNA (hlyA gene) in the solution. RCT vs. logarithmic concentrations of the target (genomic) DNA plot showed a linear range (1×10-4 to 1×10-12M) in case hybridization was performed under optimized conditions. The method proposed, is simple, free from any label, and highly sensitive for the detection of L. monocytogenes in environmental and clinical samples. © 2015 Elsevier B.V.
Phylogenetic analysis of the Listeria monocytogenes based on sequencing of 16S rRNA and hlyA genes
(Kluwer Academic Publishers, 2014) Dharmendra Kumar Soni; Suresh Kumar Dubey
The discrimination between Listeria monocytogenes and Listeria species has been detected. The 16S rRNA and hlyA were PCR amplified with set of oligonucleotide primers with flank 1,500 and 456 bp fragments, respectively. Based on the differences in 16S rRNA and hlyA genes, a total 80 isolates from different environmental, food and clinical samples confirmed it to be L. monocytogenes. The 16S rRNA sequence similarity suggested that the isolates were similar to the previously reported ones from different habitats by others. The phylogenetic interrelationships of the genus Listeria were investigated by sequencing of 16S rRNA and hlyA gene. The 16S rRNA sequence indicated that genus Listeria is comprised of following closely related but distinct lines of descent, one is the L. monocytogenes species group (including L. innocua, L. ivanovii, L. seeligeri and L. welshimeri) and other, the species L. grayi, L. rocourtiae and L. fleischmannii. The phylogenetic tree based on hlyA gene sequence clearly differentiates between the L. monocytogenes, L. ivanovii and L. seeligeri. In the present study, we identified 80 isolates of L. monocytogenes originating from different clinical, food and environmental samples based on 16S rRNA and hlyA gene sequence similarity. © 2014, Springer Science+Business Media Dordrecht.
Pregnancy - associated human listeriosis: Virulence and genotypic analysis of Listeria monocytogenes from clinical samples
(Microbiological Society of Korea, 2015) Dharmendra Kumar Soni; Durg Vijai Singh; Suresh Kumar Dubey
Listeria monocytogenes, a life-threatening pathogen, poses severe risk during pregnancy, may cause abortion, fetal death or neonatal morbidity in terms of septicemia and meningitis. The present study aimed at characterizing L. monocytogenes isolated from pregnant women based on serotyping, antibiotic susceptibility, virulence genes, in vivo pathogenicity test and ERIC- and REP-PCR fingerprint analyses. The results revealed that out of 3700 human clinical samples, a total of 30 (0.81%) isolates [12 (0.80%) from placental bit (1500), 18 (0.81%) from vaginal swab (2200)] were positive for L. monocytogenes. All the isolates belonged to serogroup 4b, and were + ve for virulence genes tested i.e. inlA, inlC, inlJ, plcA, prfA, actA, hlyA, and iap. Based on the mice inoculation tests, 20 isolates showed 100% and 4 isolates 60% relative virulence while 6 isolates were non-pathogenic. Moreover, 2 and 10 isolates were resistant to ciprofloxacin and cefoxitin, respectively, while the rest susceptible to other antibiotics used in this study. ERIC- and REP-PCR collectively depicted that the isolates from placental bit and vaginal swab had distinct PCR fingerprints except a few isolates with identical patterns. This study demonstrates prevalence of pathogenic strains mostly resistant to cefoxitin and/or ciprofloxacin. The results indicate the importance of isolating and characterizing the pathogen from human clinical samples as the pre-requisite for accurate epidemiological investigations. © 2015, The Microbiological Society of Korea and Springer-Verlag Berlin Heidelberg.
Virulence and genotypic characterization of Listeria monocytogenes isolated from vegetable and soil samples
(BioMed Central Ltd., 2014) Dharmendra Kumar Soni; Major Singh; Durg Vijai Singh; Suresh Kumar Dubey
Background: Listeria monocytogenes, a foodborne pathogen is ubiquitous to different environments including the agroecosystem. The organism poses serious public health problem. Therefore, an attempt has been made to gain further insight to their antibiotic susceptibility, serotypes and the virulence genes. Results: Out of the 10 vegetables selected, 6 (brinjal, cauliflower, dolichos-bean, tomato, chappan-kaddu and chilli), 20 isolates (10%) tested positive for L. monocytogenes. The prevalence of the pathogen in the respective rhizosphere soil samples was 5%. Noticeably, L. monocytogenes was absent from only cabbage, broccoli, palak and cowpea, and also the respective rhizospheric soils. The 30 isolates + ve for pathogenicity, belonged to serogroup 4b, 4d or 4e, and all were positive for inlA, inlC, inlJ, plcA, prfA, actA, hlyA and iap gene except one (VC3) among the vegetable isolates that lacked the plcA gene. ERIC- and REP-PCR collectively revealed that isolates from vegetables and their respective rhizospheric soils had distinct PCR fingerprints. Conclusions: The study demonstrates the prevalence of pathogenic L. monocytogenes in the selected agricultural farm samples. The increase in the number of strains resistant to ciprofloxacin and/or cefoxitin seems to pose serious public health consequences. © 2014 Soni et al.; licensee BioMed Central Ltd.