Mutation of conserved histidine residues of dengue virus envelope protein impairs viral like particle maturation and secretion.

Dengue virus (DENV) envelope protein plays crucial role in virus entry and maturation of virus during infection. Maturation of DENV occurs in the trans Golgi network at slightly acidic pH which is close to pKa of histidine. When exposed to the acidic environment of the late secretory pathway, dengue virus particles go through a significant conformational change, whereby interactions of structural proteins envelope (E) and prM proteins are reorganised and enable furin protease to cleave prM resulting in mature virus. In order to study the role of histidine of E protein in DENV maturation, we mutated 7 conserved histidine residues of envelope protein and assessed the percent of budding using viral like particle (VLP) system. Histidine mutants; H144A, H244A, H261A and H282A severely disrupted VLP formation without any significant change in expression in cell and its oligomerization ability. Treatment with acidotropic amine reversed the defect for all 4 mutants suggesting that these histidines could be involved in maturation and release. Over expression of capsid protein slightly enhanced VLP release of H244A and H261A. Similarly, furin over expression increased VLP release of these mutants. Co-immunoprecipitation studies revealed that prM and E interaction is lost for H244A, H261A and H282A mutants at acidic pH but not at neutral pH indicating that they could be involved in histidine switch during maturation at acidic pH. Detailed analysis of the mutants could provide novel insights on the interplay of envelop protein during maturation and aid in target for drug development.

Guidance for the use and interpretation of assays for monitoring anti-genotoxicity.

Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.

Antiviral Potential of Traditional Unani Medicine with Special Emphasis on Dengue: A Review.

Dengue fever has become a major public health concern. It is usually related to intravascular leaking, bleeding disorders, and thrombocytopenia and is recognized as a potent threat to humans. The scarcity of anti-dengue medication or vaccine for such a serious disease leads to an upsurge in the usage of traditional medicines for its proper management. India has diverse biodiversity and a long history of using plant-based remedies. Several medicinal plant extracts have been studied for producing anti-dengue viral activity. AYUSH traditional systems provide a plethora of plants that have been reported to be useful in the treatment of fever. Single and compound plant- based formulations in natural form have been used in Unani holistic approaches. This review serves as a new approach to illustrate the most recent evidence regarding the antiviral activity of various plants by providing scientific proof and also to validate the traditional formulations as effective treatments in dengue fever for global acceptance.

Amelioration of cyclophosphamide-induced DNA damage, oxidative stress, and hepato- and neurotoxicity by Piper longum extract in rats: The role of γH2AX and 8-OHdG.

Background: The identification of genoprotectants is a promising strategy for improving human health. Piper longum has drawn scientific attention because of its diverse biological effects and traditional utilization. The current investigation aims to evaluate the genome-stabilizing potential of Piper longum against cyclophosphamide-associated genotoxicity. Methods: We adopted a funnel screening with a three-tier evaluation approach, where Piper longum was investigated in an acellular medium, peripheral blood lymphocytes, and a rodent model. The genoprotective action of the Piper longum extract was initially performed with plasmid pBluescript SK(-) DNA. Furthermore, the extract and various fractions were screened against cyclophosphamide-induced genotoxicity using a cytokinesis-block micronucleus assay and a chromosomal aberration assay in human peripheral blood lymphocytes. The genome-stabilizing action of the extract and potent (hexane) fraction was further confirmed in vivo in Wistar albino rats by evaluating them using mammalian erythrocyte micronucleus tests, DNA fragmentation, oxidative stress markers, 8-hydroxy-2-deoxyguanosine (8-OHdG), γH2AX, and histopathological lesions in the liver and hippocampus. Additionally, acute and sub-acute toxicity studies were conducted following the Organization for Economic Co-operation and Development (OECD) guidelines for rats. Furthermore, the extract was quantified and characterized by high-performance thin-layer chromatography (HPTLC), ultra-high performance liquid chromatography-mass spectroscopy (UPLC-MS), and gas chromatography-mass spectrometry (GC-MS). Results: The Piper longum ethanol extract was shown to protect plasmid pBluescript SK(-) DNA against H2O2-induced strand breaks. In human lymphocytes, the extract and hexane fraction showed a reduction in micronucleus formation (p < 0.001) and chromosomal aberrations (p < 0.01) against cyclophosphamide. Furthermore, the extract and fraction treatment, when administered at 200 mg/kg for 28 days in Wistar rats, restored cyclophosphamide-induced genomic instability by reducing micronucleus formation and DNA fragmentation; restoring redox homeostasis; decreasing 8-OHdG, a hallmark of oxidative DNA damage; reducing γH2AX, a DNA double-strand break (DSB) marker; and preserving the liver and hippocampus against histopathological lesions. The extract and fraction revealed no signs of systemic toxicity at the used doses. Piperine and piperlongumine are the major alkaloids quantified along with the presence of flavonoids in the ethanol extract and the presence of fatty acids and terpenoids in the hexane fraction of Piper longum. Conclusion: Our investigation confirms the genoprotective action of Piper longum by reducing cyclophosphamide-associated cytogenotoxicity, oxidative stress, hepato- and neurotoxicity, oxidative DNA damage, and DNA double-strand breaks. The outcomes are critical for mitigating the genotoxic effects of chemotherapy recipients, requiring further attention.

Efficient generation and characterization of chimeric dengue viral-like particles.

Viral-like particles (VLPs) because of their non-infectious and high immunogenic properties have important applications in diagnostics, drug delivery, and vaccine production. They also serve as an attractive model system to study virus assembly and fusion processes. Unlike other flaviviruses, Dengue virus (DENV) is not very efficient in the production of VLPs on the expression of DENV structural proteins. On the other hand, the stem region and transmembrane region (TM) of G protein of Vesicular Stomatitis virus (VSV) alone are sufficient for budding. Here we generated chimeric VLPs replacing regions of stem and transmembrane domain (STEM) or only transmembrane domain (TM) of E protein of DENV-2 with corresponding regions of VSV G protein. Both chimeric proteins secreted VLPs at higher levels than the wild type (2-4 folds) without any significant change in the expression in the cell. Chimeric VLPs could be recognized by a conformational monoclonal antibody, 4G2. They were also found to interact with dengue-infected patient sera effectively thus implying that their antigenic determinants are preserved. In addition, they were able to bind to its putative receptor, heparin with similar affinity as the parent counterpart thus retaining its functional property. However, cell-cell fusion revealed that there is no significant increase in the fusion ability of chimeras as compared to the parent clone, whereas VSV G protein displayed high cell-cell fusion activity. Overall, this study suggests that chimeric dengue VLPs can be taken forward for their likely potential as vaccine production and serodiagnosis.

In silico analysis reveals hypoxia-induced miR-210-3p specifically targets SARS-CoV-2 RNA.

Human coronaviruses (HCoVs) until the emergence of SARS in 2003 were associated with mild cold and upper respiratory tract infections. The ongoing pandemic caused by SARS-CoV-2 has enhanced the potential for infection and transmission as compared to other known members of this family. MicroRNAs (miRNA) are 21-25 nucleotides long non-coding RNA that bind to 3' UTR of genes and regulate almost every aspect of cellular function. Several human miRNAs have been known to target viral genomes, mostly to downregulate their expression and sometimes to upregulate also. In some cases, host miRNAs could be sequestered by the viral genome to create a condition for favourable virus existence. The ongoing SARS CoV-2 pandemic is unique based on its transmissibility and severity and we hypothesised that there could be a unique mechanism for its pathogenesis. In this study, we exploited in silico approach to identify human respiratory system-specific miRNAs targeting the viral genome of three highly pathogenic HCoVs (SARS-CoV-2 Wuhan strain, SARS-CoV, and MERS-CoV) and three low pathogenic HCoVs (OC43, NL63, and HKU1). We identified ten common microRNAs that target all HCoVs studied here. In addition, we identified unique miRNAs which targeted specifically one particular HCoV. miR-210-3p was the single unique lung-specific miRNA, which was found to target the NSP3, NSP4, and NSP13 genes of SARS-CoV-2. Further miR-210-NSP3, miR-210-NSP4, and miR-210-NSP13 SARS-CoV-2 duplexes were docked with the hAGO2 protein (PDB ID 4F3T) which showed Z-score values of -1.9, -1.7, and -1.6, respectively. The role of miR-210-3p as master hypoxia regulator and inflammation regulation may be important for SARS-CoV-2 pathogenesis. Overall, this analysis advocates that miR-210-3p be investigated experimentally in SARS-CoV-2 infection.Communicated by Ramaswamy H. Sarma.

Interaction of novel proteins, centrin4 and protein of centriole in Leishmania parasite and their effects on the parasite growth.

Centrins are cytoskeletal proteins associated with the centrosomes or basal bodies in the eukaryotes. We previously reported the involvement of Centrin 1-3 proteins in cell division in the protozoan parasites Leishmania donovani and Trypanosoma brucei. Centrin4 and 5, unique to such parasites, had never been characterized in Leishmania parasite. In the current study, we addressed the function of centrin4 (LdCen4) in Leishmania. By dominant-negative study, the episomal expression of C-terminal truncated LdCen4 in the parasite reduced the parasite growth. LdCen4 double allele gene deletion by either homologous recombination or CRISPR-Cas9 was not successful in L. donovani. However, CRISPR-Cas9-based deletion of the homologous gene was possible in L. mexicana, which attenuated the parasite growth in vitro, but not ex vivo in the macrophages. LdCen4 also interacts with endogenous and overexpressed LdPOC protein, a homolog of centrin reacting human POC (protein of centriole) in a calcium sensitive manner. LdCen4 and LdPOC binding has also been confirmed through in silico analysis by protein structural docking and validated by co-immunoprecipitation. By immunofluorescence studies, we found that both the proteins share a common localization at the basal bodies. Thus, for the first time, this article describes novel centrin4 and its binding protein in the protozoan parasites.

Altered hallmarks of DNA double-strand breaks, oxidative DNA damage and cytogenotoxicity by piperlongumine in hippocampus and hepatocytes of rats intoxicated with cyclophosphamide.

AIM: Cyclophosphamide is an effective anti-tumor agent, however, it induces genomic instability and tissue toxicity in clinical application. This study aims to evaluate the action of piperlongumine against cyclophosphamide-induced toxicity. MAIN METHODS: The action was investigated in rodent model of genomic instability, where piperlongumine (50 mg/kg) was orally co-administered with cyclophosphamide (5 mg/kg) for 28 days to Wistar albino rats. Further, piperlongumine was also examined for acute and sub-acute toxicity. KEY FINDINGS: Piperlongumine significantly reversed genotoxicity in high-proliferation tissue (bone marrow: p < 0.05) as well as in vital tissues (hippocampus: p < 0.01 and hepatocytes: p < 0.05), calculated as micronuclei formation and %DNA fragmentation. It also restored the redox homeostasis, counteracted the formation of oxidative DNA damage product and DNA double-strand break in vital tissues, indicated by reduction of 8-OHdG and γH2AX. TUNEL assay revealed that piperlongumine diminished the cyclophosphamide-associated apoptotic cell death in hippocampus as well as in liver tissue and conferred cytoprotection to the host. These findings were finally corroborated with the histopathological findings, where piperlongumine treatment restored the cellular viability of liver and hippocampus. Further, piperlongumine did not produce any toxic effects to rats in systemic toxicity studies. SIGNIFICANCE: Piperlongumine possesses genome stabilizing effect and reduces cyclophosphamide-associated DNA damage, oxidative stress, hepato-, and neurotoxicity, diminishes the DNA damage response pathway in the rat model, at the same time, conserves the micro-architectural details of liver and hippocampus. The findings are significant in terms of reducing genotoxic impact of chemotherapy-receiving patients.

Therapeutic Potential of Medicinal Plants against Dengue Infection: A Mechanistic Viewpoint.

Dengue is a tropical disease caused by the Dengue virus (DENV), a positive-sense, single stranded RNA virus of the family Flaviviridae, which is transmitted by Aedes mosquitoes. The occurrence of dengue has grown dramatically around the globe in recent decades, and it is rapidly becoming a global burden. Furthermore, all four DENV serotypes cocirculate and create a problematic hyperendemic situation. Characteristic symptoms range from being asymptomatic, dengue fever to life-threatening complications such as hemorrhagic fever and shock. Apart from the inherent virulence of the virus strain, a dysregulated host immune response makes the condition worse. Currently, there is no highly recommended vaccine or therapeutic agent against dengue. With the advent of virus strains resistant to antiviral agents, there is a constant need for new therapies to be developed. Since time immemorial, human civilization has utilized plants in traditional medicine to treat various diseases, including infectious viral diseases. With the advancement in molecular biology, cell biology techniques, and bioinformatics, recent studies have tried to provide scientific evidence and determine the mechanism of anti-dengue activity of various plant extracts and plant-derived agents. The current Review consolidates the studies on the last 20 years of in vitro and in vivo experiments on the ethnomedicinal plants used against the dengue virus. Several active phytoconstituents like quercetin, castanospermine, α-mangostin, schisandrin-A, hirsutin have been found to be promising to inhibition of all the four DENV serotypes. However, novel therapeutics need to be reassessed in relevant cells using high-throughput techniques. Further, in vivo dose optimization for the immunomodulatory and antiviral activity should be examined on a vast sample size. Such a Review should help take the knowledge forward, validate it, and use medicinal plants in different combinations targeting multiple stages of virus infection for more effective multipronged therapy against dengue infection.

Decrypting the interaction pattern of Piperlongumine with calf thymus DNA and dodecamer d(CGCGAATTCGCG)2 B-DNA: Biophysical and molecular docking analysis.

The mechanisms of interaction of DNA with pharmacological molecules are critical to understanding their therapeutic actions on physiological systems. Piperlongumine is widely studied for its anticancer potential. Multi-spectrometry, calorimetry and in silico studies were employed to study the interaction of piperlongumine and calf thymus DNA. UV-Vis spectroscopy illustrated a hyperchromic pattern in spectra of the calf thymus DNA-piperlongumine complex, while fluorescent quenching was observed in emission spectral studies. Competitive displacement assay demonstrated higher displacement and binding constant for DNA-rhodamine B complex by piperlongumine than DNA-methylene blue complex. Differential scanning calorimetry presented non-significant changes in melting temperature and molecular docking presented the precise interaction site of piperlongumine with calf thymus DNA at minor groove. Further, piperlongumine treatment did not result in pBluescript KS plasmid DNA cleavage as revealed from the DNA topology assay. All these experiments confirmed the binding of piperlongumine with DNA through minor groove binding mode.

Pharmacotherapy for SARS-CoV-2 and Seizures for Drug Repurposing Presumed on Mechanistic Targets.

The currently circulating novel SARS-CoV-2 coronavirus disease (COVID-19) has brought the whole world to a standstill. Recent studies have deciphered the viral genome structure, epidemiology and are in the process of unveiling multiple mechanisms of pathogenesis. Apart from atypical pneumonia and lung disease manifestations, this disease has also been found to be associated with neurological symptoms, which include dizziness, headache, stroke, or seizures, among others. However, a possible direct or indirect association between SARS-CoV-2 and seizures is still not clear. In any manner, it may be of interest to analyze the drugs being used for viral infection in the background of epilepsy or vice versa. To identify the most credible drug candidate for COVID-19 in persons with epilepsy or COVID-19 patients experiencing seizures. A literature search for original and review articles was performed, and further, the Comparative Toxicogenomics Database was used to unearth the most credible drug candidate. Our search based on common mechanistic targets affecting SARS-CoV-2 and seizures revealed ivermectin, dexamethasone, anakinra, and tocilizumab for protection against both COVID-19 and seizures. Amongst the antiseizure medications, we found valproic acid as the most probable pharmacotherapy for COVID-19 patients experiencing seizures. These findings would hopefully provide the basis for initiating further studies on the pathogenesis and drug targeting strategies for this emerging infection accompanied with seizures or in people with epilepsy.

Potential nephroprotective phytochemicals: Mechanism and future prospects.

ETHNOPHARMACOLOGICAL RELEVANCE: Kidney disease (KD) is one of the serious health issues, which causes worrisome morbidity and economic burden. Therapeutic strategies are available however majority of them are associated with severe adverse effects and poor patient compliance and adherence. This explorative article was undertaken to provide a holistic review of known nephroprotective (NP) phytoconstituents along with their research-based evidences on mechanism, sources, and clinical trials that may play essential role in prevention and cure of KD. AIM OF THE STUDY: The present systematic review aimed to provide in-depth and better evidences of the global burden of KD, phytoconstituents as NP with emphasis on mechanism of action both in vitro and in vivo, their wide biological sources as well as their clinical efficacy in management of kidney disease and its related disorders. MATERIAL AND METHODS: Comprehensive information was searched systematically from electronic databases, namely, PubMed, Sciencedirect, Wiley, Scopus, Google scholar and Springer until February 2021 to find relevant data for publication on phytoconstituents with nephroprotective potential. RESULTS: In total, 24,327 articles were screened in first search for "phytoconstituents and medicinal plants for nephroprotection and kidney disorder". On the basis of exclusion and inclusion criteria, 24,091 were excluded. Only 236 papers were spotted to have superlative quality data, which is appropriate under titles and sub-titles of the present review. The phytoconstituents having multiple research evidence along with wide number of medicinal plants sources and mechanism reported for nephroprotection have been selected and reviewed. CONCLUSION: This review, based on pre-clinical and clinical data of NP phytoconstituents, provides scientific-basis for the rational discovery, development and utilization of these upcoming treatment practices. Further,-more clinical studies are warranted to improve the pharmacodynamic and pharmacokinetic understanding of phytoconstituents. Also, more specific evaluation for natural sources is needed.

Multi-Targeted Molecular Docking, Pharmacokinetics, and Drug-Likeness Evaluation of Okra-Derived Ligand Abscisic Acid Targeting Signaling Proteins Involved in the Development of Diabetes.

Diabetes mellitus is a global threat affecting millions of people of different age groups. In recent years, the development of naturally derived anti-diabetic agents has gained popularity. Okra is a common vegetable containing important bioactive components such as abscisic acid (ABA). ABA, a phytohormone, has been shown to elicit potent anti-diabetic effects in mouse models. Keeping its anti-diabetic potential in mind, in silico study was performed to explore its role in inhibiting proteins relevant to diabetes mellitus- 11ß-hydroxysteroid dehydrogenase (11ß-HSD1), aldose reductase, glucokinase, glutamine-fructose-6-phosphate amidotransferase (GFAT), peroxisome proliferator-activated receptor-gamma (PPAR-gamma), and Sirtuin family of NAD(+)-dependent protein deacetylases 6 (SIRT6). A comparative study of the ABA-protein docked complex with already known inhibitors of these proteins relevant to diabetes was compared to explore the inhibitory potential. Calculation of molecular binding energy (ΔG), inhibition constant (pKi), and prediction of pharmacokinetics and pharmacodynamics properties were performed. The molecular docking investigation of ABA with 11-HSD1, GFAT, PPAR-gamma, and SIRT6 revealed considerably low binding energy (ΔG from -8.1 to -7.3 Kcal/mol) and predicted inhibition constant (pKi from 6.01 to 5.21 µM). The ADMET study revealed that ABA is a promising drug candidate without any hazardous effect following all current drug-likeness guidelines such as Lipinski, Ghose, Veber, Egan, and Muegge.

Cyclic di-AMP: Small molecule with big roles in bacteria.

Cyclic dinucleotides are second messengers that are present in all the three domains of life, bacteria, archaea, and eukaryotes. These dinucleotides have important physiological and pathophysiological roles in bacteria. Cyclic di-AMP (cdA) is one of the recently discovered cyclic dinucleotides present predominantly in gram-positive bacteria. cdA is synthesized through diadenylate cyclase (DAC) activity from ATP in a two-step process and hydrolyzed to linear dinucleotide pApA (and to 5' AMP in certain cases) by specific phosphodiesterases. cdA regulates various physiological processes like K+ transport and osmotic balance, DNA repair, cell wall homeostasis, drug resistance, central metabolism either by binding directly to the target protein or regulating its expression. It also participates in host-pathogen interaction by binding to host immune receptors ERAdP, RECON, and STING.

A bioinformatics approach to investigate serum and hematopoietic cell-specific therapeutic microRNAs targeting the 3' UTRs of all four Dengue virus serotypes.

Hyperendemic circulation of all four Dengue virus (DENV) serotypes is a severe global public health problem, so any vaccine or therapeutics should be able to target all four of them. Cells of hemopoietic origin are believed to be primary sites of DENV replication. This study aimed to identify potential host miRNAs that target 3' UTR of all four DENV serotypes, thereby directly regulating viral gene expression or indirectly modulating the host system at different virus infection steps. We used four prediction algorithms viz. miRanda, RNA22, RNAhybrid and StarMir for predicting miRNA, targeting 3'UTR of all four DENV serotypes. Statistically, the most significant miRNA targets were screened based on their Log10 P-value (> 0.0001) of Gene Ontology (GO) term and Kyoto Encyclopaedia of Gene and Genome (KEGG) pathway enrichment analysis. The intersection test of at least three prediction tools identified a total of 30 miRNAs, which could bind to 3'UTR of all four DENV serotypes. Of the 30, eight miRNAs were of hematopoietic cell origin. GO term enrichment and KEGG analysis showed four hemopoietic origin miRNAs target genes of the biological processes mainly involved in the innate immune response, mRNA 3'-end processing, antigen processing and presentation and nuclear-transcribed mRNA catabolic process.

High viral load positively correlates with thrombocytopenia and elevated haematocrit in dengue infected paediatric patients.

BACKGROUND: Dengue fever is one of the major viral diseases worldwide transmitted by mosquitoes. Depending on the severity of disease it can range from mild fever to severe fatal cases. Rapid decline of platelet levels is one of indicators of clinical worsening. The role of viral factors in dengue pathogenesis and correlation with clinical and laboratory parameters remain unclear. METHODS: Between September 2017 to December 2018, 102 dengue confirmed paediatric cases were analysed for various viral and host parameters. Based on symptoms, they were classified into dengue without warning signs (DOS), dengue with warning signs (DWS) and severe dengue (SD) as per 2009 WHO classification. Quantitative analysis of NS1, IgM and IgG in were done by ELISA. IgM/IgG ratio revealed primary or secondary dengue infection. Serotyping of virus in serum was done by nested multiplex RT-PCR. Viral load (VL) was determined by quantitative real time polymerase chain reaction. Association between VL and NS1 in patient sera with clinical and laboratory parameters was statistically analysed. RESULTS: It was found that disease severity (as per 2009 WHO classification) significantly associated with secondary dengue infection. DENV3 was found to be the only serotype detected. The present study reports neither NS1 nor VL significantly associated with disease severity or type of infection (primary or secondary). However, VL positively correlated with haematocrit (p < 0.05). Viral load above 106 copies/mL was found in 61% of patients. Further, high viral load (>106 copies/mL) negatively correlated with platelet levels (p < 0.05). CONCLUSION: Thus, viral load could be an important predictive parameter in dengue related severe symptoms like thrombocytopenia and elevated hematocrit when it goes above a certain threshold (>106 copies/ mL).

Differential binding of SARS-CoV-2 Spike protein variants to its cognate receptor hACE2 using molecular modeling based binding analysis.

The current emergence of novel coronavirus, SARS-CoV-2 and its ceaseless expansion worldwide has posed a global health emergency that has adversely affected the humans. With the entire world striving to understand the newly emerged virus, differences in morbidity and infection rate of SARS-CoV-2 have been observed across varied geographic areas, which have been ascribed to viral mutation and evolution over time. The homotrimeric Spike (S) glycoprotein on the viral envelope surface is responsible for binding, priming, and initiating infection in the host. Our phylogeny analysis of 1947 sequences of S proteins indicated there is a change in amino acid (aa) from aspartate (Group-A) to glycine (Group-B) at position 614, near the receptor- binding domain (RBD; aa positions 331-524). The two variants are reported to be in circulation, disproportionately across the world, with Group-A dominant in Asia and Group-B in North America. The trimeric, monomeric, and RBD of S protein of both the variant groups (A & B) were modeled using the Swiss-Model server and were docked with the human receptor angiotensin-converting enzyme 2 (hACE2) employing the PatchDock server and visualized in PyMol. Group-A S protein's RBD bound imperceptibly to the two binding clefts of the hACE2 protein, on the other hand, Group-B S protein's RBD perfectly interacted inside the binding clefts of hACE2, with higher number of hydrogen and hydrophobic interactions. This implies that the S protein's amino acid at position 614 near the core RBD influences its interaction with the cognate hACE2 receptor, which may induce its infectivity that should be explored further with molecular and biochemical studies.

A systematic review on Piper longum L.: Bridging traditional knowledge and pharmacological evidence for future translational research.

ETHNOPHARMACOLOGICAL RELEVANCE: Piper longum, commonly referred as 'Pippali', has found its traditional use in India, Malaysia, Singapore and other South Asian countries as an analgesic, carminative, anti-diarrhoeic, immunostimulant, post childbirth to check postpartum hemorrhage and to treat asthma, insomnia, dementia, epilepsy, diabetes, rheumatoid arthritis, asthma, spleen disorder, puerperal fever, leprosy etc. AIM OF THE REVIEW: This review offers essential data focusing on the traditional use, phytochemistry and pharmacological profile of Piper longum thereby identifying research gaps and future opportunities for investigation on this plant. MATERIALS AND METHODS: This systematic survey was accomplished as per the PRISMA guidelines. The information was collected from books, and electronic search (PubMed, Science Direct, Lilca and Scielo) during 1967-2019. RESULTS: Many phytochemicals have been identified till date, including alkaloids as its major secondary metabolites (piperine and piperlongumine), essential oil, flavonoids and steroids. These exhibit a wide range of activities including anti-inflammatory, analgesic, anti-oxidant, anti-microbial, anti-cancer, anti-parkinsonian, anti-stress, nootropic, anti-epileptic, anti-hyperglycemic, hepatoprotective, anti-hyperlipidemic, anti-platelet, anti-angiogenic, immunomodulatory, anti-arthritic, anti-ulcer, anti-asthmatic, anthelmintic action, anti-amebic, anti-fungal, mosquito larvicidal and anti-snake venom. CONCLUSION: Amongst various activities, bioscientific clarification in relation to its ethnopharmacological perspective has been evidenced mainly for anti-amebic, anthelminthic, anti-tumor and anti-diabetic activity. However, despite traditional claims, insufficient scientific validation for the treatment of insomnia, dementia, epilepsy, rheumatoid arthritis, asthma, spleen disorder, puerperal fever and leprosy, necessitate future investigations in this direction. It is also essential and critical to generate toxicological data and pharmacokinetics on human subjects so as to confirm its conceivable bio-active components in the body.

The second messenger cyclic di-AMP negatively regulates the expression of Mycobacterium smegmatis recA and attenuates DNA strand exchange through binding to the C-terminal motif of mycobacterial RecA proteins.

Cyclic di-GMP and cyclic di-AMP are second messengers produced by a wide variety of bacteria. They influence bacterial cell survival, biofilm formation, virulence and bacteria-host interactions. However, many of their cellular targets and biological effects are yet to be determined. A chemical proteomics approach revealed that Mycobacterium smegmatis RecA (MsRecA) possesses a high-affinity cyclic di-AMP binding activity. We further demonstrate that both cyclic di-AMP and cyclic di-GMP bind specifically to the C-terminal motif of MsRecA and Mycobacterium tuberculosis RecA (MtRecA). Escherichia coli RecA (EcRecA) was devoid of cyclic di-AMP binding but have cyclic di-GMP binding activity. Notably, cyclic di-AMP attenuates the DNA strand exchange promoted by MsRecA as well as MtRecA through the disassembly of RecA nucleoprotein filaments. However, the structure and DNA strand exchange activity of EcRecA nucleoprotein filaments remain largely unaffected. Furthermore, M. smegmatis ΔdisA cells were found to have undetectable RecA levels due to the translational repression of recA mRNA. Consequently, the ΔdisA mutant exhibited enhanced sensitivity to DNA-damaging agents. Altogether, this study points out the importance of sequence diversity among recA genes, the role(s) of cyclic di-AMP and reveals a new mode of negative regulation of recA gene expression, DNA repair and homologous recombination in mycobacteria.

Changing pattern of prevalence, genetic diversity, and mixed infections of viruses associated with acute gastroenteritis in pediatric patients in New Delhi, India.

There are very few studies that have assessed multiple viral agents causing Acute-Gastroenteritis (AGE) in India. The present study compared the changing pattern of prevalence and genetic diversity of five enteric viruses associated with acute-diarrhea in Delhi children within a gap of 5 years. Fecal samples were collected from diarrheal children (<4 years) during two winter seasons: year 2009-2010 (n = 59) and year 2014-2015 (n = 85). Samples were individually tested for rotavirus-A, norovirus, astrovirus, adenovirus, and sapovirus using EIA/RT-PCR and genetically characterized by phylogenetic analysis. Rotavirus was the most predominant (54.9%) virus followed by norovirus (25.7%), astrovirus (8.3%), and adenovirus (4.9%) with rare detection of sapovirus (0.7%). While detection rate increased for both rotavirus (49.2-58.8%) and astrovirus (5.1-10.6%), norovirus detection rate decreased (30.5-22.4%) from 2009 to 2015. During the same time period, adenovirus detection remained low (4.7-5.1%). Interestingly, mixed infections increased from 8.5% to 16.5% after 5 years. G1P[8] rotavirus strain was found most predominant (40%). Both type-1 and 8 astroviruses were detected. Single sapovirus detected was of genotype GII.1. Both GI (GI.5, GI.3) and GII (GII.1, GII.4, GII.7, GII.21, GII.13) genogroups of norovirus were detected. Of particular significance was the first detection of other NoV genotypes (besides GII.4 and GI.3) in Delhi. This is also the first report of NoV GI.5 from India. A change in prevalence pattern and increased diversity from 2009 to 2015 emphasizes the need for continued enteric virus surveillance to help measure the impact of new diarrhea vaccine(s) introduced in India.