Isolation and biological evaluation 7-hydroxy flavone from Avicennia officinalis L: insights from extensive in vitro, DFT, molecular docking and molecular dynamics simulation studies.

The flavonoid based 7-hydroxy flavone (PubChem CID: 5281894; molecular formula: C15H10O3) molecule has been isolated for the first time from the methanolic extract from the leaves of Avicennia officinalis L. in the tropical mangrove ecosystem of Andaman and Nicobar Islands (ANI), India. The molecular structure of bioactive compound was characterized by spectroscopic analysis, including FT-IR, 1H, 13C NMR spectroscopy and ESI-HRMS and elucidated as 7-hydroxy flavone. An anticancer activity of isolated 7-hydroxy flavone was evaluated by in vitro study against two different human cancer cell lines namely, HeLa (cervical cells) and MDA-MB231 (breast cells) and they exhibited promising anticancer activity with IC50 values are 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL, respectively. The antioxidant property of 7-hydroxy flavone at a standard concentration of 50 µg, was found to be (IC50) 5.5486 ± 0.81 µg/mL. In summary, this investigation provides evidence that 7-hydroxy flavone exhibits both anticancer and antioxidant properties. Meanwhile, the antimicrobial activity ability of 7-hydroxy flavone were also evaluated using three Gram positive and two Gram negative strain exhibited no antimicrobial activities. Density-functional theory (DFT) studies confirm the structure is global minima in the PES, from the optimized geometry FMO and MESP map analyzed. Further, the molecular docking and molecular dynamics simulation studies result shows that 7-hydroxy flavone has the better binding ability with anti-apoptotic Bcl-2 protein with the estimated free energy of binding of -6.3 kcal/mol. This bioactive compound may be act as drug candidate for treating various kinds of cancers. HighlightsA 7-hydroxy flavone molecule has been isolated from Avicennia officinalis.The isolated pure compound was subjected to spectral analysis such as FT-IR, 1H NMR, 13C NMR spectral data and HRMS analysis for skeleton of the molecule.The anticancer activity of 7-hydroxy flavone studied against Cervical (HeLa) cancer cell lines and breast (MDA-MB231) cancer cell lines with the IC50 values of 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL), respectively.The antioxidant properties of 7-hydroxy flavone were found to be (IC50) 5.5486 ± 0.81 µg/mL at a standard concentration of 50 µg.DFT, molecular docking and MD simulation results explained that 7-hydroxy flavone could be the most promising candidate to inhibit the function of anti-apoptotic Bcl-2 protein in cancerous cell.Communicated by Ramaswamy H. Sarma.

Isolation, characterisation, anticancer and anti-oxidant activities of 2-methoxy mucic acid from Rhizophora apiculata: an in vitro and in silico studies.

The main objective of the present study is to isolate and characterise the novel bioactive molecule, 2-methoxy mucic acid (4) from Rhizophora apiculate Blume under the Rhizophoraceae family. In this study, the 2-methoxy mucic acid (4) was isolated for the first time from the methanolic extract of the leaves of R. apiculata. Anticancer activity of 2-methoxy mucic acid (4) was evaluated against HeLa and MDA-MB-231 cancer cell lines and they displayed promising activity with IC50 values of 22.88283 ± 0.72 µg/ml in HeLa and 2.91925 ± 0.52 µg/ml in the case of MDA-MB-231, respectively. Furthermore, the antioxidant property of 2-methoxy mucic acid (4) was found to be (IC50) 21.361 ± 0.41 µg/ml. Apart from in vitro studies, we also performed extensive in silico studies (molecular docking and molecular dynamics simulation) on four critical antiapoptotic Bcl-2 family members (Bcl-2, Bcl-w, Bcl-xL and Bcl-B) towards 2-methoxy mucic acid (4). The results revealed that this molecule showed higher binding affinity towards Bcl-B protein (ΔG = -5.8 kcal/mol) and the structural stability of this protein was significantly improved upon binding of this molecule. The present study affords vital insights into the importance of 2-methoxy mucic acid (4) from R. apiculata. Furthermore, it opens the therapeutic route for the discovery of anticancer drugs. Research HighlightsThis is a first report on a bioactive compound identified and characterised; a novel 2-methoxy mucic acid derived from methanolic crude extract from the leaves of R. apiculata from ANI.Estimated binding free energy of 2-methoxy mucic acid is found to be -5.8 kcal/mol to the anti-apoptotic Bcl-B protein.2-methoxy mucic acid showed both significant anti-cancer and anti-oxidant activity.Communicated by Ramaswamy H. Sarma.

Biological evaluation of gallic acid and quercetin derived from Ceriops tagal: insights from extensive in vitro and in silico studies.

Gallic acid (PubChem CID: 370) and quercetin (PubChem CID: 5280343) are major phenolic compounds in many mangrove plants that have been related to health cure. In the present study, the active fractions namely gallic acid (1) and quercetin (2) were isolated from the methanolic extract of leaves of Ceriops tagal in a Tropical mangrove ecosystem of Andaman and Nicobar Island (ANI), India. The chemical structures were determined by spectroscopic analysis: Fourier-Transform Infrared spectroscopy (FT-IR), 1H, 13C Nuclear Magnetic Resonance (NMR) spectroscopy, and High-resolution mass spectrometry (HRMS). The anticancer activity of isolated compounds (1) and (2) were evaluated by in vitro assays against two human cancer cell lines namely, HeLa (Cervical) and MDA-MB231 (Breast) cancer cells revealed that IC50 values of gallic acid (HeLa: 4.179197 ± 0.45 µg/ml; MDA-MB231: 80.0427 ± 0.19 µg/ml at 24 h) and quercetin (HeLa: 99.914 ± 0.18 µg/ml; MDA-MB231: 18.288382 ± 0.12 µg/ml at 24 h), respectively. Antioxidant properties of gallic acid (1) and quercetin (2) are found to be IC50 value of 0.77 ± 0.41 µg/ml and 1.897 ± 0.81 µg/ml, respectively. Molecular docking results explained that gallic acid (1) and quercetin (2) showed estimated binding free energy (ΔG) of -5.4 and -6.9 kcal/mol towards drug target Bcl-B protein, respectively. The estimated inhibition constant (Ki) for these two molecules are 110 and 8.75 µM, respectively. The MD simulation additionally supported that quercetin molecule is significantly improved the structural stability of Bcl-B protein. The present study provides key insights about the importance of polyphenols, and thus leads to open the therapeutic route for anti-cancer drug discovery process.Communicated by Ramaswamy H. Sarma.

A comprehensive in silico and in vitro studies on quinizarin: a promising phytochemical derived from Rhizophora mucronata Lam.

Mangrove plants are a great source of phytomedicines, since from the beginning of human civilization and the origin of traditional medicines. In the present study, ten different mangrove leaf methanolic extracts were screened for the type of phytochemicals followed by assessing antimicrobial, anti-oxidant and anti-cancer activities. The efficient methanolic crude extract of Rhizospora mucornata was further purified and characterized for the presence of the bioactive compound. Based on UV-visible spectroscopy, FTIR, NMR and HRMS analysis, the bioactive compound was 1,4-dihydroanthraquinone; also termed as Quinizarin. This identified compound was potential in exhibiting antimicrobial, antioxidant, and cytotoxic activity. Quinizarin inhibited the growth of Bacillus cereus and Klebsiella aerogenes with minimum inhibitory concentration (MIC) of 0.78 and 1.5 mg/ml. The DPPH free radical scavenging assay revealed the maximum activity of 99.8% at the concentration of 200 µg/ml with an IC50 value of 12.67 ± 0.41 µg/ml. Cytotoxic assay against HeLa (cervical) and MDA-MB231(breast) cancer cell lines revealed IC50 values to be 4.60 ± 0.26 and 3.89 ± 0.15 µg/ml. Together the results of molecular docking and molecular dynamics simulation studies explained that Quinizarin molecule showed stronger binding affinity (-6.2 kcal/mol) and significant structural stability towards anti-apoptotic Bcl-2 protein. Thus, the study put forth the promising role of the natural molecule - Quinizarin isolated from R. mucornata in the formulation of therapeutic drugs against bacterial infections and cancer. Communicated by Ramaswamy H. Sarma.

Evaluating the Clinical Risk Factors Associated With Miscarriages in Women in Karachi, Pakistan.

Introduction Spontaneous pregnancy loss is unquestionably common worldwide, with roughly 5% of pregnancies ending in this way. Miscarriage can lead to serious psychological issues for women as well as their mothers. Although, it is irreversible but can be prevented through proper risk assessment of women. The goal of this study is to find clinical predictors of miscarriages in Karachi, Pakistani women. Methodology The study is a retrospective chart review that used data of women having livebirth and miscarriages at the Liaquat National Hospital Karachi Pakistan. Data of a total of 517 women were included in the study, out of which 453 have had a live birth, and 64 had miscarriages. To determine the factors associated with miscarriages, multivariable logistic regression was used.  Results The mean age of women was 31.08 (±5.10) years. Age of mother over 40 years (adjusted odds ratio [AOR]=10.28; p-value=0.001), overweight and obesity (AOR=3.01; p-value=0.001) and history of miscarriage (AOR=2.91; p-value=0.003) are variables significantly associated with miscarriages. Conclusion Findings of the current study shown that risk factors of miscarriages included age of mother, increased BMI and previous history of miscarriages. All these factors need to be considered while providing antenatal care to mothers to mitigate the risk of miscarriages.

Effect of RGO-Y2O3 and RGO-Y2O3:Cr3+ nanocomposite sensor for dopamine.

The RGO-Y2O3 and RGO-Y2O3: Cr3+ (5 mol %) nanocomposite (NC) synthesized by hydrothermal technique. The structure and morphology of the synthesized NCs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Y2O3:Cr3+ displays spherical-shaped particles. Conversely, the surface of the RGO displays a wrinkly texture connecting with the existence of flexible and ultrathin graphene sheets. The photoluminescence (PL) emission spectra showed series of sharp peaks at 490, 591, and 687 nm which corresponding to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, and 4F9/2 → 6H11/2 transitions and lies in the blue, orange, and red region. The prepared NCs were used for the preparation of modified carbon paste electrodes (MCPE) in the electrochemical detection of dopamine (DA) at pH 7.4. Both modified electrodes provide a good current response towards voltammetric detection of DA. Doping is an effective method to improve the conductivity of Y2O3:Cr3+ and developed a method for the sensor used in analytical applications.

Left Ventricular Assist Device Therapy and Acute Pancreatitis: Higher Incidence and Worse Clinical Outcomes.

OBJECTIVE: The aim of the study was to compare incidence and outcomes of acute pancreatitis among advanced heart failure therapies. METHODS: Two retrospective cohorts are as follows: A, patients with heart failure presenting to our hospitals and B, the US National Inpatient Sample. Three groups were compared: left ventricular assist device (LVAD) recipients, transplant recipients, and controls who did not qualify for advanced therapies. Primary outcomes were pancreatitis incidence and mortality. Secondary outcomes included kidney failure, multiorgan failure, shock, and health care utilization. RESULTS: Cohort A included 1344 heart failure patients, and cohort B included 677,905 patients with acute pancreatitis. In cohort A, annual pancreatitis incidence was 6.7 cases per 1000 LVAD recipients, 4.1 per 1000 LVAD bridge-to-transplant, 2.3 per 1000 transplant recipients, and 3.2 per 1000 heart failure controls (P = 0.03). Combined, the incidence was 5.6 per 1000 LVAD users and 2.7 in 1000 non-LVAD users (relative risk, 2.1; P = 0.009). In cohort B, increased mortality was seen in LVAD users, but not in transplant recipients. Left ventricular assist device patients had higher odds of kidney failure, multiorgan failure, shock, and intensive care. CONCLUSIONS: Patients with LVAD have double risk of pancreatitis, worse clinical outcomes, and increased healthcare utilization. Studies elucidating the mechanisms behind pancreatic injury in advanced heart failure are suggested.

Microbial diversity from the continental shelf regions of the Eastern Arabian Sea: A metagenomic approach.

The marine microbiome is a complex and least-understood habitat, which play a significant role in global biogeochemical cycles. The present study reported the culture-independent assessment of microbial diversity from the Arabian Sea (AS) sediments (from Gujarat to Malabar; at 30 m depth) by using metagenome sequence analysis. Our results elucidated that bacterial communities in the Malabar coastal region are highly diverse than the Gujarat coast. Moreover, Statistical analysis (Spearman rank correlation) showed a significant correlation co-efficient value (r = P < 0.001) between microbial communities and physicochemical parameters (salinity and dissolved oxygen) in the water column. A total of 39 bacterial phyla were recorded from the eastern side of AS, of which six phyla Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria, Firmicutes, and Planctomycetes were found to be the most dominant group. The most dominant genus from Valapad region (Malabar Coast) was found to be Halomonas sp., while other regions were dominated with Psychrobacter pulmonis. The subsequent Principal Coordinate Analysis (PCoA) showed 99.53% variance, which suggests that, highly distinct microbial communities at Valapad (Malabar Coast) sampling location than other sites. Moreover, the microbial metabolic activity analysis revealed the important functions of microbial communities in the AS are hydrocarbon degradation, polymer degradation, nutrient oxidation and sulphate reduction (biodegradation process). Further extended studies are needed to be carried out for better understanding the functional diversity of microbial communities from the marine sediments.

A Review on Antidiabetic Properties of Indian Mangrove Plants with Reference to Island Ecosystem.

Mangrove ecosystem has many potential species that are traditionally used by the coastal communities for their traditional cure for health ailments as evidenced by their extensive uses to treat hepatic disorders, diabetes, gastrointestinal disorders, anti-inflammation, anticancer, and skin diseases, etc. In recent times, the diabetes mellitus (DM), a serious physiological disorder all over the world, occur due to the relative or complete deficiency of insulin in the body, characterized by an abnormally high blood glucose level. India has a rich traditional knowledge on plant-based drug formulations that are protective and curative for many health ailments. In this context, we aimed to compile the works done on the antidiabetic activities of mangrove species from Indian coastal regions especially on Andaman and Nicobar Islands as well as some recent works reported from other countries. A total of 126 published articles and 31 mangrove species related pieces of information were gathered with reference to antidiabetic properties of mangroves. This review summarizes the chemical structures, molecular formula, molecular weight, and their biological activities with an aspiration that it might be helpful for the future bioprospecting industries who are interested in develop the natural drugs for DM.

Novel T-C@AgNPs mediated biocidal mechanism against biofilm associated methicillin-resistant Staphylococcus aureus (Bap-MRSA) 090, cytotoxicity and its molecular docking studies.

Staphylococcus aureus is a commonly found pathogen that can cause food-spoilage and life threatening infections. However, the potential molecular effects of natural active thymol molecules and chitosan silver nanoparticles (C@AgNPs) in bacteria remain unclear. This gap in the literature has prompted us to study the effects of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) against biofilm associated proteins in methicillin-resistant S. aureus (Bap-MRSA) 090 and also their toxicity, anti-cancer activity, and validation of their in silico molecular docking. The results showed excellent antibacterial activity of T-C@AgNPs against Bap-MRSA 090, having a minimum inhibitory concentration of 100 µg mL-1 and a 10.08 ± 0.06 mm zone of inhibition (ZOI). The cyclic voltammogram (CV) analysis clearly showed pore forming of T-C@AgNPs at 300 µg mL-1 concentration, and evidence of the interruption of the electron transport chain was clearly seen. The 200 µg mL-1 concentration exhibited a 52.60 ± 0.25% anti-biofilm property by T-C@AgNPs against Bap-MRSA 090. The T-C@AgNPs showed no toxicity to peripheral blood mononuclear cells (PBMC) (IC50 = 221 ± 0.71 µg mL-1) compared to the control, and anti-cancer activity against human triple negative breast cancer cell line (MDA-MB-231) (IC50 110 ± 1.0 µg mL-1) compared to the standard drug Doxorubicin (IC50 = 19 ± 1.0). The excellent properties of T-C@AgNPs were validated by in silico molecular docking studies and showed best match scoring to target proteins compared to standards. These excellent properties of T-C@AgNPs highlight for the first time its pharmacology and potential in medicinal drug development applications for future research.

Anticancer potential of pyrrole (1, 2, a) pyrazine 1, 4, dione, hexahydro 3-(2-methyl propyl) (PPDHMP) extracted from a new marine bacterium, Staphylococcus sp. strain MB30.

Marine bacterium, strain MB30 isolated from the deep sea sediment of Bay of Bengal, India, exhibited antimicrobial activity against human pathogenic bacteria. Based on the 16S rRNA sequence homology and subsequent phylogenetic tree analysis, the strain MB30 was identified as Staphylococcus sp. The bioactive metabolite produced by the strain MB30 was purified through silica gel column chromatography and preparative HPLC. Purified metabolite was further characterized by FT-IR, LC-MS and NMR analyses. On the basis of spectroscopic data, the metabolite was identified as pyrrole (1, 2, a) pyrazine 1, 4, dione, hexahydro 3-(2-methyl propyl) (PPDHMP). The PPDHMP exhibited in vitro anticancer potential against lung (A549) and cervical (HeLa) cancer cells in a dose-dependent manner with the IC50 concentration of 19.94 ± 1.23 and 16.73 ± 1.78 µg ml(-1) respectively. The acridine orange (AO)/ethidium bromide (EB) and 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining of the IC50 concentration of PPDHMP-treated cancer cells exhibited an array of morphological changes such as nuclear condensation, cell shrinkage and formation of apoptotic bodies. The PPDHMP-treated cancer cells induced the progressive accumulation of fragmented DNA in a time-dependent manner. Based on the flow cytometric analysis, it has become evident that the compound was also effective in arresting the cell cycle at G1 phase. Further, the Western blotting analysis confirmed the down-regulation of cyclin-D1, cyclin dependent kinase (CDK-2), anti-apoptotic Bcl-2 family proteins (Bcl-2 and Bcl-xL), activation of caspase-9 and 3 with the cleavage of PARP. The PPDHMP-treated cancer cells also showed the inhibition of migration and invasive capacity of cancer cells. In the present investigation, for the first time, we have reported the extraction, purification and characterization of an anticancer metabolite, PPDHMP from a new marine bacterium, Staphylococcus sp. strain MB30.

Biosynthesis of silver nanoparticles using the extract of Alternanthera sessilis-antiproliferative effect against prostate cancer cells.

Green synthesis of silver nanoparticles was carried out using the aqueous extract of Alternanthera sessilis under various experimental conditions. The aqueous extract of Alternanthera sessilis showed significant potential for the quick reduction of silver ions. The synthesized silver nanoparticles were characterized with UV-visible absorption spectrophotometer, XRD, SEM, and FTIR analysis. The average crystallite size as calculated from x-ray diffraction studies and SEM analysis was found to be less than 100 nm. The cytotoxic activity of synthesized nanosilver was carried out against prostate cancer cells (PC3) by MTT assay and found to show significant activity. The present work of biosynthesis of silver nanoparticles using Alternanthera sessilis appears to be cost effective, eco-friendly, and an alternative to conventional method of synthesis.

Larvicidal and pupicidal activity of extracts and fractionates of Eichhornia crassipes (Mart.) Solms against the filarial vector Culex quinquefasciatus Say.

Petroleum ether, acetone, ethyl acetate, aqueous extract, methanol and ethanol fractionate of Eichhornia crassipes (Mart.) Solms was tested for their larvicidal efficacy against the different instars (I, II, III and IV) and pupae of Culex quinquefasciatus Say. The larval mortality was observed after 24 h of the treatment. The extracts showed a dose-dependent toxicity to larvae. The toxicity of the extracts decreased with increase in larval stage. Ethanol fractionate of E. crassipes showed the highest larvicidal and pupicidal activity against C. quinquefasciatus compared to other solvent extracts and fractionates with LC(50) 71.43, 94.68,120.42, 152.15 and 173.35 ppm for I, II, III, IV and pupae, respectively. Presence of metabolites like flavonoids, alkaloids, anthroquinones and anthocyanins in the tested extracts might be the reason for the larvicidal and pupicidal activity of the plant extracts and fractionates of waterhyacinth. Mosquito-repellent activity was not exhibited by these extracts at the tested concentrations. The results demonstrated the potential of the aquatic plant E. crassipes in the successful control of the filarial vector C. quinquefasciatus.

Prevalence, conservation and functional analysis of Yersinia and Escherichia CRISPR regions in clinical Pseudomonas aeruginosa isolates.

Here, we report the characterization of 122 Pseudomonas aeruginosa clinical isolates from three distinct geographical locations: Dartmouth Hitchcock Medical Center in New Hampshire, USA, the Charles T. Campbell Eye Microbiology Lab at the University of Pittsburgh Medical Center, USA, and the Aravind Eye Hospital in Madurai, India. We identified and located clustered regularly interspaced short palindromic repeats (CRISPR) in 45/122 clinical isolates and sequenced these CRISPR, finding that Yersinia subtype CRISPR regions (33 %) were more prevalent than the Escherichia CRISPR region subtype (6 %) in these P. aeruginosa clinical isolates. Further, we observed 132 unique spacers from these 45 CRISPR that are 100 % identical to prophages or sequenced temperate bacteriophage capable of becoming prophages. Most intriguingly, all of these 132 viral spacers matched to temperate bacteriophage/prophages capable of inserting into the host chromosome, but not to extrachromosomally replicating lytic P. aeruginosa bacteriophage. We next assessed the ability of the more prevalent Yersinia subtype CRISPR regions to mediate resistance to bacteriophage infection or lysogeny by deleting the entire CRISPR region from sequenced strain UCBPP-PA14 and six clinical isolates. We found no change in CRISPR-mediated resistance to bacteriophage infection or lysogeny rate even for CRISPR with spacers 100 % identical to a region of the infecting bacteriophage. Lastly, to show these CRISPR and cas genes were expressed and functional, we demonstrated production of small CRISPR RNAs. This work provides both the first examination to our knowledge of CRISPR regions within clinical P. aeruginosa isolates and a collection of defined CRISPR-positive and -negative strains for further CRISPR and cas gene studies.

Extensive intracranial juvenile xanthogranulomas.

JXG is a disorder classified under histiocytosis. It usually affects children and commonly presents with skin lesions. Intracranial lesions are uncommon and usually solitary. We present the case of a child who had extensive intracranial involvement with multiple enhancing solid lesions in the cerebellum, brain stem, thalami, and bilateral cerebral hemispheres on MR imaging.

Prevalence, conservation and functional analysis of Yersinia and Escherichia CRISPR regions in clinical Pseudomonas aeruginosa isolates.

Here, we report the characterization of 122 Pseudomonas aeruginosa clinical isolates from three distinct geographical locations: Dartmouth Hitchcock Medical Center in New Hampshire, USA, the Charles T. Campbell Eye Microbiology Lab at the University of Pittsburgh Medical Center, USA, and the Aravind Eye Hospital in Madurai, India. We identified and located clustered regularly interspaced short palindromic repeats (CRISPR) in 45/122 clinical isolates and sequenced these CRISPR, finding that Yersinia subtype CRISPR regions (33 %) were more prevalent than the Escherichia CRISPR region subtype (6 %) in these P. aeruginosa clinical isolates. Further, we observed 132 unique spacers from these 45 CRISPR that are 100 % identical to prophages or sequenced temperate bacteriophage capable of becoming prophages. Most intriguingly, all of these 132 viral spacers matched to temperate bacteriophage/prophages capable of inserting into the host chromosome, but not to extrachromosomally replicating lytic P. aeruginosa bacteriophage. We next assessed the ability of the more prevalent Yersinia subtype CRISPR regions to mediate resistance to bacteriophage infection or lysogeny by deleting the entire CRISPR region from sequenced strain UCBPP-PA14 and six clinical isolates. We found no change in CRISPR-mediated resistance to bacteriophage infection or lysogeny rate even for CRISPR with spacers 100 % identical to a region of the infecting bacteriophage. Lastly, to show these CRISPR and cas genes were expressed and functional, we demonstrated production of small CRISPR RNAs. This work provides both the first examination to our knowledge of CRISPR regions within clinical P. aeruginosa isolates and a collection of defined CRISPR-positive and -negative strains for further CRISPR and cas gene studies.

Construction and characterization of an auxotrophic ctxA mutant of O139 Vibrio cholerae.

Cholera caused by the O139 serogroup still remains a public health concern in certain regions of the world and the existing O1 vaccines do not cross-protect cholera caused by this serogroup. An aminolevulinic acid (ALA) auxotroph vaccine candidate against the O139 serogroup, designated as VCUSM2, was recently developed. It was found to be immunogenic in animal model studies but showed mild reactogenic effects due to the presence of two intact copies of Vibrio cholerae toxin (CTX) genetic element. In the present study we have modified the ctx operon by systematic allelic replacement methodology to produce a mutant strain, designated as VCUSM14. This strain has two copies of chromosomally integrated and mutated ctxA gene, encoding immunogenic but not toxic cholera toxin A subunit (CT-A). The amino acids arginine and glutamic acid at position 7th and 112th, respectively, in CT-A of VCUSM14 were substituted with lysine (R7K) and glutamine (E112Q), respectively. Two copies of the ace and zot genes present in the ctx operon were also deleted. Cholera toxin-ELISA using GM1 ganglioside showed that the both wild type CT and mutated CT were recognized by anti-CT polyclonal antibodies. VCUSM14 produced comparatively less amount of antigenic cholera toxin when compared to the VCUSM2 and Bengal wild type strain. VCUSM14 did not elicit fluid accumulation when inoculated into rabbit ileal loops at doses of 10(6) and 10(8) CFU. The colonization efficiency of VCUSM14 was one log lower than the parent strain, VCUSM2, which can be attributed to the ALA auxotrophy and less invasive properties of VCUSM14. VCUSM14, thus a non-reactogenic auxotrophic vaccine candidate against infection by O139 V. cholerae.

Identification of Entamoeba histolytica trophozoites in fresh stool sample: comparison of three staining techniques and study on the viability period of the trophozoites.

Entamoeba histolytica causes about 50 million infections worldwide with a death rate of over 100,000 annually. In endemic developing countries where resources are limited, microscopic examinations based on Wheatley trichrome staining is commonly used for diagnosis of intestinal amoebiasis. Other than being a time-consuming method, it must be performed promptly after stool collection as trophozoites disintegrate rapidly in faeces. The aim of this study was to compare the efficacies of Eosin-Y, Wheatley trichrome and Iodine stains in delineating the diagnostic features of the parasite, and subsequently to determine the suitable microscopy observation period for detection of erythrophagocytic and non-erythrophagocytic trophozoites spiked in semi-solid stool sample. Wheatley trichrome staining technique was performed using the standard method while the other two techniques were performed on the slides by mixing the respective staining solution with the spiked stool sample. One million of axenically cultured non-erythrophagocytic E. histolytica and erythrophagocytic E. histolytica were separately spiked into 2 g of fresh semisolid faeces. Percentage viability of the trophozoites in the spiked stool sample was determined at 30 minute intervals for eight hours using the 0.4% Trypan blue exclusion method. The results showed that Eosin-Y and Wheatley trichrome stained the karyosome and chromatin granules better as compared to Iodine stain. The percentage viability of non-erythrophagocytic trophozoites decreased faster than the erythrophagocytic form in the first 5 hours and both dropped to ~10% in the 6th hour spiked sample. In conclusion, Eosin-Y staining technique was found to be the easiest to perform, most rapid and as accurate as the commonly used Wheatley trichrome technique; Eosin-Y stained slide sealed with DPX could also be kept as a permanent record. A period not exceeding 6 hours after stool collection was found to be the most suitable in order to obtain good microscopy results of viable trophozoites.

Expression, purification and characterization of allelic variants of MSP-1(42) from Indian Plasmodium falciparum isolates.

The C-terminal 19 and 42 kDa fragments of Plasmodium falciparum merozoite surface protein 1 (MSP-1) have shown to be protective in animals against lethal parasite challenge. The MSP-1(19) being highly conserved may lack sufficient number of T-cell epitopes in order to elicit a broader response in genetically diverse populations. The inclusion of additional epitopes from the N-terminal MSP-1(42) has shown to enhance the protective efficacy of MSP-1(19) vaccine. In an attempt to examine the strain specific immunogenicity to MSP-1, we have cloned and expressed three diverse allelic variants of MSP-1(42) from Indian P. falciparum isolates in bacteria. Among three alleles, one was extremely rare and not been found before. These purified and refolded recombinant products were recognized by conformation specific monoclonal antibodies and hyper-immune sera. Immunization of mice and rabbits with the purified proteins generated high titer biologically active polyclonal antibodies supporting further development of this vaccine candidate antigen.