Construction of an Escherichia coli expression vector for the non-structural (NS)-1 protein of avian influenza virus H5N1

In the search for universal vaccine candidates for the prevention of avian influenza, the non-structural (NS)-1 protein 1 of avian influenza virus (AIV) H5N1 has shown promising potential for its ability to effectively stimulate the host immunity. This study was aimed to produce a bacterial expression plasmid using pRSET B vector to harbour the NS1 gene of AIV H5N1 (A/Chicken/Malaysia/5858/2004 (H5N1)) for protein expression in Escherichia coli (E. coli). The NS1 gene (687 bp) was initially amplified by polymerase chain reaction (PCR) and then cloned into a pGEM-T Easy TA vector. The NS1 gene was released from pGEM-T-NS1 using EcoRI and XhoI restriction enzymes (RE). The pRSET B vector was also linearized using the same RE. The digested NS1 gene and linearized pRSET B were ligated using T4 DNA ligase to form the expression plasmid, pRSET B-NS1. The NS1 gene sequence in pRSET B-NS1 was confirmed by DNA sequencing. To prepare recombinant bacterial cells for protein expression in the future, pRSET B-NS1 was transformed into E. coli strain BL21 (DE3) by heat-shock. Colonies bearing the recombinant plasmid were screened using PCR. The DNA sequencing analysis revealed that the NS1 gene sequence was 97% homologous to that of AIV H5N1 A/Chicken/Malaysia/5858/2004 (H5N1). These results indicated that the NS1 gene of influenza A/Chicken/Malaysia/5858/2004 (H5N1) was successfully amplified and cloned into a pRSET B vector. Bacterial colonies carrying pRSET B-NS1 can be used for the synthesis of NS1-based influenza vaccine in the future and thereby aid in the prevention of avian influenza

Cytotoxic and Antifungal Activities of 5-Hydroxyramulosin, a Compound Produced by an Endophytic Fungus Isolated from Cinnamomum mollisimum

An endophytic fungus isolated from the plant Cinnamomum mollissimum was investigated for the bioactivity of its metabolites. The fungus, similar to a Phoma sp., was cultured in potato dextrose broth for two weeks, followed by extraction with ethyl acetate. The crude extract obtained was fractionated by high-performance liquid chromatography. Both crude extract and fractions were assayed for cytotoxicity against P388 murine leukemic cells and inhibition of bacterial and fungal pathogens. The bioactive extract fraction was purified further and characterized by nuclear magnetic resonance, mass spectral and X-ray crystallography analysis. A polyketide compound, 5-hydroxyramulosin, was identified as the constituent of the bioactive fungal extract fraction. This compound inhibited the fungal pathogen Aspergillus niger (IC50 1.56 μg/mL) and was cytotoxic against murine leukemia cells (IC50 2.10 μg/mL). 5-Hydroxyramulosin was the major compound produced by the endophytic fungus. This research suggests that fungal endophytes are a good source of bioactive metabolites which have potential applications in medicine

Single-tube Seminested PCR Assay for Detecting Human Papillomavirus in Clinical Samples

There is a growing appreciation of the potential value for routine screening for the presence of HPV not only for cervical specimens but also from oral cavity. The purpose of this study was to develop and clinically evaluate a single-tube seminested PCR assay for the detection of HPV. Several parameters such as PCR primers, primer annealing temperature, the number of PCR cycles and concentration of PCR components were optimized. The assay was evaluated using HPV inserts of type 6, 11, 16, 18, 31, 33, 38 and 51. Evaluation of seminested PCR assay was performed with cervical scrapings from 30 patients and buccal swabs from 30 head and neck cancer patients and results were compared with those of two-tube nested PCR. The results were found to be comparable with a total of 60% (36/60) of samples being positive for HPV using the single-tube assay, while 62% (37/60) positivity was found with two-tube PCR assay. We succeeded in developing a single-tube seminested PCR method for HPV DNA detection which is easier than the conventional nested PCR and can be further evaluated as a potential screening tool for detecting HPV in oral and cervical regions

Commercial herbal slimming products: evaluation of heavy metals and microorganism contamination at different batch production

Herbal-based slimming products which are consumed orally may be contaminated with heavy metals as well as microorganisms. This study aimed to evaluate the safety level of these slimming products by determining heavy metals and microbial contamination in different batch production. Six different brands of herbal-based slimming products (A, B, C, G, H and I) with three different batch productions (1, 2 and 3) were investigated (n =18). Five heavy metals Arsenic, Cadmium, Chromium, Copper and Zinc were determined using an Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The presence of microorganisms was determined by total aerobic count and the bacteria were identified. The samples’ moisture content was determined by calculating the percentage of water loss after drying process. All batches of samples A and B had high content of zinc, over the permissible level of 5ppm while, 6 samples contained Chromium above the permissible level (1.5 ppm). All 3 batches of sample A presented with the highest total daily intake of heavy metals. Bacteria were present in all the samples tested with the highest numbers in samples G, H and A followed by B, I and C. The highest number of fungi was found in product A while product I was free from fungal contamination. Aspergillus spp. was the predominant fungus present in the samples. There was a weak correlation between moisture content and bacteria (r = 0.087) and fungal (r = 0.253) presence in the samples. As some herbal slimming products contain heavy metals as well as microorganisms, consumers need to be more vigilant and discerning when selecting products to be consumed

Dual panel multiplex PCR assay for rapid detection of medically important fungi and resistant species of candida and aspergillus

Invasive fungal infections (IFIs) have risen dramatically in recent years among high risk immunocompromised patients. Rapid detection of fungal pathogens is crucial to timely and accurate antifungal therapy. Two multiplex polymerase chain reaction (PCR) assays were developed to detect major fungal species that cause invasive infections and identify resistant species. Genus specific primers for Candida, Aspergillus, Fusarium and species specific primers for Candida glabrata, Candida krusei and Aspergillus terreus which are known to be clinically resistant species, were designed from the internal transcribed spacer (ITS) regions of ribosomal ribonucleic acid (rRNA) gene complex. Both assays were performed simultaneously to promote rapid detection of fungal isolates based on distinct amplicon sizes. Inclusion of the universal fungal primers ITS 1 and ITS 4 in the genus specific assay produced a second amplicon for each isolate which served to confirm the detection of a fungal target. The limit of detection for the genus specific assay was 1 nanogram (ng) deoxyribonucleic acid (DNA) for Aspergillus fumigatus and Candida albicans, 0.1 ng DNA for Fusarium solani, while the species-specific assay detected 0.1 ng DNA of A. terreus and 10 picogram (pg) DNA of C. krusei and C. glabrata. The multiplex PCR assays, apart from universal detection of any fungal target, are able to detect clinically important fungi and differentiate resistant species rapidly and accurately, which can contribute to timely implementation of effective antifungal regime

Fabrication of ciprofloxacin loaded alginate/cockle shell powder nanobiocomposite bone scaffold

Orthopedic implant infection is one of the most challenging issues in bone tissue engineering industry. Hence, local delivery of antibiotics incorporated into a fabricated bone scaffold possibly provides a more rapid bacteria inhibitory effect. In this study, pure ciprofloxacin loaded alginate/cockle shell powder nanobiocomposite bone scaffolds are fabricated with 5 wt% and 10 wt% ciprofloxacin respectively and tested for drug encapsulation, drug release and antibacterial properties towards common implant infecting bacterial strains (Staphylococcus aureus and Pseudomonas aeruginosa). Results from the studies showed a low drug encapsulation and drug release regardless of the concentration of drugs loaded with no significant differences noted (p<0.05). However, bacterial inhibition studies through direct contact and using eluted samples from drug release studies showed some inhibitory effects towards the growth of both bacterial strains tested. These findings were further justified with microscopy observations on biofilm and bacterial colony formation. Mineralization studies conducted additionally indicated that the scaffolds characteristics was not compromised due to drug loading. Although pure ciprofloxacin may not be the most suitable antibiotic to be incorporated into the nanobiocomposite bone scaffold, the study did provide some insight to the possible use of the scaffold for future drug delivery applications

Dual panel multiplex PCR assay for rapid detection of medically important fungi and resistant species of Candida and Aspergillus

Invasive fungal infections (IFIs) have risen dramatically in recent years among high risk immunocompromised patients. Rapid detection of fungal pathogens is crucial to timely and accurate antifungal therapy. Two multiplex polymerase chain reaction (PCR) assays were developed to detect major fungal species that cause invasive infections and identify resistant species. Genus specific primers for Candida, Aspergillus, Fusarium and species specific primers for Candida glabrata, Candida krusei and Aspergillus terreus which are known to be clinically resistant species, were designed from the internal transcribed spacer (ITS) regions of ribosomal ribonucleic acid (rRNA) gene complex. Both assays were performed simultaneously to promote rapid detection of fungal isolates based on distinct amplicon sizes. Inclusion of the universal fungal primers ITS 1 and ITS 4 in the genus specific assay produced a second amplicon for each isolate which served to confirm the detection of a fungal target. The limit of detection for the genus specific assay was 1 nanogram (ng) deoxyribonucleic acid (DNA) for Aspergillus fumigatus and Candida albicans, 0.1 ng DNA for Fusarium solani, while the species-specific assay detected 0.1 ng DNA of A. terreus and 10 picogram (pg) DNA of C. krusei and C. glabrata. The multiplex PCR assays, apart from universal detection of any fungal target, are able to detect clinically important fungi and differentiate resistant species rapidly and accurately, which can contribute to timely implementation of effective antifungal regime

Determination of ergosterol as a potential biomarker in pathogenic medically important fungal isolates

Ergosterol, a component of fungal cell membrane, has been frequently detected as an indicator of fungal presence and mass in environmental samples like soil. However, its detection in major pathogenic fungal species has not been investigated. In this study, the ergosterol contents of ten pathogenic fungal species were determined. Liquid chromatography was used for the detection and quantification of ergosterol extracted from fungal broth cultures. Results showed that ergosterol eluted as a single, well resolved peak in the chromatogram profiles of all tested fungi. Based upon relative amounts of ergosterol produced per fungal mycelial dry weight, three groups of fungal pathogens were identified, namely low ergosterol (Aspergillus niger, Candida albicans and Cryptococcus neoformans at 4.62, 6.29 and 7.08 μg/mg, respectively), medium ergosterol (Fusarium solani, Aspergillus fumigatus, Mucor sp., Penicillium sp., Cryptococcus gattii and Rhizopus sp. at 9.40, 10.79, 10.82, 11.38, 12.60 and 13.40 μg/mg, respectively), and high ergosterol (Candida tropicalis at 22.84 μg/mg), producers. Ergosterol was not detectable in bacterial samples, which were included as controls. This first report on ergosterol detection in major pathogenic fungal species indicates that ergosterol may be used as a biomarker to diagnose invasive fungal infections in clinical samples