Optimization and scale-up production of Zika virus ΔNS1 in Escherichia coli: application of Response Surface Methodology

Mannose-specific plant and microbial lectins as antiviral agents: A review

Lectins are non-immunological carbohydrate-binding proteins classified on the basis of their structure, origin, and sugar specificity. The binding specificity of such proteins with the surface glycan moiety determines their activity and clinical applications. Thus, lectins hold great potential as diagnostic and drug discovery agents and as novel biopharmaceutical products. In recent years, significant advancements have been made in understanding plant and microbial lectins as therapeutic agents against various viral diseases. Among them, mannose-specific lectins have being proven as promising antiviral agents against a variety of viruses, such as HIV, Influenza, Herpes, Ebola, Hepatitis, Severe Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) and most recent Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The binding of mannose-binding lectins (MBLs) from plants and microbes to high-mannose containing N-glycans (which may be simple or complex) of glycoproteins found on the surface of viruses has been found to be highly specific and mainly responsible for their antiviral activity. MBLs target various steps in the viral life cycle, including viral attachment, entry and replication. The present review discusses the brief classification and structure of lectins along with antiviral activity of various mannose-specific lectins from plants and microbial sources and their diagnostic and therapeutic applications against viral diseases.

Exploring the purity of chitin from crustacean sources using deep eutectic solvents: A machine learning approach

OBJECTIVE

Chitin a natural polymer is abundant in several sources such as shells of crustaceans, mollusks, insects, and fungi. Several possible attempts have been made to recover chitin because of its importance in biomedical applications in various forms such as hydrogel, nanoparticles, nanosheets, nanowires, etc. Among them, deep eutectic solvents have gained much consideration because of their eco-friendly and recyclable nature. However, several factors need to be addressed to obtain a pure form of chitin with a high yield. The development of an innovative system for the production of quality chitin is of prime importance and is still challenging.

METHODS

The present study intended to develop a novel and robust approach to investigate chitin purity from various crustacean shell wastes using deep eutectic solvents. This investigation will assist in envisaging the important influencing parameters to obtain a pure form of chitin via a machine learning approach. Different machine learning algorithms have been proposed to model chitin purity by considering the enormous experimental dataset retrieved from previously conducted experiments. Several input variables have been selected to assess chitin purity as the output variable.

RESULTS

The statistical criteria of the proposed model have been critically investigated and it was observed that the results indicate XGBoost has the maximum predictive accuracy of 0.95 compared with other selected models. The RMSE and MAE values were also minimal in the XGBoost model. In addition, it revealed better input variables to obtain pure chitin with minimal processing time.

CONCLUSION

This study validates that machine learning paves the way for complex problems with substantial datasets and can be an inexpensive and time-saving model for analyzing chitin purity from crustacean shells.

Combinatorial application of cuminaldehyde and gentamicin shows enhanced antimicrobial and antibiofilm action on Pseudomonas aeruginosa

The emergence of biofilm-induced drug tolerance poses a critical challenge to public healthcare management. Pseudomonas aeruginosa, a gram-negative opportunistic bacterium, is involved in various biofilm-associated infections in human hosts. Towards this direction, in the present study, a combinatorial approach has been explored as it is a demonstrably effective strategy for managing microbial infections. Thus, P. aeruginosa has been treated with cuminaldehyde (a naturally occurring phytochemical) and gentamicin (an aminoglycoside antibiotic) in connection to the effective management of the biofilm challenges. It was also observed that the test molecules could show increased antimicrobial activity against P. aeruginosa. A fractional inhibitory concentration index (FICI) of 0.65 suggested an additive interaction between cuminaldehyde and gentamicin. Besides, a series of experiments such as crystal violet assay, estimation of extracellular polymeric substance (EPS), and microscopic images indicated that an enhanced antibiofilm activity was obtained when the selected compounds were applied together on P. aeruginosa. Furthermore, the combination of the selected compounds was found to reduce the secretion of virulence factors from P. aeruginosa. Taken together, this study suggested that the combinatorial application of cuminaldehyde and gentamicin could be considered an effective approach towards the control of biofilm-linked infections caused by P. aeruginosa.

Development of Methyl Ester Antibody-Based Competitive Indirect ELISA for Quantitative Detection of Mitragynine in Human Urine

Mitragynine is the main psychoactive compound of Mitragyna speciosa Korth. (kratom). This alkaloid could render psychotropic effects and is often misused as a substitute for commercial drugs. Nowadays, the increasing popularity of kratom has led to the development of a rapid and effective detection method. The detection of mitragynine in a biological sample such as urine requires a highly sensitive and specific method due to the complex nature of mitragynine in urine. Enzyme-linked immunosorbent assay (ELISA) is well known as a rapid screening method for biological samples. In this study, a competitive indirect ELISA was successfully developed using MG-22-OCH3 IgG as a detection antibody for mitragynine in human urine. The mitragynine immunoassay showed a limit of detection and a limit of quantification of 0.412 and 1.25 μg/mL, respectively. The measurement range was between 0.01 and 100.0 μg/mL, with a minimal inhibition (IC50) value of 0.152 μg/mL. The developed ELISA was validated using a gold method such as high-performance liquid chromatography-mass spectrometry (HPLC-MS). The percentage of recovery and the coefficient of variation (CV) for the ELISA and LCMS/MS analyses were 84.0-95.70%, 99.20-112.0%, 7.69-9.78%, and 2.86-6.62%, respectively. This indicates that the developed ELISA is a reliable method that can be used as a rapid approach for quantifying mitragynine content in biological samples.

Enhanced production of a recombinant xylanase (XT6): optimization of production and purification, and scaled-up batch fermentation in a stirred tank bioreactor

The endoxylanase XT6 produced by Geobacillus stearothermophilus is a desirable candidate for industrial applications. In this study, the gene encoding XT6 was cloned using the pET-28a expression vector and expressed in Escherichia coli BL21 (DE3) cells. Recombinant XT6 production was improved by optimizing cell lysis (sonication, chemical, and enzymatic lysis) and expression conditions. Sonication in a 0.05 M sodium phosphate (pH 6.0) buffer resulted in the highest xylanase activity (16.48 U/ml). Screening and optimization of induction conditions using the Plackett-Burman Design and Box-Behnken Design (BBD) approaches revealed that cell density pre-induction (OD600 nm), post-induction incubation time, and IPTG concentration significantly (p < 0.05) influenced the expression levels of XT6 (16.48 U/ml to 40.06 U/ml) representing a 3.60-fold increase. BBD resulted in a further 8.74-fold increase in activity to 144.02 U/ml. Batch fermentation in a 5-l stirred tank bioreactor at 1 vvm aeration boosted recombinant xylanase production levels to 165 U/ml suggesting that heterologous expression of the XT6 enzyme is suitable for scaled-up production. The pure enzyme with a molecular weight of 43 kDa and a 15.69-fold increase in purity was obtained using affinity chromatography and a cobalt column. Future studies will include application of the purified recombinant xylanase to animal feed.

Seroprevalence of Zika in Brazil stratified by age and geographic distribution

Congenital Zika is a devastating consequence of maternal Zika virus infections. Estimates of age-dependent seroprevalence profiles are central to our understanding of the force of Zika virus infections. We set out to calculate the age-dependent seroprevalence of Zika virus infections in Brazil. We analyzed serum samples stratified by age and geographic location, collected from 2016 to 2019, from about 16,000 volunteers enrolled in a Phase 3 dengue vaccine trial led by the Institute Butantan in Brazil. Our results show that Zika seroprevalence has a remarkable age-dependent and geographical distribution, with an average age of the first infection varying from region to region, ranging from 4.97 (3.03–5.41) to 7.24 (6.98–7.90) years. The calculated basic reproduction number, , varied from region to region, ranging from 1.18 (1.04–1.41) to 2.33 (1.54–3.85). Such data are paramount to determine the optimal age to vaccinate against Zika, if and when such a vaccine becomes available.

Multi-epitope Antigen for Specific Serological Detection of Dengue Viruses

Dengue is an infectious disease of global health concern that continues to require surveillance. Serological testing has been used to investigate dengue-infected patients, but specificity is affected by the co-circulation of ZIKA virus (ZIKV), which shares extensive antigen similarities. The goal of this study was the development of a specific dengue virus (DENV) IgG ELISA based on a multi-epitope NS1-based antigen for antibody detection. The multi-epitope protein (T-ΔNS1), derived from a fragment of the NS1-protein of the four DENV serotypes, was expressed in Escherichia coli and purified via affinity chromatography. The antigenicity and specificity were evaluated with sera of mice infected with DENV-1-4 or ZIKV or after immunization with the recombinant ΔNS1 proteins. The performance of the T-ΔNS1-based IgG ELISA was also determined with human serum samples. The results demonstrate that the DENV T-ΔNS1 was specifically recognized by the serum IgG of dengue-infected mice or humans but showed no or reduced reactivity with ZIKV-infected subjects. Based on the available set of clinical samples, the ELISA based on the DENV T-ΔNS1 achieved 77.42% sensitivity and 88.57% specificity. The results indicate that the T-ΔNS1 antigen is a promising candidate for the development of specific serological analysis.

Effect of Bacillus subtilis Supplemented Diet on Broiler's Intestinal Microbiota and TLRs Gene Expression

This study aimed to investigate the effects of dietary Bacillus subtilis supplementation on gut microbiota diversity, digestive enzyme activity, and Toll-like receptor (TLR) expression in broiler chickens. A total of 240 "817" crossbred broiler chickens were randomly assigned to four groups: control (basal diet, BD), group I (BD + 300 g/d B. subtilis at 1.08 × 107 CFU/kg), group II (BD + 600 g/d B. subtilis at 2.16 × 107 CFU/kg), and group III (BD + 900 g/d B. subtilis at 3.24 × 107 CFU/kg). Gut microbiota analysis revealed significant improvements in the abundance of specific microorganisms in the treatment groups, with distinct variations in the core microorganisms between the groups. Notably, protease activity in the ileum was significantly increased in groups II (22.59%; p < 0.01) and III (14.49%; p < 0.05) compared to that in the control group. Moreover, significant up-regulation of TLR1A and TLR7 expression was observed in jejunum and cecum of the treated groups. Additionally, the TLR1B expression in the ileum was significantly increased. Furthermore, TLR2A and MyD88 transcription levels were significantly elevated in the jejunum, liver, spleen, and kidneys of experimental groups. Modulations in the expression of various TLR's (TLR2B, TLR3, TLR4, TLR15, and TLR21) were also observed in different organs. The spleen and kidney of B. subtilis-supplemented chickens exhibited upregulated expression of the proinflammatory cytokine IL-1β. Dietary supplementation with B. subtilis in broiler chickens improved the gut microbiota diversity and significantly upregulated TLR's expression in various organs. B. subtilis could be a valuable feed additive, contributing to improved disease management and overall health in broiler chickens.

Production of Recombinant Zika Virus Envelope Protein by Airlift Bioreactor as a New Subunit Vaccine Platform

The Zika Virus (ZIKV) is an emerging arbovirus of great public health concern, particularly in the Americas after its last outbreak in 2015. There are still major challenges regarding disease control, and there is no ZIKV vaccine currently approved for human use. Among many different vaccine platforms currently under study, the recombinant envelope protein from Zika Virus (rEZIKV) constitutes an alternative option for vaccine development and has great potential for monitoring ZIKV infection and antibody response. This study describes a method to obtain a bioactive and functional rEZIKV using an E. coli expression system, with the aid of a 5-L airlift bioreactor and following an automated fast protein liquid chromatography (FPLC) protocol, capable of obtaining high yields of approximately 20 mg of recombinant protein per liter of bacterium cultures. The purified rEZIKV presented preserved antigenicity and immunogenicity. Our results show that the use of an airlift bioreactor for the production of rEZIKV is ideal for establishing protocols and further research on ZIKV vaccines bioprocess, representing a promising system for the production of a ZIKV envelope recombinant protein-based vaccine candidate.

Rhamnolipid production by Pseudomonas aeruginosa (SSL-4) on waste engine oil (WEO): Taguchi optimization, soil remediation, and phytotoxicity investigation

ABSTRACTEnvironmental concerns and rising biosurfactant demand emphasize the need for this study. The objective is to maximize rhamnolipid-biosurfactant production by Pseudomonas aeruginosa (SSL-4) utilizing waste engine oil (WEO) as the sole substrate for use in soil bioremediation and commercial production. Using an L16 Taguchi orthogonal array, a signal-to-noise ratio, and an analysis of variance (ANOVA), the effects of environmental (pH, incubation temperature) and dietary parameters (carbon source concentration, carbon/nitrogen (C/N) and carbon/phosphorus (C/P) ratio) are examined. Variations of the following parameters were made within a carefully selected range: incubation temperature of 25-40℃, pH range of 5-11, WEO concentration of 1-7% (v/v), and C/N and C/P ratios of 10-40. Response variables in this batch study include surface tension reduction (mN/m), dry cell biomass (DCBM) (g/L), and rhamnolipids yield based on substrate consumption, YP/S (g/g). Rhamnolipid was synthesized under optimal conditions, providing a yield of 21.42 g/g. The oil recovery of 74.05 ± 1.481% was achieved from oil-contaminated soil at a CMC of ∼70 mg/L. FTIR, 1H NMR, and UPLC-MS techniques were utilized for the characterization of rhamnolipids, and AAS for determining heavy metals concentration in WEO and residual waste engine oil (RWEO). The Germination Index (GI) of ∼82.55% indicated no phytotoxicity associated with synthesized rhamnolipid.

Prokaryotic Expression, Purification, and Antibacterial Activity of the Hepcidin Peptide of Crescent Sweetlips (Plectorhinchus cinctus)

The hepcidin peptide of crescent sweetlips (Plectorhinchus cinctus) is a cysteine-rich, cationic antimicrobial peptide that plays a crucial role in the innate immune system's defense against invading microbes. The aim of this study was to identify the optimal parameters for prokaryotic expression and purification of this hepcidin peptide and characterize its antibacterial activity. The recombinant hepcidin peptides were expressed in Escherichia coli strain Arctic Express (DE3), with culture and induction conditions optimized using response surface methodology (RSM). The obtained hepcidin peptides were then purified before tag cleavage, and their antibacterial activity was determined. The obtained results revealed that induction temperature had the most significant impact on the production of soluble recombinant peptides. The optimum induction conditions were determined to be an isopropylthio-β-galactoside (IPTG) concentration of 0.21 mmol/L, induction temperature of 18.81 °C, and an induction time of 16.01 h. Subsequently, the recombinant hepcidin peptide was successfully purified using Ni-IDA affinity chromatography followed by SUMO protease cleavage. The obtained hepcidin peptide (without His-SUMO tag) demonstrated strong antimicrobial activity in vitro against V. parahaemolyticus, E. coli, and S. aureus. The results showed prokaryotic (E. coli) expression is a feasible way to produce the hepcidin peptide of crescent sweetlips in a cost-effective way, which has great potential to be used as an antimicrobial agent in aquaculture.

Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes

Fruiting bodies (sporocarps, sporophores or basidiomata) of mushroom-forming fungi (Agaricomycetes) are among the most complex structures produced by fungi. Unlike vegetative hyphae, fruiting bodies grow determinately and follow a genetically encoded developmental program that orchestrates their growth, tissue differentiation and sexual sporulation. In spite of more than a century of research, our understanding of the molecular details of fruiting body morphogenesis is still limited and a general synthesis on the genetics of this complex process is lacking. In this paper, we aim at a comprehensive identification of conserved genes related to fruiting body morphogenesis and distil novel functional hypotheses for functionally poorly characterised ones. As a result of this analysis, we report 921 conserved developmentally expressed gene families, only a few dozens of which have previously been reported to be involved in fruiting body development. Based on literature data, conserved expression patterns and functional annotations, we provide hypotheses on the potential role of these gene families in fruiting body development, yielding the most complete description of molecular processes in fruiting body morphogenesis to date. We discuss genes related to the initiation of fruiting, differentiation, growth, cell surface and cell wall, defence, transcriptional regulation as well as signal transduction. Based on these data we derive a general model of fruiting body development, which includes an early, proliferative phase that is mostly concerned with laying out the mushroom body plan (via cell division and differentiation), and a second phase of growth via cell expansion as well as meiotic events and sporulation. Altogether, our discussions cover 1 480 genes of Coprinopsis cinerea, and their orthologs in Agaricus bisporus, Cyclocybe aegerita, Armillaria ostoyae, Auriculariopsis ampla, Laccaria bicolor, Lentinula edodes, Lentinus tigrinus, Mycena kentingensis, Phanerochaete chrysosporium, Pleurotus ostreatus, and Schizophyllum commune, providing functional hypotheses for ~10 % of genes in the genomes of these species. Although experimental evidence for the role of these genes will need to be established in the future, our data provide a roadmap for guiding functional analyses of fruiting related genes in the Agaricomycetes. We anticipate that the gene compendium presented here, combined with developments in functional genomics approaches will contribute to uncovering the genetic bases of one of the most spectacular multicellular developmental processes in fungi. Citation: Nagy LG, Vonk PJ, Künzler M, Földi C, Virágh M, Ohm RA, Hennicke F, Bálint B, Csernetics Á, Hegedüs B, Hou Z, Liu XB, Nan S, M. Pareek M, Sahu N, Szathmári B, Varga T, Wu W, Yang X, Merényi Z (2023). Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes. Studies in Mycology 104: 1-85. doi: 10.3114/sim.2022.104.01.

Electrochemical magneto-immunoassay for detection of zika virus antibody in human serum

Zika virus (ZIKV) is a flavivirus transmitted by infected Aedes genus mosquitoes. An infected person may be asymptomatic or present symptoms such as fever, arthralgia, and in pregnancy it may lead to neurological disorders in the fetus, such as microcephaly. Based on the high dissemination potential of ZIVK and its similar antigen composition to other arboviruses, new approaches for selective virus detection are urgently needed. This work reports the development of an electrochemical immunoassay for detection of anti-ZIKV antibodies, using magnetic beads functionalized with recombinant protein derived from the non-structural protein 1 (ΔNS1-ZIKV) and anti-IgG antibodies labeled with horseradish peroxidase (HRP) enzyme. The magneto-immunoassay uses disposable microfluidic devices for detection of anti-ZIKV in serum samples. A linear response was obtained for a wide concentration range from 0.01 to 9.80 × 10⁵ pg mL^-1 (r² = 0.982), with a limit of detection of 0.48 pg mL^-1. The proposed immunoassay proved to be highly efficient for the detection of anti-ZIKV antibodies in serum, offering promising perspectives for the development of fast, simple, and affordable point-of-care diagnosis devices for ZIKV.

Identification of Zika Virus NS1-Derived Peptides with Potential Applications in Serological Tests

Zika virus (ZIKV), a mosquito-borne pathogen, is an emerging arbovirus associated with sporadic symptomatic cases of great medical concern, particularly among pregnant women and newborns affected with neurological disorders. Serological diagnosis of ZIKV infection is still an unmet challenge due to the co-circulation of the dengue virus, which shares extensive sequence conservation of structural proteins leading to the generation of cross-reactive antibodies. In this study, we aimed to obtain tools for the development of improved serological tests for the detection of ZIKV infection. Polyclonal sera (pAb) and a monoclonal antibody (mAb 2F2) against a recombinant form of the ZIKV nonstructural protein 1 (NS1) allowed the identification of linear peptide epitopes of the NS1 protein. Based on these findings, six chemically synthesized peptides were tested both in dot blot and ELISA assays using convalescent sera collected from ZIKV-infected patients. Two of these peptides specifically detected the presence of ZIKV antibodies and proved to be candidates for the detection of ZIKV-infected subjects. The availability of these tools opens perspectives for the development of NS1-based serological tests with enhanced sensitivity regarding other flaviviruses.

Mechanistic Approach for Protective Effect of ARA290, a Specific Ligand for the Erythropoietin/CD131 Heteroreceptor, against Cisplatin-Induced Nephrotoxicity, the Involvement of Apoptosis and Inflammation Pathways

ARA 290, an 11-amino acid linear nonhematopoietic peptide derived from the three-dimensional structure of helix B of the erythropoietin (EPO), interacts selectively with the innate repair receptor (IRR) that arbitrates tissue protection. The aim of this study was to investigate the protective effects of ARA290 against cisplatin-induced nephrotoxicity. For this purpose, HEK-293 and ACHN cells were treated with ARA290 (50-400 nM) and cisplatin (2.5 μM) in pretreatment condition. Then, cytotoxicity, genotoxicity, oxidative stress parameters (ROS, GPx, SOD, and MDA), and inflammatory markers (TNFα, IL6, and IL1β) were evaluated. Furthermore, apoptotic cell death was assessed via caspase-3 activity and tunnel assay. To determine the molecular mechanisms of the possible nephroprotective effects of ARA290, gene and protein expressions of TNFα, IL1β, IL6, Caspase-3, Bax, and Bcl2 were evaluated by real-time PCR and western blot assay, respectively. The findings indicated that ARA290 significantly reduced the DNA damage parameters of comet assay and the frequency of micronuclei induced by cisplatin. Besides, ARA290 improved cisplatin-induced oxidative stress by reducing MDA/ROS levels and enhancing antioxidant enzyme levels. In addition, reduced levels of pro-inflammatory cytokines indicated that cisplatin-induced renal inflammation was mitigated upon the treatment with ARA290. Besides, ARA290 ameliorates cisplatin-induced cell injury by antagonizing apoptosis. Furthermore, the molecular findings indicated that gene and protein levels of TNFα, IL1β, IL6, Caspase-3, and Bax were significantly decreased and gene and protein levels of Bcl2 significantly increased in the ARA290 plus cisplatin group compared with the cisplatin group. These findings revealed that ARA290 as a potent chemo-preventive agent exerted a protective effect on cisplatin-induced nephrotoxicity mostly through its anti-apoptotic, anti-inflammatory, and antioxidant potentials and also suggested that ARA290 might be a new therapeutic approach for patients with acute kidney injury.

New insights into the raw milk microbiota diversity from animals with a different genetic predisposition for feed efficiency and resilience to mastitis

The main objective of this study was to assess the microbiota diversity in milk samples collected from Holstein cows with different estimated breeding values for predicted feed efficiency, milk coagulation, resilience to mastitis, and consequently, to study its effects on milk quality. One hundred and twenty milk samples were collected in two seasons (summer and winter) from different commercial dairy farms in the Nord-east of Italy. For each trait, 20 animals divided into two groups of the high (10 cows) and the low (10 cows) were selected to study the microbiota profile using 16S rRNA metabarcoding sequencing. The alpha and beta diversity analysis revealed significant differences between the high and the low groups for feed efficiency and resilience to mastitis, while no significant difference was detected for milk coagulation. Moreover, remarkable differences among the taxa were detected between the two seasons, where the winter was more diverse than summer when applied the Chao1 index. Lastly, the linear discriminant analysis (LDA) effect size (LEfSe) indicated Aerococcus, Corynebacterium, Facklamia, and Psychrobacter taxa with more abundance in the high group of feed efficiency, whereas, in resilience to mastitis, only two genera of Mycoplana and Rhodococcus were more abundant in the low group. In addition, LEfSe analysis between the seasons showed significant differences in the abundance of Bacteroides, Lactobacillus, Corynebacterium, Escherichia, Citrobacter, Pantoea, Pseudomonas, and Stenotrophomonas. These findings indicate that the different genetic predisposition for feed efficiency and resilience to mastitis could affect the raw milk microbiota and, consequently, its quality. Moreover, we found more abundance of mastitis-associated bacteria in the milk of dairy cows with a higher feed efficiency index.

Nanomedicine and regenerative medicine approaches in osteoarthritis therapy

Osteoarthritis (OA), the most common chronic joint disease, is a degenerative disease that affects 7% of the worldwide population, more than 500 million people all over the world. OA is the main factor of disability in elderly people which decreases the quality of life of patients. It is characterized by joint pain, low bone density, and deterioration of the joint structure. Despite ongoing novel advances in drug discovery and drug delivery, OA therapy is still a big challenge since there is no available effective treatment and the existing therapies mainly focus on pain and symptomatic management rather than improving and/or suppressing its progression. This review aims to summarize the currently available and novel emerging therapies for OA including regenerative medicine and nanotechnology-based materials and formulations at the clinical and experimental levels. Applications of regenerative medicine and novel technologies such as nanotechnology in OA treatments have opened a new window to support OA patients by offering treatments that could halt or delay OA progression satisfactorily or provide an effective cure in near future. Nanomedicine and regenerative medicine suggest novel alternatives in the regeneration of cartilage, repair of bone damage, and control of chronic pain in OA therapy.

Membrane disruptive action of cationic anti-bacterial peptide B1CTcu3

A twenty-two-residue peptide Brevinin1 Clinotarsus curtipus-3 (B1CTcu3), identified from the skin secretion of frog Clinotarsus curtipes of the Western Ghats, exhibited a broad range of antibacterial activity against Gram-negative and Gram-positive bacteria, including the methicillin-resistant Staphylococcus aureus (MRSA). It showed anti-biofilm activity even at sub-Minimum Inhibitory Concentration (sub-MIC) against Pseudomonas aeruginosa and Staphylococcus aureus. Analysis of the scanning electron microscopic (SEM) images, confocal images, flow cytometric data and the effect of salt concentration on antibacterial potency suggests that the killing action of the peptide is through the membranolytic process. Single channel electric recording confirmed that the peptide elicited pores on the bacterial cell membrane as it induces a heterogeneous channel in the lipid bilayer.  It also showed cytotoxicity against MDA-MB-231 breast cancer cell with IC50 of 25µM. B1CTcu3 peptide could serve as the template for next-generation antibacterial agents, particularly against antibiotic resistant pathogenic bacteria.

Validation of Serological Methods for COVID-19 and Retrospective Screening of Health Employees and Visitors to the São Paulo University Hospital, Brazil

Reliable serological tests for the detection of SARS-CoV-2 antibodies among infected or vaccinated individuals are important for epidemiological and clinical studies. Low-cost approaches easily adaptable to high throughput screenings, such as Enzyme-Linked Immunosorbent Assays (ELISA) or electrochemiluminescence immunoassay (ECLIA), can be readily validated using different SARS-CoV-2 antigens. A total of 1,119 serum samples collected between March and July of 2020 from health employees and visitors to the University Hospital at the University of São Paulo were screened with the Elecsys® Anti-SARS-CoV-2 immunoassay (Elecsys) (Roche Diagnostics) and three in-house ELISAs that are based on different antigens: the Nucleoprotein (N-ELISA), the Receptor Binding Domain (RBD-ELISA), and a portion of the S1 protein (ΔS1-ELISA). Virus neutralization test (CPE-VNT) was used as the gold standard to validate the serological assays. We observed high sensitivity and specificity values with the Elecsys (96.92% and 98.78%, respectively) and N-ELISA (93.94% and 94.40%, respectively), compared with RBD-ELISA (90.91% sensitivity and 88.80% specificity) and the ΔS1-ELISA (77.27% sensitivity and 76% specificity). The Elecsys® proved to be a reliable SARS-CoV-2 serological test. Similarly, the recombinant SARS-CoV-2 N protein displayed good performance in the ELISA tests. The availability of reliable diagnostic tests is critical for the precise determination of infection rates, particularly in countries with high SARS-CoV-2 infection rates, such as Brazil. Collectively, our results indicate that the development and validation of new serological tests based on recombinant proteins may provide new alternatives for the SARS-CoV-2 diagnostic market.

Exploration of genomic and functional features of chitinolytic bacterium Streptomyces chilikensis RC1830, isolated from Chilika Lake, India

Streptomyces chilikensis RC1830 was previously isolated as a novel chitinolytic streptomycete from Chilika Lake, Odisha, India. The strain RC1830 is a representative member of the soil-dwelling, filamentous Streptomyces group that produces the majority of natural antibiotics and secondary metabolites. The objective of this work was to assess the chitin degradation ability and whole-genome sequence of Streptomyces chilikensis RC1830. TLC analysis of the fermentation product revealed that strain RC1830 can convert shrimp shell colloidal chitin to N-acetylated chitooligosaccharides (N-AcCOS). A genome-wide investigation of RC1830 was also carried out to investigate the genetic basis for chitin breakdown. The result showed that the RC1830 genome possesses a chromosome with 7,121,774 bp (73.2% GC). The genome consists of 6807 coding sequences, 69 tRNA, and 3 rRNA genes. Furthermore, carbohydrate-active enzyme (CAZyme) analysis revealed that RC1830 has 89 glycoside hydrolase family genes, which could modulate the enzymes involved in the degradation of chitin ultimately producing industrially important COS. The whole-genome information of RC1830 could emphasize the mechanism involved in the RC1830's chitin breakdown activity, endowing RC1830 with a promising alternative for COS production.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03184-5.

Tailoring enhanced production and identification of isoflavones in the callus cultures of Pueraria thomsonii Benth and its model verification using response surface methodology (RSM): a combined in vitro and statistical optimization

Background

Scientifically, isoflavones from Pueraria thomsonii Benth possess diverse pharmacological activities and have been used to treat various diseases. In vitro propagation of callus has contributed to the reliability for large-scale production of target compounds. However, the factors affecting the biosynthesis of major isoflavones daidzin, puerarin and daidzein in the callus culture of P. thomsonii are still not known. Therefore, we aimed to enhance the in vitro production of daidzin, puerarin and daidzein by optimizing three independent factors such as temperature, NAA and 6-BA concentrations.

Results

Our findings showed that the optimal concentrations for in vitro biomass production and efficient synthesis of puerarin, daidzin and daidzein were found to be 0.158%, 0.463% and 0.057%, respectively. In addition, the HPLC fingerprint with chemo-metrics analysis was constructed by linear regression of the puerarin, daidzin and daidzein which was found to be in the range of 1.0–36.0, 5.0–72.0 and 1.0–15.0 mg/mL and the LODs and LOQs were found to be 0.15, 0.52, 0.35 and 0.28, 1.50, 0.50 mg/mL for puerarin, daidzin and daidzein, respectively. Surprisingly, our results were also in agreement with the concentration obtained from the model verification for optimal and efficient production of puerarin, daidzin and daidzein which was found to be 0.162%, 0.458% and 0.049%, respectively.

Conclusions

In summary, our present investigation provides new insights that could facilitate the enhanced production of valuable isoflavones in P. thomsonii using plant cell cultures treated with appropriate elicitor combinations and temperature. As far as the authors are concerned, this is the first report on production of daidzin, puerarin and daidzein at higher yield at laboratory level for a wide range of applications in future food, medicinal and pharmaceutical companies.

Biomedical applications of L-alanine produced by Pediococcus acidilactici BD16 (alaD+)

L-alanine possesses extensive physiological functionality and tremendous pharmacological significance, therefore could be considered as potential ingredient for food, pharmaceutical, and personal care products. However, therapeutic properties of L-alanine still need to be addressed in detail to further strengthen its utilization as a viable ingredient for developing natural therapeutics with minimum side effects. Thus, the present study was aimed to explore the anticipated therapeutic potential of L-alanine, produced microbially using a lactic acid bacterial strain Pediococcus acidilactici BD16 (alaD⁺) expressing L-alanine dehydrogenase enzyme. The anticipated therapeutic potential of L-alanine was assessed in terms of anti-proliferative, anti-bacterial, and anti-urolithiatic properties. Anti-bacterial assays revealed that L-alanine successfully inhibited growth and in vitro proliferation of important human pathogens including Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus mutans, and Vibrio cholerae in a concentration-dependent manner. Current investigation has also revealed its significant anti-proliferative potential against human lung adenocarcinoma (A549; IC₅₀ 7.32 μM) and mammary gland adenocarcinoma (MCF-7; IC₅₀ 8.81 μM) cells. The anti-urolithiatic potential of L-alanine was augmented over three different phases, viz., nucleation inhibition, aggregation inhibition, and oxalate depletion. Further, an in vitro cell culture-based kidney stone dissolution model using HEK293-T cells was also established to further strengthen its anti-urolithiatic potential. This is probably the first in vitro cell culture-based model which experimentally validates the immense therapeutic efficacy of L-alanine in treating urolithiasis disease. KEY POINTS: • Assessment of therapeutic potential of L-alanine produced by LAB. • L-alanine exhibited significant anti-proliferative and anti-bacterial activities. • L-alanine as potential anti-urolithiatic agent.

Novel red color emitting Ca0.995 Mg2 (SO4 )3 :0.5Eu2+ phosphor under UV, blue and green excitation for plant growth LEDs

In the recent few years, Eu²⁺ and Mn⁴⁺ activated phosphors are widely used as potential color converters for indoor plant cultivation lighting application due to their marvellous luminescence characteristics as well as low cost. In this investigation, we are synthesized novel red color emitting Ca_(2-x) Mg₂ (SO₄ )₃ : xmol% Eu²⁺ (x = 0-1.0 mol%) phosphors via solid-state reaction method in reducing atmosphere. The PL excitation spectra of synthesized phosphors exhibited a broad excitation band with three excitation bands peaking at 349 nm, 494 nm and 554 nm. Under these excitations, emission spectra exhibits broad band in the red color region around 634 nm. The PL emission intensity were measured for different concentration of Eu²⁺ . The maximum Eu²⁺ doping concentration in Ca₂ Mg₂ (SO₄ )₃ host was observed for 0.5 mol%. According to Dexter theory, it was determined that dipole-dipole interaction is responsible for concentration quenching. The luminous red color emission of the sample was confirmed by CIE color coordinate. The results of PL excitation and emission spectrum of prepared phosphors are well-matched with excitation and emission wavelengths of phytochrome P_R . Therefore, as per the entire investigation and obtained results it was concluded that the synthesized Ca_0.995 Mg₂ (SO₄ )₃ :0.5mol%Eu²⁺ phosphor has huge potential for plant cultivation application.

Mechanistic insight into immunomodulatory effects of food-functioned plant secondary metabolites

Medicinally important plant-foods offer a balanced immune function, which is essential for protecting the body against antigenic invasion, mainly by microorganisms. Immunomodulators play pivotal roles in supporting immune function either suppressing or stimulating the immune system's response to invading pathogens. Among different immunomodulators, plant-based secondary metabolites have emerged as high potential not only for immune defense but also for cellular immunoresponsiveness. These natural immunomodulators can be developed into safer alternatives to the clinically used immunosuppressants and immunostimulant cytotoxic drugs which possess serious side effects. Many plants of different species have been reported to possess strong immunomodulating properties. The immunomodulatory effects of plant extracts and their bioactive metabolites have been suggested due to their diverse mechanisms of modulation of the complex immune system and their multifarious molecular targets. Phytochemicals such as alkaloids, flavonoids, terpenoids, carbohydrates and polyphenols have been reported as responsible for the immunomodulatory effects of several medicinal plants. This review illustrates the potent immunomodulatory effects of 65 plant secondary metabolites, including dietary compounds and their underlying mechanisms of action on cellular and humoral immune functions in in vitro and in vivo studies. The clinical potential of some of the compounds to be used for various immune-related disorders is highlighted.

NS1-based ELISA test efficiently detects dengue infections without cross-reactivity with Zika virus

OBJECTIVES

The aim of this study was to achieve greater specificity of dengue virus (DENV) serological tests based on a recombinant antigen derived from non-structural protein 1 (ΔNS1) with regard to cross-reactive Zika virus (ZIKV) anti-NS1 antibody responses. This is of relevance in endemic regions for the serological discrimination of both DENV and ZIKV, such as Brazil and other tropical countries.

METHODS

The ΔNS1 proteins were obtained as recombinant antigens and were evaluated as solid-phase-bound antigens in the ELISA test to detect anti-NS1 IgG antibodies. The performance of the ∆NS1-based DENV IgG ELISA was assessed with both mouse and human serum samples previously exposed to DENV or ZIKV.

RESULTS

The ∆NS1-based DENV IgG ELISA detected anti-DENV NS1 IgG without cross-reactivity with ZIKV-positive serum samples. The sensitivity and specificity of the assay determined using samples previously characterized by real-time PCR (qRT-PCR) or plaque reduction neutralization assay (PRNT) were 82% and 93%, respectively.

CONCLUSION

The ∆NS1-based DENV IgG ELISA conferred enhanced diagnostic specificity for anti-DENV serological tests and may be particularly useful for serological analyses in endemic regions for both DENV and ZIKV transmission.

Current evidence in high throughput ultrafiltration toward the purification of monoclonal antibodies (mAbs) and biotechnological protein-type molecules

Pressure-driven membrane-based technologies, such as microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF), have been successfully implemented in recovering different types of biomolecules and high-value-added compounds from various streams. Especially, UF membranes meet the requirements for separating specific bioproducts in downstream processes, e.g. monoclonal antibodies (mAbs), which are recognized as proteins produced mainly by plasma cells. According to the importance and functionality of the mAbs, their recovery is a current challenge with these bioseparations. Nevertheless, mAbs recovery using UF-assisted processes has been smartly performed over the last decade. To the best of our knowledge, there are no reviews of the reported developments using UF technology toward mAbs separation. Therefore, the goal of this paper is to collect and elucidate ongoing research studies implemented for the featured separation of mAbs and other biotechnological protein-type molecules (e.g. adenovirus serotype, extracellular vesicles, red fluorescent protein, cyanovirin-N, among others) via ultrafiltration-aided systems. The literature evidence (e.g. research papers, patents, etc.) has been analyzed and discussed according to the purpose of the study. Importantly, the relevant findings and novel approaches are discussed in detail. To finalize this document, the advantages, drawbacks, and guidelines in applying membrane-based techniques for such a recovery are presented.

Comparative effects of alive and pasteurized Akkermansia muciniphila on normal diet-fed mice

Recently, Akkermansia muciniphila an anaerobic member of the gut microbiota, has been proposed as a next-generation probiotic. The aim of this study was evaluation of the effect of alive and pasteurized A. muciniphila on health status, intestinal integrity, immune response, lipid metabolism, and gut microbial composition in normal-diet fed mice as well as direct effects of the bacterium on Caco-2 cell line. A total of 30 mice were distributed into three different groups, control, alive, and pasteurized A. muciniphila-treated group. After acclimation, control and treatment groups were administrated with PBS and 10⁹ CFU/200µL of bacterial suspension for 5 weeks, respectively. Besides, Caco-2 separately exposed to alive, pasteurized A. muciniphila and PBS for 24 h. The results showed that administration of A. muciniphila leads to reduction in body, liver, and white adipose weight. Histology data revealed both treatments had no adverse effects in colon, liver, and adipose tissues as well as induced better gut structure. Moreover, biochemical parameters and inflammatory biomarkers in plasma demonstrated that pasteurized A. muciniphila had more pronounce effect. Furthermore, alive A. muciniphia had better effects on the modulation of gene expression related to fatty acid synthesis, energy homeostasis, and immune response in the liver; meanwhile, these effects in the adipose was more in the pasteurized A. muciniphila administration. More importantly, the improvement of gut health by enhancing strengthen intestinal integrity and maintaining immune homeostasis was seen in both treatments; notably, pasteurized A. muciniphila had more effective. Similarly, treatment with the pasteurized form more effectively upregulated tight junction and regulated immune response-related genes in Caco-2 cell line. Both treatments triggered the improvement of microbiota communities, particularly the alive form. Therefore, both forms of A. muciniphila could modulate lipid and immune homeostasis, improved some gut microbiota, and promoted the overall health, while all these effects were dominantly observed in pasteurized form. In conclusion, pasteurized A. muciniphila can be considered as new medical supplement to maintain health state and prevent diseases in normal mice through different mechanisms.

Escherichia coli as an antibody expression host for the production of diagnostic proteins: significance and expression

This review article concerns the production of recombinant antibody fragments for applications mainly in the diagnostic sector. The so-called "point of care diagnostics" is very important for timely diagnosis and treatment, thus being able to save lives and resources. There is intense pressure for more accurate and less expensive rapid diagnostic tests, with a value preferably <$1. Thus, the large-scale cost-effective production of recombinant antibodies is vital. The importance of Escherichia coli toward the production of inexpensive rapid tests will be explained in this review paper. Details about the different strains of E. coli, the strategies used for the insertion and the expression of recombinant proteins, and the challenges that still exist are provided. Afterward, the importance of the expression scale and culture parameters in the final yield of the antibodies are examined. From this analysis, it appears that for good yields of recombinant antibodies, aside from appropriate gene transfer and expression, the culturing parameters are of paramount importance. Larger scale production is more favorable, mainly due to the higher cell densities that can be achieved. Yields of functional Fab fragments in the range of 10-20 mg/L are considered good in shake flasks, whereas in bioreactors can be up to 1-2 g/L. An amount of 10-500 mg of such antibody per million rapid tests is required. Despite the substantial importance of the production of the antibodies and their fragments, their downstream processing should be appropriately considered from the beginning for achieving the target value of the final rapid diagnostic tests.

Optimization of the extraction conditions and dermal toxicity of oil body fused with acidic fibroblast growth factor (OLAF)

INTRODUCTION

Oil body (OB), a subcellular organelle that stores oil in plant seeds, is considered a new transdermal drug delivery system. With the increasing understanding of the OB and its main protein (oleosin), numerous studies have been conducted on OB as "carrier" for the expression of exogenous proteins. In our previous study, oil body fused with aFGF (OLAF) was obtained using a plant oil body expression system that had been preliminarily proven to be effective in accelerating the healing of skin wounds. However, no dermal toxicological information on OLAF is available.

OBJECTIVE

To ensure the dermal safety of OLAF, a series of tests (the acute dermal toxicity test, 21-day repeat dermal toxicity test, dermal irritation test and skin sensitisation test) were conducted after optimising the extraction protocol of OLAF.

MATERIALS AND METHODS

To improve the extraction rate of OLAF, response surface methodology (RSM) was first employed to optimise the extraction conditions. Then, Wistar rats were exposed to OLAF (400 mg·kg^-1 body weight) in two different ways (6 hours/time for 24 hours and 1 time/day for 21 days) to evaluate the acute dermal toxicity and 21-day repeated dermal toxicity of OLAF. In the acute dermal toxicity test, clinical observations were conducted to evaluate the toxicity, behaviour, and health of the animals for 14 consecutive days. Similarly, the clinical signs, body weight, haematological and biochemical parameters, histopathological changes and other indicators were also detected during the 21 days administration. For the dermal irritation test, single and multiple doses of OLAF (125 mg·kg^-1 body weight) were administered to albino rabbits for 14 days (1 time/day). The irritation reaction on the skin of each albino rabbit was recorded and scored. Meanwhile, skin sensitisation to OLAF was conducted using guinea pigs for a period of 28 days.

RESULTS

Suitable extraction conditions for OLAF (PBS concentration 0.01, pH of PBS 8.6, solid-liquid ratio 1:385 g·mL^-1) were obtained using RSM. Under these conditions, the extraction rate and particle size of OLAF were 7.29% and 1290 nm, respectively. In the tests of acute dermal toxicity and 21-day repeated dermal toxicity, no mortality or significant differences were observed in terms of clinical signs, body weight, haematological parameters, biochemical parameters and anatomopathological analysis. With respect to the dermal irritation test and skin sensitisation test, no differences in erythema, oedema or other abnormalities were observed between treatment and control groups on gross and histopathological examinations.

CONCLUSIONS

The results of this study suggest that OLAF does not cause obvious toxicity, skin sensitisation or irritation in animals.

Optimization of Expression and Purification of Schistosoma mansoni Antigens in Fusion with Rhizavidin

Schistosomiasis causes significant morbidity and mortality. Vaccine efforts to date indicate the need to increase the immunogenicity of Schistosoma antigens. The multiple antigen-presenting system, whereby proteins are genetically fused to rhizavidin and affinity linked to biotinylated templates, enables the generation of robust immune responses. The objective of this work was to express and purify the S. mansoni antigens, SmTSP-2 and SmCD59.2, in fusion with rhizavidin. The fusion with rhizavidin greatly decreased the expression level of rSmTSP-2, but not rSmCD59.2, and both were expressed in the insoluble fraction, requiring optimization of culture conditions. Evaluation of different E. coli strains and media showed that BL21-DE3 cultured in Terrific Broth provided the highest expression levels of both proteins. Investigation of a range of time and temperature of induction showed that E. coli strains expressing rRzv:SmTSP-2 and rRzv:SmCD59.2 showed the highest protein production at 23 °C for 15 h. Recombinant proteins were purified by a single step of affinity chromatography allowing isolation of these proteins in high concentration and purity. The optimization process increased final soluble protein yield of rRzv:SmTSP-2 by fourfold and rRzv:SmCD59.2 by tenfold, providing ~ 20 mg/L of each protein. Optimized fusion protein production will allow antigen use in biotin–rhizavidin affinity platforms.

Trichoderma as biological control agent: scope and prospects to improve efficacy

A major current challenge is to increase the food production while preserving natural resources. Agricultural practices that enhance the productivity and progressively improve the soil quality are relevant to face this challenge. Trichoderma species are widely used in agriculture to stimulate the plant growth and to control different pathogens affecting crops, representing useful tools for sustainable food production. This mini-review summarizes applications of Trichoderma strains in agriculture to control fungal pathogens, nematodes and insects, the involved biocontrol mechanisms, efficacy and inoculation forms in greenhouse, field and post-harvest conditions. Aspects of Trichoderma handling that influence on biocontrol efficacy such as preventive treatments, frequency of applications and delivery methods are discussed. Strategies useful to improve the antagonistic performance such as the use of native strains, protoplast fusion, formulation, growth on pathogen cell wall medium and combination with other antagonists in integrated treatments are discussed. This mini-review provides practical knowledge to design safe and optimal biocontrol strategies based on Trichoderma and pose challenges to expand its antagonist performance.

Bio-mineralisation, characterization, and stability of calcium carbonate containing organic matter

The composition of organic matter in biogenic calcium carbonate has long been a mystery, and its role has not received sufficient attention. This study is aimed at elucidating the bio-mineralisation and stability of amorphous calcium carbonate (ACC) and vaterite containing organic matter, as induced by Bacillus subtilis. The results showed that the bacteria could induce various structural forms of CaCO3, such as biogenic ACC (BACC) or biogenic vaterite (BV), using the bacterial cells as their template, and the carbonic anhydrase secreted by the bacteria plays an important role in the mineralisation of CaCO3. The effects of Ca2+ concentration on the crystal structure of CaCO3 were ascertained; when the amount of CaCl2 increased from 0.1% (m/v) to 0.8% (m/v), the ACC was transformed to polycrystalline vaterite. The XRD results demonstrated that the ACC and vaterite have good stability in air or deionised water for one year, or even when heated to 200 °C or 300 °C for 2 h. Moreover, the FTIR results indicated that the BACC or BV is rich in organic matter, and the contents of organic matter in biogenic ACC and vaterite are 39.67 wt% and 28.47 wt%, respectively. The results of bio-mimetic mineralisation experiments suggest that the protein secreted by bacterial metabolism may be inclined to inhibit the formation of calcite, while polysaccharide may be inclined to promote the formation of vaterite. Our findings advance our knowledge of the CaCO3 family and are valuable for future research into organic-CaCO3 complexes.

Nanovaccine based on self-assembling nonstructural protein 1 boosts antibody responses to Zika virus

Self-assembling proteins may be generated after the addition of short specific amino acid sequences at both the N- and C-terminal ends. To date, this approach has not been evaluated regarding the impact of self-assembled proteins on the induction of immune responses. In the present study, we report the application of this experimental approach to the immunogenicity of protein antigens by measuring the antibody responses in mice immunized with nanoparticles made with a recombinant form of Zika virus nonstructural protein 1 (∆NS1). The results clearly indicated that ∆NS1-derived nanoparticles (NP-∆NS1) are assembled into a 3-dimensional structure with a high degree of multimerization. While ∆NS1 proved to be a weak immunogen, immunization with NP-∆NS1 enhanced subunit vaccines' immunogenicity with improved longevity in vaccinated mice. Thus, immunization with self-assembled antigens (nanovaccines) represents a new and promising strategy to enhance NS1-specific antibodies' induction based on purified recombinant proteins.

Short review on recent progress in Mn4+ -activated oxide phosphors for indoor plant light-emitting diodes

In the modern era, growing number of indoor plants for various purposes, such as vegetation, flowering, and decorations, has increased over the traditional follow-up trends for plantation. However, the indoor plantation requires different parameters for their growth; among these, light plays a significant role. In order to control the growth of plants using light-emitting diodes, Mn-doped oxide phosphors have emerged as promising candidates due to their broad and intense emission bands in the red and far-red spectral range. In this review article, recent progress on Mn-doped oxides for indoor plant growth has been reviewed. This review article is mainly divided into three parts. In the first part, different reaction conditions for the synthesis of Mn-doped oxide phosphors are compared. In the second part, the luminescent and other photometric parameters of these are discussed. The influence of different co-dopants on the luminescent characteristics has been elucidated in detail. The third part discusses the properties of light-emitting diodes fabricated using these phosphors for plant growth. The present review article elucidates the synthesis parameters, luminescent properties, and light-emitting diodes fabricated using Mn-doped oxide materials for plant growth applications.

Anti-Flavivirus Vaccines: Review of the Present Situation and Perspectives of Subunit Vaccines Produced in Escherichia coli

This article aims to review the present status of anti-flavivirus subunit vaccines, both those at the experimental stage and those already available for clinical use. Aspects regarding development of vaccines to Yellow Fever virus, (YFV), Dengue virus (DENV), West Nile virus (WNV), Zika virus (ZIKV), and Japanese encephalitis virus (JEV) are highlighted, with particular emphasis on purified recombinant proteins generated in bacterial cells. Currently licensed anti-flavivirus vaccines are based on inactivated, attenuated, or virus-vector vaccines. However, technological advances in the generation of recombinant antigens with preserved structural and immunological determinants reveal new possibilities for the development of recombinant protein-based vaccine formulations for clinical testing. Furthermore, novel proposals for multi-epitope vaccines and the discovery of new adjuvants and delivery systems that enhance and/or modulate immune responses can pave the way for the development of successful subunit vaccines. Nonetheless, advances in this field require high investments that will probably not raise interest from private pharmaceutical companies and, therefore, will require support by international philanthropic organizations and governments of the countries more severely stricken by these viruses.

Specificity of NS1-based immunochromatographic tests for dengue virus with regard to the Zika virus protein

OBJECTIVES

This study was performed to determine whether Dengue virus (DENV) immunochromatographic tests can detect and differentiate nonstructural protein 1 (NS1) from each of the four DENV serotypes and do not cross-react with the Zika virus (ZIKV) NS1 protein.

METHODS

We compared the specificity of six NS1-based DENV immunochromatographic tests (point of care) in the detection of NS1 proteins from each of the four DENV serotypes and ZIKV. The tests were performed with NS1 proteins produced in mammalian cells. Cross-reactivity was confirmed with a purified recombinant ZIKV NS1 protein and DENV⁺ or ZIKV⁺ human serum samples.

RESULTS

Cross-reaction was observed in 2 out of the 6 evaluated tests using cell culture supernatants containing NS1 protein of each tested virus. Cross-reactivity with ZIKV was confirmed with purified recombinant ZIKV NS1 produced in Escherichia coli. Further analyses with serum samples collected from DENV⁺ or ZIKV⁺ patients confirmed the cross-reactivity with ZIKV protein in 2 tests.

CONCLUSIONS

The detection of the NS1 protein is the basis for several commercially available serological DENV diagnostic tests. The present results emphasize the relevance of testing specificity of presently available NS1-based DENV serological tests and the need of adjustments of tests that cross-react with the ZIKV protein. Our results are particularly relevant for regions where both viruses are endemically found, as in the case of Brazil.