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Lateral flow type detection is becoming interesting not only in regions with a poor medical infrastructure but also for practitioners in day-to-day clinical work or for veterinary control in case of possible epidemics. In this work, we describe the first steps of development of a multi-channel strip with potential internal calibration of multiparametric and colorimetric lateral flow assays for the simultaneous detection of the lipopolysaccharides (LPS) of Salmonella typhimurium ( S. typhimurium) and Salmonella enteritidis ( S. enteritidis). We structured four channels in the nitrocellulose membrane with a Yb:KGW solid-state femtosecond laser ('cold' ablation process) to form distinct tracks of porous material and used gold nanoparticles for the labeling of the antibodies. In addition, calibration curves of the spot intensities of both serovars are presented, and it was shown that no cross reactivity between the different capture antibodies and LPS occurred. Finally, we detected LPS of both Salmonella serovars simultaneously. The color changes (spot intensities of the reaction zones) were evaluated using the open-source image-processing program ImageJ. [ABSTRACT FROM AUTHOR]

Highlights: [•] The current assessment of rabies immunity in wildlife faces technical difficulties. [•] Field sampling of fox and raccoon dog blood on filter papers (FP) is feasible. [•] The FP method allows the storage, transport and ELISA titration of blood samples. [•] The FP sampling method was found highly specific and repeatable in both wild species. [•] We report a reliable alternative to assess effectiveness of oral rabies vaccination. [ABSTRACT FROM AUTHOR]

Aim: The present study was designed to investigate the feasibility of the filter paper sampling of blood for the detection of IBDV antibodies in chicken sera using a commercial ELISA kit. Materials and Methods: Optimum dilution for filter paper extracts that would give a result equivalent to that of the corresponding serum sample in a commercial ELISA was determined. Correlation between the filter paper extracts based ELISA and conventional serum based ELISA was also examined and the reproducibility of the filter paper extracts based ELISA was tested. Results: A very good correlation (r = 0.9; n = 15; p<0.01) was observed between the results obtained with filter paper extracts based ELISA and serum based ELISA. The antibody titre determined by two systems were very close and did not exceed more than a two-fold dilution with the exception of samples having very low antibody levels, where relatively higher background reaction was observed with filter paper extracts based ELISA. The filter paper extracts based ELISA appeared to be quite reproducible with a coefficient of variation less than 10%. Conclusion: Filter paper based ELISA could be a useful alternative to serum dependant ELISA assays for sero-profiling chicken flocks for IBDV antibodies. [ABSTRACT FROM AUTHOR]

Abstract: A novel lab-on-paper device combining the simplicity and low-cost of microfluidic paper-based analytical devices (μPADs) and the sensitivity and selectivity of chemiluminescence ELISA (CL-ELISA) for the high-throughput, rapid, stable and reusable point-of-care testing is presented here. Chitosan was used to modify μPADs to covalently immobilize antibodies on μPADs. Thus, sandwich CL-ELISA on μPADs can be easily realized for further development of this technique in sensitive, specific and low-cost application. The paper device was fabricated by a low-cost, simple, and rapid wax-screen-printing method. Using tumor markers and paper microzone plate as model, the application test of this paper-based CL-ELISA was successfully performed with a linear range of 0.1–35.0ngmL−1 for α-fetoprotein, 0.5–80.0UmL−1 for cancer antigen 125 and 0.1–70.0ngmL−1 for carcinoembryonic antigen. Since the cutoff values of the three tumor markers in clinical diagnosis are 25ngmL−1, 35UmL−1 and 5ngmL−1, the sensitivity and linear ranges of the proposed method were enough for clinical application. In addition, this lab-on-paper immunodevice can provide reproducible results upon storage at 4°C (sealed) for at least 5 weeks. Ultimately, this novel chitosan modification and wax-screen-printing methodology for μPADs can be readily translated to other signal reporting mechanism including electrochemiluminescence and photoelectrochemistry, and other receptors such as enzyme receptors and DNA receptors for determination of DNA, proteins and small molecules in point-of-care testing. [Copyright &y& Elsevier]

Background: The method of collection as well as the packaging conditions in which samples are submitted to laboratories play a critical role on the acquisition of reliable results on diagnostic tests. Alternative methods however have been proposed, as the adsorption of blood or serum in filter paper. In this work, it was evaluated the viability of using serum or whole blood samples from bovines collected in filter paper for serological testing against bovine herpesvirus type 1 (BoHV-1). Materials, Methods & Results: One hundred and seven whole blood and serum samples were collected by standard methods. Serum neutralization test was used as a golden standard method for evaluation of the serum samples. The same samples of both whole blood and sera were also adsorbed on filter paper strips for further comparisons. Optimal conditions for serum and blood elution from filter paper were determined. Adsorbed samples on filter paper disks were eluted in PBS and subsequently diluted further with PBS 5% skimmed milk. The eluates were tested for antibodies to BoHV-1 in an indirect ELISA (iELISA) and matched with the results obtained by serum neutralization of standard serum samples. Comparison between results obtained by serum neutralization of standard serum samples and the ones from the iELISA of serum eluted from paper disks resulted in sensitivity, specificity, positive and negative predictive values of 95, 94, 80, 99%, respectively, and a correlation coefficient (κ) of 0.83. Comparison between the results of serum neutralization of standard serum samples and the ones from the iELISA of blood eluted from paper disks resulted in sensitivity, specificity, positive and negative predictive values of 91, 97, 87, 98% , respectively, and a correlation coefficient (κ) of 0.86. Standard serum samples were also tested in the iELISA and the results compared with those of iELISA from samples eluted from filter paper. Comparison of the results from iELISA between serum samples and serum eluted from filter paper resulted in sensitivity, specificity, positive and negative predictive values of 91, 81, 69, 95%, respectively, and a correlation coefficient (κ) of 0.66. The comparison of iELISA results between standard serum and blood samples eluted from filter paper resulted, in sensitivity, specificity, positive and negative predictive values of 78, 92, 82, 89%, respectively, and a correlation coefficient (κ) of 0.70. Fifty samples collected on filter paper were retested eight months later in order to determine whether those would retain its viability; both sensitivity and specificity remained unaltered. Discussion: Sampling on filter paper has been successfully described for antibody detection in a number of diseases such as Aujeszky's disease virus and Newcastle disease virus. In this work, it has been demonstrated that both blood and sera collected in filter paper can be used for submission of samples aiming detection of antibodies to BoHV-1 in an iELISA, without significant loss of sensitivity and specificity. Submission of samples on filter paper is a practical and economical alternative as no special conditions are required for storaging and transporting. This method also enables the collection of samples from distant places assuring its quality for serological tests. [ABSTRACT FROM AUTHOR]

Aflatoxingenetic fungi producing highly toxic and carcinogenic mycotoxins and threatening human health widely exist in our living environment and food. Taking aflatoxingenetic fungi as an analyte example, here we report a way to improve the sensitivity of paper-based sandwich immunosensor for macromolecule. With a biomarker-specific nanobody and polyclonal antibody (IgG), two modes of paper-based immunosensors were constructed, immobilization nanobody mode and immobilization IgG mode. It was found that the sensitivity of the immobilization nanobody mode was at least 500 times higher than that of the immobilization IgG mode. The reasons for the large difference in sensitivity were also theoretically. Under the optimized conditions, the immobilization nanobody mode sensitivity reached 0.035 μg/mL aflatoxingenetic mycelia, each assay was finished within 15 min, and the spiked recoveries of aflatoxingenetic mycelium reference in peanuts were 77.0∼91.6%. And then, two important application cases were successfully demonstrated to identify the abundance of aflatoxingenetic fungi in market peanuts and peanut rhizosphere soil for environmental safety evaluation. This is the first report of time-resolved paper-based sandwich immunosensor for aflatoxingenetic fungi with nanobody immobilization, and the first sensitivity comparison between nanobody immobilization and IgG immobilization, which provides a new approach to develop highly sensitive immunosensor for macromolecular hazard materials. • The sensitivity of the immobilization nanobody mode was over 500 times higher than that of the immobilization IgG mode. • It provides a new approach to develop ultrahigh sensitive immunosensor for macromolecular hazard materials. • The developed paper-based sandwich immunosensor with LOD for aflatoxingenetic fungi reference was 0.035 μg/mL. • Evaluating risk of aflatoxingenetic fungi in food and environment. [ABSTRACT FROM AUTHOR]

The pulp and paper industry together with lignocellulosic biofuel production provides plentiful streams of lignin and lignin-derived molecules (LDMs) that currently remain underutilized. The heterogeneity and complexity of lignin along with the lack of convenient tools significantly hamper its utilization. Selective separation of these LDMs from streams using specific tools would allow the recovery of aromatic compounds, as well as facilitate biological processes aiming at lignin valorization. To this end, here we report the isolation and characterization of single-chain variable fragment (scFv) antibodies against ferulate, coumarate, and caffeate, which are the molecular representatives of LDMs. Binders for the target LDMs were enriched by interrogating a synthetic scFv library with the phage display technique. As a result, scFv binders specific against each of the target molecules were obtained with affinities in the micromolar range. The selectivity of scFvs towards specific LDMs was proved by recovering caffeate from simulated LDM solution, Kraft lignin, and rice straw hydrolysate samples. Further proof of concept studies with model compounds demonstrated the applicability of antibody-based binders as a detection tool for monitoring microbial LDM conversion. Overall, this study demonstrates the potential of scFv binders as a specific toolset for lignin compound recovery and analysis. [ABSTRACT FROM AUTHOR]

This study introduced a barcode-like design into a paper-based blood typing device by integrating with smartphone-based technology. The concept of presenting a paper-based blood typing assay in a barcode-like pattern significantly enhanced the adaptability of the assay to the smartphone technology. The fabrication of this device involved the use of a printing technique to define hydrophilic bar channels which were, respectively, treated with Anti-A, -B, and -D antibodies. These channels were then used to perform blood typing assays by introducing a blood sample. Blood type can be visually identified from eluting lengths in bar channels. A smartphone-based analytical application was designed to read the bar channels, analogous to scanning a barcode, interpret this information, and then report results to users. The proposed paper-based blood typing device is rapidly read by smartphones and easy for the user to operate. We envisage that the adaptation of paper-based devices to the widely accepted smartphone technology will increase the capability of paper-based diagnostics with rapid assay result interpretation, data storage, and transmission. [ABSTRACT FROM AUTHOR]

Background and Objectives: Serological diagnosis of hydatidosis is usually performed by detecting the circulating antibodies in serum by ELISA. The present study was carried out to standardize and evaluate procedure of the ELISA using elute from dried blood spots (DBS) on filter paper and blood stored at different temperatures and at different durations for its further application under field conditions. Materials and Methods: Dried blood spots were collected from fifty study subjects and fifty control subjects and evaluated for the detection of IgG antibodies against hydatid. Samples were stored at room temperature and 4°C and tested by ELISA at 0, 15 and 30 days. Results: The present study shows that elute of DBS on filter paper can be stored at room temperature for a maximum of 30 days without a decrease in antibody titer as compared to serum samples tested by ELISA. Conclusions: The collection of blood sample on filter paper may serve useful purpose in resource limited countries for carrying out sero-epidemiological surveys at a cost effective level. [ABSTRACT FROM AUTHOR]

A paper-based lateral flow immunoassay for pathogen detection that avoids the use of secondary antibodies and is revealed by the photoluminescence quenching ability of graphene oxide is reported. Escherichia coli has been selected as a model pathogen. The proposed device is able to display a highly specific and sensitive performance with a limit of detection of 10 CFU mL-1 in standard buffer and 100 CFU mL-1 in bottled water and milk. This low-cost disposable and easy-to-use device will prove valuable for portable and automated diagnostics applications. [ABSTRACT FROM AUTHOR]

Bullous pemphigoid (BP), a common autoimmune blistering disease, is increasing in incidence and conveys a high mortality. Detection of autoantibodies targeting the noncollagenous 16A (NCI6A) domain of type XVII collagen using enzyme-linked immunosorbent assay (ELISA) has demonstrated high sensitivity and specificity for diagnosing BP. We have developed a rapid, low-cost, and widely applicable ELISA-based system to detect the NC16A autoimmune antibody and then diagnose and monitor BP disease activity using a piece of filter paper, a wax-printer, and NC16A antigens. Both sera and/or blister fluids from 14 untreated BP patients were analyzed. The control group included healthy volunteers and patients with other blistering disorders such as pemphigus vulgaris. In our established paper-based ELISA (P-ELISA) system, only 2 μL of serum or blister fluid and 70 min were required to detect anti-NC16A autoimmune antibodies. The relative color intensity was significantiy higher in the BP group than in the control groups when using either serum (P < 0.05) or blister fluid (P < 0.001) specimens from BP patients. The results of P- ELISA were moderately correlated with the titer of the commercial ELISA kit (MBL, Japan) (rho = 0.5680, P = 0.0011). This newly developed system allows for rapid and convenient diagnosis and/or monitoring of BP disease activity. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (μPADs) fabricated by wax-printing are suitable platforms for the development of simple and affordable molecular diagnostic assays for infectious diseases, especially in resource-limited settings. Paper devices can be modified for biological assays by adding appropriate reagents to the test areas. For this purpose, the use of affinity immobilization strategies can be a good solution for bioactive paper fabrication. This paper describes a methodology to capture labeled-DNA strands and hybrids on paper via the anchoring of antibodies with a fusion protein that combines a family 3 carbohydrate binding module (CBM) from Clostridium thermocellum, with high affinity to cellulose, and the ZZ fragment of the staphyloccocal protein A, which recognizes IgG antibodies via their Fc portion. Antibodies immobilized via CBM-ZZ were able to capture appropriately labeled (biotin, fluorescein) DNA strands and DNA hybrids. The ability of an antibody specific to biotin to discriminate complementary from noncomplementary, biotin-labeled targets was demonstrated in both spot and microchannel assays. Hybridization was detected by fluorescence emission of the fluorescein-Iabeled DNA probe. The efficiency of the capture of labeled-DNA by antibodies immobilized on paper via the CBM-ZZ construct was significantly higher when compared with a physical adsorption method where antibodies were simply spotted on paper without the intermediation of other molecules. The experimental proof of concept of wax-printed μPADs functionalized with CBM-ZZ for DNA detection at room temperature presented in this study constitutes an important step toward the development of easy to use and affordable molecular diagnostic tests. [ABSTRACT FROM AUTHOR]

An inkjet-printed microfluidic paper-based analytical device (μPAD) for the detection of lactoferrin has been developed. The analyte concentration dependent fluorescence emission, caused by the sensitization of pre-deposited terbium (Tb3+) upon complexation with lactoferrin on the paper device, is captured using a digital camera. The dynamic response range (0.5–3 mg mL−1) and the limit of detection (0.30 mg mL−1) of the μPAD are suitable for the analysis of normal human tears and the detection of eye disorders. Finally, lactoferrin concentrations in human tear samples were analyzed by the μPADs and the assay results corresponded within 6% error to those obtained by an immunoassay (ELISA). The μPADs provide a simple, rapid and accurate method for lactoferrin detection in tear fluid. Results are obtained within 15 min of a single application of 2.5 μL of sample. To the best of our knowledge, this is the first report of a device for lactoferrin quantification relying neither on an immunoassay nor on high cost analytical instrumentation. [ABSTRACT FROM AUTHOR]

Poly(carboxybetaine) (PCB) functionalized cellulose paper was used as a paper-based microfluidic device. The results showed that the PCB modified paper sensor was able to achieve (a) more rapid and sensitive glucose detection from undiluted human serum compared to bare cellulose and (b) specific antigen detection via covalently immobilized antibodies. [ABSTRACT FROM AUTHOR]

A new paper-based colorimetric immunosensor for the detection of carcinoembryonic antigen (CEA) was developed based on the intrinsic peroxidase activity of ZnFe2O4–multiwalled carbon nanotubes (ZnFe2O4@MWNTs). The immunosensor platform was prepared by depositing chitosan and porous gold onto filter paper and entrapping the primary antibodies (Ab1) onto the layers. Secondary antibodies (Ab2) were assembled on the surface of the functionalized ZnFe2O4@MWNTs. The immunosensor response was quantified as a color change resulting from ZnFe2O4@MWNTs catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of H2O2. The catalytic performance of ZnFe2O4@MWNTs was higher than ZnFe2O4 due to the high electrical conductance of MWNTs, moreover, the electron communications between ZnFe2O4@MWNTs and substrates are electrically “wired”. Detection was achieved by measuring the color change when the concentrations of CEA were different. The color change can be quantified with the naked eye but a digitalized picture can also be used to provide more sensitive comparison to a calibrated color scheme. This method was simple for CEA detection with a linear range from 0.005 to 30 ng mL−1 and a detection limit of 2.6 pg mL−1. Such an equipment-free immunoassay has great potential in resource-limited environments. [ABSTRACT FROM AUTHOR]

Rabies virus causes a fatal infection of the brain and spinal cord, accounting for approximately 59,000 deaths globally each year. Rabies postexposure prophylaxis (PEP), including both rabies immunoglobulin (RIG) and vaccination, is administered to 55,000 patients annually in the United States. With a nearly 100% case fatality rate, the optimal administration of rabies PEP cannot be understated. Updated rabies PEP guidelines issued by the World Health Organization (WHO) in 2018 recognized that local wound infiltration of RIG is the primary mechanism of protection, and the WHO now recommends only infiltration of wounds without distal intramuscular injection. We highlight potential points of failure involving wound infiltration of RIG, small-volume doses, and large-volume doses that may lead to suboptimal care and discuss implications of recent shifts toward evidence-based guidelines using wound type and RIG volumes., (© 2021 Pharmacotherapy Publications, Inc.)

Plasma volume (PV) variation during therapeutic apheresis (TA) (such as plasma exchange [PE] and selective PE using albumin solution as replacement solution or immunoadsorption plasmapheresis) has been considered to be unignorable. It changes the concentration of the target molecule and might impact its removal rate (RR.) This study aimed to evaluate the effects of PV variation on the calculation of the RR of fibrinogen and immunoglobulin by categorizing the hematocrit (Ht) change during TA into two patterns, that is, increased group and decreased group. In all modalities of TA, the Ht level frequently changed during apheresis sessions. In calculating RR, RR calculated with Ht adjustment was significantly higher than that calculated without adjustment in the increased group and significantly lower than it in the decreased group. Therefore, RR might have been underestimated in the increased group and overestimated in the decreased group when RR was calculated without Ht adjustment. Ht adjustment is suggested to be crucial in calculating RR in TA., (© 2021 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.)

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a global pandemic outbreak. To date, approximately one million deaths and over 32 million cases have been reported. This ongoing pandemic urgently requires an accurate testing device that can be used in the field in a fast manner. Serological assays to detect antibodies have been proven to be a great complement to the standard method of reverse transcription-polymerase chain reaction (RT-PCR), particularly after the second week of infection. We have developed a specific and sensitive immunosensor for immunoglobulin detection produced against SARS-CoV-2. Unlike other lateral flow-based assays (LFAs) involving the utilization of multiple antibodies, we have reported a label-free paper-based electrochemical platform targeting SARS-CoV-2 antibodies without the specific requirement of an antibody. The presence of SARS-CoV-2 antibodies will interrupt the redox conversion of the redox indicator, resulting in a decreased current response. This electrochemical sensor was proven effective in real clinical sera from patients with satisfactory results. In addition, the proposed format was also extended to antigen detection (the spike protein of SARS-CoV-2), which presents new possibilities for diagnosing COVID-19. • Electrochemical sensor for COVID-19 diagnostic. • Serological assay for SARS-CoV-2 antibodies was demonstrated. • Sensitivity enhancement compared to the traditional LFA devices. • Applicable to real clinical sera with satisfactory results. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate the microagglutination test (MAT) results in serum samples dried on filter paper and stored at different temperatures during 1day, 7days, 30days and 1year to determine the stability of sera antibody against leptospires. Serum samples collected onto filter paper for the detection of leptospires antibody was compared with MAT in a study of 300 serum samples from patients with suspected leptospirosis. Among 300 fresh serum samples analyzed by MAT 156 (52%) were positive and 144 (48%) negative. All the negative fresh serum samples were negative when dried on filter paper (specificity 100%). The sensitivity of MAT performed on dried serum samples was 100%. Storage on filter paper at room temperature and at 4°C for 1 and 7days did not affect the MAT titers. For up to 7days, 98.72% of dried serum samples had titers identical to those of the corresponding serum samples, and 1.18% of dried serum samples showed 1 dilution of difference. After a storage period of one month a prozone phenomenon was observed. After a storage period of one year all serum samples were negative. Serum samples collected onto filter paper are a convenient source of antibodies for serological diagnosis and epidemiological surveys. [Copyright &y& Elsevier]

Introduction and aim. The Rh blood group system consists of at least 61 independent antigens. It was first described in 1939 and has since played a key role in blood group differentiation. The classical division distinguishes Rh+ and Rh- groups, however, an atypical phenotype known as Rhnull is also present, which is associated with the formation of all-antibodies on contact with Rh antigens, which can pose a significant problem in patients who have it and require blood transfusions. Material and methods. Four case reports and one review paper were used. The articles are from 1992-2020. PubMed and Google Scholar databases were used. Key words used in the search were blood transfusion, golden blood and Rhnull. Analysis of literature. The Rhnull blood phenotype (also called "golden blood") is a rare blood type with a prevalence of about 1 in 6 million people. To date, at least 43 individuals belonging to 14 families with the Rhnull phenotype are known, with reports in the literature up to 2018. A mutation in the RHCE gene is most often responsible for its formation. The characteristic feature of "golden blood" is the absence of all Rh antigens on red blood cells. Previous reports indicate its role in the development of hemolytic anemia secondary to a defect in the erythrocyte cell membrane. Conclusion. The presence of rare blood phenotypes can pose a significant problem in the process of blood transfusion in patients. Blood marriages, common in eastern countries and Africa, play an important role in the formation of the Rhnull phenotype, which is more common there compared to other regions of the world. Further genetic studies are needed to find the mutations underlying the development of Rh group incompatibility. [ABSTRACT FROM AUTHOR]

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. Although DIVI in laboratory animal species has been well characterized for vasoactive small molecules, there is little available information regarding DIVI associated with biotherapeutics such as peptides/proteins or antibodies. Because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans and the lack of robust biomarkers of DIVI, preclinical DIVI findings can cause considerable delays in or even halt development of promising new drugs. This review discusses standard terminology, characteristics, and mechanisms of DIVI associated with biotherapeutics. Guidance and points to consider for the toxicologist and pathologist facing preclinical cases of biotherapeutic-related DIVI are outlined, and examples of regulatory feedback for each of the mechanistic types of DIVI are included to provide insight into risk assessment. [ABSTRACT FROM AUTHOR]

Background: Informing and evaluating malaria control efforts relies on knowledge of local transmission dynamics. Serological and molecular tools have demonstrated great sensitivity to quantify transmission intensity in low endemic settings where the sensitivity of traditional methods is limited. Filter paper blood spots are commonly used a source of both DNA and antibodies. To enhance the operational practicability of malaria surveys, a method is presented for combined DNA extraction and antibody elution. Methods: Filter paper blood spots were collected as part of a large cross-sectional survey in the Kenyan highlands. DNA was extracted using a saponin/chelex method. The eluate of the first wash during the DNA extraction process was used for antibody detection and compared with previously validated antibody elution procedures. Antibody elution efficiency was assessed by total IgG ELISA for malaria antigens apical membrane antigen-1 (AMA-1) and merozoite-surface protein-1 (MSP-142). The sensitivity of nested 18S rRNA and cytochrome b PCR assays and the impact of doubling filter paper material for PCR sensitivity were determined. The distribution of cell material and antibodies throughout filter paper blood spots were examined using luminescent and fluorescent reporter assays. Results: Antibody levels measured after the combined antibody/DNA extraction technique were strongly correlated to those measured after standard antibody elution (p < 0.0001). Antibody levels for both AMA-1 and MSP-142 were generally slightly lower (11.3-21.4%) but age-seroprevalence patterns were indistinguishable. The proportion of parasite positive samples ranged from 12.9% to 19.2% in the different PCR assays. Despite strong agreement between outcomes of different PCR assays, none of the assays detected all parasite-positive individuals. For all assays doubling filter paper material for DNA extraction increased sensitivity. The concentration of cell and antibody material was not homogenously distributed throughout blood spots. Conclusion: Combined DNA extraction and antibody elution is an operationally attractive approach for high throughput assessment of cumulative malaria exposure and current infection prevalence in endemic settings. Estimates of antibody prevalence are unaffected by the combined extraction and elution procedure. The choice of target gene and the amount and source of filter paper material for DNA extraction can have a marked impact on PCR sensitivity. [ABSTRACT FROM AUTHOR]

Proteins immobilized on insoluble carriers or immunoadsorbents are now widely used in many areas of biological research. They are especially efficient in studies of complex protein mixtures because immunoadsorbents are very useful for isolation of individual components for further investigation. Antibodies immobilized on paper retain their specific activity and can be applied as very sensitive measurement tool. [ABSTRACT FROM AUTHOR]

African swine fever virus (ASFV) is a dsDNA virus responsible for a severe, highly contagious, and lethal disease affecting both domestic and wild pigs. ASFV has brought enormous economic loss to a number of countries, and effective vaccine and therapy are still lacking. Therefore, a rapid, sensitive, and field-deployable detection of ASFV is important for disease surveillance and control. Herein, we developed a Cas12a-mediated portable paper assay to rapidly and precisely detect ASFV. We identified a robust set of crRNAs that recognized the highly conserved region of essential ASFV genes. The Cas12a-mediated detection assay showed low tolerance for mismatch mutations, and no cross-reactivity against other common swine pathogens. We further developed a paper-based assay to allow instrument-free detection of ASFV. Specifically, we applied gold nanoparticle–antibody conjugate to engineer homemade strips and combined it with Cas12a-mediated ASFV detection. This portable paper, instrument-free diagnostics, faithfully detected ASFV in swine samples, showing comparable sensitivity to the traditionally instrument-dependent qPCR method. Taking together, we developed a highly sensitive, instant, and economic Cas12a-mediated paper diagnostics of ASFV, with a great application potential for monitoring ASFV in the field. [ABSTRACT FROM AUTHOR]

Background: Screening and determining the immune status of individuals for hepatitis B is usually done by detecting hepatitis B surface antigen (HBsAg) and hepatitis B surface antigen-specific antibodies (HBsAb). In some countries with the highest viral burden, performing these assays is currently impractical. This paper explores the use of filter paper as a blood specimen transport medium. Methods: Samples, chosen from routine clinical laboratory pool, were applied and dried onto filter paper. Eluates, from the paper samples, were analyzed as routine clinical specimens on ADVIA Centaur 5634W immunoassay analyzers using the standard HBsAg and HBsAb kits. Dried blood samples were subjected to a range of environmental conditions in order to assess stability. Results: After drying and elution the assays showed linearity and precision comparable to clinical assays performed on fresh serum. Elutions at various times during a 149 day incubation period showed very little variability in the Index numbers. All analytes were temperature stable except for a decrease in the HBsAg signal at 42°C. Conclusions: Filter paper is an acceptable storage and transport medium for serum to be used in the detection of hepatitis B markers if atmospheric variability can be controlled. HBsAg, HBsAb and HBcAb are all stable for at least five months under storage conditions below room temperature. Drying specimens, particularly serum, on filter paper at remote locations, offers a reasonable solution to the problem of hepatitis surveillance in underdeveloped regions, although some attempt at temperature control might be desirable. [ABSTRACT FROM AUTHOR]

This paper analyzes the investigation of the distribution of the protein tenascin-C in canine mammary tumors. The method involved immunohistochemistry of tissue slices, performed by the application of an antibody to tenascin-C that specifically can be made visible for microscopic inspection. The first phase of the project is the making of the protocol, the second the deduction of a pattern of tenascin-C distribution in tumors and the third the writing of a paper. Each of the phases is analyzed separately, using the concept of resistance and accommodation. My purpose is to show that in each phase of the process of producing knowledge, the scientist meets resistances which force him to accommodate by changing his conceptual, technical and methodological approaches. In reverse, the details of the non-human agent (protocol, pattern or paper) have to be accommodated to the wishes and expectations of the scientist. Through this interaction a situation of stability of knowledge is reached at the end of each phase. In the protocol phase, resistance is found in the antibody and tissue slices. In the phase of pattern deduction the resistance is in the pathological diagnosis of the tumors and the expectations and hypothesis with which the scientist had entered the project; in the criteria to be used for assigning the slices to a tenascin-C pattern; and in the responses of colleagues and supervisor. In the paper-writing phase the interaction is between the scientist and the scientific community which should take on board the knowledge from the research project. When stabilization of knowledge is obtained in one of the phases, the agents of resistance turn into allies in the next phase, giving support to accommodating the resistances in this later phase. Second, the stabilization of knowledge of the protocol is further enhanced when stabilization of the pattern is achieved; in addition, knowledge of the pattern is more definite when it has become stabilized and closed knowledge within the science community. [Copyright &y& Elsevier]

Objective:To detect immunoglobulin M (IgM) anti-Toxoplasma gondii antibodies and determine immunoglobulin G (IgG) titer and avidity in filter paper-embedded blood (FPEB) samples of pregnant women.Study Design:A total of 100 FPEB samples of pregnant women (30 positive and 70 negative) were analyzed for anti-T. gondii-specific IgM antibodies. Eleven and nine pairs of serum and FPEB samples were used to standardize IgG titration and avidity, respectively. Then, the correlation of avidity results was determined with 23 serum/FPEB pairs from IgG-positive cases.Result:IgM detection in FPEB was 92% sensitive and 100% specific. The titration of IgG antibodies in FPEB correlated with that of serum (r 0.9). Significant difference in avidity between the acute and the undetermined/chronic cases was observed in both samples. As expected, no correlation was found between IgM levels and avidity.Conclusion:The FPEB is useful to infer infection phase, and thus to speed clinical decisions in congenital toxoplasmosis management. [ABSTRACT FROM AUTHOR]

To assess and describe the use of rabies post-exposure prophylaxis (PEP) related to mass bat exposures (MBEs) in the literature and in the state of Rhode Island. Data on MBE events occurring between 2010 and 2016 from the Rhode Island Department of Health (RIDOH) were reviewed to determine PEP usage. For comparison, a systematic review was also performed by searching PubMed, EMBASE, Cochrane Library and Web of Science using the keywords 'rabies,' 'bat' and 'exposure.' There were three MBE events in Rhode Island between 2010 and 2016 in which groups of individuals were asleep during the potential exposure. As a result, RIDOH provided PEP to those involved in the event. In a systematic review of 12 published reports, a variety of settings were involved in MBEs: camping sites, a domestic flight, a neonatal intensive care unit and dormitories. The number of potential rabies exposures ranged from five to 1,429 people. PEP recommendations for assessed persons ranged from 0% to 100% across events (median 21%). The variation in PEP recommendations following a MBE may be dependent on medical need, past precedent or preference. Federal guidance for MBE is needed to add clarity and to minimize the variability in PEP recommendations for such events in the future., (© 2020 Blackwell Verlag GmbH.)

A combination of blotting of bacterial colonies on nitrocellulose paper discs and immunoenzymatic detection of bound antigens with specific monoclonal antibodies was used to detect and serotype Actinobacillus actinomycetemcomitans directly off the initial agar culture dish. The A. actinomycetemcomitans antigens, representative of specific colonies, were identified immunoenzymatically using monoclonal antibody specific for a species-specific antigen. The serotype of the bacteria in colonies was identified by dividing the blotting paper into sections and immunoenzymatically identifying the serotype antigens with serotype-specific monoclonal antibodies. This procedure provides for simple, rapid, sensitive and accurate identification and characterization of A. actinomycetemcomitans isolates from the initial isolation agar plates. [ABSTRACT FROM AUTHOR]

Most Human African Trypanosomiasis (HAT) control programmes in areas endemic for Trypanosoma brucei gambiense rely on a strategy of active mass screening with the Card Agglutination Test for Trypanosomiasis (CATT)/T. b. gambiense. We evaluated the performance, stability and reproducibility of the CATT/T. b. gambiense on blood-impregnated filter papers (CATT-FP) in Kajo-Keji County, South-Sudan, where some areas are inaccessible to mobile teams. The CATT-FP was performed with a group of 100 people with a positive CATT on whole blood including 17 confirmed HAT patients and the results were compared with the CATT on plasma (CATT-P). The CATT-FP was repeated on impregnated filter papers stored at ambient and refrigerated temperature for 1, 3, 7 and 14 days. Another 82 patients with HAT, including 78 with a positive parasitology, were tested with the CATT-FP and duplicate filter paper samples were sent to a reference laboratory to assess reproducibility. The CATT-FP was positive in 90 of 99 patients with HAT (sensitivity: 91%). It was less sensitive than the CATT-P (mean dilution difference: -2.5). There was no significant loss of sensitivity after storage for up to 14 days both at ambient and cool temperature. Reproducibility of the CATT-FP was found to be excellent (kappa: 0.84). The CATT-FP can therefore be recommended as a screening test for HAT in areas where the use of CATT-P is not possible. Further studies on larger population samples in different endemic foci are still needed before the CATT-FP can be recommended for universal use. [ABSTRACT FROM AUTHOR]

The ongoing SARS-CoV-2 pandemic was initially managed by non-pharmaceutical interventions such as diagnostic testing, isolation of positive cases, physical distancing and lockdowns. The advent of vaccines has provided crucial protection against SARS-CoV-2. Neutralising antibody (nAb) responses are a key correlate of protection, and therefore measuring nAb responses is essential for monitoring vaccine efficacy. Fingerstick dried blood spots (DBS) are ideal for use in large-scale sero-surveillance because they are inexpensive, offer the option of self-collection and can be transported and stored at ambient temperatures. Such advantages also make DBS appealing to use in resource-limited settings and in potential future pandemics. In this study, nAb responses in sera, venous blood and fingerstick blood stored on filter paper were measured. Samples were collected from SARS-CoV-2 acutely infected individuals, SARS-CoV-2 convalescent individuals and SARS-CoV-2 vaccinated individuals. Good agreement was observed between the nAb responses measured in eluted DBS and paired sera. Stability of nAb responses was also observed in sera stored on filter paper at room temperature for 28 days. Overall, this study provides support for the use of filter paper as a viable sample collection method to study nAb responses. [ABSTRACT FROM AUTHOR]

A newly modified paper-based enzyme-linked immunosorbent assay (P-ELISA) was established by immobilizing more proteins on the paper surface through an atom transfer radical polymerization (ATRP) reaction. In addition, introducing graphene oxide (GO) sheets, Au nanoparticles (AuNps) and two primary antibodies (Ab1s) led to signal amplification and cost reduction. [ABSTRACT FROM AUTHOR]

An inkjet-printed microfluidic paper-based analytical device (μPAD) for the detection of lactoferrin has been developed. The analyte concentration dependent fluorescence emission, caused by the sensitization of pre-deposited terbium (Tb3+) upon complexation with lactoferrin on the paper device, is captured using a digital camera. The dynamic response range (0.5–3 mg mL−1) and the limit of detection (0.30 mg mL−1) of the μPAD are suitable for the analysis of normal human tears and the detection of eye disorders. Finally, lactoferrin concentrations in human tear samples were analyzed by the μPADs and the assay results corresponded within 6% error to those obtained by an immunoassay (ELISA). The μPADs provide a simple, rapid and accurate method for lactoferrin detection in tear fluid. Results are obtained within 15 min of a single application of 2.5 μL of sample. To the best of our knowledge, this is the first report of a device for lactoferrin quantification relying neither on an immunoassay nor on high cost analytical instrumentation. [ABSTRACT FROM AUTHOR]