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COVID-19 first appeared in December of 2019 in Wuhan, China. Since then it has become a global pandemic. A robust and scalable diagnostics strategy is crucial for containing and monitoring the pandemic. RT-PCR is a known, reliable method for COVID-19 diagnostics which can differentiate between SARS-CoV-2 and other viruses. However, PCR is location dependent, time consuming and relatively expensive. Thus, there is a need for a more flexible method which may be produced in an off-the-shelf format and distributed more widely. Paper-based immunoassays can fulfill this function. Here we present the first steps towards a paper-based test which can differentiate between different between the Spike protein of various coronaviruses, SARS-CoV-1, SARS-CoV-2 and CoV-HKU1 with negligible cross reactivity for HCoV-OC43 and HCoV-229E in a single assay which takes less than 30 minutes. Furthermore, our test can distinguish between fractions of the same Spike protein. This is done by an altered assay design with four test line locations where each antigen builds a unique, identifiable binding pattern. The effect of several factors, such as running media, immunoprobe concentration and antigen interference is considered. We find that running media has a significant effect on the final binding pattern where human saliva provides results while human serum leads to the lowest signal quality.

This work reports the development of a rapid, simple and inexpensive colorimetric paper-based assay for the detection of the severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) humanized antibody. The paper device was prepared with lamination for easy sample handling and coated with the recombinant SARS-CoV-2 nucleocapsid antigen. This assay employed a colorimetric reaction, which is followed by horseradish peroxidase (HRP) conjugated detecting antibody in the presence of the 3,3',5,5'-tetramethylbenzidine (TMB) substrate. The colorimetric readout was evaluated and quantified for specificity and sensitivity. The characterization of this assay includes determining the linear regression curve, the limit of detection (LOD), the repeatability, and testing complex biological samples. We found that the LOD of the assay was 9.00 ng μL-1 (0.112 IU mL-1). The relative standard deviation was approximately 10% for a sample number of n = 3. We believe that our proof-of-concept assay has the potential to be developed for clinical screening of the SARS-CoV-2 humanized antibody as a tool to confirm infected active cases or to confirm SARS-CoV-2 immune cases during the process of vaccine development.

Background Brucellosis, as a serious zoonotic infectious disease, has been recognized as a re-emerging disease in the developing countries worldwide. In china, the incidence of brucellosis is increasing each year, seriously threatening the health of humans as well as animal populations. Despite a quite number of diagnostic methods currently being used for brucellosis, innovative technologies are still needed for its rapid and accurate diagnosis, especially in area where traditional diagnostic is unavailable. Methodology/Principal findings In this study, a total of 22 B cell linear epitopes were predicted from five Brucella outer membrane proteins (OMPs) using an immunoinformatic approach. These epitopes were then chemically synthesized, and with the method of indirect ELISA (iELISA), each of them displayed a certain degree of capability in identifying human brucellosis positive sera. Subsequently, a fusion protein consisting of the 22 predicted epitopes was prokaryotically expressed and used as diagnostic antigen in a newly established brucellosis testing method, nano-ZnO modified paper-based ELISA (nano-p-ELISA). According to the verifying test using a collection of sera collected from brucellosis and non-brucellosis patients, the sensitivity and specificity of multiepitope based nano-p-ELISA were 92.38% and 98.35% respectively. The positive predictive value was 98.26% and the negative predictive value was 91.67%. The multiepitope based fusion protein also displayed significantly higher specificity than Brucella lipopolysaccharide (LPS) antigen. Conclusions B cell epitopes are important candidates for serologically testing brucellosis. Multiepitope fusion protein based nano-p-ELISA displayed significantly sensitivity and specificity compared to Brucella LPS antigen. The strategy applied in this study will be helpful to develop rapid and accurate diagnostic method for brucellosis in human as well as animal populations., Author summary Brucellosis is one of the most important zoonosis in the world and has caused tremendous economic losses in agriculture and animal husbandry in many countries. Developing rapid, sensitive and specific diagnostic methods is very important for early detection and treatment of brucellosis patients. In this study, a novel diagnostic technique, nano-ZnO modified paper ELISA, was established. The antigen used in this technique was a fusion protein containing multiple B cell epitopes, which were predicted from Brucella major outer membrane proteins such as Bp26, Omp31, Omp16, Omp2b and Omp25. Comparing to traditional LPS antigen, this multiepitope based antigen displayed considerably higher sensitivity and higher specificity in laboratory. With the strategy described in this paper, more efficient epitopes and protein antigen can be identified in the future. Currently, LPS antigen is only prepared from live Brucella, while protein antigen can be produced in large quantities in prokaryotic expression system. In addition to nano-p-ELISA, this protein antigen can also be used for development other methods such as fluorescent polarization assay (FPA) and immunochromatographic assay (ICA) to meet the varied demand for brucellosis testing.

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., Highlights • 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.

The analysis of protein antigens as biomarkers in clinical samples is particularly helpful for the early diagnosis of diseases. However, this is difficult to accomplish owing to the presence of the antigens in trace amounts as well as the complexity of the matrixes in clinical samples. In this study, a lab-on-membrane platform that can be combined with paper spray ionization mass spectrometry was developed for the in situ high-throughput sensitive detection of the prostate-specific antigen (PSA). The sensitivity of the proposed platform was enhanced via two strategies: (1) the synthesis of a biotin-streptavidin scaffold caused an increase in the capturing efficiency of PSA by a factor of 5 and (2) the immobilization of a large number of mass tag molecules on the gold nanoparticles allowed for the amplification of the mass spectrometry signals. The limit of detection was approximately 3.0 pg mL-1. The selectivity to PSA was guaranteed by using an antibody-aptamer pairing sandwich immunoassay, and PSA detection was unaffected even when other protein antigens (carcinoembryonic antigen and carbohydrate antigen 125) were present. The modified membranes maintained their performance for at least 30 days when stored at 4 °C. Finally, analysis of human serum samples confirmed that the PSA concentration as determined using the proposed platform was consistent with that determined with a conventional chemiluminescent immunoassay. Thus, this PSA analyzing platform is suitable for prostate cancer diagnosis in clinical settings.

Caused by the tick-borne spirochete Borrelia burgdorferi, Lyme disease (LD) is the most common vector-borne infectious disease in North America and Europe. Though timely diagnosis and treatment are effective in preventing disease progression, current tests are insensitive in early stage LD, with a sensitivity of $400/test) and extended sample-to-answer timelines (>24 h). To address these challenges, we created a cost-effective and rapid point-of-care (POC) test for early-stage LD that assays for antibodies specific to seven Borrelia antigens and a synthetic peptide in a paper-based multiplexed vertical flow assay (xVFA). We trained a deep-learning-based diagnostic algorithm to select an optimal subset of antigen/peptide targets and then blindly tested our xVFA using human samples (N(+) = 42, N(-) = 54), achieving an area-under-the-curve (AUC), sensitivity, and specificity of 0.950, 90.5%, and 87.0%, respectively, outperforming previous LD POC tests. With batch-specific standardization and threshold tuning, the specificity of our blind-testing performance improved to 96.3%, with an AUC and sensitivity of 0.963 and 85.7%, respectively.

Identification of specific antibodies in patient plasma is an essential part of many diagnostic procedures and is critical for safe blood transfusion. Current techniques require laboratory infrastructure and long turnaround times which limits access to those nearby tertiary healthcare providers. Addressing this challenge, a novel and rapid paper-based antibody test is reported. We validate antibody detection with reverse blood typing using IgM antibodies and then generalise the validity by adapting to detect SARS CoV-2 (COVID-19) antibodies in patient serum samples. Reagent red blood cells (RBC) are first combined with the patient plasma containing the screened antibody and a droplet of the mixture is then deposited onto paper. The light intensity profile is analyzed to identify test results, which can be detected by eye and/or with image processing to allow full automation. The efficacy of this test to perform reverse blood typing is demonstrated and the performance and sensitivity of this test using different paper types and RBC reagents was investigated using clinical samples. As an example of the flexibility of this approach, we labeled the RBC reagent with an antibody-peptide conjugate to detect SARS CoV-2 (COVID-19) antibodies in patient serum samples. This concept could be generalized to any agglutination-based antibody diagnostics with blood plasma.

We developed an ultrasensitive gold nanoparticle-based multicomponent lateral-flow strip assay for the simultaneous detection of seventeen hormone drugs from three classes: nandrolone (NR) and its analogues, dexamethasone (DEX) and its analogues, and hexestrol (HES) and its analogues. The antibodies and coating antigens were selected for the assay and the multi-immunochromatographic strip (multi-ICS) exhibited a very low limit of detection (LOD). Quantitative results were obtained using a strip scan reader, giving LOD values of 0.06–4.85 ng mL−1 for NR and its analogues, 0.005–2.85 ng mL−1 for DEX and its analogues, and 0.03–2.14 ng mL−1 for HES and its analogues. The recovery rates from milk samples were 85.8–93.3% for NR, 78.8–87.5% for DEX, and 89.4–99.4% for HES. This multi-ICS assay therefore provides a useful tool for on-site detection and rapid initial screening of hormone drugs in biological samples.

COVID-19 has evolved into a global pandemic. Early and rapid detection is crucial to control of the SARS-CoV-2 transmission. While representing the gold standard for early diagnosis, nucleic acid tests for SARS-CoV-2 are often complicated and time-consuming. Serological rapid antibody tests are characterized by high rates of false-negative diagnoses, especially during early infection. Here, we developed a novel nanozyme-based chemiluminescence paper assay for rapid and sensitive detection of SARS-CoV-2 spike antigen, which integrates nanozyme and enzymatic chemiluminescence immunoassay with the lateral flow strip. The core of our paper test is a robust Co–Fe@hemin-peroxidase nanozyme that catalyzes chemiluminescence comparable with natural peroxidase HRP and thus amplifies immune reaction signal. The detection limit for recombinant spike antigen of SARS-CoV-2 was 0.1 ng/mL, with a linear range of 0.2-100 ng/mL. Moreover, the sensitivity of test for pseudovirus could reach 360 TCID50/mL, which was comparable with ELISA method. The strip recognized SARS-CoV-2 antigen specifically, and there was no cross reaction with other coronaviruses or influenza A subtypes. This testing can be completed within 16 min, much shorter compared to the usual 1-2 h required for currently used nucleic acid tests. Furthermore, signal detection is feasible using the camera of a standard smartphone. Ingredients for nanozyme synthesis are simple and readily available, considerably lowering the overall cost. In conclusion, our paper test provides a high-sensitive point-of-care testing (POCT) approach for SARS-CoV-2 antigen detection, which should greatly facilitate early screening of SARS-CoV-2 infections, and considerably lower the financial burden on national healthcare resources., Highlights • Point-of-care antigen tests for screening of SARS-CoV-2 infection were established. • Chemiluminescence improves sensitivity of paper test and benefits early screening. • Nanozyme with high peroxidase activity and stability catalyzes chemiluminescence. • Nanozyme chemiluminescence paper test brings high efficiency and low cost.

Myxovirus protein A (MxA) is a biomarker that can be used to distinguish between viral and bacterial infections. While MxA lateral flow assays (LFAs) have been successfully used for viral vs. bacterial differential diagnosis for children, the clinically relevant level of MxA for adults has been reported to be 100 times lower, which is too low for traditional LFAs. We present results applying the use of surface enhanced Raman spectroscopy (SERS) to detect MxA. AuAg nanoshells (AuAg NSs) were used to enhance the Raman signal of mercaptobenzoic acid (4-MBA), enabling readout by SERS. The AuAg NSs were conjugated to antibodies for the biomarker of interest, resulting in a “nanotag”, that could be used in a dipstick immunoassay for detection. We first optimized the nanotag parameters using anti-human IgG/human IgG as a model antibody/antigen system, and then demonstrated detection of MxA using anti-MxA antibodies. We show that SERS readout of immunoassays for MxA can quantify MxA levels at clinically relevant levels for adult viral infection., This work was carried out within the “Doctorat en Quìmica” PhD programme of Universitat Autònoma de Barcelona, supported by the Spanish MINECO (MAT2015-70725-R) and from the Catalan Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) (2017-SGR-143). Financial support from the HISENTS (685817) Project financed by the European Community under H20202 Capacities Programme is gratefully acknowledged. It was also funded by the CERCA Program/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV2201320295. CRQ was funded by a Rafael del Pino Fellowship, a UMass Boston Beacon Student Success Fellowship and a Goranson Award. BML was funded by a fellowship from Ronald E. McNair grant (P217A170241), Beacon Student Success Fellowship, and an Oracle/Sanofi student fellowship.

Routine childhood vaccinations are key for the protection of children from a variety of serious and potentially fatal diseases. Current pediatric vaccine schedules mainly cover active vaccines. Active vaccination in infants is a highly effective approach against several infectious diseases; however, thus far, for some important viral pathogens, including respiratory syncytial virus (RSV), vaccine development and license by healthcare authorities have not been accomplished. Nirsevimab is a human-derived, highly potent monoclonal antibody (mAb) with an extended half-life for RSV prophylaxis in all infants. In this manuscript, we consider the potential implications for the introduction of an anti-viral mAb, such as nirsevimab, into the routine pediatric vaccine schedule, as well as considerations for coadministration. Specifically, we present evidence on the general mechanism of action of anti-viral mAbs and experience with palivizumab, the only approved mAb for the prevention of RSV infection in preterm infants, infants with chronic lung disease of prematurity and certain infants with hemodynamically significant heart disease. Palivizumab has been used for over two decades in infants who also receive routine vaccinations without any alerts concerning the safety and efficacy of coadministration. Immunization guidelines (Advisory Committee on Immunization Practices, Joint Committee on Vaccination and Immunization, National Advisory Committee on Immunization, Centers for Disease Control and Prevention, American Academy of Pediatrics, The Association of the Scientific Medical Societies in Germany) support coadministration of palivizumab with routine pediatric vaccines, noting that immunobiologics, such as palivizumab, do not interfere with the immune response to licensed live or inactivated active vaccines. Based on the mechanism of action of the new generation of anti-viral mAbs, such as nirsevimab, which is highly specific targeting viral antigenic sites, it is unlikely that it could interfere with the immune response to other vaccines. Taken together, we anticipate that nirsevimab could be concomitantly administered to infants with routine pediatric vaccines during the same clinic visit.

Diagnostic testing of blood samples for parasite antigen Og4C3 is used to assess Wuchereria bancrofti in endemic populations. However, the Tropbio ELISA recommends that plasma and dried blood spots (DBS) prepared using filter paper be used at different dilutions, making it uncertain whether these two methods and dilutions give similar results, especially at low levels of residual infection or resurgence during the post-program phase. We compared results obtained using samples of plasma and DBS taken simultaneously from 104 young adults in Myanmar in 2014, of whom 50 (48.1%) were positive for filariasis antigen by rapid antigen test. Results from DBS tests at recommended dilution were significantly lower than results from plasma tested at recommended dilution, with comparisons between plasma and DBS at unmatched dilutions yielding low sensitivity and negative predictive values of 60.0% and 70.6% respectively. While collection of capillary blood on DBS is cheaper and easier to perform than collecting plasma or serum, and does not need to be stored frozen, dilutions between different versions of the test must be reconciled or an adjustment factor applied.

The recently emerged coronavirus disease COVID-19 has now evolved into a global pandemic. Early detection is crucial for its effective control. Nucleic acid testing for viral pathogen and serological testing for host antibodies are playing important roles in current COVID-19 diagnosis. However, while nucleic acid testing is complicated, facility-restricted and time-consuming, antibody testing may result in high rates of false-negative diagnoses, especially during the early stages of viral infection. Thus, a more rapid and reliable test for both early COVID-19 diagnosis and whole-population screening is urgently needed. Here, we developed a novel nanozyme-based chemiluminescence paper assay for rapid and high-sensitive testing of SARS-CoV-2 spike antigen. Our paper test uses a newly established peroxidase-mimic Co-Fe@hemin nanozyme instead of natural HRP that catalytically amplifies the chemiluminescent signal, allowing for target concentrations to be as low as 0.1 ng/ml. Furthermore, our nanozyme-based chemiluminescence test exhibits a linear range that is 32-fold wider compared to ELISA tests. Importantly, testing is completed in less than 16 min, compared to 1-2 h required for ELISA or nucleic acid tests. Critically, signal detection is feasible using a smartphone camera. Ingredients for our test are simple and readily available, rendering overall cost considerably lower than those used in current diagnoses. In conclusion, our novel test provides a high-sensitive, point-of-care testing (POCT) approach for SARS-CoV-2 antigen detection, which should greatly increase current early screening capacities for suspected infections, and considerably lower demand for national healthcare resources.

In the light of the current global situation, a new inexpensive rapid test for COVID-19 has been conceptually developed and the details are outlined in this document. Given the lack of approved vaccines and anti-viral drugs, the importance of quick diagnoses cannot be understated. Research suggest that antigen material should be readily available in serological samples from the onset until the end of infection. Hence, a direct antigen rapid test, such as the one to be presented here, has the advantage of not being dependent on immune response and the availability of specific immunoglobulin antibodies. Diagnosis should therefore be possible from the first day of symptoms. This is very significant and means that acute diagnosis is theoretically possible.

Antimalarial IgG and IgM were detected by enzyme immunoassay in finger‐stick blood samples collected in capillary tubes and also spotted onto Whatman filter paper. Assay was performed in 92 blood samples obtained from 53 falciparum malaria patients, representing 23 fever cases (malaria negative) and 16 healthy individuals. A simple indirect ELISA was done using Plasmodium falciparum lysate and MSP119 peptide as antigens. Total IgG and IgM contents were also estimated in individual sera and filter paper eluate by single radial immunodiffusion (SRID). Assay results of both serum and filter paper eluates were compared. The sensitivity and specificity of the assays for IgG measurement were comparable between serum and filter paper eluates (P

The quantification of human immunodeficiency virus type 1 (HIV-1) by an assay measuring heat-dissociated (HD) p24 antigen (Ag) in specimens of whole blood and plasma stored on filter paper, and of plasma stored in tubes, was compared to HIV-1 RNA plasma levels determined by real-time reverse transcription (RT)-PCR. The stability of p24 Ag on filter paper under conditions simulating specimen transport was also evaluated. The HD p24 Ag in both plasma and whole-blood specimens stored on filter paper correlated with plasma HIV-1 RNA levels (Spearman rank ρ = 0.74 [ P < 0.0001] and ρ = 0.56 [ P = 0.0001], respectively). The sensitivity of the HD p24 Ag assay was similar when plasma and whole blood on filter paper were contrasted to the real-time RT-PCR assay (80% versus 82.5% and 78.6% versus 83.3%, respectively). However, while the specificity of the HD p24 Ag assay of plasma on filter paper was 100%, the specificity was diminished in whole-blood specimens. The storage of specimens on filter paper for 2 weeks at 37°C, 24°C, or 0°C did not alter the detection or quantification of HD p24 Ag. These results suggest that transport and storage of plasma on filter paper and quantification of HD p24 Ag may be a reliable method for HIV-1 load monitoring.

Background: To screen for congenital toxoplasmosis, we developed a time-resolved immunofluorometric assay for the simultaneous detection of Toxoplasma gondii-specific IgM and IgA in filter-paper samples collected from newborns 4–7 days after birth. Methods: The assay was performed on the AutoDELFIATM, and results were calculated based on the ToxoM WHO Third International Reference Serum. Comparison with an in-house μ-capture immunoassay was carried out retrospectively on filter-paper samples from children with confirmed congenital toxoplasmosis. Prospectively the assay was compared with a μ-capture immunoassay on 68 394 samples and a commercially available assay on another 69 467 samples. Before serum was requested from the newborn, positive samples were tested for IgA and IgM separately and in an IgM-immunosorbent agglutination assay developed for filter-paper samples. Results: Intra- and interassay variations (CVs) were 8% and 16%, respectively. The cutoff of 5 units/mL produced a 0.5% retest rate. The assay detected 13 of 18 (72%) samples from newborns diagnosed with congenital toxoplasmosis in the retrospective study. Prospectively, the assay identified 24 newborns who were later diagnosed with congenital toxoplasmosis. Results for all 24 cases were positive by the respective comparison method. No cases were detected solely by the IgA antibodies in the sample. Conclusion: Neonatal screening for congenital toxoplasmosis can be automated by use of purified europium-labeled antigen for detection of T. gondii-specific IgM and IgA eluted from filter-paper samples.

Background Point-of-care testing and diagnosis of HIV acute infections play important roles in preventing transmission, but HIV rapid diagnosis tests have poor capacity to detect early infections. Filter paper can be used for capillary blood collection and HIV testing using 4th generation immunoassays. Objectives Antigen/antibody combined immunoassays were evaluated for their capacity to identify early HIV infections using filter paper in comparison with rapid test. Study design Thirty nine serum samples collected from HIV seroconverters were spotted onto filter paper and tested by the Roche Elecsys ® HIV Combi PT test and the DiaSorin Liaison XL Murex HIV Ab/Ag assay. Results Fourth generation immunoassays identified 34 out of 39 HIV early infections using dried serum spot, whereas the Determine™ HIV-1/2 rapid test detected 24 out of 39 HIV positive serum (87.2% vs 61.5% respectively, p = 0.009). p24 antigen was detected by the Liaison XL in 19 dried serum samples (48.7%). In the group characterized by a negative western blot, 7 out of 8 (87.5%) and 6 out of 8 (75.0%) samples were found positive for HIV using the Elecsys and the Liaison XL, respectively. None of these eight samples classified in this group of early acute infections were found positive by the rapid test. Conclusion Fourth generation Ag/Ab immunoassays performed on dried serum spot had good performance for HIV testing during the early phases of HIV infection. This method may be useful to detect HIV early infections in hard-to-reach populations and individuals living in remote areas before rapid tests become positive.

Background and Objectives: Paper biodiagnostics for blood typing are novel, cheap, fast and easy to use. Agglutinated red blood cells cannot travel through the porous structure of paper, indicating a positive antibody-antigen interaction has occurred. Conversely, non-agglutinated blood can disperse and wick through the paper structure with the ease to indicate a negative result. This principle has been demonstrated to detect blood group phenotypes: ABO and RhD. However, typing for red blood cell antigens such as Rh, Kell, Duffy and Kidd has not yet been explored on paper. Materials and Methods: Two paper testing methods - an elution and a direct flow-through method - were investigated to detect red blood cell antigens excluding the ABO system and RhD. Antigens explored include the following: C, c, E, e, K, k, Fy a , Fy b , Jk a , Jk b , M, N, S and s, P1, Le a and Le b . The variables tested include the following: reaction time and reagent concentration. The importance of antibody type/structure for successful agglutination on paper was confirmed. Results: Some blood group phenotypes showed less agglutination due to weaker antibody-antigen interactions. Most blood groups with antibodies available as IgM, such as C, c, E, e, K and k, and Jk a and Jk b , and P1, were successful using both methods. However, other blood groups, especially those with antibodies only available as polyclonal antibodies, were unsuccessful and require further scrutiny. Conclusion: Paper can be used as an alternative blood grouping diagnostic tool for selected blood group phenotypes.

In this work, a novel paper-based electrochemiluminescence (ECL) immunosensor for ultrasensitive and selective detection of corresponding antigens on living cells was developed employing AuPd nanoparticles as a signal amplifier and macroporous Au-paper working electrodes (Au-PWE) for efficient cell capture. The porous AuPd nanoparticles are chosen as label nanomaterials due to their controllable three-dimensional porosity and peroxidase like activity, large surface area, superior conductivity, and favorable catalytic activity to H2O2 which could enhance the ECL intensity for signal amplification. CdTe QDs and luminol groups as ECL probes were linked with the antibodies to recognize the corresponding antigens on the cell surface and the wide potential range between them compared to conventional antigens sensors could prevent interfacing with each other. Using this strategy, human carcinoembryonic (CEA) and alphafetoprotein (AFP) antigens on living MCF-7 cancer cells as models were quantified serially through a potential scanning way. Significantly, this strategy may be quite promising in cancer early diagnosis due to the excellent analytical performance.

It is increasingly accepted that sunscreens should protect against ultraviolet radiation (UVR)-induced immunosuppression, with an index of protection that can be compared with the sun protection factor (SPF). Five groups of immunoprotection researchers met to discuss the status of immune protection factor (IPF) evaluation in human skin in vivo. Current methods rely on a suncreen's inhibition of UVR-induced local suppression of the contact hypersensitivity (CHS) response or the delayed-type hypersensitivity (DTH) response, using either the induction or the elicitation arms of these responses. The induction arm of the CHS response has the advantage of being sensitive to a single sub-erythemal exposure of solar-simulating radiation (SSR) that allows a direct comparison with the SPF. This approach, which necessitates sensitization, requires a large number of volunteers and is too labor intensive and time consuming to become a routine method. The elicitation arm of the CHS or DTH responses exploits prior sensitization to contact or recall antigens and has the advantage of being possible to apply on small groups of volunteers. Some current protocols, however, require repeat SSR exposures, which invalidates a direct comparison with SPF that is based on a single exposure. There is a need for a new simpler method of IPF that will have to be validated against existing models.

Background: In vitro stimulation of whole blood or isolated blood cells with specific antigens is used for several purposes. Immediately following incubation with antigens, samples have to be centrifuged to stop the reactions by remaining cells and the supernatant refrigerated or analysed directly to preserve the analytes of interest, which makes samples difficult to prepare outside laboratories. We have tested whether spotting whole blood on filter paper after activation can be used in one of the tests for Mycobacterium tuberculosis infection (MTI), the QuantiFERON®-TB Gold In Tube test (QFT), where the spotting technique can make it suitable for use in locations without facilities like a centrifuge and a refrigerator. Materials and methods: Samples from 22 individuals undergoing screening for MTI and 10 healthy controls were incubated, centrifuged and IFN-γ measured by Enzyme-linked immunosorbent assay (ELISA), as described in the kit insert. In parallel, activated blood was spotted on filter paper (Schleicher & Schuell) and dried. The dried blood spot samples were analysed for 21 inflammatory markers with an in-house assay based on Luminex technology. Results: Our multiplex measurements of inflammatory markers in samples from suspected MTI patients confirmed the IFN-γ findings in the QFT. IL-2, GM-CSF, IL-5, and IL-1β were also found as useful markers for MTI. We were not able to distinguish between active tuberculosis and latent MTI. Conclusion: Applying blood on filter paper after incubation makes in vitro stimulation tests feasible in locations where heat and electricity is unavailable.

Bioactive papers are usually challenged by four major limitations: sensitivity, selectivity, simplicity and strength (4S). Gold nanoparticles (AuNPs) treated paper has previously been demonstrated as a Surface Enhanced Raman Scattering (SERS) active substrate, capable of addressing the 4S issues. In this study, AuNPs on paper substrate were functionalized by a series of biomolecules to develop a generic SERS platform for antibody-antigen detection. The functionalization steps were performed by taking advantage of the high affinity association between Streptomyces avidinii-derived protein, streptavidin, and biotin. Streptavidin was firstly bound onto the AuNPs treated paper using biotinylated-thiol. Subsequently, desired biotinylated-antibody was bound onto the streptavidin. SERS spectra of each functionalization step were obtained to ensure specific adsorption of the bio-molecules. The binding interaction of the antibody with its specific antigen was detected using SERS. Shifts of Raman band associated with α-helix and β-sheet structures indicated structural modification of the antibody upon interaction with its antigen. Predominant tryptophan and tyrosine residue bands were also detected, confirming the presence of antigen. Reproducible spectral features were quantified as AuNP papers were subjected to different concentrations of antigen; the spectra intensity increased as a function of the antigen concentration. The retention of AuNPs on paper remained constant after all the consecutive washing and functionalization steps. The feasibility of AuNPs paper as a low-cost and generic SERS platform for bio-diagnostic applications was demonstrated.

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 42 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.

BACKGROUND Lewis serologic reagents frequently give inaccurate phenotyping results. Furthermore these serologic reagents are often used in nonserologic assays such as inhibition and immunohistochemistry. In both scenarios knowledge of the fine specificity and cross-reactivity of these reagents will improve the quality of results obtained. STUDY DESIGN AND METHODS A range of contemporary and historical workshop and developmental Lewis reagents including mouse monoclonal (MoAb) and human and goat polyclonal (PoAb) reagents were evaluated. All were evaluated both against Lewis kodecytes expressing only single Le(a) , Le(b) , ALe(b) , BLe(b) , Le(x) , Le(y) , ALe(y) , or BLe(y) antigens and against the same antigens inkjet printed on a paper-based microplate and analyzed by enzyme immunoassay. Nine clinical samples were also evaluated. A kodecyte antigen dilution sensitivity assay was used to establish the ratio of Le(b) antigen between group A1 /A2 and O RBCs. RESULTS A continuum of cross-reactivity from Le(x) through to H was observed with MoAbs. All PoAb and few MoAb anti-Le(a) samples and reagents cross-reacted to some degree with Le(b) antigen. Some PoAb and MoAb anti-Le(b) did not cross-react with Le(a) . All polyclonal goat anti-Le(b) reagents showed substantial activity against ALe(b) and BLe(b) , while no MoAb reagent had this activity. A1 RBCs had less than half the Le(b) antigen of A2 /O RBCs. CONCLUSIONS Substantial cross-reactivity of both MoAbs and PoAbs with related antigens highlights the risks of using serologic reagents in nonserologic assays or against synthetic antigens. The lack of ALe(b) activity in anti-Le(b) MoAbs explains their poor performance against blood group A1 Le(a-b+) phenotypes.

Serological diagnosis of filariasis is generally known to be more reliable than detection of microfilariae. The recently developed Og4C3 enzyme-linked immunosorbent assay (ELISA) for detecting Wuchereria bancrofti circulating antigen has been shown to be very sensitive in diagnosing filiariasis using serum samples. The commercially available form of this ELISA, using whole blood collected on filter paper, has not been validated independently. We evaluated the sensitivity of this new method against standard 20 microL night blood films in 1808 paired samples from 18 communities in different endemic areas of Ghana. The diagnostic performance of the method was consistently low in all but 2 communities (sensitivity = 50.3%). This method of diagnosing filariasis is not suitable for field use in its present form.

BackgroundA simple filter paper method was developed for, the transport and storage of monoclonal antibodies (Mabs) at room temperature or -20°C after spotting on filter paper, for subsequent serotyping of outer membrane antigens ofN.meningitidisby dot-blot ELISA.MethodsMonoclonal antibodies (Mabs) were spotted within a 0.5–1 cm diameter area of Whatman grade 903 paper, which were stored individually at room temperature or at -20°C. These MAbs were stored and analyzed after periods of one week, 4 weeks, 12 months, or 13 years in the case of frozen Mab aliquots, or after 4 weeks at -20°C or at room temperature (RT) in the case of Mabs dried on filter paper strips. Assays were performed in parallel using dot-blot ELISA. In addition to the MAbs specific for serotyping class 1, 2 or 3, we used a larger number of Mabs for polysaccharides, lipooligosaccharides (LOS), class 5 and cross-reactive antigens for native outer membrane ofN.meningitidis. The Mabs dried on filter paper were eluted with phosphate-buffered saline (PBS) containing 0.2% gelatin.ResultsMabs of the isotypes IgG and IgM dried on filter papers were not affected by duration of storage. The detection by serotyping Mabs was generally consistent for dried filter paper MAb samples stored frozen for over 1 year at -20°C, and although decreased reactive antibody titers were found after storage, this did not interfere with the specificity of the Mabs used after 13 years as dry spots on filter paper.ConclusionThe use of filter paper is an inexpensive and convenient method for collecting, storing, and transporting Mab samples for serotyping studies. In addition, the samples occupy little space and can be readily transported without freezing. The efficiency of using immunoglobulin G (IgG) or M (IgM) eluted was found to be consistent with measurement of IgG or IgM titers in most corresponding, ascites Mabs stored frozen for over 1 year. The application of meningococcal typing methods and designations depend on the question being asked.

Proper food choices are part of preventing or reducing the risk of dental caries and periodontal disease. A significant association has been proven between oral diseases and the incidence of systemic diseases. Obesity, just like smoking, is one of the major risk factors for oral disease and is a serious social problem that has reached epidemic proportions in many developed countries. The results of studies on periodontitis confirm the relationship between the values of body mass index (BMI) and the prevalence of periodontal diseases. Adipose tissue is an active endocrine organ and it performs many important functions in the body, such as thermal isolation and protection, storage, and secretion. Many cytokines are secreted proportionally to the amount of fat present and are actively involved in the metabolism of the whole system, including the functioning of the immune system. Therefore, obesity may alter the response of the host to the antigens derived from bacterial plaque, and thus cause disturbances in the inflammatory response in the course of periodontal disease.

The objective of the present work was to standardize and evaluate indirect plate and dot- enzyme linked immunosorbent assay (ELISA) using purified Paramphistomum epiclitum homologous antigens in the small ruminants. Electrophoretic separation of somatic antigen (PeSAg) in reducing condition on 15% polyacrylamide gel resolved into 16 proteins of the molecular weight ranging from 14 -100 kDa. Two step ethanolic precipitation of supernatant of in-vitro culture of the fluke yielded P. epiclitum excretory-secretory antigen (PeESAg) of molecular weight 28 kDa. The animals (Goats=123; Sheep=91) were broadly kept into post-mortem and faecal examined groups. At many occasion the PeSAg found to cross reacts with other helminths parasites thus minimizing the specificity of the tests and antigens. There was no any direct correlation between the parasites load and ELISA reactivity pattern. The noted prevalence rate after combining the results of post-mortem examination and PeESAg based ELISA (plate and paper/ dot) was 30.08% (37/123) in goats and 28.57% (26/91) in sheep. While using PeESAg, the calculated overall sensitivity% was 92.86 (goats)/ 100 (sheep) in both plate and dot-ELISA, specificity% was 91.58 (goats)/ 91.55 (sheep) in plate ELISA while 88.42 (goats)/ 92.96 (sheep) in dot-ELISA, positive predictive value% was 76.47 (goats)/ 76.92 (sheep) in plate ELISA while 70.27 (goats)/ 80 (sheep) in dot-ELISA and negative predictive value% was 97.75 (goats)/ 100 (sheep) in plate ELISA while 97.67 (goats)/ 100 (sheep) in dot-ELISA, these values were optimum for the field sera sample so the tests and PeESAg can be recommended for the detection P. epiclitum infection in the small ruminants.

Background Monoclonal (MoAb) reagents are routinely used and are usually very reliable for the serologic determination of ABO blood types. However, the fine specificity and cross-reactivity of these reagents are often unknown, particularly against synthetic antigens used in some diagnostic assays. If nonserologic assays or very sensitive techniques other than those specifically prescribed by the manufacturer are used, then there is a risk of incorrect interpretation of results. Study Design and Methods Forty-seven MoAbs and two polyclonal ABO reagents were tested against red blood cell (RBC) kodecytes prepared with A trisaccharide, A Type 1, A Type 2, A Type 3, A Type 4, B trisaccharide, B Type 1, B Type 2, acquired B trisaccharide, and Lea trisaccharide function-spacer-lipid (FSL) constructs. Natural RBCs were tested in parallel. In addition these FSL constructs were printed onto paper with a desktop inkjet printer and used in a novel immunoassay that identifies reactivity through the appearance of alphanumeric characters. Results Mapping of MoAbs with kodecytes and printed FSL constructs revealed a series of broad recognition patterns. All ABO MoAbs tested were reactive with the RBC dominant Type 2 ABO antigens. Unexpectedly some anti-A reagents were reactive against the B Type 1 antigen, while others were poorly reactive with trisaccharide antigens. Conclusions All ABO MoAbs detect the RBC dominant Type 2 ABO antigens; however, some reagents may show minor reactivity with inappropriate blood group antigens, which needs to be considered when using these reagents in alternative or highly sensitive analytic systems.

This week’s article highlights the contribution of T cell reactivity to nonviral antigens to the success of adoptive T cell transfer in treating a virus-driven cancer.

The Og4C3 enzyme-linked immunosorbent assay (ELISA) to detect circulating Wuchereria bancrofti antigen uses 50 microL of serum. In this study, a whole blood sample absorbed on filter paper was tested as a substitute for serum. Serum samples were obtained from 60 Sri Lankan subjects by venepuncture and finger-prick blood samples from the same individuals were directly absorbed on filter paper. Og4C3 ELISAs using serum and filter paper blood were compared. Despite the fact that the estimated amount of serum available for the ELISA with filter paper blood was only one-fifth of that available when serum was used, the 2 ELISAs gave almost identical results. Of the 39 positive serum samples, 38 were detected using filter paper blood. Employing the ELISA using filter paper blood, 619 people in Matara, Sri Lanka, were examined for antigenaemia. The positivity rate was 22.5%, 3.1 times higher than the rate of microfilaraemia detected by examination of 60 microL blood films.

Whole saliva samples collected from HIV-1 seropositive subjects by simple spitting without using any devices were dried on filter paper strips, from which filter paper discs of 3-mm diameter were punched out. The eluates of the discs were subjected to the immune complex transfer enzyme immunoassay for antibody IgG to HIV-1 using recombinant reverse transcriptase of HIV-1 as antigen and a two-site enzyme immunoassay for whole IgG. The signals for antibody IgG to HIV-1 and the amounts of whole IgG obtained with one disc per assay tube were 126-290% of those obtained with 1 microliter of whole saliva samples, provided that filter paper strips were treated with nonspecific rabbit serum prior to drying whole saliva samples and that filter paper discs were tested within a few days after drying whole saliva samples. From these results, diagnosis of HIV-1 infection was indicated to be possible with whole saliva samples dried on filter papers, since the diagnosis was previously shown to be possible with 1 microliter of whole saliva samples. The test for HIV-1 infection with whole saliva samples dried on filter papers was suggested to be useful for various purposes.

There is a striking gender difference in atherosclerotic vascular disease. For decades, testosterone was considered detrimental to the cardiovascular system. Recent studies, however, have presented some alternative results. The aim of this study was to evaluate the effect of testosterone, using physiological and supraphysiological concentrations, on antigen and mRNA levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), and tissue factor pathway inhibitor (TFPI) released by human umbilical vein endothelial cells and to investigate the cellular mechanism. Cells within 2–3 passages were cultured in 25 cm2 flasks or plated onto 96-well plates with a density of about 1 × 105 cells/mL as recommended. The cells were incubated in the presence or absence of testosterone (3, 30, 3 × 103, 3 × 104 nmol/L) for 48 h. Levels of tPA, PAI-1, and TFPI antigen were assayed with ELISA kits. Reverse transcriptase PCR was carried out to detect tPA, PAI-1, and TFPI mRNA levels. Cells were incubated in androgen-receptor antagonist (flutamide 10 µmol/L) or aromatase inhibitor (aminoglutethimide 50 µmol/L) for 3 h, and then the experiments were repeated. Testosterone at a physiologic concentration (30 nmol/L) increased the antigen levels of tPA and TFPI significantly (P < 0.05). However, tPA and TFPI levels were markedly reduced (P < 0.05) at a larger dose (3 × 104 nmol/L). On the other hand, PAI-1 antigen levels decreased significantly at the testosterone concentrations ranging from 3 to 3 × 104 nmol/L (P < 0.05). The change in the levels of tPA and TFPI were reflected in the corresponding change in mRNA levels. Flutamide attenuated the effect of testosterone at physiological concentration (30 nmol/L). The results demonstrated that testosterone at physiological concentrations may have a beneficial influence on the haemostatic system through enhancement of anticoagulant activity, resulting from stimulation of TFPI and tPA expression and inhibition of PAI-1 secretion by the endothelium.

The signaling lymphocyte-activating molecule (SLAM) family immunoreceptors are expressed in a wide array of immune cells, including both T and B lymphocytes. By virtue of their ability to transduce tyrosine phosphorylation signals through the so-called ITSM (immunoreceptor tyrosine-based switch motif) sequences, they play an important part in regulating both innate and adaptive immune responses. The critical role of the SLAM immunoreceptors in mediating normal immune reactions was highlighted in recent findings that SAP, a SLAM-associated protein, modulates the activities of various immune cells through interactions with different members of the SLAM family expressed in these cells. Importantly, mutations or deletions of the sap gene in humans result in the X-linked lymphoproliferative syndrome. In this review, we summarize current knowledge and survey the latest developments in signal transduction events triggered by the activation of SLAM family receptors in different cell types.

Adults diagnosed with Glioblastoma multiforme (GBM) are frequently faced with a 7% chance of surviving 2 years compared with pediatric patients with GBM who have a 26% survival rate. Our recent screen of possible glioma-associated antigen precursor protein (TAPP) profiles displayed from different types of pediatric brain tumors showed that pediatric patients contained a subset of the tumor antigens displayed by adult GBM patients. Adult GBM possess at least 27 tumor antigens that can potentially stimulate T cell immune responses, suggesting that these tumors are quite antigenic. In contrast, pediatric brain tumors only expressed nine tumor antigens with mRNA levels that were equivalent to those displayed by adult GBM. These tumor-associated antigens could be used as possible targets of therapeutic immunization for pediatric brain cancer patients. Children have developing immune systems that peak at puberty. An immune response mounted by these pediatric patients might account for their extended life spans, even though the pediatric brain tumors express far fewer total tumor-associated antigens. Here we present a hypothesis that pediatric brain tumor patients might be the best patients to show that immunotherapy can be used to successfully treat established cancers. We speculate that immunotherapy should include a panel of tumor antigens that might prevent the out-growth of more malignant tumor cells and thereby prevent the brain tumor relapse. Thus, pediatric brain tumor patients might provide an opportunity to prove the concept of immunoprevention.

Highly multiplexed immunoassays could allow convenient screening of hundreds or thousands of protein biomarkers simultaneously in a clinical sample such as serum or plasma, potentially allowing improved diagnostic accuracy and clinical management of many conditions such as autoimmune disorders, infections, and several cancers. Currently, antibody microarray-based tests are limited in part due to cross reactivity from detection antibody reagents. Here we present a strategy that reduces the cross-reactivity between nanoparticle-bound reporter antibodies through the application of ultrasound energy. By this concept, it was possible to achieve a sensitivity 10(3)-fold (5 pg mL(-1)) lower than when no ultrasound was applied (50 ng mL(-1)) for the simultaneous detection of three different antigens. The detection limits and variability achieved with this technique rival those obtained with other types of multiplex sandwich assays.

Eight pure triterpenoid saponin compounds isolated from the root of Polygala senega L., a plant indigenous to the Canadian prairies, were evaluated for their immunological activity in mouse models. The specific antibody responses of the IgG2asubclass increased significantly when isolated P. senega saponins were used as adjuvants in the immunization of mice with OVA antigen. In addition, increased IL-2 levels were observed in spleen cell cultures from P. senega saponin-immunized mice after in vitro secondary antigen stimulation. The saponins were tested for their toxicity in mice by using a haemolytic activity assay and found to be less toxic than Quillaja saponaria saponins that have long been used as adjuvants in vaccine formulations. This study has shown the potential of P. senega saponins to be considered as a natural source of vaccine adjuvants with biological activity equivalent to the current commercially available saponin adjuvants.

This paper describes the development of an inexpensive, but robust and easy-to-use point-of-care diagnostic device that can be used for the detection of dengue fever at the molecular level (i.e., the detection of dengue virus via using a piece of paper). To date, the clinical diagnosis of dengue fever mainly relies on ELISA-based examinations for a specific antigen. However, the protein-based diagnostics is at the relatively late stage, and it is needed to develop a simple and low-cost diagnostic device for the detection of dengue fever at the early stage after the infection. Here, we have developed a procedure for monitoring dengue virus serotype 2 RNA (in the buffer system), including: i) amplifying the nucleic acids via RT-LAMP (reverse transcription loop-mediated isothermal amplification), and ii) examining the amplified products via a colorimetric assay in paper. We have demonstrated the ability to amplify dengue virus via RT-LAMP with the virus concentration of 60 PFU/mL; the current results indicated that this paper-based diagnostic device was capable of detecting the RT-LAMP products in the buffer system with the concentration of 300 ng/mL.

Determinants of Toxoplasma gondii virulence are still unknown, although genetic markers associated with T. gondii pathogenicity or host susceptibility to infection have been identified. To define indicator proteins of mouse virulence, type I strain parasites were attenuated by continuous passage in fibroblast culture and compared with the parental strain passaged in mice. The loss of acute virulence, evident by a 1000-fold higher pathogen dose causing 100% lethality in mice correlated with a less efficient infection of inflammatory cells at the site of inoculation, while parasite proliferation and invasiveness in vitro proved unimpaired. Infection with the attenuated parasites elicited earlier local interleukin-12 and strong interferon-gamma responses in vivo, although the activity that triggers interleukin-12 secretion in macrophages is reduced in the attenuated compared to the virulent strain variant. The interleukin-12-inducing T. gondii stimulus was identified as a protein(s) present in tachyzoite excretory products. Comparative proteome analysis combined with immunodetection and quantitation of a variety of T. gondii antigens indicated that the steady-state levels of actin, catalase, microneme protein 5, as well as dense granule proteins 1, 2, 3, 4, 5, 7, 8 and nucleoside triphosphate hydrolase 1 are decreased in the attenuated phenotype, whereas the surface antigen 1 and rhoptry protein 1 are produced at a similar level by virulent and attenuated parasites. In conclusion, these findings reveal a correlation between the efficient establishment of T. gondii infection in vivo and parasite synthesis of actin, catalase and several excretory proteins, and thus postulate a role for these molecules in acute virulence.

Dengue fever is one of the acute flavivrus-borne infectious diseases caused by dengue virus with four serotypes. To date, there are no efficient diagnostic tools available for monitoring the disease activity of dengue fever. It is needed to develop a diagnostic device with the characteristics of inexpensiveness, ease-to-use and robustness for the detection of dengue fever. In this study, we have developed an ELISA-based diagnostic device prepared via wax printing method through using filter paper. The antigens that we targeted to quantify in the buffer system were both non-structural protein 1 with the detection limit of about 100 pg/mL and envelope protein with the diluted virus culture soup of about 100 times of serotype 2 dengue virus (only 2 μL sample). We believe that this study would provide insight on the development of in-vitro diagnostic devices for dengue fever and various diseases in the different divisions of medicine.

To identify antigenic peptides of the parasite Cryptosporidium parvum, an expression library that allows for the production of chimeric proteins fused with a 6-histidine tag was made. The library was screened with C. parvum sporozoite rabbit anti-serum, and three positive clones (sa20, sa35, and sa40) were identified. The corresponding recombinant proteins (SA20, SA35, and SA40) were expressed in Escherichia coli and purified by metal-affinity chromatography. The sequence of sa20 and sa35 clones did not show any homology with known genes or proteins, whereas the 5′ end of the sa40 clone showed homology with two previously identified C. parvum sequences. Hybridisations to intact chromosomes fractionated by pulsed-field gel electrophoresis revealed that the sa35 and sa40 sequences are localised on chromosome VII, whereas the sa20 sequence is localised on chromosome VI. Reverse transcriptase–PCR experiments showed the presence of mRNAs for sa35 and sa40 in the oocyst, whereas the sa20 mRNA was undetectable in this stage. The serological response to the three proteins was assayed in C. parvum-immunised rabbits and in immunocompetent individuals with cryptosporidiosis. The Western blot results indicated that rabbits, challenged with a sporozoite crude antigen or with an oocyst crude antigen, were highly responsive to these three antigens. Human serum samples showed a response to the three proteins, although the response to SA20 appeared to be unrelated to a recent C. parvum infection. These results suggest that the SA35 and the SA40 proteins may be useful in detecting C. parvum infections.

In this study, the gene encoding Babesia equi merozoite antigen-2 was inserted into a baculovirus transfer vector, and a recombinant virus expressing B. equi merozoite antigen-2 was isolated. Two B. equi merozoite antigen-2-related recombinant baculovirus-expressed peptides of 25 and 30 kDa were detected with a murine anti serum against B. equi merozoite antigen-2; these corresponded to the native B. equi merozoite antigen-2 and were secreted into the supernatants of insect cell cultures. Recombinant B. equi merozoite antigen-2 was not effected by tunicamycin treatment, indicating that B. equi merozoite antigen-2 was not glycosylated. The potential of recombinant B. equi merozoite antigen-2 for use in the ELISA was evaluated by measuring the antibody response to B. equi merozoite antigen-2 in horses experimentally infected with B. equi.

Neospora hughesi is a newly recognised parasite that is closely related to Neospora caninum, and is a cause of equine protozoal myeloencephalitis. We have characterised two N. hughesi immunodominant tachyzoite antigens which exhibit antigenic and molecular differences from the homologous tachyzoite antigens on N. caninum. These antigens on N. hughesi are referred to as NhSAG1 and NhSRS2, using the same mnemonics as used for the N. caninum antigens (NcSAG1 and NcSRS2), and are homologous to Toxoplasma gondii surface antigen 1 (SAG1) and SAG1-related sequence 2 (SRS2). The NcSAG1 and NcSRS2 were antigenically conserved in six different N. caninum isolates from cattle and dogs. The two equine-derived Neospora isolates, one designated as N. hughesi, were similar to each other but different from N. caninum. There was 6% difference in amino acid identity between NcSAG1 and NhSAG1, whereas there was a 9% difference when NcSRS2 and NhSRS2 were compared. The polymorphism of these genes and their corresponding proteins provide additional markers which can be used to distinguish N. caninum from N. hughesi.

Immune-inflammatory processes are increasingly discussed as possible pathogenetic factors involved in the development of atherosclerosis. Here, we summarize data on which we have built our "immunological" hypothesis of atherogenesis. This concept is based on the observation that nearly everybody shows protective cellular and humoral immune reactions against microbial heat shock protein 60 (HSP 60). Because a high degree of antigenic homology exists between microbial (viral, bacterial, parasitic) and human HSP 60, this protective immunity may have to be "paid for" by the danger of cross-reactivity with human HSP 60 that is expressed by endothelial cells of stressed arteries. Arterial endothelial cells are more prone to produce HSP 60 and various adhesion molecules upon exposure to stress factors, including classical risk factors for atherosclerosis, due to their life-long exposure to the high arterial as compared to venous blood pressure. Also, endothelial cells are the first potential targets encountered by circulating HSP 60-specific T cells or antibodies. This concept not only opens new avenues for diagnostic approaches, but also may form the basis for new ways of therapeutic intervention.

Two cDNA clones each encoding a 20.8-kDa protein (Sm20.8) were identified from the human blood fluke Schistosoma mansoni sporocyst and adult worm cDNA expression libraries by antibodies derived from rabbits vaccinated with irradiated cercariae and purified over an NP-40 extract of 3h schistosomula. Each identified cDNA has an open reading frame encoding a protein of 181 amino acids and shows homology (29–30%) with Sm21.7, Sm22.6, and Sj22.6, previously identified as belonging to a family of soluble schistosome tegumental antigens. An EF-hand calcium-binding motif is found in Sm20.8 protein in two different positions. However, neither motif binds 45calcium (45Ca) Recombinant Sm20.8 showed immunoreactivity with sera from infected humans and rabbits vaccinated with irradiated cercariae. Polyclonal rabbit sera against the Sm20.8 recognized the native protein in an extract of infected snail (sporocyst), cercariae, 3 hour schistosomules (3 h NP-40) and an adult worm preparation but not in uninfected snail tissue or eggs. Further demonstration that Sm20.8 was expressed in the different developmental stages of the parasite was by RT-PCR. Confocal microscopy demonstrates that Sm20.8 localizes to the tegument of adult worms and 3 h np-40. The IgG fraction specific to Sm20.8 mediated complement killing of schistosomules in vitro by 34%. Vaccination of mice with naked DNA containing the Sm20.8 gene and subsequently challenged with cercariae showed 30% reduction in worm burden compared to controls.