Detection Of Viral Proteins Research Articles

Development of aptamer-based lateral flow devices for rapid detection of SARS-CoV-2 S protein and uncertainty assessment

The outbreak and spread of COVID-19 have highlighted the urgent need for early diagnosis of SARS-CoV-2. Nucleic acid testing as an authoritative tool, is cumbersome, time-consuming, and easy to cross-infect, while the available antibody self-testing kits are deficient in sensitivity and stability. In this study, we developed competitive aptamer-based lateral flow devices (Apt-LFDs) for the quantitative detection of SARS-CoV-2 spike (S) protein. Molecular docking simulation was used to analyze the active binding sites of the aptamer to S protein, guiding complementary DNA (cDNA) design. Then a highly efficient freezing strategy was applied for the conjugation of gold nanoparticles (AuNPs) and DNA probes. Under optimal conditions, the linear range of the constructed Apt-LFDs was 0.1–1 μg/mL, and the limit of detection (LOD) was 51.81 ng/mL. The cross-reactivity test and stability test of the Apt-LFDs showed good specificity and reliability. The Apt-LFDs had recoveries ranging from 89.45 % to 117.12 % in pharyngeal swabs. Notably, the uncertainty of the analytical result was evaluated using a “bottom-up” approach. At a 95 % confidence level, the uncertainty report of (453.37±54.86) ng/mL with k = 2 was yielded. Overall, this study provides an important reference for the convenient and reliable detection of virus proteins based on LFDs.

Handheld, Graphene Multiplexed Sensor for Wastewater-Based Epidemiology

Wastewater-based epidemiology (WBE) is emerging as a vital tool for early detection of the emergence of diseases without the need for individual testing and reporting. This is enabled via virus shedding through bodily waste, which can be present up to two days before symptoms appear in infected individuals, albeit at low levels. Current detection methods, such as HPLC-MS and PCR, are time-consuming and require specialized equipment with highly trained personnel. This drives up the cost and turnaround time while limiting the widespread implementation of WBE for local detection, especially in resource-limited settings. Therefore, a fast, cost-effective, multiplexing, and sensitive viral wastewater detection platform could help health officials effectively implement measures to mitigate the spread of diseases. Here, I will present our recently developed handheld, graphene-based multiplexed platform utilizing high-specificity aptamers for rapid, sensitive, and simultaneous detection of virus proteins for SARS-CoV-2, Influenza A, and RSV in wastewater to accurately assess infected individuals in municipal communities. In addition, the device allows normalizing to the population, contributing to the signal by simultaneously measuring the presence of virus proteins and caffeine in wastewater. These results will highlight the selectivity and specificity of the platform in wastewater as well as the limits of detection.

Rapid and simple viral protein detection by functionalized 2D MoS2/graphene electrochemiluminescence aptasensor

In this work we present the development of an electrochemiluminescence aptasensor based on electrografting molybdenum disulphide nanosheets functionalized with diazonium salt (MoS2–N2+) upon screen-printed electrodes of graphene (SPEs GPH) for viral proteins detection. In brief, this aptasensor consists of SPEs GPH electrografted with MoS2–N2+ and modified with a thiolated aptamer, which can specifically recognize the target protein analyte. In this case, we have used SARS-CoV-2 spike protein as model protein. Electrochemiluminescence detection was performed by using the [Ru(bpy)3]2+/TPRA (tripropylamine) system, which allows the specific detection of the SARS-CoV-2 spike protein easily and rapidly with a detection limit of 9.74 fg/mL and a linear range from 32.5 fg/mL to 50.0 pg/mL. Moreover, the applicability of the aptasensor has been confirmed by the detection of the protein directly in human saliva samples. Comparing our device with a traditional saliva antigen test, our aptasensor can detect the spike protein even when the saliva antigen test gives a negative result.

Recent Advances in Lateral Flow Assays for Viral Protein Detection with Nanomaterial-Based Optical Sensors.

Controlling the progression of contagious diseases is crucial for public health management, emphasizing the importance of early viral infection diagnosis. In response, lateral flow assays (LFAs) have been successfully utilized in point-of-care (POC) testing, emerging as a viable alternative to more traditional diagnostic methods. Recent advancements in virus detection have primarily leveraged methods such as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and the enzyme-linked immunosorbent assay (ELISA). Despite their proven effectiveness, these conventional techniques are often expensive, require specialized expertise, and consume a significant amount of time. In contrast, LFAs utilize nanomaterial-based optical sensing technologies, including colorimetric, fluorescence, and surface-enhanced Raman scattering (SERS), offering quick, straightforward analyses with minimal training and infrastructure requirements for detecting viral proteins in biological samples. This review describes the composition and mechanism of and recent advancements in LFAs for viral protein detection, categorizing them into colorimetric, fluorescent, and SERS-based techniques. Despite significant progress, developing a simple, stable, highly sensitive, and selective LFA system remains a formidable challenge. Nevertheless, an advanced LFA system promises not only to enhance clinical diagnostics but also to extend its utility to environmental monitoring and beyond, demonstrating its potential to revolutionize both healthcare and environmental safety.

An Advanced Healthcare Sensing Platform for Direct Detection of Viral Proteins in Seconds at Femtomolar Concentrations via Aerosol Jet 3D‐Printed Nano and Biomaterials

AbstractSensing of viral antigens has become a critical tool in combating infectious diseases. Current sensing techniques have a tradeoff between sensitivity and time of detection; with 10–30 min of detection time at a relatively low sensitivity and 6–12 h of detection at a high (picomolar) sensitivity. In this research, uniquely nanoengineered interfaces are demonstrated on 3D electrodes that enable the detection of spike antigens of SARS‐CoV‐2 and their variants in seconds at femtomolar concentrations with excellent specificity, thus, overcoming this tradeoff. The 3D electrodes, manufactured using a high‐resolution aerosol jet 3D nanoprinter, consist of a microelectrode array of sintered gold nanoparticles coated with graphene and antibodies specific to severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) spike antigens. An impedance‐based sensing modality is employed to sense several pseudoviruses of SARS‐CoV‐2 variants of concern (VOCs). This device is sensitive to most of the pseudoviruses of SARS‐CoV‐2 VOCs. A high sensitivity of 100 fm, along with a low limit‐of‐detection of 9.2 fm within a test range of 0.1–1000 pm, and a detection time of 43 s are shown. This work illustrates that effective nano‐bioengineering of interfaces can be used to create an ultrafast and ultrasensitive healthcare diagnostic tool for combating emerging infections.

A non-human primate model for human norovirus infection.

Norovirus infection can cause gastrointestinal disease in humans. Development of therapies and vaccines against norovirus have been limited by the lack of a suitable and reliable animal model. Here we established rhesus macaques as an animal model for human norovirus infection. We show that rhesus macaques are susceptible to oral infection with human noroviruses from two different genogroups. Variation in duration of virus shedding (days to weeks) between animals, evolution of the virus over the time of infection, induction of virus-specific adaptive immune responses, susceptibility to reinfection and preferential replication of norovirus in the jejunum of rhesus macaques was similar to infection reported in humans. We found minor pathological signs and changes in epithelial cell surface glycosylation patterns in the small intestine during infection. Detection of viral protein and RNA in intestinal biopsies confirmed the presence of the virus in chromogranin A-expressing epithelial cells, as it does in humans. Thus, rhesus macaques are a promising non-human primate model to evaluate vaccines and therapeutics against norovirus disease.

Large language models improve annotation of prokaryotic viral proteins.

Viral genomes are poorly annotated in metagenomic samples, representing an obstacle to understanding viral diversity and function. Current annotation approaches rely on alignment-based sequence homology methods, which are limited by the paucity of characterized viral proteins and divergence among viral sequences. Here we show that protein language models can capture prokaryotic viral protein function, enabling new portions of viral sequence space to be assigned biologically meaningful labels. When applied to global ocean virome data, our classifier expanded the annotated fraction of viral protein families by 29%. Among previously unannotated sequences, we highlight the identification of an integrase defining a mobile element in marine picocyanobacteria and a capsid protein that anchors globally widespread viral elements. Furthermore, improved high-level functional annotation provides a means to characterize similarities in genomic organization among diverse viral sequences. Protein language models thus enhance remote homology detection of viral proteins, serving as a useful complement to existing approaches.

Characterizing a visual lateral flow device for rapid SARS-CoV-2 virus protein detection: pre-clinical and system assessment.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections have affected more than 769 million individuals worldwide over the last few years. Although the pandemic is transitioning into an endemic, the COVID-19 outbreak is still a global concern. A rapid screening platform is needed for effective preventive and control measures. Herein, a visual rapid lateral flow platform for SARS-CoV-2 nucleocapsid protein detection is developed. Under optimal conditions, the system demonstrated good detection sensitivity and selectivity against tested respiratory viruses. The system provides direct visual detection with a limit of 0.7 ng of the nucleocapsid protein per mL of a sample (0.7 ng mL-1) within 15 minutes. Further, a correlation between direct visual detection and semi-quantitative analysis using a reader showed a similar detection limit (R2 = 0.9571). The repeatability and reproducibility studies highlighted the potential of the system for the rapid screening of SARS-CoV-2 infection, with variations within 5% and 10% at high and low protein concentrations, respectively. Subsequent pre-clinical validation to correlate the performance with the standard molecular approach (RT-PCR) using 170 nasopharyngeal swabs demonstrated 98% estimated sensitivity (95% CI, 89.35-99.95%) and 100% specificity (95% CI, 96.38-100%). The positive and negative predictive values were reported to be 100% and 99%, respectively, with an accuracy of 99.3%. With high viral load samples (Ct value ≤25, n = 47), the system demonstrated 100% detection sensitivity and specificity. The proposed technique provides a valuable platform for potential use in rapid screening, particularly during pandemics, where diagnostic capacity and mass screening are crucial.

Selection and characterization of ssDNA aptamer targeting Macrobrachium rosenbergii nodavirus capsid protein: A potential capture agent in gold-nanoparticle-based aptasensor for viral protein detection.

The giant freshwater prawn holds a significant position as a valuable crustacean species cultivated in the aquaculture industry, particularly well-known and demanded among the Southeast Asian countries. Aquaculture production of this species has been impacted by Macrobrachium rosenbergii nodavirus (MrNV) infection, which particularly affects the larvae and post-larvae stages of the prawn. The infection has been recorded to cause mortality rates of up to 100% among the affected prawns. A simple, fast, and easy to deploy on-site detection or diagnostic method is crucial for early detection of MrNV to control the disease outbreak. In the present study, novel single-stranded DNA aptamers targeting the MrNV capsid protein were identified using the systematic evolution of ligands by exponential enrichment (SELEX) approach. The aptamer was then conjugated with the citrate-capped gold nanoparticles (AuNPs), and the sensitivity of this AuNP-based aptasensor for the detection of MrNV capsid protein was evaluated. Findings revealed that the aptamer candidate, APT-MrNV-CP-1 was enriched throughout the SELEX cycle 4, 9, and 12 with the sequence percentage of 1.76%, 9.09%, and 12.42%, respectively. The conjugation of APT-MrNV-CP-1 with citrate-capped AuNPs exhibited the highest sensitivity in detecting the MrNV capsid protein, where the presence of 62.5 nM of the viral capsid protein led to a significant agglomeration of the AuNPs. This study demonstrated the practicality of an AuNP-based aptasensor for disease diagnosis, particularly for detecting MrNV infection in giant freshwater prawns.

Single virus fingerprinting by widefield interferometric defocus-enhanced mid-infrared photothermal microscopy

Clinical identification and fundamental study of viruses rely on the detection of viral proteins or viral nucleic acids. Yet, amplification-based and antigen-based methods are not able to provide precise compositional information of individual virions due to small particle size and low-abundance chemical contents (e.g., ~ 5000 proteins in a vesicular stomatitis virus). Here, we report a widefield interferometric defocus-enhanced mid-infrared photothermal (WIDE-MIP) microscope for high-throughput fingerprinting of single viruses. With the identification of feature absorption peaks, WIDE-MIP reveals the contents of viral proteins and nucleic acids in single DNA vaccinia viruses and RNA vesicular stomatitis viruses. Different nucleic acid signatures of thymine and uracil residue vibrations are obtained to differentiate DNA and RNA viruses. WIDE-MIP imaging further reveals an enriched β sheet components in DNA varicella-zoster virus proteins. Together, these advances open a new avenue for compositional analysis of viral vectors and elucidating protein function in an assembled virion.

Aptamer-based electrochemical biosensor with S protein binding affinity for COVID-19 detection: Integrating computational design with experimental validation of S protein binding affinity

Aptamer-based biosensors capable of rapid one-step detection of viruses provide new capabilities for large-scale detection of COVID-19. Here we report a combined aptamer-based electrochemical and computational approach to characterize the interaction between a 60 base single stranded (ss)DNA aptamer and the viral S protein using molecular docking and bioinformatics tools. To construct the biosensor, the DNA aptamer was immobilized to the surface of a gold nanoparticles (AuNPs) modified electrode and methylene blue (MB) was used as redox indicator. Based on thermodynamic calculations for the aptamer sequence as well as several runs in APBS (Adaptive Poisson-Boltzmann Equation), we found that S protein GLN104-ASP115 pocket is the candidate for DNA 30–39(GGGAGTGGTT) sequence interaction. In the presence of S-protein, the target induced conformational changes in the aptamer’s structure, generating an increase in the MB redox signal, with a linear range between 10 pM to 6 nM and a limit of detection of 91.1 pM using differential pulse voltammetry (DPV). The aptasensor was investigated in spiked human saliva and serum samples, demonstrating performance in both media. This study demonstrates the potential of the MB-labeled electrochemical aptasensor for direct one-step detection of viral proteins, COVID-19 and potentially other viral agents.

Neuropathology in COVID-19 autopsies is defined by microglial activation and lesions of the white matter with emphasis in cerebellar and brain stem areas.

This study aimed to investigate microglial and macrophage activation in 17 patients who died in the context of a COVID-19 infection in 2020 and 2021. Through immunohistochemical analysis, the lysosomal marker CD68 was used to detect diffuse parenchymal microglial activity, pronounced perivascular macrophage activation and macrophage clusters. COVID-19 patients were compared to control patients and grouped regarding clinical aspects. Detection of viral proteins was attempted in different regions through multiple commercially available antibodies. Microglial and macrophage activation was most pronounced in the white matter with emphasis in brain stem and cerebellar areas. Analysis of lesion patterns yielded no correlation between disease severity and neuropathological changes. Occurrence of macrophage clusters could not be associated with a severe course of disease or preconditions but represent a more advanced stage of microglial and macrophage activation. Severe neuropathological changes in COVID-19 were comparable to severe Influenza. Hypoxic damage was not a confounder to the described neuropathology. The macrophage/microglia reaction was less pronounced in post COVID-19 patients, but detectable i.e. in the brain stem. Commercially available antibodies for detection of SARS-CoV-2 virus material in immunohistochemistry yielded no specific signal over controls. The presented microglial and macrophage activation might be an explanation for the long COVID syndrome.

Hybridization Chain Reaction Lateral Flow Assays for Amplified Instrument-Free At-Home SARS-CoV-2 Testing.

The lateral flow assay format enables rapid, instrument-free, at-home testing for SARS-CoV-2. Due to the absence of signal amplification, this simplicity comes at a cost in sensitivity. Here, we enhance sensitivity by developing an amplified lateral flow assay that incorporates isothermal, enzyme-free signal amplification based on the mechanism of hybridization chain reaction (HCR). The simplicity of the user experience is maintained using a disposable 3-channel lateral flow device to automatically deliver reagents to the test region in three successive stages without user interaction. To perform a test, the user loads the sample, closes the device, and reads the result by eye after 60 min. Detecting gamma-irradiated SARS-CoV-2 virions in a mixture of saliva and extraction buffer, the current amplified HCR lateral flow assay achieves a limit of detection of 200 copies/μL using available antibodies to target the SARS-CoV-2 nucleocapsid protein. By comparison, five commercial unamplified lateral flow assays that use proprietary antibodies exhibit limits of detection of 500 copies/μL, 1000 copies/μL, 2000 copies/μL, 2000 copies/μL, and 20,000 copies/μL. By swapping out antibody probes to target different pathogens, amplified HCR lateral flow assays offer a platform for simple, rapid, and sensitive at-home testing for infectious diseases. As an alternative to viral protein detection, we further introduce an HCR lateral flow assay for viral RNA detection.

Modulation of the Aryl Hydrocarbon Receptor Signaling Pathway Impacts on Junín Virus Replication.

Junín virus (JUNV), a member of the family Arenaviridae, is the etiological agent of the Argentine hemorrhagic fever, an endemic disease in the rural region of Argentina lacking a specific chemotherapy. Aryl hydrocarbon receptor (AHR) is expressed in several mammalian tissues and has been indicated as a sensor of ligands from variable sources and a modulator of the cell immune response. Interestingly, recent studies have suggested that the activation or depression of the AHR signaling pathway may play a role in the outcome of diverse human viral infections. In the present report, the effect of the pharmacological modulation of AHR on JUNV in vitro infection was analyzed. An initial microarray screening showed that the AHR pathway was overexpressed in JUNV-infected hepatic cells. Concomitantly, the infection of Vero and Huh-7 cells with the JUNV strains IV4454 and Candid#1 was significantly inhibited in a dose-dependent manner by treatment with CH223191, a specific AHR antagonist, as detected by infectivity assays, real-time RT-PCR and immunofluorescence detection of viral proteins. Furthermore, the pro-viral role of AHR in JUNV infection appears to be independent of the IFN-I pathway. Our findings support the promising perspectives of the pharmacological modulation of AHR as a potential target for the control of AHF.

From the lab to the field: handheld surface enhanced Raman spectroscopy (SERS) detection of viral proteins.

Translating sensors from the lab benchtop to a readily available point-of-need setting is desirable for many fields, including medicine, agriculture, and industry. However, this transition generally suffers from loss of sensitivity, high background signals, and other issues which can impair reproducibility. Here we adapt a label-free surface-enhanced Raman spectroscopy (SERS) sensor for SARS-CoV-2 antigens from a lab-based assay to a handheld device. Utilizing a peptide capture molecule, which we previously employed for a surface-based assay, we optimize a simpler and more cost-efficient nanoparticle-based assay. This new assay allows for the direct detection of these viral antigens by SERS, now with the advantages of robustness and portability. We highlight considerations for nanoparticle modification conditions and warn against methods which can interfere with accurate detection. The comparison of these two assays will help guide further development of SERS-based sensors into devices that can be easily used in point-of-care settings, such as by emergency room nurses, farmers, or quality control technicians.

Liver alterations and detection of SARS-CoV-2 RNA and proteins in COVID-19 autopsies

The most severe alterations in Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) infection are seen in the lung. However, other organs also are affected. Here, we report histopathologic findings in the liver and detection of viral proteins and RNA in COVID-19 autopsies performed at the Semmelweis University (Budapest, Hungary). Between March 2020 through March 2022, 150 autopsies on patients who died of COVID-19 were analyzed. Cause-of-death categories were formed based on the association with SARS-CoV-2 as strong, contributive, or weak. Samples for histopathologic study were obtained from all organs, fixed in formalin, and embedded in paraffin (FFPE). Immunohistochemical study (IHC) to detect SARS-CoV-2 spike protein and nucleocapsid protein (NP), CD31, claudin-5, factor VIII, macrosialin (CD68), and cytokeratin 7, with reverse transcriptase polymerase chain reaction (RT-PCR), and in situ hybridization (ISH, RNAscope®) for SARS-CoV-2 RNA were conducted using FFPE samples of livers taken from 20 autopsies performed ≤ 2 days postmortem. All glass slides were scanned; the digital images were evaluated by semiquantitative scoring and scores were analyzed statistically. Steatosis, single-cell and focal/zonal hepatocyte necrosis, portal fibrosis, and chronic inflammation were found in varying percentages. Sinusoidal ectasia, endothelial cell disruption, and fibrin-filled sinusoids were seen in all cases; these were assessed semiquantitatively for severity (SEF scored). SEF scores did not correlate with cause-of-death categories (p = 0.92) or with severity of lung alterations (p = 0.96). SARS-CoV-2 RNA was detected in 13/20 cases by PCR and in 9/20 by ISH, with IHC demonstration of spike protein in 4/20 cases and NP in 15/20. Viral RNA and proteins were located in endothelial and Kupffer cells, and in portal macrophages, but not in hepatocytes and cholangiocytes. In conclusion, endothelial damage (SEF scores) was the most common alteration in the liver and was a characteristic, but not specific alteration in COVID-19, suggesting an important role in the pathogenesis of COVID-19-associated liver disease. Detection of SARS-CoV-2 RNA and viral proteins in liver non-parenchymal cells suggests that while the most extended primary viral cytotoxic effect occurs in the lung, viral components are present in other organs too, as in the liver. The necrosis/apoptosis and endothelial damage associated with viral infection in COVID-19 suggest that those patients who survive more severe COVID-19 may face prolonged liver repair and accordingly should be followed regularly in the post-COVID period.

Long-Range SERS Detection of the SARS-CoV-2 Antigen on a Well-Ordered Gold Hexagonal Nanoplate Film.

The development of an effective method for identifying severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) via direct viral protein detection is significant but challenging in combatting the COVID-19 epidemic. As a promising approach for direct detection, viral protein detection using surface-enhanced Raman scattering (SERS) is limited by the larger viral protein size compared to the effective electromagnetic field (E-field) range because only the analyte remaining within the E-field can achieve high detection sensitivity. In this study, we designed and fabricated a novel long-range SERS (LR-SERS) substrate with an Au nanoplate film/MgF2/Au mirror/glass configuration to boost the LR-SERS resulting from the extended E-field. On applying the LR-SERS to detect the SARS-CoV-2 spike protein (S protein), reagent-free detection achieved a low detection limit of 9.8 × 10-11 g mL-1 and clear discrimination from the SARS-CoV S protein. The developed technique also allows testing of the S protein in saliva with 98% sensitivity and 100% specificity.

(Digital Presentation) Development of an Electrochemical Microfluidic Device with on-Platform Sample Collection

As the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to develop, the need for portable rapid testing platforms remains prevalent to provide patients with accurate and quantitative diagnostic and serosurveillance information at the point-of-care. The current gold standard detection techniques like RT-PCR and ELISA require trained personnel to perform lengthy protocols, resulting in a long turnover from sample collection to result acquisition. Herein, we propose an electrochemical microfluidic device for on-platform detection of viral proteins and antibodies at the point-of-care in a multiplexed manner. Miniaturization technology through the use of microfluidic devices offers numerous advantages including low reagent consumption, high fluidic control, reduced reaction times, inexpensive applications, and the possibility of throughput analysis. Electrochemical detection can provide advantages in cost effective fabrication, high sensitivity and simple instrumentation using a standard 3-electrode (working, reference, and counter) setup. Our platform proposes the design of an electrochemical cell with an enhanced working electrode to act as the detection assay with microfluidic channels to facilitate sample collection and pre-treatment; an integrated saliva collection kit and lancing device enabled the use of both untreated saliva from direct self-collection and whole blood from a finger prick. Automated fluid manipulation reduced the potential of user contamination through the implementation of suction-based flow. The electrochemical microfluidic device was encased in a 3D-printed cartridge for the fabrication of a fully integrative technology on a single platform with the potential to be used at the point-of-care in both clinical and commercial applications using direct biofluids.

Development of Parallel Reaction Monitoring Mass Spectrometry Assay for the Detection of Human Norovirus Major Capsid Protein.

Human Norwalk viruses (HuNoVs), the most common etiological agents of acute gastroenteritis, are genetically diverse RNA viruses that frequently cause mass food poisoning internationally. Although nucleic acid detection methods, such as reverse transcription–quantitative polymerase chain reaction (RT-qPCR), are the gold standard for the diagnosis of norovirus infection, alternative methods are needed for the specific and sensitive viral protein detection for rapid diagnosis and surveillance. In this study, we developed a robust and high-throughput targeted proteomic assay workflow to directly detect the VP1 major capsid protein of HuNoVs. A parallel reaction monitoring (PRM) assay using a high-resolution mass spectrometer was used to detect representative peptides derived from VP1 in six different HuNoV genotypes. An optimized protocol using synthesized heavy isotope-labeled peptides as internal standards was also used to simultaneously genotype and quantify the VP1 protein in human stool specimens. This method is expected to become a new tool for studying the molecular epidemiology of HuNoV and to shed new light on targeted proteomics in clinical practice.

Foot-and-mouth disease virus localisation on follicular dendritic cells and sustained induction of neutralising antibodies is dependent on binding to complement receptors (CR2/CR1).

Previous studies have shown after the resolution of acute infection and viraemia, foot-and-mouth disease virus (FMDV) capsid proteins and/or genome are localised in the light zone of germinal centres of lymphoid tissue in cattle and African buffalo. The pattern of staining for FMDV proteins was consistent with the virus binding to follicular dendritic cells (FDCs). We have now demonstrated a similar pattern of FMDV protein staining in mouse spleens after acute infection and showed FMDV proteins are colocalised with FDCs. Blocking antigen binding to complement receptor type 2 and 1 (CR2/CR1) prior to infection with FMDV significantly reduced the detection of viral proteins on FDCs and FMDV genomic RNA in spleen samples. Blocking the receptors prior to infection also significantly reduced neutralising antibody titres, through significant reduction in their avidity to the FMDV capsid. Therefore, the binding of FMDV to FDCs and sustained induction of neutralising antibody responses are dependent on FMDV binding to CR2/CR1 in mice.