A 1-minute blood test detects decreased immune function and increased clinical risk in COVID-19 patients.

Upon infection with SARS-CoV-2, the virus that causes COVID-19, most people will develop no or mild symptoms. However, a small percentage of the population will become severely ill, and some will succumb to death. The clinical severity of COVID-19 has a close connection to the dysregulation of the patient's immune functions. We previously developed a simple, nanoparticle-enabled blood test that can determine the humoral immune status in animals. In this study, we applied this new test to analyze the immune function in relation to disease severity in COVID-19 patients. From the testing of 153 COVID-19 patient samples and 142 negative controls, we detected a drastic decrease of humoral immunity in COVID-19 patients who developed moderate to severe symptoms, but not in patients with no or mild symptoms. The new test may be potentially used to monitor the immunity change and predict the clinical risk of patients with COVID-19.

A nanoparticle pseudo pathogen for rapid detection and diagnosis of virus infection.

We herein report a new rapid blood test for virus infection detection and diagnosis. A citrate gold nanoparticle is first coated with a virus lysate to form a gold nanoparticle pseudo pathogen. The gold nanoparticle pseudo virus is then mixed with a blood plasma or serum samples. If the blood sample is from a positive patient, the activated immune molecules in the blood such as antibodies, complement proteins and others will react with the nanoparticle pseudo virus, leading to nanoparticle aggregate formation. The nanoparticle aggregate formation is detected and measured using a particle sizing technique called dynamic light scattering. In this study, we applied this test for Zika virus infection detection. We tested blood plasma samples from 85 Zika positive patients, 40 Dengue positive patients, 10 Chikungunya positive patients, and 78 non-patient control samples collected from both endemic and non-endemic locations. The study shows that the new test has a higher sensitivity compared to some existing commercial tests in the market, while maintaining a similar specificity. Within 7 days from the symptom onset, the new test can detect 43% of the infected patients while a commercial anti-Zika IgM test detects only 26% of the infected patients. Within 14 days from the symptom onset, our new test detects 73% of the infected patients while the same commercial anti-Zika IgM test detects 53% of the infected patients. The test is extremely simple, easy to develop, with test results obtained within minutes. This new test platform may be potentially adapted for the detection and diagnosis of a wide range of viral infectious diseases, for example, the currently ongoing COVID-19.

A rapid blood test to monitor immunity shift during pregnancy and potential application for animal health management.

The immune health of a farm animal can have significant impact on its overall health, welfare and productivity. One of the most vulnerable physiological states for both humans and animals is pregnancy. Many systemic changes correlate with the gravid state, including shifts in the immune system that may impact the ability to respond optimally to pathogen challenge. Because of this, it would be beneficial to be able to monitor the immune health of the pregnant animals closely. Recently, we developed a new nanoparticle-enabled rapid blood test that can detect ongoing immune responses from both laboratory and farm animals. Here, we report that this novel test reveals highly repeatable and acute changes associated with pregnancy and peri-parturition period in laboratory mice and in cattle. We hypothesize that the test score change reflects changes in the immune status of the gravid females related to the humoral immune response. The test is easy to conduct, of low cost, with results obtained in less than 20 min. This rapid test could be potentially used as an onsite test in local farms and small clinics for animal health management.

A Single-Step Gold Nanoparticle-Blood Serum Interaction Assay Reveals Humoral Immunity Development and Immune Status of Animals from Neonates to Adults.

A well-developed, functional immune system is paramount to combat harmful attacks from pathogenic organisms and prevent infectious diseases. Newborn animals and humans have only limited immunity upon birth, but their immune functions are expected to develop within weeks to months and eventually to reach a maturity that will provide full protection. Despite the importance of immune activity in animal and human health management, there is no convenient test available that allows for rapid assessment of the state of immune function in nonlaboratory settings. Here we report an extremely simple and rapid blood test that may be used in point-of-care clinics or field settings to evaluate the humoral immune status of animals. The test detects a cooperative interaction between a gold nanoparticle and arguably the three most important proteins involved in the immune system: immunoglobulin M (IgM), immunoglobulin G (IgG), and at least one complement protein, C3, in the blood serum. Such interactions cause the gold nanoparticles to form clusters and aggregates. The average particle size of the gold nanoparticle-serum mixture, measured by dynamic light scattering, corresponds positively to the immune status and activity of the subject. Our study demonstrates that the test may be used not only for monitoring the immune function development from neonates to adults, but also for detecting active immune responses during infection. Although data reported here are largely based on murine and bovine models, it is likely that this test will be applicable to humans as well.

Cations Modulate Actin Bundle Mechanics, Assembly Dynamics, and Structure.

Actin bundles are key factors in the mechanical support and dynamic reorganization of the cytoskeleton. High concentrations of multivalent counterions promote bundle formation through electrostatic attraction between actin filaments that are negatively charged polyelectrolytes. In this study, we evaluate how physiologically relevant divalent cations affect the mechanical, dynamic, and structural properties of actin bundles. Using a combination of total internal reflection fluorescence microscopy, transmission electron microscopy, and dynamic light scattering, we demonstrate that divalent cations modulate bundle stiffness, length distribution, and lateral growth. Molecular dynamics simulations of an all-atom model of the actin bundle reveal specific actin residues coordinate cation-binding sites that promote the bundle formation. Our work suggests that specific cation interactions may play a fundamental role in the assembly, structure, and mechanical properties of actin bundles.

Linear self-assembly formation between gold nanoparticles and aminoglycoside antibiotics.

Ribostamycin is a broad-spectrum aminoglycoside antibiotic with a molecular weight of 454.5 g/mol. Under neutral pH conditions, ribostamycin is highly positive charged because it carries multiple amino groups in its structure. Negatively charged citrate ligand capped-gold nanoparticles (AuNPs) have been studied extensively for their interactions with a wide range of biomolecules including proteins, carbohydrates, and small drug compounds. These studies are aimed at developing new therapeutics and diagnostics by exploiting the unique properties of gold nanoparticles. Under this general aim, we studied the interaction between ribostamycin and AuNPs. Using a suite of analytical techniques including dynamic light scattering (DLS), UV-vis absorption spectroscopy, and dark field optical microscope imaging (DFM), we analyzed the mixture products of AuNPs with various sizes and ribostamycin under different concentrations. Our study revealed for the first time that ribostamycin has a tendency to self-assemble into linear oligomers at increased concentrations (above 250-500 µM). Such self-assembled oligomers then interact with negatively charged AuNPs to produce rod-like AuNP assemblies. Similar findings were observed from another structurally related aminoglycoside antibiotic, amikacin. It is technically challenging to detect and characterize oligomer formation of small molecules. It is especially challenging when the interactions that are holding the oligomers are not very strong. Through their interaction with gold nanoparticles that have exceptionally strong light scattering properties, we were able to observe the self-assembling of ribostamycin and amikacin in solution using various spectroscopic and microscopic techniques. This concentration-dependent self-assembling behavior of ribostamycin and amikacin may have direct relevance to the antibiotic effect of ribostamycin, amikacin and other structurally similar antibiotics.

Membrane Binding and Pore Formation by a Cytotoxic Fragment of Amyloid ß Peptide.

Amyloid ß (Aß) peptide contributes to Alzheimer's disease by a yet unidentified mechanism. In the brain tissue, Aß occurs in various forms, including an undecapeptide Aß25-35, which exerts a neurotoxic effect through the mitochondrial dysfunction and/or Ca2+-permeable pore formation in cell membranes. This work was aimed at the biophysical characterization of membrane binding and pore formation by Aß25-35. Interaction of Aß25-35 with anionic and zwitterionic membranes was analyzed by microelectrophoresis. In pore formation experiments, Aß25-35 was incubated in aqueous buffer to form oligomers and added to Quin-2-loaded vesicles. Gradual increase in Quin-2 fluorescence was interpreted in terms of membrane pore formation by the peptide, Ca2+ influx, and binding to intravesicular Quin-2. The kinetics and magnitude of this process were used to evaluate the rate constant of pore formation, peptide-peptide association constants, and the oligomeric state of the pores. Decrease in membrane anionic charge and high ionic strength conditions significantly suppressed membrane binding and pore formation, indicating the importance of electrostatic interactions in these events. Circular dichroism spectroscopy showed that Aß25-35 forms the most efficient pores in ß-sheet conformation. The data are consistent with an oligo-oligomeric pore model composed of up to eight peptide units, each containing 6-8 monomers.

A Rapid Blood Test To Determine the Active Status and Duration of Acute Viral Infection.

The ability to rapidly detect and diagnose acute viral infections is crucial for infectious disease control and management. Serology testing for the presence of virus-elicited antibodies in blood is one of the methods used commonly for clinical diagnosis of viral infections. However, standard serology-based tests have a significant limitation: they cannot easily distinguish active from past, historical infections. As a result, it is difficult to determine whether a patient is currently infected with a virus or not, and on an optimal course of action, based off of positive serology testing responses. Here, we report a nanoparticle-enabled blood test that can help overcome this major challenge. The new test is based on the analysis of virus-elicited immunoglobulin G (IgG) antibody present in the protein corona of a gold nanoparticle surface upon mixing the gold nanoparticles with blood sera. Studies conducted on mouse models of influenza A virus infection show that the test gives positive responses only in the presence of a recent acute viral infection, approximately between day 14 and day 21 following the infection, and becomes negative thereafter. When used together with the traditional serology testing, the nanoparticle test can determine clearly whether a positive serology response is due to a recent or historical viral infection. This new blood test can provide critical clinical information needed to optimize further treatment and/or to determine if further quarantining should be continued.