Neutralizing antibodies – the immune system’s Hero

By Sebastian Fiedler, Lead Application Scientist Life Sciences at Fluidic Analytics

Infectious diseases—a problem of the past or the present?

Modern medicine has provided an exceptional set of tools to prevent and treat infectious diseases – conditions that used to decimate the human population with frightening regularity. As the world struggles to battle the COVID-19 pandemic, however, we are starkly reminded that infectious diseases are not merely a problem of the past.

It is not only global pandemics like COVID-19 that evade the tools of modern medicine. We are in fact fighting this battle every day and on multiple fronts.  Humans remain under constant attack by bacteria and viruses, and even in modern times these pathogens still cause the death of millions of people around the world each year.

How do you catch an infectious disease?

Infectious diseases are caused by a variety of pathogenic microorganisms including bacteria, viruses, fungi and parasites. These pathogens typically enter our bodies through our mouths, eyes, noses or open wounds.

Once inside our bodies, these microorganisms take advantage of their new favorable environment and quickly start multiplying. This process can severely damage and even kill the host cells resulting in visible and often well-described symptoms of specific diseases.

Luckily, our bodies are not wholly without defense because the pathogens trigger an immune response to help fight the infection. This activity unfortunately can also create collateral damage within the body, with fever, rash, inflammation, and general malaise all hallmarks of an active immune response.

Thankfully, modern medicine has delivered powerful antibiotics that are effective at supporting our own immune response across a broad spectrum of bacterial pathogens. The treatment of viral infections, however, has been much more challenging, and reliable therapeutics have so far eluded our best efforts. The most effective approach to fighting viral infections still is prevention by using vaccines that prime the immune system prior to a first encounter.

What happens when a virus enters the body?

When a virus enters the human body, it literally “goes viral”, producing as many copies of itself as possible. To do so, the virus exploits a cell’s own metabolism to release the new virus copies into the body, initiating the infection cycle over and over again. Once cells are infected, their natural function is badly impaired and, even worse, they often die. The resulting deficit of functional cells is the cause of tissue and organ failure, sometimes to an extent that is fatal.

But as mentioned earlier, our immune system does not leave us defenseless against viruses. To prevent a large-scale viral spread in our bodies, several innate mechanisms protect us at each stage of infection.

The first time we encounter a novel virus it typically avoids detection by the immune system and is able to enter a healthy cell.

At this stage, this now-infected cell will utilize its internal defense mechanism to display fragments of the virus on its surface using special receptor proteins. This display of virus fragments alerts the body that the cell is infected and activates the immune system to kill and eliminate the cell before the virus can spread.

In addition, the infected cells will also produce molecules, called interferons, which directly interfere with the process of viral replication to slow down the reproduction rate. Interferons also send a handy warning signal to nearby cells to alert them of the growing viral threat.

Antibodies – our best defense

The best defense against viruses, however, is to stop the infection in its tracks. This immune mechanism is made possible not by the cells themselves, but by antibodies which can identify and eliminate viruses before they start the infection cycle.

Over the course of our lives, our bodies produce thousands of different types of antibodies that comprise our antibody-mediated immune response. Antibodies are proteins that are produced by B cells, which are a specialized type of blood cell. Once produced, these antibodies patrol our circulatory system and tissues, ready to deal with the pathogens.

Antibodies have several mechanisms to prevent infections. They can either neutralize viruses directly to prohibit their entry into the host cell, or they can crowd around a virus to increase its visibility to other immune cells. Once bound to a virus, antibodies can also tag the virus for phagocytes, which in turn ingest and destroy the pathogen.

When a virus enters the human body, it literally “goes viral”,
producing as many copies of itself as possible.

Our antibodies’ ability to recognize and bind to pathogens starts with their structure. Fully assembled antibodies resemble the shape of the letter “Y”.

The top of the two “arms” of the “Y” is where the magic happens. Imagine the arms as thousands of different jigsaw-puzzle pieces that give each antibody a unique shape. Each of those antibody jigsaw-puzzle pieces has the potential to fit specific virus antigens while fitting poorly with others.

The better the antibody and antigen fit, the higher their affinity to each other. In other words, the stronger they bind to each other the more effective the antibody is at preventing infection by the virus.

Figure 1: The better the antibody and antigen fit, the stronger they bind to each other the more effective the antibody is at preventing infection by the virus.

How do neutralizing antibodies earn their superhero status?

To infect, viruses must first enter a healthy cell. They accomplish cell entry by binding to receptor molecules on the surface of their host cells. For example, SARS-CoV-2 utilizes so-called spike proteins on its surface for initial cell binding. These spike proteins fit perfectly to the shape of a receptor protein (ACE-2 receptor) typically found on the surface of human lung cells. Once the virus spike protein binds to the receptors of the lung cells, the virus enters and begins to replicate.

Virus-neutralizing antibodies are designed to interfere with this binding event. To prevent entry to lung cells, an effective neutralizing antibody resembles the jigsaw-puzzle shape mimicking the lung-cell receptor ACE-2. In fact, it displays an even better fit than the receptor itself, resulting in the virus surface becoming covered by antibodies. This in turn prevents the virus from entering the lung cells. Moreover, such antibody-covered viruses become very sticky and attract each other to form large virus clusters, which, unlike individual viruses, are more easily recognized by other immune cells.

Figure 2: Neutralizing antibodies bind to spike proteins on the surface of SARS-CoV-2 and prevent the virus from binding and entering the host cell. As each antibody can bind to two spike proteins from different viruses, the start forming virus clusters that can be better recognised and destroyed by phagocytes.

If antibodies offer such great protection, then why do some people become severely ill with COVID-19?

This raises the question as to why some patients experience mild symptoms of COVID-19 while others suffer severely, or even die from, an otherwise identical disease.

One hypothesis is that the progression and manifestation of the disease depends on the ability and strength of the antibodies in our bodies to protect us. It is believed that an antibody will be an effective neutralizer only if it fits perfectly to the shape of the spike proteins and therefore binds strongly to the virus (i.e., it binds with a high affinity).

If a patient’s immune system produces only lower-affinity antibodies (or even non-neutralizing antibodies that do not block the receptor binding site of the spike protein at all), cellular protection becomes compromised, even though the immune system might try to compensate by producing increasing amounts of these weak or non-neutralizing antibodies.

So are there tests that assess if we have neutralizing antibodies?

Although it is reasonably straightforward to determine the presence of antibodies in COVID-19 patients using standard but crude immunoassays such as ELISA tests, assessing the virus-neutralizing capacity of antibodies in patient serum still relies on a cell-based neutralization assays. Although these assays do assess whether serum antibodies have the ability to block replication of the virus, they have significant drawbacks. They often require live biological materials and strict biosafety regulations, and most importantly, they are slow.

Because they rely on the growth of living cells in culture, cell-based neutralization assays take several days to complete. During this time, a patient’s infection continues to develop. A multi-day wait for clinically actionable information could lead to several days of isolation from loved ones and absence from work at best; or a severe deterioration of symptoms and death at worst.

Another limitation of cell-based neutralization assays specifically impacts the development of vaccines and antibody-based treatments. Current cell-based neutralization assays cannot characterize and quantify specific antigen–antibody interactions, but rather provide a binary readout of whether or not neutralizing antibodies are present. Because this binary outcome does not provide insights in the mechanisms of action of vaccines and therapeutics, key information about the relative effectiveness of vaccines or antibody-based treatments could be missed.

No-fuzz detection and characterization in hours, not days!

COVID-19 with all its impact on people, societies and everyday life, is a stark reminder that there is an urgent need in modern medicine for a test that informs patients, clinicians and researchers—in hours, not days—about the presence and, more importantly, the quality of neutralizing antibodies in their blood samples.

To address this need, we have created a rapid, cell-free, virus-neuralization assay based on our in-solution technology and made it available on our Fluidity One-W Seruminstrument. The assay measures the binding interaction between the ACE-2 receptor and the SARS-CoV-2 spike protein, as well as the subsequent displacement of the spike protein in the presence of virus-neutralizing antibodies directly in patient serum, all within a couple of hours. Nanjing Norman Biological Technology Co.,Ltd

Figure 3. Our in-solution assay allows for the direct measurement of virus spike displacement from the ACE-2 receptor in the presence of neutralising antibodies.

We are excited that this easy and fast approach could make a positive impact on patients’ lives and help researchers, clinicians and biopharma companies to better understand protective immunity and develop more effective vaccine and therapeutics candidates to fight COVID-19 (more information on this test shortly).

Nanjing Norman Biological Technology Co.,Ltd is committing to offer comprehensive IVD solution covering self-developing and manufacturing raw material,reagent,equipment,get more COVID-19 Antibody Test Kit and Antigen Test Kit from https://www.normanbio.com.

Novel Coronavirus (COVID-19) Neutralizing Antibody Testing Kit (Colloidal Gold)

#SARS-CoV-2, COVID-19, saliva, diagnostics kit

Abstract

Rapid and accurate SARS-CoV-2 diagnostic testing is essential for controlling the ongoing COVID-19 pandemic. The current gold standard for COVID-19 diagnosis is real-time RT-PCR detection of SARS-CoV-2 from nasopharyngeal swabs. Low sensitivity, exposure risks to healthcare workers, and global shortages of swabs and personal protective equipment, however, necessitate the validation of new diagnostic approaches. Saliva is a promising candidate for SARS-CoV-2 diagnostics because (1) collection is minimally invasive and can reliably be self-administered and (2) saliva has exhibited comparable sensitivity to nasopharyngeal swabs in detection of other respiratory pathogens, including endemic human coronaviruses, in previous studies. To validate the use of saliva for SARS-CoV-2 detection, we tested nasopharyngeal and saliva samples from confirmed COVID-19 patients and self-collected samples from healthcare workers on COVID-19 wards. When we compared SARS-CoV-2 detection from patient-matched nasopharyngeal

and saliva samples, we found that saliva yielded greater detection sensitivity and consistency throughout the course of infection. Furthermore, we report less variability in self-sample collection of saliva. Taken together, our findings demonstrate that saliva is a viable and more sensitive alternative to nasopharyngeal swabs and could enable at-home self-administered sample collection for accurate large-scale SARS-CoV-2 testing.

Introduction

Efforts to control SARS-CoV-2, the novel coronavirus causing COVID-19 pandemic, depend on accurate and rapid diagnostic testing. These tests must be (1) sensitive to mild and asymptomatic infections to promote effective self isolation and reduce transmission within high risk groups1 ; (2) consistent to reliably monitor disease progression and aid clinical decisions2 ; and (3) scalable to inform local and national public health policies, such as when social distancing measures can be safely relaxed. However, current SARS-CoV-2 testing strategies often fail to meet these criteria, in part because of their reliance on nasopharyngeal swabs as the widely recommended sample type for real-time RT-PCR.

Although nasopharyngeal swabs are commonly used in respiratory virus diagnostics, they show relatively poor sensitivity for SARS-CoV-2 detection in early infection and are 2–6 inconsistent during serial testing . Moreover, collecting nasopharyngeal swabs causes discomfort to patients due to the procedure’s invasiveness, limiting compliance for repeat testing, and presents a considerable risk to healthcare workers, because it can induce patients to sneeze or cough, expelling virus particles7 . The procedure is also not conducive to large-scale testing, because there are widespread shortages of swabs and personal protective equipment for healthcare workers8 , and self-collection of nasopharyngeal swabs is difficult and less sensitive for virus detection9 . These challenges will be further exacerbated as the COVID-19 pandemic intensifies in low income countries. Given the limitations, a more reliable and less resource-intensive sample collection method, ideally one that accommodates self-collection in the home, is urgently needed. Saliva sampling is an appealing alternative to nasopharyngeal swab, since collecting saliva is non-invasive and easy to self-administer. An analysis of nasopharyngeal and saliva concordance for RT-PCR detection of respiratory pathogens, including two seasonal

human coronaviruses, suggests comparable diagnostic sensitivity between the two sample ^10,11of COVID-19 patients and (2) self-collected saliva samples have comparable. Preliminary findings indicate that (1) SARS-CoV-2 can be detected from the saliva ¹² typesmSARS-CoV-2 detection sensitivity to nasopharyngeal swabs collected by healthcare¹³ workers from mild and subclinical COVID-19 cases . Critically, however, no rigorous evaluation of the sensitivity of SARS-CoV-2 detection in saliva with respect to nasopharyngeal swabs has been conducted from inpatients during the course of COVID-19 infection.

In this study, we evaluated SARS-CoV-2 detection in paired nasopharyngeal swabs and saliva samples collected from COVID-19 inpatients and asymptomatic healthcare workers at moderate-to-high risk of COVID-19 exposure. Our results indicate that using saliva for SARS-CoV-2 detection is more sensitive and consistent than using nasopharyngeal swabs. Overall, we demonstrate that saliva should be considered as a reliable sample type to alleviate COVID-19 testing demands.

Results

Higher SARS-CoV-2 titers detected from saliva than nasopharyngeal swabs from inpatients
To determine if saliva performs as well as the U.S. CDC recommendation of using nasopharyngeal swabs for SARS-CoV-2 diagnostics, we collected clinical samples from 44 COVID-19 inpatient study participants (Table 1). This cohort represents a range of COVID-19 patients with severe disease, with 19 (43%) requiring intensive care, 10 (23%) requiring mechanical ventilation, and 2 (5%) deceased as of April 5th, 2020. Using the U.S. CDC SARS-CoV-2 RT-PCR assay, we tested 121 self-collected saliva or healthcare worker-administered nasopharyngeal swabs from this cohort. We found strong concordance between the U.S. CDC “N1” and “N2” primer-probe sets (Extended Data Fig. 1), and thus calculated virus titers (virus copies/mL) using only the “N1” set. From all positive samples tested (n = 46 nasopharyngeal, 37 saliva), we found that the geometric mean virus titers from saliva were about 5⨉ higher than nasopharyngeal swabs (p < 0.05, Mann-Whitney test; Fig. 1a). When limiting our analysis to only patient-matched nasopharyngeal and saliva samples (n = 38 for each sample type), we found that SARS-CoV-2 titers from saliva were significantly higher than nasopharyngeal swabs (p = 0.0001, Wilcoxon test; Fig. 1b). Moreover, we detected SARS-CoV-2 from the saliva but not the nasopharyngeal swabs from eight matching samples (21%), while we only detected SARS-CoV-2 from nasopharyngeal swabs and not saliva from three matched samples (8%; Fig. 1c). Overall, we found higher SARS-CoV-2 titers from saliva than nasopharyngeal swabs from hospital inpatients.

Table 1. COVID-19 inpatient cohort characteristics

Figure 1. SARS-CoV-2 titers are higher in the saliva than nasopharyngeal swabs from hospital inpatients. (a) All positive nasopharyngeal swabs (n = 46) and saliva samples (n = 39) were compared by a Mann-Whitney test (p < 0.05). Bars represent the median and 95% CI. Our assay detection limits for SARS-CoV-2 using the US CDC “N1” assay is at cycle threshold 38, which corresponds to 5,610 virus copies/mL of sample (shown as dotted line and grey area). (b) Patient matched samples (n = 38), represented by the connecting lines, were compared by a Wilcoxon test test (p < 0.05). (c) Patient matched samples (n = 38) are also represented on a scatter plot. All of the data used to generate this figure, including the raw cycle thresholds, can be found in Supplementary Data 1. Extended Data Fig. 1 shows the correlation between US CDC assay “N1” and “N2” results.

Less temporal SARS-CoV-2 variability when testing saliva from inpatients

As temporal SARS-CoV-2 diagnostic testing from nasopharyngeal swabs is reported to be ^2,3 variable , we tested longitudinal nasopharyngeal and saliva samples from inpatients to determine which sample type provided more consistent results. From 22 participants with multiple nasopharyngeal swabs and 12 participants with multiple saliva samples, we found that SARS-CoV-2 titers generally decreased in both sample types following the reported date of symptom onset (Fig. 2a). Our nasopharyngeal swab results are consistent with ^2,3 previous reports of variable SARS-CoV-2 titers and results : we found 5 instances where a participant’s nasopharyngeal swab was negative for SARS-CoV-2 followed by a positive result during the next collection (5/33 repeats, 33%; Fig. 2b) . In longitudinal saliva collections from 12 patients, however, there were no instances in which a sample tested negative and was later followed by a positive result. As true negative test results are important for clinicians to track patient improvements and for decisions regarding discharges, our data suggests that saliva is a more consistent sample type than nasopharyngeal swabs for monitoring temporal changes in SARS-CoV-2 titers.

Figure 2: SARS-CoV-2 detection is less variable between repeat sample collections with saliva. (a) Longitudinal SARS-CoV-2 titers from saliva or nasopharyngeal swabs are shown as days since symptom onset. Each circle represents a separate sample, which are connected to additional samples from the same patient by a dashed line. Our assay detection limits for SARS-CoV-2 using the US CDC “N1” assay is at cycle threshold 38, which corresponds to 5,610 virus copies/mL of sample (shown as dotted line and grey area). (b) The data are also shown by sampling moment (sequential collection time) to highlight the differences in virus titers between collection points. All of the data used to generate this figure, including the raw cycle thresholds, can be found in Supplementary Data 1.

More consistent self-sampling from healthcare workers using saliva

Validating saliva for the detection of subclinical SARS-CoV-2 infections could prove transformative for both remote patient diagnostics and healthcare worker surveillance. To investigate this, we enrolled 98 asymptomatic healthcare workers into our study and collected saliva and/or nasopharyngeal swabs on average every 2.9 days (range = 1-8 days, Table 2). To date, we have detected SARS-CoV-2 in saliva from two healthcare workers who were negative by nasopharyngeal swabs using both the US CDC “N1” and “N2” tests and did not report any symptoms. The saliva from one of these individuals again tested positive alongside a matching negative nasopharyngeal swab upon repeat testing 2 days later. Virus titers from asymptomatic healthcare workers’ saliva are lower than what we typically detect from symptomatic inpatients (Fig. 3a), which likely supports the lack of symptoms.

Our limited data supports that saliva may be more sensitive for detecting asymptomatic or pre-symptomatic infections; however, a larger sample size is needed to confirm. As nasopharyngeal swab sampling inconsistency may be one of the potential issues for false negatives (Fig. 2), monitoring an internal control for proper sample collection, human RNase P, may provide an alternative evaluation technique. While human RNase P detection was better from saliva in both the inpatient and healthcare worker cohorts (Fig. 3b) , this alone may not indicate better virus detection. More importantly, we found that human RNase P detection was more variable from nasopharyngeal swabs collected from inpatients (p = 0.0001, F test for variances) and self-collected from healthcare workers (p = 0.0002; Fig. 3b). Our results suggest that saliva may also be an appropriate, and perhaps more sensitive, alternative to nasopharyngeal swabs for screening asymptomatic or pre-symptomatic SARS-CoV-2 infections.

Table 2. Healthcare worker cohort

Figure 3. Saliva is an alternative for SARS-CoV-2 screening from healthcare workers and asymptomatic cases. (a) SARS-CoV-2 titers measured from the saliva of healthcare workers and inpatients. Our assay detection limits for SARS-CoV-2 using the US CDC “N1” assay is at cycle threshold 38, which corresponds to 5,610 virus copies/mL of sample (shown as dotted line and grey area). (b) RT-PCR cycle thresholds (Ct) values for human RNase P, and internal control for sample collection, from either inpatients (left panel) or health care workers (right panel) were compared by variances using the F test (p = 0.0001 for inpatients; p = 0.0002 for healthcare workers). All of the data used to generate this figure, including the raw cycle thresholds, can be found in Supplementary Data 1.

Discussion

Our study demonstrates that saliva is a viable and preferable alternative to nasopharyngeal swabs for SARS-CoV-2 detection. We found that the sensitivity of SARS-CoV-2 detection from saliva is comparable, if not superior to nasopharyngeal swabs in early hospitalization and is more consistent during extended hospitalization and recovery. Moreover, the detection of SARS-CoV-2 from the saliva of two asymptomatic healthcare workers despite negative matched nasopharyngeal swabs suggests that saliva may also be a viable alternative for identifying mild or subclinical infections. With further validation, widespread implementation of saliva sampling could be transformative for public health efforts: saliva self-collection negates the need for direct healthcare worker-patient interaction, a source of ^14–16 several major testing bottlenecks and overall nosocomial infection risk , and alleviates supply demands on swabs and personal protective equipment.

AsSARS-CoV-2viralloadsdifferbetweenmildandseverecases ,a limitation of our study is the primary focus on COVID-19 inpatients, many with severe disease. While more data are required to more rigorously compare the efficacy of saliva in the hospital setting to earlier in the course of infection, findings from two recent studies support its potential for ^13,18 detecting SARS-CoV-2 from both asymptomatic individuals and outpatients . As ¹² infectious virus has been detected from the saliva of COVID-19 patients , ascertaining the relationship between virus genome copies and infectious virus particles in the saliva of ¹⁹ pre-symptomatic individuals will play a key role in understanding the dynamics of ^1,20 asymptomatic transmission.

Stemming from the promising results for SARS-CoV-2 detection in asymptomatic 13

individuals ,asalivaSARS-CoV-2detectionassayhasalreadygainedapprovalthroughthe 18

U.S. Food and Drug Administration emergency use authorization . To meet the growing testing demands, however, our findings support the need for immediate validation and implementation of saliva for SARS-CoV-2 diagnostics in certified clinical laboratories.

Methods

Ethics

All study participants were enrolled and sampled in accordance to the Yale University HIC-approved protocol #2000027690. Demographics, clinical data and samples were only collected after the study participant had acknowledged that they had understood the study protocol and signed the informed consent. All participant information and samples were collected in association with study identifiers.

Participant enrollment

Inpatients
Patients admitted to Yale New Haven Hospital (a 1541-bed tertiary care medical center in New Haven, CT, USA), who tested positive for SARS-CoV-2 by nasopharyngeal and/or oropharyngeal swab (CDC approved assay) were invited to enroll in the research study. Exclusion criteria were age under 18 years, non-English speaking and clinical, radiological or laboratory evidence for a non-infectious cause of fever or respiratory symptoms or a microbiologically-confirmed infectious source (e.g. gastrointestinal, urinary, cardiovascular) other than respiratory tract for symptoms and no suspicion for COVID-19 infection.

Healthcare workers
Asymptomatic healthcare workers (e.g., without fever or respiratory symptoms) with occupational exposure to patients with COVID-19 were invited to enroll in the study. Study participation enabled active surveillance to ensure early detection following exposure and to further protect other healthcare workers and patients.

Sample collection

Inpatients
Nasopharyngeal and saliva samples were obtained every three days throughout their clinical course. Nasopharyngeal samples were taken by registered nurses using the BD universal viral transport (UVT) system. The flexible, mini-tip swab was passed through the patient's nostril until the posterior nasopharynx was reached, left in place for several seconds to absorb secretions then slowly removed while rotating. The swab was placed in the sterile viral transport media (total volume 3 mL) and sealed securely. Saliva samples were self-collected by the patient. Upon waking, patients were asked to avoid food, water and brushing of teeth until the sample was collected. Patients were asked to repeatedly spit into a sterile urine cup until roughly a third full of liquid (excluding bubbles), before securely closing it. All samples were stored at room temperature and transported to the research lab at the Yale School of Public Health within 5 hours of sample collection.

Healthcare workers
Healthcare workers were asked to collect a self-administered nasopharyngeal swab and a saliva sample every three days for a period of 2 weeks. Samples were stored at +4°C until being transported to the research lab.

SARS-CoV-2 detection

On arrival at the research lab, total nucleic acid was extracted from 300 μl of viral transport media from the nasopharyngeal swab or 300 μl of whole saliva using the MagMAX Viral/Pathogen Nucleic Acid Isolation kit (ThermoFisher Scientific) following the manufacturer's protocol and eluted into 75 μl of elution buffer. For SARS-CoV-2 RNA ^21,22 detection, 5 μl of RNA template was tested as previously described , using the US CDC real-time RT-PCR primer/probe sets for 2019-nCoV_N1 and 2019-nCoV_N2 and the human RNase P (RP) as an extraction control. Samples were classified as positive for SARS-CoV-2 when both N1 and N2 primer-probe sets were detected <38 C . Virus copies were ^T quantified using a 10-fold dilution standard curve of RNA transcripts that we previously ²¹ generated . As results from N1 and N2 were comparable (Extended Data Fig. 1), all virus copies are shown as calculated using the N1 primer-probe set.

Statistical analysis

Statistical analyses were conducted in GraphPad Prism 8.0.0 as described in the Results.

Acknowledgments

We gratefully acknowledge the study participants for their time and commitment to the study. We thank all members of the clinical team at Yale-New Haven Hospital for their dedication and work which made this study possible. We also thank S. Taylor and P. Jack for technical discussions.

Funding

The study was partially funded by the Yale Institute for Global Health. The corresponding authors had full access to all data in the study and had final responsibility for the decision to submit for publication.

Extended data

Novel Coronavirus (2019-nCoV) Anterior Nasal Swab Antigen Testing Kit (Colloidal Gold)

Novel Coronavirus (2019-nCoV) Paper Saliva Antigen Testing Kit (Colloidal Gold)

Extended Data Fig. 1. Concordance between SARS-CoV-2 detection using US CDC “N1” and “N2” primer and probe sets. Ct = RT-PCR cycle threshold. Dotted line and grey areas indicate the limits of detection.

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Source: https://www.medrxiv.org/content/10.1101/2020.04.16.20067835v1.full.pdf

AnneL.Wyllie1*,JohnFournier2, ArnauCasanovas-Massana1, MelissaCampbell2, MariaTokuyama3, Pavithra Vijayakumar4 , Bertie Geng4 , M. Catherine Muenker1 , Adam J. Moore1 , Chantal B.F. Vogels1 , Mary E. Petrone1 , Isabel M. Ott5, Peiwen Lu3 , Arvind Venkataraman3 , Alice Lu-Culligan3 , Jonathan Klein3 , Rebecca Earnest1 , Michael Simonov6 , Rupak Datta2 , Ryan Handoko2 , Nida Naushad2 , Lorenzo R. Sewanan2 , Jordan Valdez2 , Elizabeth B. White1 , Sarah Lapidus1 , Chaney C. Kalinich1 , Xiaodong Jiang3 , Daniel J. Kim3 , Eriko Kudo3 , Melissa Linehan3 , Tianyang Mao3 , Miyu Moriyama3 , Ji Eun Oh3 , Annsea Park3 , Julio Silva3 , Eric Song3 , Takehiro Takahashi3 , Manabu Taura3 , Orr-El Weizman3 , Patrick Wong3 , Yexin Yang3 , Santos Bermejo7 , Camila Odio8 , Saad B. Omer1,2,9,10, Charles S. Dela Cruz7 , ShelliFarhadian2, RichardA.Martinello2,7,11, AkikoIwasaki3,12, NathanD.Grubaugh1#*,AlbertI.Ko1#*

1 Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT 06510, USA 2 Department of Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, 06510, USA
3 Department of Immunobiology, Yale School of Medicine, New Haven, CT, 06510, USA
4 Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale School of Medicine, New Haven, CT, 06510, USA
5 Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA
6 Program of Applied Translational Research, Yale School of Medicine, New Haven, CT, 06510, USA
7 Department of Internal Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Yale School of Medicine, New Haven, CT, 06510, USA
8 Department of Medicine, Northeast Medical Group, Yale-New Haven Health, New Haven, CT 06510, USA
9 Yale Institute of Global Health, New Haven, CT 06510, USA
10 Yale School of Nursing, New Haven, CT 06510, USA
11 Department of Infection Prevention, Yale-New Haven Health, New Haven, CT 06520
12 Howard Hughes Medical Institute, New Haven, CT 06510, USA

# Joint senior authors
* Correspondence: anne.wyllie@yale.edu (ALW); nathan.grubaugh@yale.edu (NDG); albert.ko@yale.edu (AIK)

      Chemiluminescence Analyzer consists of the two parts of fully automated reaction system and chemiluminescence assay system. Fully automated reaction system is the process of indirect specific binding of luminescent marker to solid phase carrier by means of incubation and magnetic separation. Chemiluminescence assay system refers to the process of photomultiplier’s capture of photon with maximum wavelength of 430nm emitted by luminescent marker upon oxidization with hydrogen peroxide when acid environment suddenly changes into alkaline environment.

      The system uses acridinium ester and its derivatives as luminescent marker, and it becomes luminous through injection of activator within seconds, which makes it flash-type chemiluminescence. As luminescent marker used for assay and analysis, acridinium ester and its derivatives boasts of simple reaction, rapidness, absence of catalyst, excellent stability, less nonspecific binding, high sensitivity and other strengths, which make it a new effective compound.

      The core detector of this instrument is photomultiplier (PMT), which detects single photons and transfer to amplifier. High-voltage current’s added for amplification, amplifier converts analog current into digital current, digital current transfer luminescence signal to mainboard for calculation of relative luminescence unit (RLU), and contents of test antigens or antibodies in measurement sample are calculated through standard curve.

Chemiluminescence tests are a fascinating intersection of chemistry and biology, widely utilized in scientific research and practical applications. But what exactly is this test, and why is it so valuable? Let’s dive into its principles, uses, and significance.
What is Chemiluminescence?
Chemiluminescence refers to the emission of light during a chemical reaction without the involvement of external light sources like fluorescence or phosphorescence. This process occurs when an excited intermediate molecule releases energy in the form of visible or near-visible light as it returns to its ground state.
In tests, chemiluminescence is harnessed to detect and measure specific substances, as the emitted light is directly proportional to the concentration of the target compound.
How Does the Chemiluminescence Test Work?
1. Reaction Setup: A sample containing the substance of interest is mixed with reagents that trigger the chemiluminescent reaction.
2. Light Emission: The reaction produces light, often with the help of enhancers or catalysts.
3. Detection: Instruments like luminometers or specialized cameras capture the emitted light, quantifying the substance of interest based on its intensity.
Key Applications of the Chemiluminescence Test
1. Medical Diagnostics
Chemiluminescence immunoassays (CLIA) are widely used in medical testing. These tests detect hormones, proteins, or antigens in blood or other bodily fluids, aiding in diagnosing diseases such as cancer, autoimmune disorders, and infectious diseases.
2. Environmental Monitoring
Chemiluminescence plays a role in detecting pollutants like nitrogen oxides (NOx) in the atmosphere. This application is critical for understanding air quality and mitigating environmental hazards.
3. Pharmaceutical and Food Industries
These tests help ensure quality control by detecting contaminants or verifying the concentration of active compounds in drugs and food products.
4. Forensic Science
In forensic investigations, chemiluminescence is used to detect trace amounts of substances, such as blood at crime scenes. Luminol, a chemiluminescent reagent, is a classic example used for such purposes.
5. Biological Research
Researchers use chemiluminescence to study cellular processes, gene expression, or protein interactions. It is a sensitive method for tracking biomolecular activity.
Advantages of Chemiluminescence Tests
- High Sensitivity: Detects even trace amounts of substances.
- Specificity: Reactions can be tailored for specific targets.
- Rapid Results: Quick reaction times lead to fast readings.
- Low Background Noise: Absence of excitation light reduces interference.
Challenges and Limitations
While powerful, chemiluminescence tests require precise conditions for optimal performance. Factors like reagent stability, light measurement accuracy, and the presence of interfering substances can influence results.
Conclusion
The chemiluminescence test is a versatile tool that spans disciplines, from healthcare to environmental science. Its ability to provide accurate and rapid analysis makes it indispensable in modern science and industry. Whether used to detect diseases, pollutants, or forensic evidence, this test continues to illuminate pathways to innovation and discovery.
What do you think about the applications of chemiluminescence in your field? Let us know in the comments!

Why Choose Antibody Test

Although the English expert from the World Health Organization (WHO) subsequently tested negative, it was not immediately clear if the earlier result was a false positive, or the result of previous infection or a Sars-CoV-2 vaccination.

WILL VACCINATED PEOPLE GET POSITIVE ANTIBODY RESULTS?

It is possible, but not always, experts say. Most vaccines target the “spike” protein on the virus surface to trigger an immune response that could include IgM antibodies.

“We can assume that any Sars-CoV-2 vaccine containing the spike protein will induce IgM and therefore a diagnostic assay designed to detect spike specific IgM will not be able to differentiate vaccination from infection,” said Helen Fletcher, a professor of immunology at the London School of Hygiene & Tropical Medicine.

Published data on Oxford University/AstraZeneca Plc’s Sars-CoV-2 vaccine shows spike protein-triggered IgM is detectable in some people at least 56 days after immunization, Fletcher said.

IS IT POSSIBLE TO USE DIFFERENT ANTIBODY TESTS?

Tests to detect antibodies triggered by non-spike protein can yield negative results for those who got vaccines targeting spike protein, said Jin Dong-Yan, a professor of virology at the University of Hong Kong.

Vaccines targeting spike protein include those from AstraZeneca, Pfizer Inc and its partner BioNTech, and Moderna.

THERE ARE STILLNEED TO BE CLARIFIED

Such tests, But, can be problematic for other types of vaccines, including whole virus-based shots .some experts said.

“Where a person is injected with whole virus-based inactivated Sars-CoV-2 vaccine...there’s a strong chance that the person may also have positive result from non-spike protein IgM antibody tests,” said Ian Jones, a virologist at Britain’s University of Reading.

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Cardiovascular disease (CVD) is the world's number one killer, causing over 18.6 million deaths per year. CVD is a class of diseases that affect the heart or blood vessels (veins and arteries). More people die from CVD worldwide than from any other cause: over 18.6 million every year. Of these deaths, 85% are due to coronary heart diseases (e.g heart attacks) and cerebrovascular diseases (e.g. strokes) and mostly affect low-and middle-income countries.

Do you know that sometimes medicines or irregularities in your heart rate may warrant a visit to your doctor? And, if your pulse is very low, very high, or frequently switches between, you also need to consult a doctor right away?

Keeping track of your health and wellness has become more crucial than ever. Everything matters: what you eat, how much Sleep you get, are you working out, and what you are doing to keep your mind, body, and soul intact.

Working from nine to five, looking after the family and yourself, can be overwhelming. But you cannot avoid them. You must take care of their heart.

Maintaining good health will avoid problems like absenteeism or other physical, mental, emotional, and spiritual imbalance and remain productive. It will help you thrive in both your personal and professional life. So, setting your health goals today will help you succeed in the long run.

Every heartbeat counts, and the health of every employee matters. Together let's care for our heart health and take action to beat cardiovascular disease.

As a top in vitro diagnostic equipment enterprise in China, Normanbio has been at the forefront of developing comprehensive tests in aid of evaluating the risk of cardiovascular diseases, which enables healthcare professionals to provide real-time diagnosis, make informed treatment decisions and improve patient outcomes.

Dining out or enjoying a family meal at home can often lead to messy situations, especially when it comes to young children or even adults who tend to spill food. This is where a disposable bib comes in handy. A disposable dining bib offers a convenient, hygienic, and practical solution to prevent stains and keep your clothing clean while enjoying your meal. Whether you're at a restaurant or at home, disposable bibs are becoming a must-have for any dining situation.

The disposable bib is designed with simplicity and efficiency in mind. Made from high-quality, lightweight materials, these bibs provide comfort and durability while being easy to dispose of after use. Available in different sizes and styles, disposable dining bibs cater to various needs, from protecting your clothes during meals to ensuring cleanliness during messy activities like crafting or painting. These bibs are especially popular for children, who are often more prone to creating a mess when eating.

One of the standout options in the market today is the disposable printing bib, which offers customization options for businesses and events. Whether you're looking to create personalized bibs for a restaurant, a promotional giveaway, or an event, these printed bibs can be branded with logos, images, or slogans, providing an extra touch of marketing while serving a functional purpose. The disposable printing bib can help enhance your business’s visibility, all while offering a clean and practical solution for your customers.

At Telijie, we understand the importance of both product quality and service excellence. As a trusted manufacturer, we offer a range of high-quality disposable bib options, including disposable dining bibs and disposable printing bibs, that meet the highest standards of hygiene and comfort. Our products are designed to be gentle on the skin yet highly durable, ensuring that you can enjoy your meals without worry. Beyond the product itself, Telijie is committed to providing exceptional service to our clients. With efficient production timelines, reliable shipping, and customizable options, we ensure that your business or personal needs are met with utmost satisfaction.

Whether you’re looking for a practical solution for your restaurant, a promotional item for your event, or a way to keep your family clean during mealtime, Telijie’s range of disposable bibs offers the perfect combination of convenience, style, and functionality. With our expertise in providing both quality products and top-tier service, you can trust Telijie to meet all your disposable bib needs with professionalism and efficiency.

In the realm of advanced materials, alumina ceramic rods, also known as aluminum oxide (Al2O3) rods, stand out as superior alternatives to traditional metallic materials in numerous applications. Their exceptional properties and characteristics set them apart, offering unparalleled advantages that metallic materials often struggle to match.

Hardness and Wear Resistance

One of the most significant advantages of alumina ceramic rods over metallic materials lies in their exceptional hardness. On the Mohs hardness scale, alumina ceramic rods rank second only to diamond, far exceeding the hardness of most metals. This superior hardness translates into unparalleled wear resistance, making alumina ceramic rods ideal for applications where mechanical stress and abrasion are prevalent. In contrast, metallic materials, despite their strength, are prone to wear and tear over time, especially in harsh environments.

Thermal Stability

Another crucial advantage of alumina ceramic rods is their exceptional thermal stability. These rods can withstand temperatures up to 1,800°C (3,272°F) without significant degradation, whereas most metals exhibit significant softening or loss of strength at much lower temperatures. This makes alumina ceramic rods the material of choice in high-temperature applications such as furnace components, kiln linings, and turbine engines. Metals, on the other hand, often require cooling systems or specialized alloys to maintain their performance at elevated temperatures.

Electrical Insulation

Alumina ceramic rods also excel in electrical applications due to their superior electrical insulation properties. These rods are highly resistant to the flow of electric current, making them invaluable in the electronics industry for use in capacitors, transformers, and other electrical components. In contrast, most metals are good conductors of electricity, which limits their use in electrical insulation applications.

Chemical Resistance

The excellent chemical resistance of alumina ceramic rods is another key advantage over metallic materials. These rods can withstand exposure to a wide range of corrosive substances, acids, and alkaline solutions without significant degradation. This makes them ideal for use in the chemical processing industry, where metallic materials may suffer from corrosion and premature failure.

Lightweight and Strong

Despite their exceptional strength and durability, alumina ceramic rods are relatively lightweight compared to many metals, especially at comparable strengths. This weight advantage is crucial in applications where weight reduction is essential, such as in aerospace and automotive industries.

Cost-Effectiveness in the Long Run

While the initial cost of alumina ceramic rods may be higher than some metallic materials, their exceptional durability and longevity often make them more cost-effective in the long run. Their ability to withstand harsh conditions and resist wear and corrosion means fewer replacements and lower maintenance costs over the lifetime of the product.

In conclusion, alumina ceramic rods offer a unique combination of properties that make them superior to metallic materials in numerous applications. Their exceptional hardness, wear resistance, thermal stability, electrical insulation, and chemical resistance, combined with their lightweight strength, make them indispensable in a wide range of industries. The advantages of alumina ceramic rods translate into improved performance, reliability, and safety, ultimately contributing to cost savings and increased efficiency in various industrial processes.

Aluminium oxide (Al2O3) rods, commonly known as alumina ceramic rods, stand out as an exceptional category of engineering materials, distinguished by their unique blend of superlative characteristics. Renowned for their unparalleled hardness, durability, and outstanding thermal stability, these rods have become indispensable in a myriad of industrial applications. A notable feature of alumina ceramic rods is their impressive thermal endurance, capable of enduring temperatures soaring up to 1,800°C (3,272°F) without substantial structural alterations or deterioration. This exceptional heat resistance renders them the perfect fit for high-temperature environments, including furnace constructions, kiln linings, and intensive industrial processes.

 

Moreover, alumina ceramic rods excel not only in their mechanical and thermal prowess but also in their exceptional electrical insulation capabilities. These rods exhibit remarkable resistance to electrical current flow, rendering them invaluable assets in the electronics industry, where they find application in a diverse array of electrical components and devices. Their superior dielectric strength coupled with low thermal conductivity further solidifies their position as the preferred choice for electrical applications.

 

The automotive industry is another sector that has embraced the exceptional properties of alumina ceramic rods, utilizing them in a wide range of applications that enhance the performance, reliability, and safety of modern vehicles.

One of the primary uses of alumina ceramic rods in the automotive industry is in the manufacture of engine components, such as spark plug insulators and glow plug tips. The high thermal stability and electrical insulation properties of these rods make them an ideal choice for applications where exposure to high temperatures and electrical currents is a constant concern. Their ability to withstand the harsh operating conditions of an internal combustion engine ensures reliable performance and extended component life.

In addition to engine components, alumina ceramic rods are also employed in the production of various brake system components, including brake pads and brake discs. The exceptional hardness and wear resistance of these rods allow them to maintain their performance characteristics even under the intense stresses and temperatures encountered during braking operations, contributing to improved braking efficiency and extended component life.

Furthermore, alumina ceramic rods find application in the manufacture of various structural and suspension components for vehicles, such as bearing housings, valve guides, and shock absorber components. The high strength-to-weight ratio and corrosion resistance of these rods make them an attractive choice for applications where weight reduction and durability are of paramount importance, enhancing the overall performance and fuel efficiency of the vehicle.

Beyond their use in primary vehicle components, alumina ceramic rods are also employed in the production of various auxiliary systems, such as sensor housings, electrical insulators, and high-temperature seals. Their versatility and adaptability ensure that they can be effectively integrated into a wide range of automotive applications, contributing to the overall reliability, safety, and efficiency of modern vehicles.

The exceptional properties of alumina ceramic rods have made them an indispensable material in the automotive industry, where their ability to withstand the demanding operating conditions and enhance the performance of various vehicle systems is widely recognized and valued.

 

In conclusion, alumina ceramic rods, with their unparalleled blend of mechanical, thermal, and electrical properties, have emerged as a cornerstone in the automotive industry and beyond. Their high thermal stability, electrical insulation capabilities, and remarkable durability have transformed them into essential components in a multitude of applications, ranging from engine and brake systems to structural and suspension parts. The automotive sector, in particular, has embraced these rods for enhancing vehicle performance, reliability, safety, and fuel efficiency. The versatility and adaptability of alumina ceramic rods ensure their continued relevance in the industry's quest for innovation and optimization, making them a vital material for the future of automotive technology.

Alumina tubes are widely utilized in diverse applications due to their exceptional properties such as high temperature resistance, chemical inertness, and mechanical strength. However, selecting the most suitable alumina tubes for a specific application necessitates a thorough understanding and evaluation of several key factors. This article aims to provide an overview of the critical selection criteria for alumina tubes, enabling users to make informed decisions that ensure optimal performance and suitability.

Understanding Application Requirements for Alumina Tubes

Understanding the specific demands of the application is paramount. This includes evaluating the operating conditions such as temperature ranges, chemical exposure, mechanical stress, and electrical requirements. Matching the alumina tube's properties to these demands ensures reliable and long-lasting performance. For instance, high-temperature applications require alumina tubes with superior thermal stability.

Dimensional Specifications for Alumina Tubes

Precision in the tube's diameter, wall thickness, and length is essential, particularly in applications where the tubes must fit into specific equipment or systems. Ensuring dimensional tolerances ensures a proper fit and seamless integration with other components.

Purity and Composition Considerations for Alumina Tubes

The purity and composition of the alumina material are crucial. Higher-purity alumina tubes, with minimal impurities, are preferred for applications requiring chemical compatibility, electrical insulation, or optical transparency. The presence of additives or dopants can also affect the tube's properties and performance.

Manufacturing Process and Quality Control of Alumina Tubes

Selecting a reputable manufacturer with a proven track record of producing high-quality alumina tubes is vital. Evaluating factors such as the tube's surface finish, internal structure, and adherence to industry standards ensures consistent performance and reliability.

Cost and Availability of Alumina Tubes

Cost and availability are significant considerations, especially for large-scale or high-volume applications. Understanding pricing structures, lead times, and supply chain reliability aids in effective procurement planning and informed decision-making.

Compatibility of Alumina Tubes with Other Components

Assessing the compatibility of the alumina tubes with other components or systems in the application is crucial. This includes evaluating thermal expansion characteristics, thermal shock resistance, and the ability to integrate seamlessly with the overall system design.

In conclusion, selecting the optimal alumina tubes for a specific application requires a comprehensive understanding and evaluation of several key factors. By considering application requirements, dimensional specifications, purity and composition, manufacturing process and quality control, cost and availability, and compatibility with other components, users can ensure that the chosen alumina tubes meet their specific needs and provide the desired performance, reliability, and cost-effectiveness. This informed decision-making process ultimately contributes to the success and efficiency of various industrial applications.