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Technical Service Platform

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In vitro–differentiated Th1/Th17/Treg cells

CD4+ helper T cells (Th cells) serve as mediators of cellular immunity and play a critical role in activating other immune cells, such as B cells and cytotoxic T cells, as well as in regulating immune responses.

Antibody-Dependent Cell-Mediated Cytotoxicity Assay (ADCC)

Antibodies, as integral components of the immune system, play a crucial role in defending against disease. Antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the mechanisms by which antibodies exert their effector functions: when IgG antibodies specifically bind via their Fab fragments to antigenic epitopes on the surface of target cells—such as virus-infected cells and tumor cells—the Fc portion of the antibody can engage Fc receptors on effector cells, including natural killer (NK) cells, monocytes–macrophages, and neutrophils, thereby triggering the effector cells’ cytotoxic activity and directly killing the target cells. The ability to elicit ADCC against target cells is an important functional criterion for antibody candidates that are directed against cancer-associated antigens.

Antibody-dependent cellular phagocytosis

Antibody-dependent cellular cytotoxicity (ADCC) is one of the mechanisms by which antibody-based therapies exert their antitumor and other therapeutic effects. Currently, therapeutic strategies aimed at enhancing macrophage responses to therapeutic antibodies have garnered significant attention from researchers, including the identification of novel targets and the development of antibodies with enhanced functionality.

Complement-dependent cytotoxicity (CDC)

Complement is a group of heat-labile, enzymatically active proteins found in human and vertebrate serum and tissue fluids, comprising more than 30 soluble and membrane-bound proteins. Complement-dependent cytotoxicity (CDC) refers to the lytic effect on target cells resulting from the formation of a membrane attack complex after complement is activated by specific antibodies that bind to corresponding antigens on the cell membrane via the classical pathway of complement activation. Initially, antibodies bind to complement component C1q, which then triggers the sequential activation of C2 through C9 to form the membrane attack complex, ultimately leading to lysis of the target cell.

Cytokine Release Syndrome Risk Assessment (CRS)

Cytokine release syndrome (CRS) refers to a hyperactive immune response that occurs following infection with pathogenic microorganisms, leading to the rapid activation of numerous immune cells and the massive release of multiple cytokines—including TNF-α, IL-1, IL-6, IL-12, IFN-α, IFN-β, and IFN-γ—within a short period. This results in a severe systemic inflammatory response syndrome. The excessive production of these cytokines can damage tissues and organs, thereby giving rise to a wide range of clinical manifestations. Currently, the standard approach is to closely monitor and target the specific cytokines that trigger the cytokine storm.

Flow Cytometry-Based Cell Characterization Experiments (FACS)

The targets of antibody drugs are primarily disease-associated antigens or specific receptor molecules on the cell surface. Competitive binding between ligands and antibodies is assessed by using flow cytometry to determine the population of antigen-positive cells. By employing antigen-presenting cells in these assays, the spatial conformation of surface antigens more closely resembles their in vivo configuration, thereby yielding results that better reflect physiological conditions.

Introduction to Neutralizing Antibodies Against Authentic Viruses

Currently, pseudovirus-based assays closely mimic physiological infection mechanisms and can largely replicate the in vivo therapeutic efficacy; however, there is a substantial discrepancy between neutralization assay results obtained with live viruses and those obtained with pseudoviruses. Therefore, live-virus neutralization assays are an indispensable step in the development of antiviral drugs and vaccines.

Neutralizing antibodies are produced in response to the invasion of pathogenic microorganisms into the host. For a pathogen to infect a cell and subsequently replicate, it must rely on specific molecules expressed by the pathogen itself that bind to receptors on the host cell surface.

Neutralizing antibodies bind to surface antigens of pathogenic microorganisms, thereby blocking the pathogen’s adhesion to target-cell receptors and preventing its entry into cells. Neutralizing antibodies are induced by pathogen surface antigens, whereas non-neutralizing antibodies are induced by viral internal antigens or by non-neutralizing surface antigens. Neutralizing antibodies are also referred to as “functional antibodies.”

Non-neutralizing antibodies cannot prevent pathogenic microorganisms from adhering to host cells, and therefore cannot inhibit pathogen entry into cells. Moreover, not all non-neutralizing antibodies are truly neutral; some can even exert adverse effects.

Key Points in Neutralizing Antibody Testing

Key Point 1 Target virus strain type and source

Key Point 2 Cell type

Key Point 3 How to observe the results

Microcytopathic Effect Assay vs. Plaque Reduction Assay

Compared with the plaque reduction assay, the microcytopathic effect assay is more time- and labor-efficient, exhibits smaller inter-well variability in cell numbers, and yields more stable results, making it well suited for high-throughput testing of large numbers of samples, such as vaccine evaluation.

Neutralizing antibodies bind to antigens on the surface of pathogenic microorganisms, thereby preventing these pathogens from adhering to target cell receptors and inhibiting their entry into cells. As a type of protective antibody, the measurement of neutralizing antibody titers can effectively reflect the host’s state of protection.

Methods for Observing Minute Cytopathic Changes

Figure 1

Figure 2

Figure 3

Figure 1: Direct microscopic observation of the lesion

Example: COVID-19, rotavirus
Figure 2: Microscopic observation after fluorescent staining

Example: Varicella-zoster virus (VZV)
Figure 3: After fluorescent staining, the fluorescence intensity is measured using an instrument.

Example: Rabies virus

Application Scenarios

Monitor vaccine immune efficacy to provide technical guidance for developing rational immunization schedules;
Support the development of vaccines, diagnostics, and therapeutic drugs.

Service Features

Neutralizing antibody testing is performed using standard viral strains.
Conduct testing services in accordance with GLP regulatory standards to meet the requirements for drug IND submissions.
Has assisted numerous companies in completing IND submissions for antiviral drugs (vaccines);
Some virus neutralization antibody assays can be performed in a P3 laboratory;
To date, neutralizing antibody testing has been completed for thousands of samples.

Virus Type

Respiratory syncytial virus, influenza virus, human herpesvirus, varicella-zoster virus, rotavirus, SARS-CoV-2, HIV, adenovirus, poliovirus vaccine strain, mumps virus, and measles virus.

Currently Offered Services