Virus-neutralizing antibody

Antibodies that neutralize viruses

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Virus-neutralizing antibodies (VNAs) are a subset of antibodies that can directly neutralize the infectivity of viruses. These antibodies are a critical component of the adaptive immune system and play a vital role in the defense against viral infections.

Structure and Function

Virus-neutralizing antibodies are typically IgG or IgA isotypes, although other isotypes can also exhibit neutralizing activity. They function by binding to specific epitopes on the surface of a virus, thereby blocking the virus's ability to enter host cells. This can occur through several mechanisms:

• Blocking viral attachment: VNAs can bind to viral proteins that are necessary for attachment to host cell receptors, preventing the virus from adhering to the cell surface.
• Inhibiting fusion: Some VNAs prevent the fusion of the viral envelope with the host cell membrane, a critical step for viral entry.
• Inducing conformational changes: Binding of VNAs can induce conformational changes in viral proteins, rendering them non-functional.

Role in Immunity

Virus-neutralizing antibodies are a key component of the humoral immune response. Upon initial exposure to a virus, the immune system generates a primary response, producing antibodies that can neutralize the virus. Upon subsequent exposures, memory B cells rapidly produce VNAs, providing immunity against reinfection.

VNAs are also the basis for many vaccines, which aim to elicit a strong neutralizing antibody response without causing disease. For example, vaccines against measles, mumps, and rubella are designed to stimulate the production of VNAs that confer long-lasting immunity.

Clinical Significance

The presence of virus-neutralizing antibodies is often used as a correlate of protection in vaccine studies. High titers of VNAs are generally associated with protection against infection or disease severity.

In therapeutic settings, VNAs can be administered as monoclonal antibodies to treat viral infections. For instance, monoclonal antibodies targeting the SARS-CoV-2 virus have been used to treat COVID-19 patients.

Research and Development

Research into VNAs is ongoing, with efforts to identify and characterize antibodies that can neutralize emerging viral threats. Techniques such as phage display and single-cell sequencing are used to discover potent VNAs.

Also see

• Antibody-dependent enhancement
• Monoclonal antibody therapy
• Vaccine
• Adaptive immune system