Antibody fragments are engineered, smaller versions of full-sized antibodies, known as immunoglobulins. These fragments maintain the crucial ability to bind to specific antigens, similar to full antibodies, but they lack certain structural components found in complete antibody molecules. Antibody fragments are highly valuable in various biomedical and therapeutic applications, particularly when the size of full antibodies may be a limitation.

1. Fab (Fragment Antigen-Binding):

The Fab fragment is the essential antigen-binding region of an antibody. It encompasses one of the antibody's arms, containing the variable regions of both the heavy and light chains. Fab fragments are commonly used in scientific research and diagnostics, serving as valuable tools for capturing or detecting specific antigens.

2. F(ab')₂ (Fragment Antigen-Binding)2:

F(ab')₂ fragments are larger than Fab fragments and possess two distinct antigen-binding regions. They are generated by enzymatically cleaving full antibodies, often using the enzyme pepsin. F(ab')₂ fragments are known for their enhanced stability compared to Fab fragments and are applied in diverse research and diagnostic settings.

3. Fv (Variable Fragment):

The Fv fragment consists solely of the variable regions of both the heavy and light chains of an antibody. It is the smallest antibody fragment that retains its antigen-binding activity. Fv fragments are instrumental in antibody engineering and research, enabling the creation of bispecific antibodies and other customized antibody-based constructs.

4. Single-Chain Variable Fragment (scFv):

scFv is a fusion of the variable regions of the heavy and light chains, connected by a short peptide linker. These scFvs are compact and stable antibody fragments that can be efficiently produced in various expression systems. They are widely used in scientific research, diagnostics, and therapeutic applications, including cancer therapy and targeted drug delivery.

5. Isolation of Panels of Llama Single-Domain Antibody Fragments Binding All Nine Neuraminidase Subtypes of Influenza A Virus.