ELISA

Definition

ELISA, or Enzyme-Linked Immunosorbent Assay, is a widely used laboratory technique designed to detect and quantify proteins, hormones, antibodies, and antigens in a sample. This method is particularly important in diagnosing viral diseases, as it allows for the detection of specific viral proteins or antibodies produced in response to an infection. By using enzyme-linked antibodies, ELISA provides a measurable signal that can indicate the presence of a virus in biological samples.

5 Must Know Facts For Your Next Test

1. ELISA is highly sensitive and can detect low levels of antigens or antibodies, making it valuable for early diagnosis of viral infections.
2. The assay works by immobilizing an antigen on a solid surface, then adding a sample containing antibodies; if the antibodies bind to the antigen, they can be detected by an enzyme-linked secondary antibody.
3. Results from ELISA tests can be quantitative, allowing researchers to measure the concentration of a specific antibody or antigen in a sample.
4. This technique is commonly used for screening blood donations for viruses such as HIV, hepatitis B, and hepatitis C.
5. There are various types of ELISA, including direct, indirect, sandwich, and competitive ELISA, each suited for different types of assays and sample conditions.

Review Questions

• How does ELISA contribute to the diagnosis of viral diseases?
  • ELISA contributes to the diagnosis of viral diseases by allowing for the specific detection and quantification of viral proteins or antibodies in patient samples. By identifying these components, healthcare professionals can determine if an individual has been exposed to a virus or if they are currently infected. The sensitivity and specificity of ELISA make it an essential tool in clinical diagnostics for various viral infections.
• Compare and contrast the different types of ELISA assays and their applications in detecting viral diseases.
  • Different types of ELISA assays include direct ELISA, which detects antigens directly; indirect ELISA, which measures antibodies; sandwich ELISA that captures antigens between two layers of antibodies; and competitive ELISA that quantifies antigens based on competition with labeled antigens. Each type has unique applications depending on whether the goal is to detect antibodies produced in response to a viral infection or to quantify viral antigens present in a sample. For instance, sandwich ELISAs are particularly effective for measuring proteins that are secreted during infections.
• Evaluate the impact of using ELISA in public health screening programs for viral diseases and discuss potential limitations.
  • Using ELISA in public health screening programs significantly impacts disease control by enabling early detection and monitoring of viral infections, which can inform treatment decisions and help prevent outbreaks. However, potential limitations include false positives or negatives due to cross-reactivity with similar antigens or variations in individual immune responses. Moreover, while ELISA is highly sensitive, it may require confirmation with more specific tests like PCR for definitive diagnosis. This combination ensures accurate public health interventions while acknowledging inherent test limitations.

Related terms

Antigen: A substance that induces an immune response, often a component of a pathogen like a virus that the immune system recognizes.

Antibody: A protein produced by the immune system in response to an antigen, which helps neutralize or eliminate pathogens.

Serology: The study of blood serum, particularly the presence of antibodies in serum as an indicator of immune responses to infections.