Diagnostic ELISA: commercially available enzyme immunoassay kits are widely used to detect which of the following in clinical samples?

Introduction / Context:
ELISA (enzyme-linked immunosorbent assay) platforms are versatile diagnostic tools able to detect either antigens or antibodies. They are standard for viral diagnostics, vaccine screening, and public health programs because they combine sensitivity, specificity, and throughput.

Given Data / Assumptions:

• ELISAs can be configured as sandwich (antigen detection) or indirect/competitive (antibody detection).
• Common clinical targets include rotavirus antigen, HBsAg, and anti-HIV antibodies.

Concept / Approach:
In sandwich ELISA, capture antibodies immobilize target antigen from the sample; a second enzyme-labeled antibody enables colorimetric detection. Indirect ELISA detects patient antibodies binding to coated antigen. Both formats are used across many pathogens and biomarkers.

Step-by-Step Solution:

Verification / Alternative check:
Clinical lab catalogs list ELISAs for stool rotavirus antigen, serum HBsAg, and anti-HIV screening/confirmatory workflows (now often combined with Ag/Ab combo assays).

Why Other Options Are Wrong:

• Single-target choices are incomplete.
• “Only bacterial culture growth” is not an ELISA application.

Common Pitfalls:

• Confusing detection of antigens versus antibodies—ELISA supports both.

Final Answer:
All of these