Reagent used in ELISA test is

Reagent used is :

ELISA is

A person's immune system is suppressed, and ELISA test, gives positive indication of a pathogen. Which cells of the body are affected by the pathogen?

A person's immune system is suppressed, and ELISA test, gives positive indication of a pathogen. Name the disease the patient is suffering from.

A person's immune system is suppressed, and ELISA test, gives positive indication of a pathogen. What is the causative organism?

What is the basis of detection using ELISA test?