In brucellosis serology, the 2-mercaptoethanol (2-ME) agglutination test is primarily used to detect which antibody class?

Introduction:
Brucellosis serology employs agglutination tests to differentiate antibody classes and disease phase. The 2-ME test helps distinguish between early and chronic/ongoing infection.

Given Data / Assumptions:

• 2-ME reduces disulfide bonds in pentameric antibodies.
• We must identify which class remains agglutinating after treatment.

Concept / Approach:
2-ME disrupts IgM (pentamer) more readily than IgG (monomer). Persistence of agglutination after 2-ME treatment indicates IgG, commonly associated with chronic or ongoing infection.

Step-by-Step Solution:
Apply chemical effect: 2-ME reduces IgM activity. Assess remaining agglutination: due to IgG. Conclude that the test is used to detect IgG.

Verification / Alternative check:
Serology protocols define 2-ME positivity as evidence of IgG antibodies.

Why Other Options Are Wrong:

• IgM: Largely inactivated by 2-ME; not the intended readout.
• IgA / IgE / IgD: Not the principal targets in standard brucellosis agglutination workflows.

Common Pitfalls:
Confusing the standard agglutination test (detects mostly IgM) with the 2-ME modified test (reveals IgG).

Final Answer:
The 2-ME agglutination test primarily detects IgG.