Which component distinguishes a fourth-generation HIV immunoassay from earlier generation screening assays?

• A It uses Western blot confirmation integrated into the same platform
• B It directly measures HIV RNA by nucleic acid amplification
• C It detects only IgM antibodies, shortening the window period
• D It simultaneously detects p24 antigen and antibodies to HIV-1 and HIV-2 ✓

Explanation

Fourth-generation combination assays detect p24 capsid antigen together with anti-HIV-1 and anti-HIV-2 antibodies, reducing the window period to roughly 2 to 3 weeks because p24 appears before antibodies. Nucleic acid testing is a separate fifth step used in some algorithms for very early infection or indeterminate results. IgM-only assays were second generation, and Western blot remains a distinct confirmatory test rather than part of the screening platform.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.