What Is Dengue NS1 Antigen?

What it is

NS1 is a non-structural protein secreted by the dengue virus during replication. Unlike antibodies, it is a direct viral product, so its presence indicates active viral replication.

Why it matters

NS1 is detectable from the first day of fever, before IgM antibodies appear — making it the earliest serological marker of acute dengue.

Specimen

Whole blood / serum / plasma

Interpretation

Positive = dengue NS1 antigen detected (acute infection). Negative = below detection limit.

Limitations

Best in the first week; sensitivity varies by serotype; a negative result does not exclude dengue.

Related test: Dengue NS1 Rapid Test — specimen: WB / S / P