Dengue Antigen NS1 (NS1Ag) detects the virus's non-structural protein component (NS1), while IgG & IgM are antibodies the body produces in response to the infection. NS1 and IgM are secreted into the blood during infection and are detectable within 3-4 days of illness. This test aids early diagnosis and treatment of dengue infection. IgG antibodies appear after the 14th day of infection and persist for life.