SUMMARY AND EXPLANATION THE TEST
Dengue viruses, a family of four distinct serotypes of viruses (Den 1,2,3,4), are singlestrained, enveloped, positive-sense RNA viruses. The viruses are transmitted by mosquitoes of the daytime-bitting Stegemyia family, principally Aedes aegypti, and Aedes albopictus. Today, more than 2.5 billion people living in the areas of tropical Asia, Africa, Australia, and the Americas are at risk for dengue infection. An estimated 100 million cases of dengue fever and 250,000 cases of life-threatening dengue hemorrhagic fever occur annually on a worldwide basis1-3.
Serological detection of IgM antibody is the most common method for the diagnosis of dengue virus infection. Lately, detection of antigens released during virus replication in the infected patient showed very promising result. It enables diagnosis from the first day after the onset of fever up to day 9, once the clinical phase of the disease is over, thus allows early treatment in placed promptly4-.The Dengue IgG/IgM Rapid Test is developed to detect circulating dengue antigen in serum ,plasma or whole blood. The test can be performed by untrained or minimally skilled personnel, without laboratory equipment.
PRINCIPLE
The Dengue IgG/IgM Rapid Test is a lateral flow chromatographic immunoassay. The test cassette consists of: 1) a burgundy colored conjugate pad containing dengue recombinant envelope antigens conjugated with colloid gold (dengue conjugates) and rabbit IgG-gold conjugates,2) a nitrocellulose membrane strip containing two test bands (G and M bands) and a control band (C band). The G band is pre-coated with the antibody for the detection of IgG anti-dengue virus, M band is coated with antibody for the detection of IgM anti-dengue virus, and the C band is pre-coated with goat anti rabbit IgG.
When an adequate volume of test specimen is dispensed into the sample well of the test cassette, the specimen migrates by capillary action across the cassette. IgG anti-dengue virus if present in the specimen will bind to the dengue conjugates. The immunocomplex is then captured by the reagent coated on the G band, forming a burgundy colored G band, indicating a dengue virus IgG positive test result and suggesting a recent or repeat infection. IgM anti-dengue virus, if present in the specimen, will bind to the dengue conjugates. The immunocomplex is then captured by the reagent pre-coated on the M band, forming a burgundy colored M band, indicating a dengue virus IgM positive test result and suggesting a fresh infection.
Absence of any test bands (G and M) suggests a negative result.The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex of goat anti rabbit IgG/rabbit IgG-gold conjugate regardless of the color development on any of the T bands. Otherwise, the test result is invalid and the specimen must be retested with another device.
