Filariasis IgG/IgM Rapid Test Cassette

Filariasis IgG/IgM Rapid Test Cassette

INTENDED USE

The Filariasis IgG/IgM Rapid Test is a lateral flow immunoassay for the simultaneous detection and differentiation of IgG and IgM anti‐lymphatic filarial parasites (W. Bancrofti and B. Malayi) in human serum, plasma or whole blood. This test is intended to be used as a screening test and as an aid in the diagnosis of infection with lymphatic filarial parasites. Any reactive specimen with the Filariasis IgG/IgM Rapid Test must be confirmed with alternative testing method(s).

SUMMARY AND EXPLANATION OF THE TEST

The lymphatic filariasis known a s Elephantiasis, mainly caused by W. bancrofti and B. malayi, affects about 120 million people over 80 countries 1,2. The disease is transmitted to humans by the bites of infected mosquitoes within which the microflariae sucked from a n infected human subject develops into third‐stage larvae. Generally, repeated and prolonged expo sure to infected larvae is required for establishment of human infection. The definitive parasitologic diagnosis is the demonstration of microflariae in blood samples3. However, this gold standard test is restricted by the requirement for nocturnal blood collection and lack of adequate sensitivity. Detection of circulating antigens is commercially available. Its usefulness is limited for W. bancrofti4. In addition, microfilaremia and antigenemia develop from months to years after exposure. Antibody detection provides an early means to detect filarial parasite infection. Presence of IgM to the parasite antigens suggest current infection, whereas, IgG corresponds to late stage of infection or past infection5. Furthermore, identification of conserved antigens allows ‘pan‐filaria’ test to be applicable. Utilization of recombinant proteins eliminates cross‐reaction with individuals having other parasitic diseases6. The Filariasis IgG/IgM Rapid Test uses conserved recombinant antigens to simultaneously detect IgG and IgM to the W. bancrofti and B. malayi parasites without the restriction on specimen collection.

TEST PRINCIPLE

The Filariasis IgG/IgM Rapid Test is a lateral flow chromatographic immunoassay. The test cassette consists of: 1) a burgundy colored conjugate pad containing recombinant W. bancrofti and B. malayi common antigens conjugated with colloid gold (Filariasis conjugates) and rabbit IgG‐gold conjugates, 2) a nitrocellulose membrane strip containing two test bands (T1 and T2 bands) and a control band (C band). The T1 band is pre‐coated with monoclonal anti‐human IgM for the detection of IgM anti W. bancrofti and B. malayi, T2 band is pre‐coated with reagents for the detection of IgG antiW. bancrofti and B. malayi, 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 cassette, the specimen migrates by capillary action across the cassette. W. bancrofti or B. malayi IgM antibodies if present in the specimen will bind to the Filariasis conjugates. The immunocomplex is then captured on the membrane by the pre‐coated anti‐human IgM antibody, forming a burgundy colored T2 band, indicating a W. bancrofti or B. malayi IgM positive test result. W. bancrofti or B. malayi IgG antibodies if present in the specimen will bind to the Filariasis conjugates. The immunocomplex is then captured by the pre‐coated reagents on the membrane, forming a burgundy colored T1 band, indicating a W. bancrofti or B. malayi IgG positive test result. Absence of any test bands (T1 and T2) suggests a negative result.

Rebecca Yan