This rapid test kit is a panel of rapid qualitative lateral flow test kit designed for the qualitative detection of IgG/IgM antibodies to Toxoplasma gondii (TOXO), Cytomegalovirus (CMV), Rubella, Herpes Simplex virus (HSV-2) present in human serum or plasma samples.
SUMMARY AND CLINICAL SIGNIFICANCE for TOXO
T. gondii is an obligate intracellular protozoan parasite; the serological data indicates that approximately 30% of the population of most industrialized nations is chronically infected with this organism. When a sero-negative woman becomes infected with T. gondii during the pregnancy period the parasite is transmitted across the placenta to the fetus. The severity of the infection in the fetus differentiates with the trimester during which the infection was acquired. If infected during the trimester it may lead to spontaneous abortion, stillbirth or overt disease in the neonate. Approximately 75% of congenitally infected newborns are symptomatic. However, nearly all children born with subclinical toxoplasmosis can develop adverse neurologic sequelae or ocular later in life. Approximately 80 to 85% develops chorioretinitis and some may also experience blindness or mental retardation.
A variety of tests for antibodies to T. gondii have been used as an aid in the diagnosis of acute infection and to assess previous exposure to the organism. The more widely used test includes the Sabin-Feldman dye test, indirect hemagglutination, latex agglutination, direct agglutination, indirect immunofluorescence, and ELISA test.
SUMMARY AND EXPLANATION OF THE TEST FOR CMV
Cytomegalovirus is a herpes virus and is a known biological factor for causing congenital abnormalities and complications among those who receive massive blood transfusions and immunosuppressive therapy. About half of the pregnant women who come in contact with a primary infection spread the disease to their fetus. When acquired in uterus, its infection may cause blindness, mental retardation, and/or deafness.
Serological tests for detecting the presence of antibody to CMV can provide valuable information regarding the history of the previous infection. It is used for diagnosis of active or recent infection, as well as in screening blood for transfusions in newborns and immuno-compromised recipients.
SUMMARY AND EXPLANATION OF THE TEST FOR RUBELLA
Rubella is a herpes virus; it is generally considered a mild adolescence disease. However, a maternal infection can be transmitted through the placenta to the fetus, causing congenital rubella. Congenital rubella may result in chronic cardiac disease, hepatosplenomegaly, growth retardation, malformations, and other severe anomalies. Children born asymptomatic may develop these abnormalities later in their life.
For reducing the risk of such severe complications, accurate serological methods should be performed to determine the serologic status of childbearing-aged women. The presence of rubella-specific IgG in the bloodstream indicates immunity to rubella. A woman who is tested to be non-immune can be educated on the availability of its vaccine. An increase in rubella indicates an acute infection and differentiates rubella from other exanthematous diseases.
Expecting women with current rubella infection should be counseled on the consequences of the congenital infection.
SUMMARY AND EXPLANATION OF THE TEST FOR HSV-2
HSV-2 cause genital and neonatal infections, however, the tissue specificity are not absolute. Infants infected with HSV appear to be normal at birth but almost invariably develop symptoms during the period of 1, 4, and 5. Neonatal HSV infection may remain localized or become disseminated; localized infection may involve one or a combination of sites, these are skin, eyes, mouth or central nervous system. Disseminated infection is manifested by pneumonitis, disseminated intravascular coagulopathy, hepatitis, and encephalitis. The infants with neonatal HSV, about one-half of the surviving infants develop severe neurological or ocular sequelae.
A number of serological procedures have been developed to detect the antibodies to HSV. These include complement fixation, indirect immunofluorescent antibody, ELISA (2, 4, and 6) and plaque neutralization. An antibody of the IgM class is produced during the first 2 to 3 weeks of the infection with HSV and exists only transiently.
In many patients, Serological procedures that measure the presence of IgM helps to differentiate between the primary and recurrent infections as IgM are rarely found in recurrent infections.
High-affinity IgG antibodies to HSV, if present in the sample, may interfere with the detection of IgM specific antibody. If present along with the antigen-specific IgG may bind to IgG causing false positive IgM results. Both the problems can be eliminated by deactivating the IgG in the sample before testing for IgM.
PRINCIPLES OF THE TESTS
This quick one-step test utilizes a sandwich immunoassay system and the Immunochromatography detection assay, to be performed in one assay. If TORCH antibody is present in the sample in a concentration above the detection level, a labeled antibody-dye complex will be formed. This complex is then captured by the antigen immobilized in the Test Zone (T) of the membrane, producing a visible pink band on the membrane. The color intensity will depend upon the concentration of TORCH antibody in the sample. On the other hand, a color band will always appear in the control zone (C).
Develop buffer solution in a dropper bottle.
PRECAUTIONS FOR USER AND GENERAL SAFETY INSTRUCTIONS
It is used for in-vitro only.
Do not use after the expiry date
Do not use the reagents from different kits
Store the reagents at 4 to 30° C. Do not freeze.
The devices should be kept dry in the re-closeable foil pouch with desiccant. Allow the strips and pouch to equilibrate to room temperature before opening it to avoid any condensation of moisture onto the strips. Always reseal the foil pouch after use.
Avoid smoking, eating or drinking in areas where the testing is conducted.
Does not mouth pipette, the universal precautions should be practiced, PVC gloves and proper protective eyewear and clothing should be worn, wash hands thoroughly afterward.
Specimens and non-acid-containing spills should be wiped thoroughly with 5% sodium hypochlorite.
All waste materials should be properly disinfected before disposing of. Liquid and solid wastes should be autoclaved for at least 1 hour at 121.5° C.
Once the assay has been started, all subsequent steps should be completed without any interruption and within the recommended time limits.
SPECIMEN COLLECTION AND PREPARATION
This test can be performed on either serum or plasma; it is recommended that the fresh samples should be used if possible. If this is not possible, then samples should be stored in a refrigerator at 2 to 8° C before being analyzed. For longer storage the specimens should be frozen at –20°C.
Dispense 5ul of the specimen into the location (between T line region and an end edge of the view window). The T line region must be wetted by the sample.
After 30 seconds, add 2 drops of developing buffer into each sample well.
Read the results: Torch-IgM and Torch -IgG Panel Test: 10 minutes.
INTERPRETATION OF RESULTS
Positive Result: If there is 1 rose-pink band in the control region (C), and 1 rose-pink band in the test region (T), TORCH antibody is present and the specimen is positive.
Negative Result: Absence of a color band in the test region (T) indicates the absence of any detectable TORCH antibody.
Invalid Result: If a color band does not appear in the control region "C". The sample may have been added to the wrong window, or the Test Device may have deteriorated. This specimen should be retested using a new Test Device.
LIMITATIONS OF THE PROCEDURE
Use fresh samples whenever possible, frozen and thawed samples contain particulate that can block the membrane. This slows the flow of reagents and can lead to a high background color, making the interpretation of results difficult.
Assay performance requires strict adherence to the procedure described in the insert sheet. Deviations may lead to aberrant results.
A repeatedly positive result in this test is presumptive evidence of the presence of antibodies in the specimen, but it does not exclude the possibility of exposure to or infection with TORCH.
False positive and negative results might be expected with a test kit. The proportions of false results will depend on the sensitivity and specificity of the test, and on the prevalence TORCH antibody in the population to be screened.
Caution should be used when interpreting the results of this test with pre-diluted samples.